Split case transmission rebuild DIY

[Vinnems]

Late model guy report in. Really cool topic. I always wanted to tear into a transmission. I'm going to get an early model for my next car so maybe I will. Excellent write up, excellent pictures.

[Schwing]

Bringing this one back from the dead, hope you don't mind

Did you replace the synchros at all? Reason I ask is that I have a spare splitcase trans I am thinking about rebuilding since my existing one is leaking bad and coming out of 3rd gear.

As for parts, what I have now is NOS 2nd, 3rd, and 4th gear synchros, a complete split case from a '56, and the very same rebuild kit from 1954 that you show in your pics. I also have the same dial indicator with the high powered magnet for measuring play.

Part of me is tempted to just fill it full of gear oil and use it, but it seems like a lot of work if its no good.

For the rebuild did you use a jig at all? If the gears look healthy, what else would you all recommend replacing?

Really on the fence whether to farm this out or just dive in and see what happens. Any advice would be appreciated. Thanks!
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Shadetree Westy
http://www.thesamba.com/vw/forum/viewtopic.php?t=657279&highlight=

Single Cab - BBXXVII Long Distance Winner
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[Schwing]

[Snort]

It's been a while since I watched my transmission builder work, but my recollection is that there are two sets of clutch teeth. One set is on the gear being driven, the other set is on the operating sleeve which engages each gear in turn. These are on the pinion shaft where all of the main shifting is happening. If the teeth are worn they will not hold the gear in position. With my builder it was a matter of visual inspection as he simply knew what he was looking at. I don't know if there is a way to measure them. You're correct to look at the shift forks as well, but without good clutch teeth it's still going to pop out.

[seefest]

I just built my split case transaxle about a year ago.I had about 1/6 of an inch plus clearance between 3rd shift fork and operating sleeve,could not find a new one so I welded twelve spot welds on the third side of the fork,got my micrometer and high speed grinder out ,grind and mike,gring and mike ,got my twelve thousand clearance .then reset shift fork on the shift rail in the neutral position with the pinch bolt,if the shift fork was fastened with a roll pin on the shift rail you could not do this.The wear on 3rd fork and sleeve seems to be from always downshifting for hills (36 hp) and hamfisted shifting gets a lot of use.My transaxle does not pop out of gear shifts smooth and tight I took the time to get end play and clearance correct.I also used to build transmissions.

[Chalklinedetail]

Well done nlornston, well done
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[Stocknazi]

To the original poster:

How did the transmission turn out? Curious how it operates.
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[nlorntson]

[Stocknazi]

I am rebuilding a bug splitcase to use in a bus.

When a splitcase ring gear is flipped, essentially flipping the diff housing, can the shims be swapped as well? Or would everything need to be re-measured and re-shimmed from scratch.

If so, will someone who has done this please post explain the process; I have a Bently, but can be hard to follow sometimes.
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WANTED:
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"When the people are afraid of the government, that's tyranny. But when the government is afraid of the people, that's liberty."
"Resistance to tyrants is obedience to God."

Thomas Jefferson

[splitjunkie]

as far as the preload on the bearings you should be fine but the mesh of the ring and pinion could possibly be off so you would have to check everything and re-shim to get that back in line. If the gap is wider than original then the ring gear will be noisy. If it is tighter it will either be noisier if it is very slight or it could quickly destroy the ring and pinion if it is too tight.
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Chris

You know, a lot of these scratches will buff right out... Jerry Seinfeld

[Snort]

Wild guess here. Maybe if the ring gear adjustment shims stayed on their original left/right locations relative to the case it would be correct. You would probably still have to check the pinion gear adjustment to fine tune the fit but that seems like a lot easier than starting from scratch with the whole thing.

[Bruce]

[splitjunkie]

I had thought about what snort said and almost posted this morning but I thought better of it. However if the bearings stayed on their original side as well as the shims staying in their original location in relation to the case it might be very close because the center of the pinion is not changing. The backlash would still need to be checked no matter what you do.
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Chris

You know, a lot of these scratches will buff right out... Jerry Seinfeld

[Stocknazi]

Thanks for the imput.

The shims will be swapped along with the diff housing to the other case half.
Bently says in the shim measuring procedure, which is quite extensive, that BOTH sides of the case halves need to be measured; meaning to me that the case halves and bearings will differ to some extent.

I have the backlash gauge and will check things out when I get the diiff re-assembled. I'll post the results here.
_________________
WANTED:
58 Westfalia cabinet knobs (3 needed), roof rack, and (7) privy tent poles (silver painted).

"When the people are afraid of the government, that's tyranny. But when the government is afraid of the people, that's liberty."
"Resistance to tyrants is obedience to God."

Thomas Jefferson

[Stocknazi]

Is there a specific adjustment for the reverse gear shift fork?

The fork has a slot that allows for some adjustment, but it is not mentioned in the Bently.
_________________
WANTED:
58 Westfalia cabinet knobs (3 needed), roof rack, and (7) privy tent poles (silver painted).

"When the people are afraid of the government, that's tyranny. But when the government is afraid of the people, that's liberty."
"Resistance to tyrants is obedience to God."

Thomas Jefferson

[Snort]

I had a timely visit with my local transmission builder so I decided to do some followup and asked him about this. He reports that he has indeed been successful flipping the ring gear on split case transmissions by leaving the differential shims in their respective left and right case half sides.

He provided a simple way to determine success and that is to simply check the lash before you open the case, and again when you are finished re-assembling. If it's the same then no further adjustment required. This assumes that you haven't made any adjustments to the pinion shaft as well as that adjustment assures the pinion gear makes contact along the centerline of the ring gear teeth. It also assumes that you started with a transmission which has previously been set up correctly.

Maybe if you are a transmission builder and your reputation demands perfection this simplified technique would not be acceptable, I understand. But for the hobbyist willing to take a chance I think it's worth a try.

[Stocknazi]

OK, so the shims STAY where they were originally in the case when the diff housing is flipped?

Just want to make sure I have this correct; someone else is telling me that the shims FOLLOW the diff housing as it is flipped and are swapped to the opposite case half they were originally.
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WANTED:
58 Westfalia cabinet knobs (3 needed), roof rack, and (7) privy tent poles (silver painted).

"When the people are afraid of the government, that's tyranny. But when the government is afraid of the people, that's liberty."
"Resistance to tyrants is obedience to God."

Thomas Jefferson

[Stocknazi]

[Snort]

[Stocknazi]