Boxeer + Aircooled Trans + grinding going into 2nd

[charleslabri]

Curious out there if anyone (like me) has a Boxeer conversion on a 2wd Aircooled trans (091) and experiences issues with 2nd gear grinding when shifting into 2nd.
It will happen on 1st very occasionally when going from neutral to 1st
never happens on 3rd, 4th, or R

Only happens when warm, first part of the day before the trans is warmed up it'll shift fine, but without fail once it warms up it'll grind.

Rebuilt the trans
using swepco 202
newly rebuild clevis on the clutch
new slave cyl + a bleed
very in-spec shift linkage

didnt grind with my original 2.0 engine.
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[Zeitgeist 13]

If engine or trans mounts have shifted, you may need to play with the shifter adjustments. My ALH w/DK trans was kind of a chore to get dialed in, but I got it to shift really nice...until the trans grenaded.
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Casey--

'89 Bluestar ALH w/12mm Waldo pump, PP764 and GT2052
'01 Weekender --> full camper
y u rune klassik?

[MarkWard]

I ran a low mileage 091 with a diesel bellhousing bolted to our ALH for a couple cross country trips with stock 82 diesel shifter. Stock 1.6 diesel clutch and flywheel. Zero problems. Replaced for an 091/1 because there were more options.

I recall a thread where someone had a problem with 1 and 2 mated to a similar setup. I recall member Gears was asking for opinions which was unusual since he is one of the Gurus. A lot of internet opinion was not using a DMF setup.

Sorry I don’t have it bookmarked. I also have for sale an original diesel trans Mount for the 091 and all 3 sections of the diesel specific shift rods in the classifieds.

Sorry you’re having problems. My TDI wore out my pro built 091/1 in 60,000 miles. I rebuilt it myself to have better quality control, some upgrades, and a DMF or dual mass flywheel.
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[charleslabri]

Ill have to hunt for that thread.
I’m not using a diesel bell housing, just stock. I shaved my input shaft down.

I’ve adjusted my shift linkage perfectly, so i dont think it’s that. I’ve also have no movement on the trans to engine mating.

So the opinion was NOT to use a dmf?
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[OlisGarage]

DMF seems to be the absolute preferred way to run a tdi with the original transmissions.
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1981 VW Vangagon TDI (in progress)
1984 VW Rabbit Convertible (daily)
2003 VW Jetta Wagon TDI (recovering from a hit and run)

[MarkWard]

Had some time to search.
https://www.thesamba.com/vw/forum/viewtopic.php?t=737404&highlight=tdi

See if this works. While I’ve proven to myself any clutch flywheel setup will get the van down the road, VW was on to something with going to a DMF mated to the TDI. Something needs to absorb the vibration/harmonics. I had similar wear to the post above with a 1.9 TDI. The CR 2.0 is even more power/torque. Plus no telling what tune is on the ECU at this point. I posted pictures of the beating my 4th gear syncro and dogs took over 60,000 miles. Eventually it was partially jamming in 4th.

Our van has tons of power available, but I baby it.
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[charleslabri]

Yeah I’ve been babying the thing. Runs great, but this grinding 90% of the time in 1st and 2nd got me stressing
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[Sodo]

Are you a 'diesel idler'?

Meaning, do you let your engine idle when not 'using' the van;
longer than a gas engine person idles their engine?
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'90 Westy EJ25, 2Peloquins, 3knobs, pressure-oiled GT mainshaft, filtered, cooled gearbox
'87 Tintop w 47k 53k, '12 SmallCar EJ25, cooled filtered gearbox
....KTMs, GasGas, SPOT mtb

[charleslabri]

Like.. do i just sit around in the driveway and let it idle on the weekends for fun?
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[Sodo]

I was wondering if you do extended idle warmups and long cooldowns.

There is a “Diesel idler” feller who was having trouble busting new 2nd gear synchronizers. New rebuild, replaced with new, quickly broke again. 2 quick successive 2nd gear Synchronizer failures and warranties. Non dual-mass flywheel.

There’s a theory afloat is that the clack-clack flings the gear back and forth
and and the helical gear cut may drive the gear into the “new” synchronizer, which sticks too hard to the cone and busts the synchronizer. Pretty sure its a Syncro trans which has a lot more rotational inertia than a 2wd trans. Dunno if Syncro is a factor.

