411/412 004 four speed trans rebuild (new 12-7 @ 12:51 pm)

[raygreenwood]

Ok.....I am going to "START" this thread. I have no idea how soon I might finish it. Hopefully around Christmas. This really should be one of those postable/downloadable word documents and may morph into that. In the end it WILL be a pictorial with text.

This first part will be wordy. You need to get oriented and understand the issues. Then there will be rather crappy diagrams so you can understand the design issues. Then pictures of the real thing.

I am not at the point in time where I "need" to be working on my 004 transmission (I must finish the front end and get it back on the ground)...but there are several people here asking questions....that I can guarantee you will need help with so I might as well get into it. I have several 004 Transmissions. Three complete (one with issues) and a big box of parts from several destroyed and stripped...and one disassembled with issues.

I have been through maybe eight of them completely....and a couple of them more than once.

Lets get this started:

There are some serious issues facing those who want to "refurbish" a 004 four speed. I say "refurbish" instead of rebuild.....because the parts just do not exist to do any more than swap in used spares and change some (but not all) bearings and make sure the adjustment is correct.

The Problems:

1. Replacement gaskets: this is not a huge problem but it is a problem. You can easily cut your own and I will post the patterns. The issue is finding the correct thickness and hardness of gasket paper.

Unlike some other transmissions where you an opt to leave them out and just use adhesive or RTV...it causes issues here because the main gear sets and their relative position to the counter shaft are located off the case center section and there is not a readily useful way to make up for a missing .003" to .005" of spacing in this transmission.
The main shaft IS the pinion shaft...you cant just spacer issues away. If you had new gear sets to put in....you would not have to worry but the gears you have....have been run-in to each other for a specific fit and lash. You cannot change that mesh without wear issues.
This is why I have been experimenting with gasket materials in the past two months. Its not a hard thing...but important.

2. Replacement bearings: The differential side bearings and races...in good quality...are available. (same bearings as 091). The pinion shaft bearings...were unique. They may "seem" to be readily available...until you realize that they are a different letter code.

The difference in the two bearings is that the readily available bearing letter code...has a .0015" SMALLER ID and a slightly smaller chamfer. You WILL NOT be able to install it without destroying the shaft no matter what amount of chilling/heating you use. The spare shaft I have was damaged this way. The wrong bearing letter suffix was sold to me (because even at that time...early 90's...its all there was)....and I was too young and stupid to realize the difference.
And....on the pinion gear end, the bearing backs up to a shim on top of the very fragile pinion gear. One slip in the press and any pounding with a hammer and the gear set will be destroyed. On the opposite end, the bearing must slip over at least four sets of splines.

Two things I am exploring right now:
A. I can have the pinion end machined and/or polished to remove .0015" and install the new bearing no problem. I "could" polish .0015" off the tips of the splines on the shaft to get the other end on....but I would not like to risk gear fit/chatter. I have a damaged shaft I can test these things on.

B. I could have the inner bores of the bearings honed .0015". Some say this cant be done. I dont believe that. I can mask the bearing areas by filling them with medium temperature wax and have a shop do this with a multi-puck expanding diamond hone.

Above all....DO NOT REUSE BEARINGS in a 004. No matter how good they look or what their original quality/brand was...they have a jillion miles on them. Yes...save them for spares if you can remove them.
I can find a 002 or a 091 or even a 003 transmission any time I want one. You cannot easily get a 004...and there were very few made (relative to other types) and very few shipped to the US. Its time to replace what bearings you have and preserve maximum life

Needle bearings: The large mainshaft needle bearings can probably be found as individual needles to drop into the nylon needle cages....but I have NEVER found them to be needed.

Also there is so much information and specification needed to replace loose needle bearings ....what crown (if any) what end radius, how much float tolerance, what material, engineering load, rotational speed etc....and we have none of that information. Unless the transmission has been run out of oil or got water or dirt contamination, I have never even found measurable wear in these bearings. Clean them well...keep them oriented and re-install them.

The smaller steel caged needle sets on the main shaft and the 3rd speed bush can all be replaced if necessary. I have never found significant wear here either.

The counter shaft needle bearings can be gotten easily...but are very problematic. They are under-designed for load and poorly oiled. When we get to the design features section we will address both issues. There are several options.

3. Adjustments and special tools:
Although the differential looks similar in type to 003 and similar in adjuster layout to 091....they are nothing alike. None of the special VW tools used for adjusting differential gear fit and bearing pre-load exist and they are different tools. This is not to say we cannot make simple precision tools that use dial indicators and micrometers to set the tolerances we need.

For instance...when we get to the point of adjusting differential side bearing pre-load i will also direct you to SGKent's excellent 091 thread and will also enlist input from Pablo and other gear gurus as we move forward.

I have set preload on a 004 several times. The real problem is that if the pinion shaft position is disturbed or if the replacement pinion end bearing changes the pinion gear mesh depth (with reference to the differential ring gear centerline).....unlike most gear sets....most 004 ring and pinion I have found seem to have no markings at all on them at all.

So.....it means that the first and most important thing we need to do once we remove the tailcone, the center case section covering the 1st through 4th gears, the counter shaft assembly and mainshaft gear sets and the pressed on centering ring......and get the transmission basically down to the differential case and bare pinion/mainshaft assembling...still mounted in the differential....is to measure a few things. These are:

A. Distance from a marked point on the pinion gear to a marked position on the differential housing (pinion centerline). This needs to be within .001" or better.
B. Distance from a marked point on the differential housing (ring gear side) to a marked point on the case (not 100% necessary but it aids set-up. Again...within .001" or better
C. Gear lash as measured at the pinion gear.
D. Positions of the pinion shaft adjuster ring and the outer adjusting rings for the differential side bearing. These set not only the ring gear backlash but the bearing pre-load.

