924Board.org

[-nick]

A genuine question - Sequential, what in the G31 box failed? I'm curious what the weak link in the box is?

I've always heard the rumor repeated that the G31 box is the strongest out of the production line. The Carrera GT box has some different internals according to PowerHausII. I'm sure the GTS/R boxes have had quite a lot of work done to them.

I'm not convinced that just because Porsche went to the Audi box means it's stronger. Cost is certainly a factor in those decisions. I wouldn't base the argument of strength solely upon that.

There are countless stories of the 944na Audi 5-speed ring&pinion practically exploding. That's with 150 flywheel hp and often in plain jane street cars. I don't recall hearing any 931 Audi 'box owners reporting R&P failures. Of course, the turbo torque curve is much gentler on trans than equivalent na power.

ps- I've also heard a rumor that 944S2 boxes are tougher than the 951 units (trans cooler units excluded).

nick

[sequential]

Nick,
Porsche choosed the audi box ( my opinion raceboy ) because off the shelf it was better and stronger than the stock 931 /cgt box. Now could the standard box be made stronger or better than the audi box, yes ! this is true for anything but from a cost point of view it did not make any sense.
From what i have seen the 924 gtr had a much modified gearbox as they failed consistently in testing in 1980 and was upgraded for 24 hr stints...

Now if anyone wants to modify a 931 box with powerhause gears etc,
well go ahead you will have a good box , but here in the states with 951 boxes available at 700 a pop it does not make economic sense to maintain a 931 box. i have never had a box explode it's differential( 951)
that does not mean it never happened , if you have a bad box , it is just a bad box, i have never had one fail on me like that and years ago i ran my 4 spd , with boost until you cold hear the gear whine before you saw the car an it never failed or at least i got rid of it before it did , i just cannot see someone running a box beyond where i had gone with that one ...

also the cgt box has to be rebuilt pretty often when used consistently on the track , this is where the 951 box is huggable.
_________________
928 gts prototype
baby blue engine block
steam in 1,2,3,4 sometimes
cold star issues while on stands
112 whp with new 4 valve head and MIS 2

[john h]

[sequential]

Hello John ,
My comments where based on cars making more than 300 bhp, i have customers with 951 boxes who have not have to rebuild boxes after 3 yrs of racing they all had quaife Diff and oil coolers installed in the beginning , no problems to date except for CV' joints.
_________________
928 gts prototype
baby blue engine block
steam in 1,2,3,4 sometimes
cold star issues while on stands
112 whp with new 4 valve head and MIS 2

[john h]

[pez]

expensive is right...
US$2350 for parts & that is not including the dog teeth

I will look to recoup lost cash by removing my drinking habit for the next few months
_________________
CGT #330 - & she's all mine....