Anyway the theory holds that the diesel was breaking the new 2nd gear Synchronizer (quickly).

GTA warranted it the 3rd time, assembled with a used synchronizer and it hasn’t broken since. Don’t know if modern synchronizers are weaker. Or if the lesser grip of the old synchronizer didn’t grab the cone as hard (if that’s what’s happening). Or both. GTA recommends a GL4 oil which will grip the cones harder.

Nothing concrete about the extended idling part either. Lots of minds grasping for answers in the puzzling issue. Hope you find it.
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'90 Westy EJ25, 2Peloquins, 3knobs, pressure-oiled GT mainshaft, filtered, cooled gearbox
'87 Tintop w 47k 53k, '12 SmallCar EJ25, cooled filtered gearbox
....KTMs, GasGas, SPOT mtb

[charleslabri]

No, i wouldn’t call myself an idler with this. Id say my warm up procedure is pretty standard, giving it a few minutes to get the juices flowing. I don’t have a cool down period.

Interesting about the stickiness of the new syncronizers
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[Nuthin2It]

I had the same problem with my Boxeer conversion. When I got my van back from Greg three years ago, I had to push the clutch all the way to the floor to get it into first gear without crunching. Just slightly lifting my foot would engage the engine. It would often crunch or refuse to go into second gear. Like you, I replaced the master cylinder (the slave cylinder was replaced when the engine was installed). I thoroughly flushed the fluid. When I discovered a bolt missing from the slave cylinder bracket, I knew I had found the problem! I hadn't.

The transmission was rebuilt at a VW transmission shop near Nashville when it was out, but I pulled it again and sent it to Matt Steedle. He found several problems that helped, but it would still sometimes refuse to go into second.

When I first picked up my van, it had tremendous torque but that made it almost impossible to shift smoothly into second. There was a big improvement when Greg Blachon reprogrammed the ECU a couple of years ago. The new program reduced my second gear crunching considerably and made the van drive much smoother. If yours still has the old ECU program, that could be part of the problem.

When I got the transmission back from Matt Steedle, I had a heck of a time trying to get the shifter adjusted. I finally made a bracket so I could accurately fine tune the position of the shifter shaft.

https://www.thesamba.com/vw/forum/viewtopic.php?p=9889646&highlight=#9889646

As ALIKA T3 pointed out in that thread, it shouldn't be that hard to adjust the shifter. But just a 1/2 turn of the adjuster screw on the bracket would change the shifting problem from 1-2 to 3-4 and back again. It took a lot of adjusting and road testing before I got it right. It shouldn't be that sensitive.

My suspicion is that it has something to do with the clutch and/or pressure plate used for the conversion, but that's way above my pay grade. At any rate, now it rarely resists going into second gear.

Another thing I've been considering is replacing the clutch master cylinder, but it drives so well now it's hard to get motivated.
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1985 Westfalia 15 degree EA288 Boxeer

[allmotormatt]

Hi Charles. Sorry to hear about your troubles. I find it really odd that both yourself and Steve are having the same issues. As I have built both gearboxes and you are both experiencing the same issues, I wonder if it is a part selection issue. I used OEM Volkswagen molybdenum coated synchronizers in both of your transaxles. Pretty sure both units have new OEM Volkswagen 1st and 2nd gear idlers as well. Both have new OEM Volkswagen catch keys and springs too. I am willing to tear down unit and document everything to try to figure out what is happening. All my aircooled transaxle builds tend to be the same high dollar components with the "best of the best" components list. I have built plenty of this same combo in Subaru powered 80-83 style vans with no issues. It is just so weird to me that both are in the boxeer coverted vans. I don't know what is going on but I would like to help get this resolved for you. Again my apologies for your troubles and I am here to help. Let me know. Thanks to SODO for sending me this link.

[skills@eurocarsplus]

are you guys shifting too early or winding them out before the shift?

also, how is the input shaft engagement? is it too deep into the engine and dragging slightly?
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[Sodo]

Two good suggestions!

Being a 4-speed does invite over-rev at the shift points.
And if “the tune” causes RPMs to drop quickly, then the synchronizer has to work much harder to match the gear speeds.