If you loosen the pinion bearing preload or unbolt the five 17mm nuts inside of the bell housing BEFORE you do these measurements...it will be exceedingly difficult to set the correct pinion depth on this transmission. It is not something that you can simply adjust from the outside like the bearing pre-load or gear lash.
It is set by a combination of one shim between the final drive case and pinion/mainshaft carrier and a shim between the pinion gear and bearing or alternately a shim between the pinion gear and pinion shaft face. Those original shims....were calculated for THIS gear set...based upon final drive CASE DIMENSIONS.

There are other issues as well. There are several Design issues that created wear points that lead to wearable replacement items...that no longer exist. They can be gotten around without too much issue....but you MUST catch them before they get past a certain point or they WILL do damage you cannot get around. I will get into these deeper as we go. They are:

1. Poor oiling and high wear on the counter shaft and its needle bearings. This will cause the destruction of 100% of the 004 trans eventually if not corrected.

2. Wear issues with the spider gears in the differential. This is a combination of very high ratio spider gears with long teeth, and wear to the thrust washers inside caused partly by normal wear and partly by long-term wear at the outer spacers between the differential output shaft faces and the CV flange hub. Because of the high spider gear ratio...which makes for quick turning...as the thrust washers begin to wear, the teeth change geometry and start spalling. Once that begins the end is certain...if not exactly near. When a tooth chips or cracks, 100% of the time it will instantly destroy the differential as the oil drain port in the differential housing dumps directly into the pinion gear mesh area. If you catch it before spalling starts its a very easy fix with some shims.

The spider gears are unique to type 4. There are others that could be put in....but its considerable machine work. The differential housing and ring gear fit area and bolt pattern are also a unique size. Nothing else will fit inside of the differential case except possibly a 003....again with considerable machine work.

3. The counter gear shaft is all one piece. All four gears are included on one shaft. You cannot swap out gear sets unless they are complete and have been run into each other. The gear set spacing is slaved to the case. If you replace a gear set...get the case it was in. Its not insurmountable but its considerable work.

4. The main shaft ball bearing is unique to this trans. I have been looking for new ones for three decades. But, if yours is in good shape there is a spacer and end-float issue that must be fixed. Simple but must be done

As I noted, there are some small similarities to several other ACVW transmissions out there...small similarities.

1. Like the 003 automatic....the 004 has a full hypoid ring and pinion arrangement. It also has one adjusting ring for pinion bearing pre-load. The difference is that the pinion mesh depth is set by a shim. This makes things more difficult later. Also like the 003, there is a locking adjustment ring on each differential output shaft that are used to set bearing pre-load and gear lash.
2. The differential output adjuster rings noted above...are identical to those found in the 091 bus...as well as the same differential side bearings but that is the only similarity to the 002/091.

More to come![/b]
Ray

[rkurz]

Finally checking in on this rebuild post. I have mine torn down to the differential. The countershaft and gear cluster are with a machinist. He mic'ed the counter shaft and said it was still in-round and with little variation along the shaft, and although it showed some discoloration, there was not wear that he thought worth replacing. But he/we are looking into the dimensions of the shaft as spec'ed in the Without Guesswork booklet, which he is borrowing now.

Using Torlon to replace the needle bearings, he is planning on lightly engraving a helical groove into the outer bearing surface to help it pump oil out. And then enlarging the oil hole and scooping it in the proper direction to aid intake.
Ray, would it be helpful to add another one or two intake holes?
+Rich K

[raygreenwood]

That shaft is shot. The original shaft is case hardened. Its not a matter at this point of whether the internal 18mm shaft is still round and smooth with only discoloring...its that its not micron polished smooth like needle bearings require.

That discoloring is the case hardening ruined. You caught it in plenty of time.

The problem is that even with careful case hardening...the shaft was designed to be softer than the needle bearings so the needle bearing does not destroy itself. Both the needle bearing and the shaft were designed as wear parts for easy replacement.

The shaft will be JUST FINE...for using torlon. It does not need to have a hardened shaft surface.....just a relatively smooth one. i would polish it with 1500 grit....and clean it and reuse it.

No...I would not add any extra oil holes. The reason there is only one is that its in the only place you can put one without risking weakening the shaft.

With the torlon bushings...just widening that hole will be more than plenty. In fact....making the hole wider is not a real priority....but adding a shallow scoop to the side that faces the direction it turns will will help to cram oil in there.

You are really lucky. About another 5-7k miles...and the needle bearing would have been damaged. The maddening thing is that it will not even make any noise until its REALLY damaged...and even then is a very low howl or hum only in 4th gear...highest rpm and smallest gear on the shaft. When that hum starts...its because there has been wear to the 4th gear. It eventually shatters.

The Torlon bushings make this a permanent fix. Ray

[thesatanicmechanic]

Ray, i apologize if it's covered previously either here or on STF, but what is the efficacy of installing a 914 in the 411. The R&P is flippable. Been covered already?

