Rebuilding 091 DM transmission (early diesel)

[epowell]

[epowell]

[gears]

Waldi and I have both been doing waterboxer transaxles (091/1 & 094) almost exclusively for years, and these models do not require a jig. The earlier 091 DOES require a jig to do the job properly .. the risk being that an improperly positioned fork will cause the trans to pop out of gear or prematurely wear out the fork. I know. I've done MANY 113, 002, and 091s in a past life.

While the previous position of the fork can be measured on the shift rail (some have done this and gotten away with it), a jig is required to do the job correctly. This assures not only proper forward-aft position, but also the proper rotation on the rail.

With 4 transaxles available to you, you obviously have a spare housing. So, if you're confident that you're going ahead with the job, why not do it correctly? It would actually be easier.

While I can't explain exactly how to make your jig this moment, I will be able to photograph one for you in early December. As they say, a photo (or two) is worth 1,000 words.
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aka Pablo, Geary
9.36 @ 146 in '86 Hot & Sticky
'90 Syncro Westy SVX
'87 Syncro GL 2.5
https://guardtransaxle.com

[AndyBees]

ePowell,

Allow me to clarify.

I "mark" the position of the forks on the shifting rods...... at least two marks for reference. It is a very good idea to take pics for reference... pics that clearly show the marks and their relationship to the forks on the rods.

Yes, I have two Bentley Manuals, 80-84 and 80-91, that have complete info to disassemble and re-assemble the various Vanagon trannies.

No PayPal on the Pinion Nut socket ......... got to come up with those references, as, my socket is not for sale, loan only! The cash (PayPal) would be useless to me when I need the socket.

The suggestion to pressure wash is so that you will have a clean tranny to work with ....... paint it, sand blast, etc., is your decision! Pressure washing is all that's necessary in my opinion.

Here are the only pics of my tranny uploaded to the Samba Photo Gallery..

Below, empty case pushed against a Diesel Bell Housing and no carrier on the other end.

Below, is the carrier without the shifter nose. This is where the metal plate goes that I mentioned in the other post. I have photos somewhere...

........................ . . . .... . . . . . . .

EDIT: This info may already be posted somewhere... excuse me if it is. Anyway, this may be helpful to you and those following.

Below is a list of Vanagon Transmission codes with gear ratios, etc. (my tranny is the last one on the list)

Below, is a reference as to where you can find your Tranny code and build date.

Hope this is helpful..
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'84 Vanagon Tin-top, ALH TDI. 1989 Tin-top
1983 Air-cool, 225k miles, 180k miles mine. Seven trips to Alaska from 1986 thru 2003.

[Waldi]

[epowell]

[epowell]

[gears]

Yes, exactly. Both VW and translation have changed nomenclature over the years (gear carrier / intermediate housing).

You can see from that photo exactly where you would cut a large section of the main case away to simulate a jig. The larger the window, the more light gets in to really see what's going on. So a window on the opposite side is a good idea, too.

I'd highly recommend that you obtain a Bentley. That's the first "tool" you should consider. Anyone working on their own car needs a factory level manual for reference. The Bentley has errors in it, but we've already cataloged most of them.
_________________
aka Pablo, Geary
9.36 @ 146 in '86 Hot & Sticky
'90 Syncro Westy SVX
'87 Syncro GL 2.5
https://guardtransaxle.com

[epowell]

[AndyBees]

I have practically every Bentley manual from 2005 back on VWs, including those pictured.... and a few on BMWs.
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'84 Vanagon Tin-top, ALH TDI. 1989 Tin-top
1983 Air-cool, 225k miles, 180k miles mine. Seven trips to Alaska from 1986 thru 2003.

[epowell]

As well as the 4 trannys I have, I also have the innards of a slaughtered DK 091 excluding the RP + housing. Right now I am slowly slowly working thru this pile of parts - along with the diagnostic section of the LONG CD --- and attempting to learn more about what is and what is not acceptable.

Here are 15 photos - can anyone find anything unacceptable in these?

I myself could not yet find anything obviously unacceptable --- some of the bearing surfaces seems slightly worn, but they still seem nice and smooth.

The gears I have looked at don't show any defects.

The tiny little gear teeth on 1st gear don't look perfect - but still the ware does not seem extravagant - there still seems to be some definition in the tooth flanks.... but perhaps this amount of ware in not acceptable?

I show one synchro here which to me seems pretty healthy, but I guess in any case all synchros should be replaced?

Finally, I show 1st gear needle bearing... which to my eyes also looks OK, but I'm also assuming that all needle bearings should also be replaced?

