LethalTT

My car is TT making 1280/1180 and will be turning it up soon. I have LVL 6 RPM TR6060 with Z51 gearing. I have been told this isn't best for 1/2 mile events which I will be trying out soon. I put some numbers in the calculator and seems I could get some good results for MPH in each gear with 2.93 or 3.15 gear swap from the stock 3.42. I also enjoy 60 rolls in Mexico so I'm trying to see would this be a good route to just swap gears or to send in Trans for the 1-3 Z06 gears and 5th ZR1(This is what I see most doing or if there's another combo let me know). Last question would be is this going to affect how the car comes in boost I would think so. Negatives? Positives? Here is the Calculator website I used. Any 1000+ cars gone through 1/2 with Z51 gears?

My gears are currently 2.97 2.07 1.43 1.00 0.71 0.57 3.28 Gear-3.42
Z06 gears 2.66 1.78 1.30 1.00 0.74 0.50
ZR1 2.29 1.61 1.21 1.00 0.81 0.67

http://www.catherineandken.co.uk/sti/tyres.html

inspector12

Well I haven't on my TT Corvette, but I did run 3:08's in my TT Camaro with a T56 and it was pretty sweet for roll racing! And you may not believe me but dig racing was better with it as It allowed me to bring the RPM's up on the launch and the car would just roll out and then take off pretty seamlessly on the street. The negatives would be unless your car is a standard C6, would be the size and strength of the cases and gear sets themselves. RPM said they would hold up for a while is all they told me as I looked at changing the rear gears, but nothing is made for the Z06/ZR1 diff's so if it is a Z06/ZR1 you will be loosing some strength but how much I couldn't tell you GL!

LethalTT

Copy that. Thanks! Yeah my car has a base rear thats machined for 30 spline input shaft.

yur2slo

Ideally you would want to cross the line in 1:1 gear ratio (4th) in 1/2 mile

The orange (now white) Vengeance Z06 had a RPM built 3.15 or 2.93 rear in it I believe when it was 6 speed manual. That saw over 200mph. You can ease into in for the 1/2 mile, the roll racing may take a little more toll/abuse.

Unreal

Other option is the 3.73s and steeper coming out, and plan on just using more of 5th.

neverstop

I know torco Josh with his JBSblownc5 with ~850whp used to have 3.73 and I believe broke a gear and went to 3.42 and basically found no different in 1/2 mile but I believe he has a custom G force zr1 5th gear too. Which I was surprised by as I would have thought that lower 5th gear would be big benefit with 3.73

I have z51 t56 gearing in my 900whp setup and that 4th ->5th shift is horrible, car just falls on its face and acceleration slows badly, and the high load on the car pulling that tall of a gear is also rough on the setup and tune.

can also play with rear tire size to help as well. I've been tempted to go with the super smaller diameter hoosier drag radials on 17" rim to bring down the rear gearing but that is probably not a good option for 1100whp big. 3.15 gearing and 28" tire and 7200rpm for last gear seems like would be good combo

RecMech

We have an RPM built 3.15 in the car now. Was a 3.42 ZR1 case last year, so I have data for both.

ZR1 gears in the TR6060 with over 1000 to the wheels.

Currently 4-5 shift is 175 mph, 5-6 is 210 mph at 7000 rpm.

I have found the calculator to be off by one cell (up one) compared to the data logs. Maybe just need to fine tune the tire size due to expansion.

ysb02

What rear end do they use to put in the 3.15s? Regular c6?

RecMech

Unfortunately, yes its a base C6 case. I spent months trying to get someone to build a gearset for the ZR1 case.

chpmnsws6

As far as gear strength goes:
2.66 > 2.97 for your 1st gear gearset
2.93/3.15 > 3.42 for your diff. The taller the gear, the stronger it is.

Unreal

If it is the same size ring gear, yes.

A 3.42 9" ring can be much stronger than a 7.8" 3.15 gear. The 3.42 is z06 gear is a larger gear than the 2.96/3.15 base gear.

chpmnsws6

The Z gears are that much larger over the base gears!?!

Unreal

Yes, they are significantly larger.

The thread about z06 3.73s/3.90s had a side by side.

Post 117
https://www.corvetteforum.com/forums...6z-diff-6.html