To be fair, these trannies have lasted a good long time. After a long street life, we're asking them to put max power down while racing.
The bearings don't fail, they get worn and loose and THAT affects the tightness of the ring and pinion relationship. We replace the side carrier bearings and set the gear lash of the R & P with shims. That takes care of some of the slop and is cheaper and quicker than replacing the bearings on the main shaft. Once you get over $400-$500 to redo a tranny, most guys choose to get another tranny. Trannies go for at least $250 out here in SoCal. A verified low mileage tranny can go for $750-$800, if LSD, even more.
I'd at least do the side carrier bearings before you kill the R & P. Especially if you have an LSD unit, which can sustain damage from the metal fragments.
I would still entertain getting new Pinion gear/shafts made, but a group buy of original parts seems simpler. Porsche has 115 R & P units available. We would need at least 10 orders to make a parts warehouse pay attention. Pricing? There's retail, there's wholesale, then there's group buy wholesale.

Thanks Tim!

Joe, Temperature can be a contributing factor. Your solution is very interesting.
I have some interesting observations. I don't have a trans temp guage on my Spec yet, but I do on my Race Turbo S. That trans takes a lot more abuse and should see higher fluid temperatures. I currently have a trans in without a trans oil cooler. Without my front splitter on, I have RARELY seen trans temps over 240F, even at SoCal desert tracks. Normal is around 200-210. However, if I am running the splitter and wing, the airflow under the car is reduced so much that I have had to slow down when it shot above 275F for fear of damage. So, cooling is critical, but on an NA Spec car, I would guess that it is not a big problem as long as you are running a quality trans fluid like Swepco.

Admittedly this car was a big turbo 944 track car so the power and use were different. I was seeing 250-300F with a standard 951 tranny with OEM LSD with 935 clutch plates and upped to an 80/80 split (a stock LSD would be worse as it will be slipping more and creating heat).

The entire tranny looked great except the R&P which was bluing and wearing, even with a very good mesh. The bearings were changed and a new R&P (new OEM not used or aftermarket) installed. After two weekends (same temps) the new R&P was showing bluing again and wear was starting. So we pulled the stock oil drive and cooler and installed a Tilton pump with an aftermarket radiator style cooler. Temps dropped to 200-220F and the bluing did NOT increase. We went the remainder of the season and pulled it again and found the wear had increased as had the bluing but not as bad as before.

We then got a new non cooler side plate and drilled and tapped the tranny case for a spray jet return onto the R&P mesh point, another new R&P went in. We also added 100 HP and bigger slicks and a solid puck clutch disk. We then ran the entire following season and the R&P looks like the day it went in. Seemed pretty clear to me that spot cooling and spot lubrication was the trick.

We used Swepco fluid, carried an extra liter of oil, and ran all the standard track aero goodies (big wing, front spoiler/splitter etc...). The car made 300HP the first year and 400HP the second year. We did go through a half a dozen rear axles in year two though!

ChuckS wrote:

Found this just now. Week end before the race. Wish we could come up with something that would help this. Kinda like making the Accusump legal. Not needed but may help longevity.

Accusumps are legal.

I may try and log trans temps in my enduro if I can get it installed in time for some real data on this. My initial thought is with Tim. It's bearing wear and lash that do most of these in. We just don't make that much power.

Another thought, Tyler just lost a Ring gear at Auto Club. No noise or warning. when the new tire goes on the car the R/P will be put under more pressure because the cars will be hooked up alot more.