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www.edwardpowell.com

[gears]

I'm gone for the rest of the day, but a couple comments:

It is quite difficult to "OK" parts based on photos.

New operating sleeves (sliders) are among the parts that should be replaced in every rebuild (along with bearings etc).

Some of these early 091 idler gears are silly cheap right now from Weddle.

The gear below would be rejected because of the wear on the engagement teeth. This will likely begin popping out of gear pretty soon.

_________________
aka Pablo, Geary
9.36 @ 146 in '86 Hot & Sticky
'90 Syncro Westy SVX
'87 Syncro GL 2.5
https://guardtransaxle.com

[epowell]

[MarkWard]

When you go to select a gear, the shift fork moves the slider/operating sleeve towards the gear you intend to select. That movement forces the brass syncro ring onto the cone of the gear you intend to select. That stops the gear from rotating so that the slider/operating sleeve can move up over the brass syncro ring and on to the little teeth Gears pointed out. At that point the gear is selected.

You will rarely see the outer teeth of a gear wear unless they sheared off, normally the wear is on the engagement teeth, the syncro ring, and the slider operating sleeve.

To practice, there would be nothing wrong with doing your first rebuild with old parts just to gain familiarity, but for a rebuild, you'd want to change all the wear items.

Also, gears are in pairs one gear is fixed and the partner is on a needle bearing free to float until selected. Reverse is a little different in that it adds a 3 rd gear to a pair which in physics changes the final rotation direction.
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☮️

[epowell]

[MarkWard]

Maybe "slows" would be a better description.

Yes, all gears sets are always meshed. Just not "engaged". If you somehow engaged two gear sets at the same time, the transmission would be "frozen". Nothing would turn. Shifting/selecting a gear is actually "locking" a set. When you miss a shift, the grinding noise is the slider slipping past the engagement teeth on the floating gear.

It is always best to replace gears in sets even though the wear is on the floating gear engagement teeth. The reason is over time, they wear into each other. Introducing a non matched gear could make some noise that may not be desirable.

In my racing gear box. There are no synchronizer rings. There are large lugs on the face of the gear and matching lugs on the slider. You actually force the shift. I also shift with no clutch. These are sometime referred as dog boxes or crash boxes. Lots of fun to race, but would be terrible in city traffic. The other main difference is the gear teeth are straight cut not helical like stock gears. They make a lot of noise. It is almost deafening.

edit: the slider has several other pieces. The hub it slides on is splined to the shaft. Look at the inside of the slider and you can see the splines it moves on. There are also 3 metal lugs around the center of the slider, that are spring loaded and are forced against the brass syncro ring when the slider is moved forward. These are what fix the brass syncro ring to the slider assembly and keep it from spinning.

Here is an assembled slider assembly.

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☮️

[epowell]

[DanHoug]

this is the 3/4 slider hub that was cracked in my 091/1... a pre-emptive rebuild at 225K miles on a perfectly functioning transaxle. the replacement slider has rounded holes vs the square cut and hence less focal stress. it's an absolute must to replace the old style with the new.

-dan

[gears]

Edward, that is a 1st/2nd slider hub, which doesn't have a full compliment of teeth like the 3rd/4th hub has.

Dan, that is a cracked 091/1 slider hub. The 091 hubs don't readily crack like the 091/1 (094) hubs. That doesn't mean they've never cracked or that they can't wear out .. just that cracking isn't a common problem with those.
_________________
aka Pablo, Geary
9.36 @ 146 in '86 Hot & Sticky
'90 Syncro Westy SVX
'87 Syncro GL 2.5
https://guardtransaxle.com

[Waldi]

You dont need to replace the needle bearing from 1st and 2nd gear if the inner and outer surface is ok.
3rd needle bearing is 3€, 4the metal cage needle bearing is 12€.

This surface lookis not good on the pic

https://www.thesamba.com/vw/gallery/pix/1713601.jpg

Also this one from 4th gear with length stripes. If they go away in a drill bench with water sand paper the shaft can be used. Hard to say from here.

https://www.thesamba.com/vw/gallery/pix/1713590.jpg

The idler gear showed by Gears is a risk. If didnt drive this box before without out jumping gear, i would not install it.

To check the messing synchron rings you need to messure the distance between the synchronring and the gear.
Everything over 1mm is good. 0,5mm is minimum.

You can buy all parts from me.

Edit:
You can ask for the maual in the Austrian forum.
I have the pdf somewhere, but cant find in atm.