For starters the Porsche clubs require you use a Porsche gearbox but when they break they are not totally lost. For a while Porsche was selling new GTS 5th gears for under $500. No longer the case

 

5th gear is different for every box unfortunately.

 

Mark
Bummer.....but at least you caught it BEFORE it broke on the track!!!

 

G28/57, 3002338. I'll miss it, allright....

 

OEM parts that keep breaking, I have a feeling Todd would just make his own

I think it's time you drop in an automatic with a flappy paddle conversion (assuming that's legal). Our local speed shop just completed a similar conversion on a 60's mustang, it works brilliantly.

 

You would think but I'm taking it anyway. When it lets go the only thing I'll loose is track time. Tomorrow I'll look to see what used boxes I have that I can swap if necessary. Fontana is less than 1 hour from my shop so lots of possibilities including taking that slower rear engine car.

 

\
Robby Gordon's offroad shop is next door and they went to automatics because
of the same issue. I guess I'm just making too much torque

 

So the case is the only thing you'll recogonize?

 

Get'er Fixed!!!!

Cal Speedway needs the monster out there!

mk

 

Mark
But Fontana would use 5th gear quite a bit right? Isn't that where you regularly get over 170mph?

I'd just put some JB weld in there.....that or chicken wire + duct tape

 

The problem is, EVERY gear uses 5th gear!

Its the main coupling for the transmission to the torque tube. If you think about it, that little torque tube and gear shaft takes 450ft-lbs. Its like someone jumping on 2 foot long wrench over and over again. Its amazing that little shaft lasts as long as it does. I guess my 400 ft-lbs is not that much lower, but it must be near the limit.

I broke one on the dyno, but i had a huge vibration due to the ebrake being partially on. There must be some kind of instantaneous force that is over its capability on the race track. maybe the 7000 rpm to the next shift clutch dump is more instantaneous force than it can regularly take. Its a lot less KE with a 6400rpm clutch dump to the next gear.

Maybe cryo'ing the 5th gear set might help.

Bad news! Sorry to hear!

BUT, you need to get the beast out there with the new motor!

mk

 

Are you able to have anything done to the gear which may prevent it from grenading? Say drilling a hole and having it filled by a TIG welder?

 

ha ha thats funny you have the case number already

Oh is that from the build sheet that Chuck sent you? Is that info on there?

 

Ryan-

Yes it is. and the engine # too.

 

oh very cool, i will have to get me a GTS to get a nice printout like that