[raygreenwood]

[Chris Walden]

Forgive me if it's deemed I don't what the hell I'm talking about. So a 901 is a 901 no matter if it's mid engined 914 or rear engined 911 (or 912E)? With 914 trans. I've always read of early "rear" shift or the later "side" shift (though it rather more looks like a "bottom" shift to me). This the hocky stick you're talking about Ray? Would the rear shift be similar to the shifting mechanism on the 004?
Chris

[raygreenwood]

The differences that cause problems are.....as you note...where the hockey stick or sbift rod exits the tail cone of the transmission.

There is no room between the chassis and rear cross member for a tail rod or hockey stick that exits in the center of the tail cone or top of the tail cone....to either pass over the rear croasmember or lift the transmission and higher.
It must either be a shiftrod mounted near the bottom of the trans....or no shiftrod at all like a side shifter.

A side shift would be fine. Either way a 911 version of the 901 would be preferable...because then you dont have to flip the R&P and adjust everything...which is not just a cinch. In reality to make sure it lives....you shoul do all new ring and pinion bearings all differential adjustments.

There are no other ACVW transmissions that will bolt into a vw 411 or 412...without major....major fabrication.

In the 911 and 912...its a rear engjned car. In the 914 its mid engine. The diff is flipped. Ray

[thesatanicmechanic]

Went searching for the 914 901s I had in the garage this weekend. Found both a tail & side shifter (along with a '72 915 I had forgotten about). Unfortunately, there is no handy type 4 for me to have a look at. Have type 1,2, & 3 at my fingertips, but no type 4. It has been some time since I've even seen one, much less looked underneath one. I'd really like to examine the area you're describing Ray. Hell, I even found a 901/02 with AFMSX gearing.

I should clean my garage.

[Chris Walden]

911/912 Porches are torsion bar semi trailing arm (or full trailing arm?) rear suspension? 914's are coil sprung (semi trailing) as are type 4's.

Chris

[raygreenwood]

Update: finally really getting started. Today will just be a before and after starting picture set.

I pulled one of my three complete assembled 004 transmissions out last night to clean it up enough to open up and start refurbishment.

In my collection I have the transmission in the car (I have to check my logbooks to see what the status and condition of it was because its been so long).

I have another transmission complete that from the case sealant I can tell I have been inside of it but cannot remember what its status/condition is.

I have one totally disassembled in a box that has had some minor problems and mods. In the long run if its good enough it will be assembled as a spare.

The one I am working on in these pictures I acquired in September of 2011 from a gentleman and his wife who are total VW nuts in Maryland. It came complete with upper cross member, mounting bushings and starter attached.

All I have done is open the cover plate to inspect the counter shaft gear for spalling and wear. It was in excellent condition.

This one is an FC series transmission. The next major series were from May of 1972- FA series for sedans only and Fe series for wagons only

An interesting side note: There were three sets of final drive gears in the 004.

FC: uses 11:43....11 teeth on the pinion and 43 on the ring for a 3.909:1 ratio
Sedan and wagon
FA: uses 11:41....11 teeth on the pinion and 41 on the ring for a 3.727:1 ratio
Sedan only
FE: uses 10:39....10 teeth on the pinion and 39 on the ring for a 3.90:1 ratio
Wagon only.
I can only assume that having less teeth on the FE version allowed it to be stronger than the 3.91:1 in the FC version. I do know that the outside/end of helix teeth on the pinion gear were very thin and delicate. Any debris or foreign object entering the differential housing....or slip/mishap pressing on bearings can destroy the pinion gear easily by chipping that last tooth.

This will be a general walk around of the late model 004 transmission just for starters....to familiarize any of those who have not really been acquainted with them .
This is an FC series which was used starting from August of 1970 in both Sedan and wagon models. It has (according to the "Without Guesswork" book.....an 11:43 final drive gear ratio (3.91:1). We will see if that holds true when I get inside.

Apologies: sorry these pictures are a little rough. I changed my lighting and work location in the garage and am still working it out. The blue tinge is from the light contamination of the fluorescent lights interfering with my 6500 kelvin daylight spots. The camera cannot deal with two different light sources.

WARNING: I have been inside and refurbed numerous of these transmissions to various degrees. PLEASE DO NOT....follow along working on your own step by step.
A. This may take a while
B. There are numerous parts you MUST NOT loosen or remove....except in the proper sequence. I will get to what NOT to do in an upcoming installment. The issue is that the special tools and shop manuals for simple resetting of various tolerances in the final drive and one or two in the main gear transfer section......DO NOT EXIST. These are not hard to get around....but you must measure certain tolerances upon disassembly....in order so that you can know baseline relationships. I will explain all of that moving forward.

A general view of the whole monster.

Drivers side bell housing. Make note of the 44mm clutch slave, the brownish urethane bushing rings at the top corner of the bell housing attached to each end of the slip in tube bushings.

You will also notice the plastic flange locking plate behind the stub axle and if you look close it has booth screws and curved stiffening plates still attached. These are all must have parts.

The aft section of the left side has five notable points of interest. From left to right:
1. You can barley make it out, upper left attached to the stud at 11:00 is a steel strap with a hole in it (a plate actually) bent to the right. This part...if memory serves ( I will verify) holds the harness for the reverse light switch.

2. the round plug is the two wire reverse light switch. Work hard not to destroy this. It is unique to the car/transmission. I will be working to replicate them or re-purpose another type.

3. The long oval plate with the two phillips screws covers three horizontal bores and seals with a gasket. Underneath are three bullet shaped plungers and three springs. These are the detents for the shift rods.

