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Transaxle Rebuild Shop
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Beartooth  



Joined: 05 Apr 2022
Posts: 213
Location: Roberts, MT

PostPosted: Tue Apr 30, 2024 2:18 pm    Post subject: Reply with quote

I emailed both EBS and CMS; I didn't hear anything from EBS, but CMS got back to me promptly and seemed pretty helpful. Their response:

"Hi William, thank you for contacting us. Low gear grinds are common and synchros and synchro teeth are available. But 1st/reverse shift sleeve not which certainly ups the difficulty level if needed – and its very likely. Estimate attached for what we can provide. LMK what else is needed after you open and inspect the gearbox."

So I probably have a major missing puzzle piece in the 1st gear shift sleeve; hopefully I don't get stuck digging for the best used one I can find... It looks like I'd be at $1800 for the parts they have - that's including the 2nd/3rd wear items (syncros, shift sleeve, and dog rings). I think I understand the dog rings - those are splined to the gear with teeth on the outer end, and together with the syncro and shift sleeve form the engagement mechanism, correct? It's just that on other transmissions I've messed with, those are either integral or maybe pressed onto the gear.

The good news is, I drove it recently, and I couldn't make 3rd-5th misbehave, so I may not need much outside of first and second gear. And of course that's the hard part (1st gear anyway); pretty frustrating that Porsche couldn't address those NLA parts. I'm going to make an effort though - even if it means throwing a bunch of money at having it repaired (assuming that's even an option). Although it's driveable, it really is a drag to work around in stop-and-go. At least there doesn't seem to be too much more to address; I'll just have to see, but I might get away with just a synchro on 2nd. With care, I can always get 2nd without a problem, but I really have to be careful with the upshift.

Anyway, I hope I'm not thread-jacking too much here! It definitely seems like CMS will be good to work with. It's too bad about the 1st/reverse shift sleeve; I'm guessing the precious few NOS sleeves on someone's shelf either aren't likely to come out, or they'd cost more than the price for a decent used box (not that those are easy to find!).
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chuck21401  



Joined: 20 Feb 2005
Posts: 532
Location: Annapolis, MD

PostPosted: Fri May 10, 2024 10:29 pm    Post subject: Reply with quote

Beartooth wrote:
Low gear grinds are common and synchros and synchro teeth are available. But 1st/reverse shift sleeve not which certainly ups the difficulty level if needed – and its very likely.


Some good news on the horizon. Catellus Engineering doing a run of the 1st/reverse shift sleeve part. Timeline is the next couple of months. The euro G31 that I'm having rebuilt is disassembled and I'll wait until the new part is ready. Will post more details about my rebuild in a different thread. Sorry to thread jack but thought you all might want know.
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1981 Porsche 931 w/S1 engine & g31 transmission. Water-cooled intercooler
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Beartooth  



Joined: 05 Apr 2022
Posts: 213
Location: Roberts, MT

PostPosted: Sat May 11, 2024 3:38 am    Post subject: Reply with quote

That's good news; it jibes with a follow-up email from CMS that mentioned a reproduction may be in the works. No thread-jack at all because it seems the first gear parts are the most needed and the most lacking components for the G31. Based on other posts, I'm betting hundreds of rebuildable G31s have been scrapped because first gear got trashed and the parts couldn't be found, probably at any cost. I'm sure the price will hurt (the 2nd/3rd sleeve was quoted at $467; I'd think a small run of 1st/rev sleeves would be significantly more), but it'll be great if we have the option. The good news is, I might be able to slip in under $1000 for the other parts I need, but of course that's just an optimistic guess until I get it apart. So here's hoping that materializes and we're able to fully repair our 'boxes. I can only imagine how much a solid gearbox and shift linkage will transform my driving experience!
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Cedric  



Joined: 27 Aug 2004
Posts: 2617
Location: Sweden

PostPosted: Sat May 11, 2024 3:59 am    Post subject: Reply with quote

Beartooth wrote:
That's good news; it jibes with a follow-up email from CMS that mentioned a reproduction may be in the works. No thread-jack at all because it seems the first gear parts are the most needed and the most lacking components for the G31. Based on other posts, I'm betting hundreds of rebuildable G31s have been scrapped because first gear got trashed and the parts couldn't be found, probably at any cost. I'm sure the price will hurt (the 2nd/3rd sleeve was quoted at $467; I'd think a small run of 1st/rev sleeves would be significantly more), but it'll be great if we have the option. The good news is, I might be able to slip in under $1000 for the other parts I need, but of course that's just an optimistic guess until I get it apart. So here's hoping that materializes and we're able to fully repair our 'boxes. I can only imagine how much a solid gearbox and shift linkage will transform my driving experience!


I bought parts in 2012, looking back at ideolas old site the first gear dogring costed 230usd, and the syncro 115. Different times:) CMS made them back then, somehow they made it designed to rotate backwards and i had to sendit back to cali for a new one, should be sorted by now
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kevingross  



Joined: 15 Apr 2015
Posts: 35
Location: Stow, MA, USA

PostPosted: Wed May 15, 2024 11:07 pm    Post subject: Reply with quote

Cedric wrote:
I bought parts in 2012, looking back at ideolas old site the first gear dogring costed 230usd, and the syncro 115. Different times:) CMS made them back then, somehow they made it designed to rotate backwards and i had to sendit back to cali for a new one, should be sorted by now


CMS still has the 1st gear dog rings (engagement teeth). They don't rotate backwards: the asymmetry is in the tooth profile. It is opposite the asymmetry Porsche / Getrag introduced at some point in the type 915 transmission 1st gear dog ring. Cheers,
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Catellus Engineering, Inc.
http://www.catellusengineering.com/
catelluseng@gmail.com
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