Trans re-gear - Anyone done it?

[bornrich]

Now I talked to my tech, Bob at RMG, about some transmission work as I was considering the install of a LSD. He said
that I would get better result as far as performance with a trans rebuild and gearing changes(lower) to 2nd, 3rd and 4th( leaving 1st and 5th alone). He said this will better match the power band of the engine. While I may get some benefit from the LSD I would also have to get a new adjustable rear bar to compensate for the under steer the LSD would induce.
Sounds like a good idea to me as I probably haven't gotten to be fast enough at the track to take advantage of the LSD anyway.
I think I may do this in the spring. More money into the car
but what the hell it just a toy anyway!

Has anyone done this to their transmission? Feedback?

TIA

[coloradoporsche]

A couple of things to consider....

I talked to a tranny rebuilder in Boulder, CO this week and he mentioned that he just rebuilt a transmission with modified gearing....at a total cost of $10,000! I guess when you start changing gears, the parts cost starts to go way up.

And, modifying the gearing may cause you to move up a class if you are ever planning to race the car.

But if those things are not of a concern, you may reap some performance benefit. Other will have to chime in as to how beneficial.

[Bill Verburg]

1^st and 2^nd aren't very useful on most tracks.

The usual route is to redo 3, 4 and 5 so that they are lower and closer together.

the sacrifice, of course, is a freeway gear

other considerations are the tires to be used

an early 40% lsd is very desireable for track use as are adjustable sways.

there are even more desireable setups but the cost is the usual ultimate determinant

you can spend a lot of money on these sorts of thing

[bornrich]

Thanks for the quick feedback. My tech figures the trany will run ~$3k for the regear and rebuild (of course depending on parts needing replacment). The idea of keeping 5th the same is the hwy gear. I have never used it at the track (not yet at least).
I'm probably not going to race the car (never say never) just a weekend/occational trackday toy, so class rules don't apply.
I using the 16" fuchs 7x9 - 205/245 tires.

[Bill Verburg]

I certainly understand the need for a highway gear. Mine is geared for 200mph which is perfect for 80 - 90 on a freeway

here is Jacks $10k regeared trans, used w/ a 964 engine and rather tall tires.




There are other ways to look at it, I like this perspetive for a US 3.2 w stock vs short stack of gears

Thrust being the actual push in the tush that you feel