4. The smaller/lower plate with two screws and a dome is the reverse idler gear adjustment eccentric plunger.
WARNING...DO NOT remove this cap. There is a careful way to remove it that preserves the adjustment position that I will outline later. It entails lifting the cap slightly and holding the plunger/eccentric in position so it doe not turn...with an O-ring pick so you can mark its position. Otherwise....the plunger usually either turns or pulls out. Its not that adjusting the reverse position is hard at all....but this is one more item that is telltale to what has been done and what has not.

I usually measure the reverse idler gap to mainshaft gearing FIRST...before marking and removing the eccentric plunger.

5. The large hex bolt underneath the reverse idler eccentric is a shoulder bolt bolt with a sealing washer. There is one on each side of the transmission. It holds the ends of the reverse gear shifting rod cross shaft. Wait to remove it until you can remove the cover plate so you can retrieve the cross shaft and idler dog.

NOTE:....this picture ilustrates one of my worries. I always hope that the transmission I get are "undisturbed" (unless its by a dealer).....mainly because there is so little information...that if someone with no experience on these gets inside...a lot of damage can be done. This case shows blue RTV strings on the outside. Hopefully it was just an external "reseal". We will find out.

This is the tail cone end. Items of interest:

1. Upper left "u" shaped bracket. Dont bend this one up or lose it. It is the hold down bracket for the clutch slave fluid supply line. From the factory...there was a hard line all the way to this bracket. It used the same flange and spring clip the front and rear soft brake lines use to clip to the struts and rear trailing arms.

It was kind of a backward design. A 3 foot long high pressure brake hose bolts into the female connector of the hard line at this bracket. Since the only purpose of the hose was to give some flexible movement to the hose....and the hardline was there because there is supposed to be virtually no transmission movement...it worked....but becomes a major pain when shifting the transmission around when doing work with engine out and transmission in.

I replaced my rear metal fluid line from the mid joint aft...with a shorter line. I used a vanagon short fluid hose from the forward side of this bracket to the steel line and use a 3 foot rigid line to the slave from the bracket aft. More on this later.

2. The large round cap. This cap covers the special locknut and clip that covers the splined mainshaft where it connects to the pressed on hub that transfers power from clutch disc to the mainshaft.

This is really cool design. It means that if you WANT to remove the engine while leaving the transmission in the car.....look under the back seat...remove the cover plate. then remove the plug pictured. Remove the "C" clip and 15mm nut....and the whole drive shaft pulls out under the back seat disengaging from the clutch.

3. The stud on either side of the tail cone shaft is where the tail cone bushing bolts on.

4. The nut at 3:00 o'clock position is where the ground strap bolts on.

5. Right behind the bracket, next to the nut at the 12 0'clock position is the pressure/condensation/overflow vent...just a small hole.

Right/Passenger side overall view. The points of interest from left to right are:

1. Starter location on bell housing

2. The series and serial number at the 7:00 position under the stub axle

3. The drain plug at 6:00 position under the stub axle

4. The reverse cross shaft bearing/shoulder bolt to the right of the stub axle and lower edge of picture.

5. The oil filler plug center near the tail.

Back upper view showing clutch slave, bushings and the upper pivot point for the clutch fork.

At first glance...this looks complete....the retaining and positioning plate for the clutch, its snap ring holding it in...and the fork are all there.

However...in reality this is what I expected to find. This part....is actually a defective design. It will eventually DESTROY the clutch fork, clutch cover and throwout bearing.

I will detail this and the repair for it later. But in general...note the rounded D-shaped edge to the upper left of the disc...opposite the kind of forked shape section to the right . Note that the section to the left looks a little distorted..and slightly darker rust in color. There is a piece of that plate missing here.

It was a small flat piece of metal that is missing on almost all of these cars north of 70k miles. It was tack welded on and used a a strengthener to the pivot point of the clutch fork. With grit and no lube and a very weak part, the clutch fork pivot wears it away cracking away the bearing point plate. The metal then stretches and tears on the plate...allowing the upper fork pivot point to move rearward.
This eventually brings the clutch fork into contact with the fingers on the pressure plate..destroying both parts in just a little less than 100 miles.

There is also another part missing from almost every transmission I have seen. The dust cover for this whole pivot point assembly. It is #45 in the diagram and is part of the reason why this part wears out.

Inside the Bell housing.
The clutch fork is still hanging in there with the TO bearing. The dome or knob in the center of the clutch fork is the contact point from the clutch slave pushrod.
The five 15mm nuts hold the mainshaft/pinion shaft carrier housing and the TO snout or guide tube is part of this.

DO NOT loosen the five nuts...yet. There is a special shim between this carrier and the case. Their position and torque set the position of the pinion shaft to ring gear, the pinion shaft bearing preload and the mainshaft position relative to the counter shaft gearing....all in one shot...and this is some of what you need to measure FIRST.

Front and back side view of the clutch TO fork.

General bottom side view of the trans case.

Detail of interest on the bottom side of the tailcone....the neutral safety switch. I have never found one of these hooked up or working. I generally install a flanged plug as its a common leak point.

Important detail....there is one long screw that holds the cover plate on. It has green machinist dye coloring it. It is totally different than all the other screws and is the shaft locking screw for the reverse idler gear shaft. DO NOT lose it.

NOTE: the best way to unlock and remove all the cover plate screws is with a hand impact driver and the proper bit. DO NOT SKIP THIS. If you do you will generally strip all or some of the screws. They will usually be very tight and slightly gummed up.

