Hercules Rockefeller

So I'm thinking that my transmission on my track oriented Z06 is pretty much dead... which already has me thinking about how I want to upgrade on the rebuild. I'm tired of having a useless 6th gear, and I'm not a big fan of the large gap from 4th to 5th. So I'm thinking of going to the ZR1 transmission (with the improved carbon synchros), and coupling it to 3.73 diff gear. If the numbers I'm looking at are correct, this will give me redline top speeds in 1st through 6th (on Hoosier 345/35 tires) as follows:

1st: 65 MPH
2nd: 93 MPH
3rd: 124 MPH
4th: 150 MPH
5th: 185 MPH
6th: 223 MPH

Seems more in line with what I'd want in a 2800 lb track car with approx. 600 RWHP. Taller low gears, shorter high gears, everything closer together to keep the engine in the power band (always above 5.5k RPM). Thoughts? I'm thinking 2nd through 5th would now be ideal on most road courses, and I'd always have 6th for a high speed 1+ mile run (if I ever decide to give that a try).

AtomicZ

I just switched 5th and 6th gear - now .82 & .70. Kept Z06 3:42 rear. Much better. now a very useable 5th gear for the tracks that you see those kinds of speed. Setup also ran 193.xx at TX Mile with roughly 560rwhp in a full weight street car.

mcar00

Have you already found a 3.73 rear gear that will handle 600 rwhp?

Hercules Rockefeller

No... I hadn't thought about that. Is there a particular issue finding strong 3.73 gears?

Hercules Rockefeller

BTW, I'm not sure if my tranny really is dead, but based on the noises and symptoms I was getting after coming off the track, I don't think it's going to be good. The transmission sounded like it had straight cut gears in it, sort of a whirring/whining noise that increased with engine RPM, even when the car was in neutral. So long as the clutch was out, in any gear or neutral, I was getting a whine noise. I even let the clutch out in neutral once and the drag on the engine from the trans stalled the engine. Also I got a "high transmission temp" warning on the DIC which I've never seen before, and the shifting was EXTREMELY notchy/grinding as if the sychros were barely working. Something ain't right!

AU N EGL

May want to look at Rockland Standard Gear http://www.rsgear.com/

http://www.rsgear.com/products/trans...tranzilla.aspx

mcar00

I'm not aware of one that would work but I haven't looked for about a year. I think the 3.73 diff. only comes in a base C6 application.

Han Solo

You're gonna hafta take it apart to find the culprit. Could be as simple as driveshaft bearings. I've seen a bad pilot bearing cause enough drag to make one shift poorly.

AU N EGL

Rockland standard has race ready 3.73s and others

http://www.rsgear.com/products/trans...rmance/c5.aspx

dvandentop

hercules has a c6z track car

Pumba

Your calculations are correct, except for 1st gear. Your speed at 7,000 rpms would be 68 mph, not 65 mph.

You might want to take a look at either a 3.90 or 4.10 final drive ratio. Here are the speed in each gear with your Hoosier 345/35R18 tire and a 7,000 rpm shift point:

-------- 3.90 - 4.10

1st ----- 65 ----- 62
2nd----- 89 ----- 85
3rd---- 118 ---- 113
4th---- 143 ---- 136
5th---- 177 ---- 168
6th---- 214 ---- 203

You would be wise to talk to Jeremy at RPM Transmissions - www.rpmtransmissions.com in Anderson, Indiana. They can upgrade a standard ZR1 box, and build you a C6 Base Car rear axle assembly that would be reliable for your road race application. As others have questioned, the only available gear ratio for either the C6 Z06 or ZR1 Corvette differential is the GETRAG 3.42:1 gear set.


Good luck with your decision.
-

Poor-sha

The tranny in my 08Z went last year and I put in an RPM built ZR1 tranny and a Quaife diff. I couldn't be happier other than the fact that the taller first gear is even harder to get going with the stage 3 cam.

95jersey

I find this somewhat surprising, I have done many many events at many tracks and can't remember the last time I got past 4th gear and that was doing 155+ down pretty long straits

Hercules Rockefeller

Yep... just found out my transmission is hosed, so it looks like I will be doing the same thing. Just got off the phone with RPM and I decided to go with their ZR1 tranny, I like the idea of taller low gears and shorter high gears so all in all it should be a big step forward. I might actually be able to use 1st now on hot R-comps (although I doubt it). 2nd will definitely be more useful. Besides, my '08 trans never really worked properly anyway, from the day it was new I had trouble with the 1-2 shift grind from those 1st gen synchos in the TR6060. I'm looking forward to those carbon synchos and closer gears.

Part of me wanted to go nuts and get this, but after sleeping on it I decided maybe it was just too much:

http://www.lgmotorsports.com/product...oducts_id=2179

Hercules Rockefeller

Fastest speed I've hit at a track was 161, and that was near redline in 4th in the stock Z06 trans.

95jersey

That sounds about right, I think I hit 160 in 4th once at Pocono on the long back strait, and that is probably one of the biggest tracks outside of Daytona where you can go that fast.

Hercules Rockefeller

I (and several others) break the 160 MPH barrier on the front straight at the California Speedway, aka ACS, "roval" configuration. Sounds like you've been in a similar situation... what was it you found surprising?

95jersey

Surprising, because I have never needed to go to 5th gear, let alone 6the at the track. If I hit 160 on rare occasions, I immediately went into a braking zone and did not need to grab another gear. I am just surprised you have run on tracks where you run out of gear on the C6Z.

I know up and down the east coast I can't find a track where I have top speed higher than 160mph (maybe Daytona), but that is also referring to a relative stock car, so I can't comment on your particular situation.

1ED1

I can get to 164 by traqmate at VIR in 4th bumping the rev limiter.

Lasco001

I have the ZR1 with 4.1
If you still have a really good motor, which then makes good runs into the high speeds a lot of fun.

Here I have two video of me of "Circuit de Dijon *


Cölestin