Z51 auto trans overheats
 

Has anyone come up with a reasonable fix for this yet? I took my car out to a HPDE once and the automatic trans is only good for about 15 minutes of hard driving before it overheats. I have not heard of anything reasonable to fix this and summer is not here yet.

Paddle shift.

My Z51 began to overheat when I ran it on auto one session and (after letting it cool down), the paddle shifting didn't overheat it. Also I found that I was learning more by consciously paddle shifting instead of letting the car do it.

At the Corvette Driving School (Ron Fellows), which is held in Pahrump NV in the desert under far hotter conditions that we drive in, they force you to paddle shift only so that you don't overheat the car.

Of course you can always turn off the a/c, and turn on the heater to dissipate the heat as well. I also keep the hood open in between sessions to let it cool down.

That is an interesting comment because I was paddle shifting and if you are not watching the trans temp like a hawk that is how you know it is overheated, it won't respond to the paddles any more. I goes into full auto mode and ignores your paddle selections.

I posted a similar comment on another forum and found that people are heat wrapping the exhaust where it passes the transmission. LG motorsports is adding a larger trans fluid pan and there is discussion that the Z06 front trans cooler may be retrofitted into the Z51 but I have not heard confirmation of anyone that actually performed the install.

Well this is annoying to hear. A family member picked up a C7 Z51 that is an A8 and I was going to track it. I have had ZERO issues with my A6 in my ZL1 and I track the piss out of that thing, doing 30+ minute sessions down here in HOT Texas weather.

The Z51 already has a trans cooler so that begs the question of is the ZL1 and/or Z06 trans cooler really that much better? Honestly I'm a bit surprised that the ZL1's A6 doesn't have issues but the C7's A8 does.

I have not made any changes myself, my car is still completely stock (other than motul brake fluid) but I ran out at eagles canyon on a day that had max temps in the 50's and I could only get about 20 minutes of laps before the trans overheated. There were other C7's out there in the green group and they were running just a little slower than I was and not having any problems. It seems like if you drive it at 80-90% it is fine but if you drive it at 95% it overheats.

I think the biggest difference between ZL1 and C7 is the transmission location. In the C7 it is in the back of the car and the exhaust is right up against it. I really think heat wrapping the pipes would make all the difference in the world. I have not scheduled a track day since but told myself I would not do it until I got something fixed.

Change the brake fluid and see if you can get some heat wrap on the exhaust pipes across the length of the transmission and I think it will work pretty well.

The Z51 automatic cars have an electric fan on the cooler, computere controlled. I wonder if those of you experiencing overheating might be having issues with the fan not turning on at a low enough temperature? On a side note, the Z06 cooler is nearly twice as big as the Stingray's, with a correspndingly larger fan. From what I've seen, the hard line connections look very similar, so an upgrade shouldn't be too big a challenge.

The fan is running fine. You can hear it when I come in the pits. I asked about changing to the Z06 trans cooler in the fender and was told it does not fit in the Z51. The Z06 has a wider fender to hold a larger rear tire and the larger trans cooler. Now if I put a Z06 rear fender on the car I could put on the Z06 trans cooler.....and add the wider tires.

Jessrayo, Did you get any solutions?

The air temp was in the high 80's/low 90's.

I could not finish one single session. 20-22 minutes in, I would get the transmission too hot warning:idle engine.

I've never seen it this bad. Everything is stock in it.

I talked to the mechanic and he warned against heat wrapping. He said that this would make whatever you wrap much hotter and degrade that metal much faster (which would probably void the warranty for those parts).

He said to add a cooler plate or a second cooler.

Since it's still under warranty, I'll probably just take it to the dealer to see what they can find. I believe that one should be able to drive 30 minutes without anything happening.

It was a sad day for Corvettes everywhere, as to try to keep the transmission cooler, I ran the heater on high and would drive hard 3-4 laps and then take a cool down lap and then repeat. I think my car died a little inside to let all the Porsches (and even a spec miata) go by.:pout:

I still have not had mine worked on but I have not been back to the track since March....

When I owned a CTS-V I had the exhaust wrapped around the diff to keep the differential from overheating. With heat wrapping on the corvette, the only thing you would wrap is the exhaust pipe from in front of the transmission behind the diff. The metal in the exhaust pipe will be red hot in the area wrapped but it is not load bearing and it is pretty heavy stainless steel. It will not hurt that pipe a bit to wrap it. If you heat wrap a turbo or any other moving part you are asking fr trouble, exhaust pipe is no problem. It is going to be a bit of a pain because you have to take the exhaust off because it is so close to the transmission. Which is even more reason to wrap it.

I talked to Anthony at LG in Plano and they are going to add a cooler for me and a larger trans fluid pan. I will have them wrap the exhaust also. Problem is my other car has been in the shop since last Oct so I don't have anything to drive if I bring in the vette for work. I really doubt your dealer is going to have a fix. This is a specialized problem that a small percentage of corvette owners are experiencing and you will need to find an expert to fix it. Those guys at LG are working through stuff all of the time and may have some alternate fixes by now. I recommend you give them a call.

Well this past weekend my club had another private track event. As usual I ran the piss out of my ZL1 and had zero issues. I had a family members C7 Z51 out on the track too and tracked it for two sessions, it's an A8 btw. First session only did ~12 minutes so I could get a feel for the car, didn't have any problems. Second session I did ~20 minutes and the trans started shifting on its own and then I got the trans overheat warning.

It's a shame that the C7's are having this problem and my two ton modified ZL1 has zero issues.

Please update once you have the work done. I'll let you be the guinea pig. We're in the same area, so after you have the work done, we could goto Motorsports Ranch in Cresson and see how well it works. I'm a member there, so you could get on as my guest.

Until then I guess I'll be stuck doing 15 minute sessions.

Thanks for the offer. I have still not run at Cresson. I'm an Eagles Canyon guy. As soon as I get a another car to drive I'll get some work done on this C7. I may tell my work I want a company car for a while.... I'll keep you posted.

For the most part, it's the A8's that are having high trans temp issues... I have tracked my M7 Z06 7x already and 3 of those times were on very hot & humid days. Pushed it consistently hard too lap after lap, session after session. No trans temp issues for me but I do know of 2 other A8 C7 Stingray owners who had high trans temp warnings and they weren't even pushing their cars as heavy as I did. Sucks, GM needs to address this...

There are a lot of factors, ambient temp, track layout, driving style, etc, autos are much worse than manuals but some have even had trouble with manuals overheating. The problem is the transmission is pretty much sandwiched between two hot exhaust pipes over its entire length inside a little tunnel under the car. Automatic transmissions have more frictional power loss so they can't handle the extra heat as well as the manuals. Another reason to recommend a manual trans to the guys who actually plan to track a car.