Some general views after the first round of cleaning. This wrecked the solvent in my parts washer tank .
It is still filthy in the bell housing. A combination of corrosion and clutch dust. I will wire wheel the rest of the crap away and one more solvent wash before I open it up. More to come!
Ray

[ClassicCamper]

Looks great and very informative! Looking forward to the next post.

[raygreenwood]

Update @ 5:35pm 12-2-2015:

So I am wire wheeling the case to get the corrosion and gunk off. Then one last external solvent wash. I am trying to minimize contamination. Everything will be disassembled, stripped, clean solvent washed...but its best to start being clean sooner.

So this transmission...leaks nowhere. Except...it looks like the RTV I found was just external to the gasket edges to stop seeping (so far)....but it has had one annoying leak...putting about 2oz a night onto the work bench.

And.....I found the source ....it was also one of the expected issues. The tail cone is cracked.

This probably happened one of two ways...either the trans got dropped at some point (not while in my possession)....or...and this is more likely as I have broken two this way....long before I learned....the transmission was left to hang on the tail cone bushing while the engine was out.

This is a weak point in this transmission. It WILL happen to all of you who work on 004 transmissions. All it really takes is for the two nuts on the tail cone bushing plate to be loose. The steel bushing plate and tube fits flush on the tail cone casting. An old or shot bushing...or poor alignment of the drivetrain....or letting the trans weight hang on the bushing....when the two nuts are loose...and it will snap the tail housing.

Not a big deal. There is a fairly painless fix for this. You remove the hockey stick...,,crack off the remains of the tail casting....file or mill the housing flush...then strip the rubber bushing from the tail cone bushing plate...weld a disc into the end....drill a centered hole and install a bushing. A better way is to insert a solid piece of bar stock into the tube on the rear bushing plate and then drill a hole and install a bronze bushing and new tail con seal.

Then simply cut a gasket and RTV both faces...and bolt onto the tail housing...and then re-install the hockey stick. I have one like this done eons ago. I will post pictures in the future when I get there. Its on the transmission in the car right now.

Sorry for the cheesy diagram but it gives the gist of what to do to repair this type of issue. Ray

[Lahti411]

Lots of great information, Ray! I ha e two orthree spare gearboxes + the two that are installed on my cars. I hope i have the courage to start working on one of those boxes after i have read this topic through couple of times
_________________
My cars: 1972 VW 411 Variant; 1973 VW 412 4d sedan

[raygreenwood]

[raygreenwood]

Yesterdays update 12-3-2015:

Sorry for the slow progress. I am at a bit of an impasse for a couple of days. The outside is now clean enough. My parts washer solvent was already dirty...about 1.5 years old. Now it is shot. I cant go any further without changing it out and cleaning the unit. Maybe by the weekend.

I have to proceed this way because building this in my cramped, frozen garage on a covered workbench ....I will be removing parts in a staged tear down...cleaning each one in clean parts washer solvent, then a final clean dip in MEK and alcohol mixture, blow dry and then place in order on the other covered workbench...then cover with plastic at night. If I dont work in this order I will A. be re-cleaning parts constantly and B. getting stinking gear oil everywhere.

I have been here before

So....after wire wheeling with die grinder and dremel, The cover plate was pulled for a quick glimpse inside. Remaining gear oil...about a half pint was drained. The transmission was placed level (plate side up) and filled with about 1.5 gallons of standard Xylene based paint thinner and a quart of MEK to give it some kick.

At this point I realized I made a mistake I should have told everyone to look out for. The reason why the words PLATE SIDE UP...meaning the trans was upside down are highlighted...is because I forgot to remove the hydraulic line bracket....and plug the vent hole! ....so solvent begins pouring out all over the workbench.

So I immediately tipped it vertical and placed shaft end down on two blocks of wood. After plugging the vent hole....I place the trans horizontal and grasping both output stubs I rotated the gear train about 50-75 revolutions. Worked through all four gears and reverse.

You could feel the mechanism loosening up and the oil breaking down.

I drained the spent solvent and oil into the parts washer to be sent to the recycler.
After draining the oil earlier and removing the cover plate later these are the things I found just looking around.

1. Glitter in the drained oil. The normal super fine brass from synchros. Not abnormal.
2. Silver metal flakes in te thick oil on the cover plate. These....I expected. It is most probably from the counter shaft bores (in the best case...because we will be refurbing all of that).....and possibly from wear in the spider gears (worst case but ok as long as no spalling has happened yet).

Note: on this last point....I suspect some spider gear thrust washer wear as the action of the differential became noticeably stiffer once the solvent washed away much of the oil.


3. The counter gear has a good amount of axial play between its thrust washers. I have not measured yet to see whether its out of spec.....but the thrust washers rarely wear enough to see noticeable axial play....unless the needle bearings are wearing and they have been putting metal out onto the faces of the the thrust washers.....causing faster wear. Again....this was expected and fixable.

4. The counter gear has no apparent radial play...which is good.

More to come!

On the bench after the vent hole was plugged!

Removing cover plate screws. This one happens to be the "green" screw.

Just to show the difference between the green screw that locks the reverse idler gear shaft as compared to the others screws.

A view of the inside. The counter shaft is the main group of gears running left to right...all one piece. The bar or rod running top to bottom on the left is the reverse idler gear actuator pivot shaft.