And: inspect the tip of the input shaft - see if theres evidence its spinning the mainshaft. That’s not super-difficult to check. But it would affect more gears than 2nd. Wouldn’t that be a blessing if an 😇 Angel 😇 grinder solves it.
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'90 Westy EJ25, 2Peloquins, 3knobs, pressure-oiled GT mainshaft, filtered, cooled gearbox
'87 Tintop w 47k 53k, '12 SmallCar EJ25, cooled filtered gearbox
....KTMs, GasGas, SPOT mtb

[MarkWard]

A few things pop out, but this thread is about more than one vehicle. A clutch engaging just off the floor is one. Something does sound mismatched there. The tune is another interesting detail. In our TDI van, I by nature don’t do a lot of downshifting. There is so much torque, it will climb a flagpole in 4th. When I grab a lower gear, it will be third. I can’t think of a situation downshifting all the gears. When I see a stop light, I usually shift in to neutral and roll up on the light using the brakes if needed. If the light goes green, I grab the correct gear and off I go. My dad taught me brakes are cheaper than clutches and gears.

The input shaft length has come up in other threads with conversions. It is a very important step that can’t be assumed. I have yet to see a Boxeer measurement for the input shaft end relative to the end of the bell housing.

In my sporty days it was always second gear synchro that would wear. Speed shifting used to abuse it.

I drive our van with a light touch. So, my experience would only relate to someone with a similar driving style. It’s nice of Matt S to step up to try and sort this out. In theory, the transmission shouldn’t care what it is bolted to. Its purpose remains unchanged. Torque and harmonics would not be invisible to the trans. Something TDI engines of that displacement would have.

I’m not familiar with the Boxeer conversion to know much. Details like flywheel weight, pressure plate and clutch utilized would be interesting comparison points. The flywheel governs to a point how quickly an engine winds up and winds down.
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[Sodo]

[MarkWard]

In theory, rpm speed wise, the gear stacks are actually spinning quite a bit slower with a TDI vs a gasser. That should actually lessen the job of the synchronizer rings. Hustling I’m up shifting at 3000 rpm. In lower gears, rpm drop is not much between shifts.

As far as I know, the synchronizer ring has only one job. It is to grab the idling gear being selected and get it to rpm quickly to allow a smooth engagement. It’s actually harder in the lower 2 gears because of their mass vs the upper 2 gears.

Plus having zero of these issues using all VW engineered parts, I have to be more suspect of something not playing well together in the above cases. It might also be related to the installation. I have a torque limiter to steady my engine. It’s possible that this conversion is allowing the driveline to move up and down so much, the shift rod is being put in bind with every shift. That is an external force that could be transferred into the shift forks similar to tooling down the highway with your hand riding on the shift knob. Don’t do this.
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[Nuthin2It]

[charleslabri]

This has sparked a more interesting conversation than I expected.

First off, I want to thank you, Matt, for being open to cracking this open and checking out what's going on. I want to do everything I can to ensure that I know exactly what's going on before I attempt that route- but I'll be in touch.

Second, it sounds like I really, really, need to be sure that the shifting mechanism is buttoned up perfect- and it sounds like I may have a need for tighter tolerances than stock. I recently adjusted the shifter to stock, but I'll go back and fiddle with it to see if the 40 years it's been around gives me some play. I do have a full bushing rebuild set if I need to yank it and redo everything (iirc I have to drop the tank to do this, so I am avoiding unless absolutely necessary).

Third- input shaft has come up here a few times so I wanted to show my cut, plus someone had asked to see the distance from bell housing to cut, so I have that info:

1. Method is that I used a level to find the point on the input shaft which matched the bell housing edge:

2. I marked this inner edge with a blue marker:

3. I then measured the total length from the 'edge of the bell housing' mark to the end of this stock 091 input shaft; this is 27.68mm:

4. I then made a mark 10mm from the end of the shaft with a blue marker. This was my cut line. I believe that there were a number of different opinions on how much to cut off, I took 10mm per Greg from Boxeer's recommendation to remove 3/8"(aka 9.52mm):

5. Cut the input shaft 10.10mm all said and done:

6. beveled the edge for insertion:

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My Build Thread:
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