Looking at the next stages of my upgrades, since I'm wanting a bit more power. However, I'm getting curious about the transmission and differential. I still have the stock units and they both are still going strong, no signs of issues. Yet? So I've sent the obvious emails to folks like RKT and RPM to try and plan a replacement setup in the event that one breaks unexpectedly, or to try and be proactive before a failure happens. They usually recommend the TR6060 setup. This is expensive (although used combinations are actually reasonable), and I'm just simply not convinced it's necessary. This is what drives my question and topic.

Why do the units fail, and under what conditions?

For example, is the diver just buzzing along during a half mile, mile run, or road course and shifting casually/safely and it randomly pops during shifting or when at high rpm? Or, are they running it hard at a dragstrip, mashing gears like a madman and the trans explodes into a million pieces of hateful carnage? I see these two scenarios as two completely different experiences.

 

The gears in the TR6060 are 30% bigger so they can handle the added pressures of high powered cars. A certain member on here had a T-56 fail during a 3rd gear pull. The gears gave up. Improving the pieces that are involved in shifting will help in failure, but you really gain by upgrading the output shaft to a 30 spline or a 27 spline with stronger material. RPM has a process to machine your ring gear to a 30 spline.

FYI - I have a RPM level 3 T-56 with 30 spline output shaft for sale. I went to a TR-6060 transmission. The 6060 is so much smoother than a T-56. Wish I would have done it a long time ago.

Hopefully some others will chime in with more knowledge than me. (Which doesn't take much).

 

^^^ ^^^

Rebuilding your existing trans makes it shift better, but a full rebuild does absolutely nothing to increase its power handing ability.
Trans with bigger gears, shafts and bearings along with the slider keys removed from the design. The 10.00 keys fail and your transmission fails. The T56 is starved for fluid on acceleration, pushing all your fluid to the rear of the case. The TR6060 will recirculate the fluid and return it to the countershaft, where it's needed. The C5 diff is weak. Ask a builder and they never see a stock one, with miles taken apart where the springs aren't broken. The carrier is small and the case is weak. The side covers are weak. The geometry where it ties down causes great stress at the junction point between the transmission and differential. GM solved these issues in the C6Z design, reinforcing the tail housing, changing the mounting point to the differential for far better support, monstrous carrier and gears along with huge reinforcements throughout the case and side covers.

Full conversion to the 6060 & diff with supporting parts: http://forums.corvetteforum.com/c5-p...r-your-c5.html
Spend the money once and be done. Instructions in the stickies at the top of this section and more support throughout the installation if you need it.

 

I actually need to pull my diff/trans right now to take a look at a clutch problem. How much do you think my stock components would go for with 60k miles?

 

My failures have all come at the track. I have had to redo the 3rd gear in the transmission due to grinding while shifting into 3rd twice now. Both started after some passes at the track.

As for the diff, I have broken two of those as well. Both broke at the track and upon launching the car. One diff I had managed to shear the cross pin in the 3 places. The gears inside the carrier then proceeded to eat each other apart. The car was still drive-able, but whenever I stopped and started going again there was a big clunk. The second diff I broke stopped me dead in my tracks. I launched the car it jumped about 3-6 feet and stopped moving. The housing on the diff broke on the passenger side, and I had numerous teeth missing off the ring and pinion gear. My thoughts are the ring/pinion failed and when the broken teeth got mixed up with some good teeth that in turn caused the diff housing to crack.

 

Thank for sharing your results. I don't really dragrace, so I wonder if I will ever have problems with the stock stuff. Unless it gives out randomly while running up the RPM's in gear at a Road Course or 1/2 Mile Event.

 

Read up on T56 fluid pumps. Keeping fluid on the front gears could help save the life of the transmission.

I broke a c5 diff at the strip wheel hoping. It happened so fast the damage was done before I could get off the gas. Since then I put poly bushings on all control arms, and it hasn't come back.

 

I have not been on a track with my car in 5 years since my last diff broke. I put a stock one in back then in 2009 and it has been living fine. It was daily driven until last year and now I just take it out and beat on it weekends cruising.

 

What kind of track?

Dragrstrip or road race?

 

Drag strip. I broke one diff at State Capital raceway and another at No Problem raceway. Two different local tracks.

 

Broke my rear diff at the track launching on some ET streets after 6 passes. The case cracked and 7 of the 8 ears broke of the carrier. Took out the mainshaft in the trans as well.

 

Talk about a bad day.... Damn

What size tires, power level, and launch RPM?

 

IMO if you aren't drag racing there is no need for the tr6060

 

I got my 6060 for $500 with a broken main shaft or there wouldn't be one in my car .

Upgraded to carbon blockers and a 30 spline OPS. Have less than a grand in it.

 

That's the common theme I'm seeing here. Everyone is breaking the stock units on dragstrips.

 

26x11.5x17 bias et street, car makes 650 to the wheels was launching at 4.5k.

The pass before the breakage it went 11.0. Just wanted to get into the 10's lol.

I got lucky and got a killer deal on a just refreshed rpm level 3 diff. I pulled the trans apart to replace the mainshaft and also found the 5/6/reverse shift shaft was slightly bent. Not sure how that happened.

 

If you just roll race or have a street car the t56 can live a long time.

Once you start launching on it though your days are numbered. Tr6060 is one hell of a setup though, if you can afford it it's a no brainer.

 

I jsut broke my 40k mile stock z06 trans at Road America. Shifted 3-4/4-3 about 800 times at high load in 3 days at the track. Too much for it apparently, broke a syncro key trans is stuck in 4th. I don't abuse the car on the street or take it to the strip.

At least with billet keys its a fixable issue.

Different failure mode then is being discussed but pretty common and has to come out all the same, though I could probably fix it for $50 in theory. It has never had any shifting issues.

 

Lost my built T56 the last time in a roll race. Started in 3rd with the clutch fully engaged and about 1/2 second later, it popped. Skinned the teeth off 3rd and the counter shaft. That's the day I decided I was done with the T56.

 

When I snapped the mainshaft on my Z06, I decided I was done with manuals lol. Was always fighting shift lockout as well. I might switch back someday, but I'm having lots of fun with a stalled auto.