This poor picture is just to show the reverse light switch and its "off" detent location on the shaft...lower left of the picture.
An important note .....look just to the right of the shift rod that activates the reverse light switch...and you will barely see a small square head, dog point bolt. You will need to spend $6-8 to buy a 1/4" drive, 12 point socket.

I will post the part # tomorrow. Its easy to get and buy in many places. It needs to be able reach down in a very tight area to remove this screw. the screw holds the 1/2 shift fork onto the shaft. If you do not remove this bolt you cannot remove the shift rods and therefore cannot remove the housing.

It cannot be done via a wrench.

This pictures shows the reverse idler shaft below and inline to the green bolt so you can wee what its holding. Once the plate is off...I replace the green bolt to hold the shaft.


Ray

[raygreenwood]

Update for 12-7-2015:[/color][/size]

Again I will apologize for the photo quality on this set. These are not my normal photo quality. Since I am working on the bench next to the parts washer while I am "mucking" out the basic transmission...I am not able to use most of my best lighting, my tripod or my good macro lenses. A lot of one hand work at the moment trying to keep my camera equipment clean.

When we get to assembly and adjusting...I promise things will be much better.

At this point the outside is clean enough, the cover plate is off and I start disassembly of the gear change section. Before we go much further, a word about tools:

Tools and books you should have for this:

The very cool thing about the 004 gearbox is that it requires very few special tools to disassemble. Measurement is a different story but that is later.

1. You need a small diameter magnetic pickup. Less than .250" helps. I use a Craftsman screw starter.

2. Thin flat blade screwdrivers, regular flat blade screwdrivers and a set of strong o-ring picks

3. A 10mm bolt

4. A rubber mallet

5. Several containers to hold parts in.

6. A small piece of board or plastic for holding bolts in order

7. A scribe or dremel tool with burr for marking metal.

8. a small container to fit under the bell housing to catch any oil after you remove the drive shaft.

9. Several 8mm X 1.25 thin jamb nuts

10. A camera...hopefully one better than your phone

11. feeler gauges

12. A 5/16" or 8mm, triple square 12 point internal, 1/4" drive socket for removing the shift rail bolts. THIS IS A MUST HAVE OR YOU WILL NOT BE ABLE TO DISASSEMBLE THE TRANSMISSION.
Blackhawk tools makes a 5/16" socket part #W-1210 or equivalent. It is the same socket that fits the square dog point bolt on the shifter linkage. Check it for fit before you begin.
http://www.amazon.com/Blackhawk-By-Proto-GW-1210-16-Inch/dp/B007I9SPBW

13. BOOKS THAT ARE HELPFUL. In order of importance:

Without Guesswork types 1, 2, 3, 4 1971-1974 or equivalent
Haynes for 411/412 1968-1974 green or 1968-1973 blue book
InterEurope workshop manual # 158 for 411/412 1968 and on

Of less importance but has some useful info:
Chiltons Volkswagon 1970-81
Clymer Volkswagon 411 and 412 1968-1974


You need to take things apart in order to make this easy and repeatable.

WARNINGS!
DO NOT remove ANYTHING from the differential section.

Do not loosen anything on the differential section.

Do not loosen any of the five 15mm nuts inside the bell housing

As you remove any needle bearing sets, set them down oriented so you know which direction they faced on each gear (more on this later).

DO NOT remove any of the Phillips screws and small sheet meal covers from the drivers side of the transmission until the appropriate time...so the adjustment can be verified.

Here we go:

Start with the transmission upside down (plate side up). Block it up level and securely. Cover plate off.

Remove the round screw in plug from the tail cone. This is a 7/8" socket. It is 22mm.

What you are looking at is the special locking nut and E-clip that locked the splined drive shaft to the mainshaft ball bearing hub.

The simplest way to lock the drive shaft is with an old clutch and pair of Vise-grip pliers (mole-wrench to you UK types )

15mm socket and very little effort takes this loose

DO NOT LOSE THIS NUT! As you can see its a split lock nut. It deforms under torque to lock securely.

With the lock nut out of the way you can see the special Round E-clip...and this IS a special E-clip. DO NOT LOSE IT!.
In a pinch on the road...if you have to remove just the engine...you can take this nut, the E-clip and the drive shaft out...through the port under the back seat.
In order to do that you have to dislodge the E-clip with an o-ring pick.
Since we are pulling the drive shaft out through the bell housing end..just leave it in place for the moment in the hub.

Push the drive shaft toward the bell housing. It should take very little pressure.

Remove the clutch disc and pull the drive shaft all the way out through the bell housing.

Here is the shaft.

The mainshaft hub end. It looks excellent.

The clutch end is not so good. The seal area to the left can be polished and has no rust in critical areas. I can remove the rust from the splines. As long as it still fits tight in the clutch splines with no appreciable axial play...it will be fine.

The pilot bearing area I can polish but it will likely never be usable with a needle bearing again. That is not a huge worry. If I have to use this shaft I will put a solid bronze or torlon bushing in the flywheel.

On that last note....the driveshafts from any 004 trans can be swapped in about a minute. There are no special tolerances or adjustments.

Also, this shaft may look spindly for power transmission...but I can assure you they are very hard and very strong. I cut one years ago with a hacksaw. It was extremely hard and dense. It was very similar to cutting an induction hardened shock absorber shaft.

Remove the nuts from the tail shift housing.

Remove the neutral safety switch if you have one.

