davidk72008

I am currently parting out my RPM built transmission and differential in favor of a stock T56 and differential for my 02 Z06. My thoughts behind this is to offset the cost of buying better brake pads, a decent square setup (instead of my current drag radials), Bilsteins or JOC shocks instead of my current QA1 drag shocks, and different wheels for doing autoX and track days. I'm only making 400whp, so I don't think the stock trans or rearend will have any problems. I just think the money is better spent on tires, brakes, and suspension since I'll be doing more tracking that drag racing with this car. I don't ever see too many people talking about upgrading the trans and rear much...

In your opinion, am I making an okay choice in running a stock trans/rear on a slightly modded C5Z? Spending a lot of extra money on track wheels/tires and brakes are out of the question right now, so I figured selling this stuff would be a good way to offset that cost since I won't be doing any hard launches with this car.

Scooter70

You will eventually need a rebuild the stock T56 when the synchros go. The 3-4 synchro will go even on a car that isn't used on the track. At that point, you will want to upgrade a few other things in the trans (billet keys, etc) so if you already have a trans with those things done, I'd keep it.

RichieRichZ06

A stock trans will work for auto x and road course, but the key to prolonging them is maintenance and using good synthetic fluids. Our C6Z track car (~590 rwhp) has 34k miles on it and at least are track miles. I finally rebuilt the transmission this off season due to it being taken out for other upgrades. The internals still looked good, but we upgraded to billet keys, carbon blockers and other HD parts. I see street cars come in that require synchros after less mileage than that, but many of them are still on the factory fill fluid.

klodkrawler05

IMO for road course use you probably don't need the built diff as like you said you won't be doing hard launches, maintaining the fluid in the stock diff should be fine for a good long while.

With regard to the transmission as others have said, eventually on a stock one the 3-4 synchro will need work, and while you're in there you will want to do the other longevity items like billet keys and the carbon blockers that make the trans more reliable and consistent for 20 minute HPDE sessions. My car survived 36k miles of 60/40 road course/street driving with consistent fluid flushes and being careful when shifting.

I've gotta think the cost of buying a stock $1000-1200 transmission hoping it has no flaws when you receive it (which if it does will entirely offset the project), selling yours for somewhere around the going $2500 rate and pocketing that $1300 for other upgrades is not really worth keeping the transmission you have in the car and not having to worry about when it will need to be rebuilt.

SunnydayDILYSI

If your current tranny and diff are used, you likely won't get enough of a cash bump out of the swap to make it worth while. That said, how much are you looking to get out of it cash wise? I have a stock C5Z trans and diff that I'm selling in the DFW area. I have an ST2 race car and could use the upgrade on my spare racing parts to the RPM gear.

davidk72008

Well I posted this after I posted the parts up for sale, and now I have a guy that is trading me his stock 40k mile trans and diff. He assures me that there are NO issues whatsoever with them, so I think they'll be ok for a while. I'm making enough off the swap to buy me some Forgeline F14 and almost enough to purchase a brand new set of tires all around. Once I sell my current wheels and tires I'll be able to get some Carbotech pads to go with them. I think it'll be a good deal for me. Hopefully I won't run into any major problems with it...thanks for your advice anyways guys. Sorry I asked a little late...

Gordy M

If you are going to refresh your trans, autocross and running Hoosier's, etc. then also include a hardened output shaft.