zrtman1

LS3, forged bottom, cam, headers, ported heads, Vortec V3 (for now-YSI in the future possibly). Guessing 600-650 whp. I want to upgrade to a T6060 since the stock T56 has some high miles on it. Was thinking the ZR1 ratios would help it hookup better off the line, but I know the ZR1 probably has huge torque/power at low rpm due to roots style s/c. Would the centrifugal s/c not pull the taller first gear? Staying with 3.42 rear gear 26" tire.

Just a street car... messing around light to light and roll ons. Maybe a hpde someday.

This is in a C5 - but most of driveline is now C6..

Any thoughts or comments?

lt1z

I would use Z06 for 1-4 and a ZR1 5th gear. I already have a TR6060 but in Z51 ratios which are too steep for the power I'm making. If/when I hurt the trans I will be doing what I said above with an RPM TR6060.

zrtman1

I agree with your choice of 5&6th ratios. But for now it will be a stock T6060 to get the project rolling. Basically trying to decide between a 2.29 or 2.66 first gear.

The Z51 T6060 has the old LS6 gearing correct? Tire smoker 1st gear.. ?

Louis Gigliotti

2.66 is better all around for what YOU want to do.

If you were not blown, and NA wanting to do HPDEs, the 2.29 would be better.

The Z51 is out, the ratios just suck. 3rd too tall for 60 rolls, 2nd to short.

The 2.29 has you shifting a lot, and while that doesnt sound bad, it gets annoying. The ratios rock, but the super short 6th gear will reduce mpg significantly.

zrtman1

I would not consider the Z51 trans - that was a comment to a previous post.

The MM6 T56 I have now has the 2.66 ratio. With the stock LS1 and supercharger 517whp it was barely hooking with Nitto 05R's. Should have 100hp more with new combo and I think traction will be an issue. Was thinking 2.29 might help keep it hooked up better through 1st. and the close ratio 2-5th gear would be a benefit to really keep rpm's in the boost??

I do agree 6th gear on the ZR1 trans for me would not be a good thing. It would be better to have the Z06 6th to keep highway rpm's down. But that could be changed at a later date.

My vette is not a daily driver. Play toy/fun toy..

Louis Gigliotti

I really like the ZR1 box, Ive had several. ( Its the 229 you listed, for those that dont know)

Pros- Shift extension is short, 1100-800 rpm drops due to the Close ratio. Always a right gear for the occasion.

Cons- Lots of shifting. High RPM cruising. Tall first gear (Pro or con) Taller over all 1-3, same 4th, shorter 5th, shorter 6th.

zrtman1

Thanks for the replies. What were you running for power in front of it?

Louis Gigliotti

Anywhere from 550-800.

EvanZR1

One more vote for NOT using the Z51/GS/C5Z ratios. I like those ratios for NA, but once I put the blower on my GS I very quickly realized that don't work as well for that setup. Personally if I ever switch, it will be to ZR1/2.29 ratios. I didn't buy the car for the gas mileage, and a lot of time now, I currently run in 5th anyway.

zrtman1

I think the Grand sport has the Z51 ratio (2.97 first gear)?? Not positive...

LemansbluebyU

Does anyone know what the ratios are in an 07 Z T56 and what would be the difference between this trans and the one in a 10 zr1?

zrtman1

https://www.corvetteforum.com/forums...ar-ratios.html

EvanZR1

Correct. GS IS a Z51, so manual GS has the 2.97 1st tranny ratios.

5 Liter Eater

Not sure if the T56 Z51 ratios are similar to the 6060 Z51 but my T56 Z51 ratios sucked. In the 1/4 mile first and second were run out very quickly. And 5th was a huge drop. Looking forward to what I'll do in the 1/4 with my '08 Z06 ratio 6060.

EvanZR1

Yes, they are the same ratios. I think they work ok stock, but once I added the blower, 1st became useless and 2nd isn't much better. From a dig I'd probably be better off just starting in 2nd as it's 2.07 which is closer to the ZR1 1st of 2.29.

neverstop

I have a t56 with c6 z06 ratios in it now and when i got to tr6060 i'll go with Zr1 ratios for sure. The box i have now works great but 1/2 gear are shorter than I wish and who cares about 5/6 imo

schpenxel

1/2 are short in mine too. 05 Z51

5 Liter Eater

If you're doing a 1/2 mile or mile event they're plenty important. Shoot I almost have to grab 5th in the 1/4.

ace32x

^ this 4th with a 28" tire and 7800 rpm i still cant get away with 4th in the half. peak out at 188 ish

Streetk14

When I sheared off the 27-spline main shaft in my Z51 TR6060 in my old car, I had it rebuilt with Z06 1-4 (2.66 1st), along with a ZR1 (.80) 5th. I actually wanted and asked for the standard Z06/MN6 0.50 6th gear for nice cruising/MPG -- but the trans somehow got built with the ZR1 6th gear instead, which works out to a 0.63 when combined with the 2.66 1st gear.

While I originally wanted the 0.50 6th, I actually liked the shorter ZR1 6th gear. I'm sure it cost me some fuel economy on the highway, but it made the car a lot more lively when cruising in top gear with my cam/centri combo. I really didn't build the car for gas mileage, and it wasn't a daily driver. In the end, I think it was a good choice. The ZR1 5th gear was great for the 1/2 mile events at my power level, and I think the close 5-6 ratios would have worked well for higher speed events. Those gears are really close with the ZR1 gearset.

If I ever hurt the trans in my GS, I'd probably do the same thing again. Like everyone else has said, the Z51 ratios pretty much suck. But seeing as how I already have the 30-spline main shaft from the factory in this car, that probably won't happen.

Hope that helps.