Then you can separate the tail shift housing. You will need to pull the middle shift rod rod outward slightly and jiggle the shift hockey stick to disengage the tail assembly. This will be frustrating. DO NOT PRY. Take your time.

IMPORTANT NOTE:

The very best way to remove...and especially re-install....the tail shift housing is to remove the studs. This is what the jamb nuts in the tool list are for.

The method outlined in the Haynes manual for re-installing the tail shift housing is horrible. That method WILL insure that at least one time ...if not twice...you re-install the tail shift housing with its gasket and sealant... if you choose to use any....goes on perfectly...but then you are incapable of selecting ANY gears.
You will then have to remove the tail housing and start over. The Haynes method requires that you position the shift rods in and out just perfectly...to allow mating the sliders up...just perfectly.
Its a very risky method. It takes so much time and screwing around...it almost always results in a leaking gasket even if you get the shifter rods aligned perfectly.

The easier method is to remove the studs...put them in and order location. There are three types of stud. Just to be anal about it I measure the amount each stud protrudes outside of the tail shift assembly.

Putting the wrong stud in the wrong location or screwing it back into the case too far with not enough threads sticking out to hold brackets, lock washers and nut...is also a frustrating do-over situation.

I did not have jamb nuts on hand so I removed the tail housing the hard way. I first measured their outer protrusion and then removed, the tail housing and then removed the studs and stored them in order

The inside of the tail shifter housing. Looks similar to most other types

This confirms that at one time the tailcone at least...was removed and resealed...with too much "goop".

The sealant peeled away easily.

next step is removing the reverse gear actuator cross shaft bearing bolts which are the large 24mm hex bolts in this picture

You can use the appropriate sized socket ...24mm...or use an 8mm Allen key in the inside.

The bearing bolt and sealing ring.

IMPORTANT NOTE: There is a flat sealing ring on each one of these bearing bolts. DO not destroy or lose it. It is reusable. You will also find that there is virtually "0" torque on these parts. The torque does NOT lock these bolts in position. The bolts simply seal against the washer and are locked in place by a special "detent" in the gasket and metal cover plate.
You simply tighten them so that the washer makes sealing contact and the point of the hex is at 12:00 position. The cover plate does the mechanical locking.

Jiggle the shaft and remove it complete.

On the workbench.

Notice that the reverse gear selector pivot on the right and end comes out...DO NOT LOSE IT! It frequently falls down in the case while you are removing the cross shaft. This is one of the places the magnetic pickup comes in handy.

This transfer pivot arm is what the cross shaft was attached to on one end. This pivot is on an adjustable eccentric shaft. DO NOT REMOVE IT RIGHT NOW.

Take your camera and photograph which way the bends/angles go on this part. It will fit either way but will only work one way. Ask me how I know!

The slot on the gear in the foreground (the reverse idler gear) is where the pivoting spade fits in. When you move the reverse shift rod, the transfer pivot moves the reverse slider gear and engages and connects the reverse gear on the counter shaft.

A blurry view of the back-up light switch and the shift rail locking screw. You can remove the back-up light switch now Leave the shift rail screw alone for the moment.

Important Note!: before removing the counter shaft, take your feeler gauges and check the play between the countershaft end faces and the bronze thrust shim. You only need to check one end. Push the counter gear to one end and insert your feeler gauge. The smaller end is the easiest to check this on.

The listed tolerance is .002" to .014". A tight feeler gauge drag is what you are looking for....just short of a no-go. This one is at .011"

Insert the 10mm bolt in the threaded hole iin thee counter shaft end

Screw it in about five turns.

Pull outward. It should take very little force. It typically takes less than it should. We will be doing a modification to insure that this shaft never rotates. If it begins to rotate it will eventually destroy the case.

From this picture you can see the dull colored area where the needle bearing has been. While this is still serviceable...with the needle bearing that is on it now, it has enough wear marking to insure that no new needle bearing can ever be put on this shaft. The needles themselves (we will show later) already have lines on them. The needle bearings can also never be reversed on this shaft or they will destroy themselves in short order.

While it is currently serviceable....it is very, very, very poor economy to NOT fix this problem and replace the needles NOW. This issue will be the destroyer of almost all type 004 transmissions. It has been the issue of all of the ones that have ever broken. When that happens it is NOT repairable.

We will be either replacing the shaft...or installing Torlon bushings that do not require perfect shaft tolerances and polish.

The shaft removed. the locating step diameter is 15mm.

Lift the countershaft out. DO NOT let the bearings fall out of either end. Do not mix up the bearings or turn them around.

End view showing needle bearings. You can see that there are no oil relief grooves in these gear faces to allow oil to flow through the bearings and out of the gear. We will be adding them.

The bronze thrust washers showing some of the wear that has left us with .011" end thrust.

The back of each thrust washer has VW part #'s and thickness in millimeters. I think there were at least 10 different sizes available. We will measure each one to find out what it lost to restore the tolerances.

The gear case with the countershaft, thrust washers and reverse crosshaft removed.

Some notes:

These are not yet important but you should start noticing small important details.

The rings the pick is pointing to on the gear sliders are important. they tell which way the slider MUST go. We will examine this in detail later but is just another reason why you cannot simply disassemble these transmission indiscriminately.

Note the special snap ring the pick is pointing to. This will have to be removed before removing the mainshaft ball bearing and hub. The case can be removed with the snap ring in place but its easier to remove the snap ring with case in place and being held down by the weight of the transmission.

