butzip

My 912, which in the past 15 yrs has only really seen track and autox duty, is starting to make a little noise. It shifts perfectly, no synchro issues, grinding nothing!! I have always been mindful of bushings, oil changes and 'proper' technique. But seriously this tranny has close to 350k miles on it and I suspect the ring and pinion is starting to wear to the point of being noisey.

I'm thinking of replacing bearings and R & P only, possible ltd slip? If it ain't broke don't fix it is my thinking on the gears and synchros......

I guess a call or trip to Gary Fairbanks is in order

Peter Zimmermann

4-speed or 5-speed? With that many miles (your trans has already had bearings replaced - typical life expectancy is between 100K and 120K miles) you will probably find problems with the intermediate plate. After market manufacturers make/sell beefed up units, so that might be worth considering. Synchros can be measured/inspected so that remaining life expectancy can be evaluated. Tough call, because today 901 transmission repairs are no longer "repairs," they're almost always "restorations."

butzip

Hey Pete,

It's a five speed and believe it or not aside from seals & oil, this tranny has never been touched. I know because it's a one owner (us) car. I will most likey just do a full ground up when I install the 3.0

Peter Zimmermann

Wow! Then it must be an aluminum housing, and your noise is most likely the double-ball main shaft bearing at the intermediate plate.

GTgears

That's an impressive number of miles on that gearbox. Please post pictures when you get it apart. This sort of thing is Porsche archeology. There's very few uncracked 901's out there anymore and probably not a single virgin one with this many miles on it!!!

butzip

Will do.... I have a line on a good used one that I will swap in while I take my existing one apart. Honestly, trannys have been a bit of a mystery to me. Having never really been 'in' one and all. I'm kind of excited to explore new territory...

Erik@GBox

Let me know if you need a 901 pinion bearing for your rebuild. These can be somewhat expensive from some sources, but we have several of them here and I would be happy to help.

Good luck with your build.

Erik Johnson
GBox Performance Transaxles
(303) 440-8899 work
(303) 895-4828 cell
www.gboxweb.com

butzip

Hi all, I haven't been in here for a long time. 2011 brought some big (good) changes i.e. new job and relocation to Houston (The Woodlands) Texas. We're closing on a new house next week and I have been lucky enough to custom build my garage a bit which nice since I had to sell my 900sqft garage in CT. yeah it had a house attached to it too but that wasn't so important!

That said, I still haven't pulled my trans and reading the old thread below, I neglected to mention a couple of symptoms that may be important to folks like Pete, Erik and GTgears. As follows:

When the trans is 'cold' for the first mile or so, it is perfectly quiet, presumably because the oil is still viscous and doing a good job of masking wear. After a mile or so, the noise grows. it's in every gear, so I assume it's a bearing or the R&P, something that's always turning and (here's the kicker) only when I'm OFF the gas does the noise appear. Under the lightest of acceleration, it's fine, no noise. Let off, noise..... throttle no noise..... you get the idea. Perhaps this behavior will give the experts a further clue of the likely problem.

All info is greatly appreciated as usual!

Thanks and Brgds, Peter