Tribaltalon

Welp. Made it about 15,000 mostly trouble-free miles at the 700+/- rwhp mark with 4" pulley T-Trim, cam/intake/full exhaust LS2. That ended a couple weeks ago driving down to the corner store under mild acceleration (probably not even in boost) and BANG. luckily i was close enough to tow it back to the house with my truck. The shop just pulled the driveline and sent me this picture.






Still waiting to hear if the differential made it out alright. I'm having some serious internal debates about what to do at this juncture. Do i just put another stock T-56 in it? Do i build this transmission? (until now, it's never had any problems. never missed a shift, etc) My friends are saying to go TR6060. One major concern that I have is that right now, I owe just a little less than the car's worth. If i dump a ton of money into a built transmission, I'll never get that money back out of the car.. I don't really know that a TR6060 and Z06 differential would really even be strong enough for my combo. It's easily capable of 900 plus if i had the fuel system and total lack of care if the motor blew. lol.

silver408z

I am starting a build on my car (well having blownbluez06 do the work) but part of it is going to be a c6z tr6060. My car is a c5z so I have a t56 as well. You can fix and build a t56 cheaper than you can do the swap and if you keep the car around 700 a t56 should be fine really if you do some of the upgrades to help hold the power. The tr6060 will hold more power though. It has bigger surface areas of the gears and everything else to hold the power. The tr6060 is also supposed to be a smoother transmission and has a fluid pump that keeps the gears oiled and cooler. The t56 does not have that. it makes a difference for those long roll races 2 thru the end of 4th. In the t56 the fluid moves to the back of the case and causes the gears to not get fluid.

darknit

I broke the output shaft on my stock t56 also...

T56 shifts smoother because of larger syncros, TR6060 holds more power because of larger gear surfaces...

I now have a stage 6 RPM t56 with the larger z06 output shaft...

You can send RPM the part of your rear diff gear that the shaft goes into and they machine it to accept larger output shaft...

RPM told me my stage 6 with larger output shaft will take 750 horsepower all day long...

z51 and z06 t56's have a pump on the front of the trans that runs the fluid up to the cooler, base models do not have this pump...

Rick@RKT Performance

To repair it under budget and hold 700 RWHP, just replace the main shaft with 30 spline Z06 shaft and purchase a Z06 differential with the upgraded shafts. This combination has run low 10's with sticky tires without issues.

Tribaltalon

Man that sounds encouraging. I've run low 11s so far (only made like 5 passes total) leaving with a 2.0ish 60 foot trying to keep the rear end together. I might have to look into this option of running a z06 shaft and getting a z06 differential. I'd love to be able to bust off some decent 60 foots without being totally paranoid about blowing the back diff out of the car.

neverstop

fwiw I've been at 900whp and 860tq running 17" et street R tires for many miles without issues, running built rpm c6 z06 diff with the stronger spline output shaft and level 5 rpm t56 with c5 z06 axles. I'm not really into drag racing but a few 1/2 mile days and plenty of street hits.

Theoretically the tr6060 is stronger, especially 5th gear, but lots of guys putting down 1k whp plus with serious abuse on t56 without issue although that spline upgrade seems key.

https://www.corvetteforum.com/forums...-6th-gear.html

NormWild

T56 is a solid time proven trans. If I ever need a new one my plan is just go with a built one from RPM. 45K miles on this stock one with more highway pulls than I can remember.

stevieturbo

When the 6060's or Magnums are available, it really doesnt make a lot of sense to go with an older T56. The new boxes are just better in every respect.

Unless of course budget simply doesnt permit.

That said, as others say, the T56 is damn well proven despite it's low rating from the factory.

That said....my old FBody T56 of many years old finally gave up last weekend. Not an actual gear failure...nor shaft. But it exploded the 5/6 synchro drive/slider hub when I was trying to go from 4-5 at a 1/2 mile even there in the UK.
I will say a large part of the failure is down the the stupid ******* clutch I've ended up with, but that's another story.

In doing so also took out some teeth on 5th gear too, not that there was any drive to do much with them lol.

Fortunately the huge magnets in the bottom seemed to catch most of the debris and just doing some 1/4's then driving home hasnt caused any further damage