Shift rail removal:

Sorry for the blurry picture. You need a 1/4" drive, 12 point socket of either 5/16" or 8mm size.

NOTE: REMOVE THE RAILS/RODS STARTING WITH THE REVERSE ROD AND WORKING YOUR WAY DOWN. This is important so you can remove the detent balls between each rod as you go. You can start with any rod but it makes it more difficult because the detent balls fall out of place and lock the other rods in place.

Start by removing the two Phillips screws on the larger/onger sheet metal cover.

Remove the cover and gasket to expose three springs.

Remove the springs.

Pull out the three detent plungers with a pick

CAUTION: Notice the mark I made on this cap to index it to the case. DO THIS...with a dremel or a file BEFORE YOU LOOSEN OR REMOVE THE SCREWS.

Once the screws are removed. DO NOT REMOVE THIS CAP!!!!!!

With the cap screws loosened and turned almost all the way out....push the shaft outward from the inside with a pick or screwdriver.

You want it to protrude like this so that you can remove the shaft with the outer cap STILL ON.

Wipe it with clean solvent, dry it and make a mark with a sharpy next to the index mark.

This is why you need to mark the shaft. The cap is splined to hold the shaft in position. The shaft itself is an eccentric shaft. This sets the reverse idler gear adjustment. Its not hard to adjust but can only be properly done to be noise free....when the trans is in the car. You will have to set it by factory specs, then usually drain the transmission, pull the pan and readjust to make sure "real" clearance is correct.
Its usually simpler to "assume" the adjustment is already correct...and it usually is. So...preserving that adjustment is a time saver.

Remove the transfer lever now.

You can now pull out the reverse shift rod...the top one in this picture with the snap ring on it.

Now remove the 8mm, square drive, dog point screw holding the fork onto the shift rod in the middle.

Remove the large fork from the middle rod.

Put your 1/4" diameter magnetic pickup down this hole and pull out the detent ball. You can now remove the shift rod.

You can go ahead and remove the screw from the other fork. Just dont remove the rod yet.

Put the magnetic pickup down the hole again and remove the second detent ball.

as you start removing the last shift rod and pulling it out of its fork...you will notice that it uncovers a 4-5mm detent and hole in the rod. If you are quick you can catch that detent plunger with your magnet. If not, just be sure to fish it out of the case.

Last shift rod out of the case...note the detent plunger on the end of the magnet.

Remove the fork now.

All three shift rods out with all detent balls and plungers.

Just so you understand what plungers, detent balls and springs exist inside of the shift rod system so you are sure to get them all. This is the cross section of the detent system with the outside of the case on the left.

If you have not already done so...it is time to remove the snap ring. Notice the small gray flat blade screwdriver pointing to the upper snap ring ledge on the extreme left of the picture. Start here to remove the snap ring it is easier on the higher side.

I use a small screwdriver and an O-ring pick. Let it drop into the case and fish it out later.

Loosen and remove all case nuts and washers.

Use the rubber mallet in this area to strike upward until the case separates.

Case separation.

Usually the mainshaft ball bearing and synchro hug stay stuck in the case. This leaves the two needle bearings exposed. Do not drop them, mix them or flip them. the bearing and hub will pop out wit ha light tap from the outside.

NOTE: If the main shaft ball bearing assembly came out easily you will usually find that the bore has been worn inward much like the problem BUS 091 transmission has. We will be checking for and fixing this problem as well later.

The complete mainshaft gear stack and differential.

Interesting. This is the first gear set in a 004 that I have ever found with gear markings. this notes that it is a Gleason gear set, 11/43 which means its final drive ratio is 3.909:1 (3.91:1).

I also found these markings. They "may" be from the factory but I have never seen any like that. Its most probable that this gearbox was opened by a competent transmission shop for new bearings and that these are the differential position marks.
I will inquire with people who know more than I do.

More to come. Ray

[lhd_service]

I found this thread some days ago and look forward how things are developing. I have to add something to the last post:

The numbers on the ring are factory marks. These are comparatively good readable, they look sometimes like scratches. The 3-digit number (331) is the mating number with the pinion since these parts have to be kept together. Same number should have to be found on the pinion shaft somewhere. The 2-digit number (38) is the position in 1/100mm from the zero-position of the pinion. So this pinion should be 0,38 mm off the zero position plus/minus 0,04mm (for the 004 trans).

Early VW ring-and-pinion sets had this marks allways. In early 70s Volkswagen changed production and r&p which where used in production had no marks any longer. This marks should afterwards only be used in r&p-sets sold as spare parts. But I found this marks also on r&p sets used in produstion for some transmissions.

You can't be sure, that transmission was opened just by finding this marks inside, they also might have been on original r&p since this transmission left the factory.

Joerg

[raygreenwood]

[lhd_service]

I certainly agree: If you have the marks, it's a better basis for assembling the transmission then only have the position measured before disassembly. I would measure the position before disassembly anyway (even with marks) just for control.

But if you don't have marks you should measure before disassembly and try to get this position with +/- 0.04mm. So my thought is: First assembly tried to get the position with this tolerance too. But I don't know how near they went to the desired position. So in worst case tolerances might add up with every disassembly / reassembly (0.08mm for first, 0.12mm for second and so on). Most transmissions never get disassembled anyway but one should give it a thought.

Sorry for metric numbers, I'm from Europe and like to do european parts the european way.

Joerg

[raygreenwood]