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C7 auto trans overheating on track


Guest SeeSeven

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Guest SeeSeven

It appears that the auto trans overheating issue is not a new one on auto Corvettes from other posts. But many thought it might be addressed in the C7, being a new ground up (almost) car. Well, it does not appear to be the case.

I've had the problem every track day from the get go (November '13). The manual says, "First time on track do not run the car as long or as hard or overheating could occur which may damage the trans and not be covered under warranty." Well, I took it easy (lead and follow, novice stuff) the first time on track and it acted fine for all 20 min sessions (ambient air temp 50°). 2nd time on track: by session 3 (air temp: 50-70° - AM to PM) when I was beginning to get the hang of track line and increased speed (passed all the Porsches) trans got to 250° and with no DIC codes started up-shifting on its own (about the 15 min point). I got off track and idled to cool it down with trans fan running on high. Next session, same thing. No fun, so went home, took car to dealer, no codes, "Can't help you. Will open an issue with GM." No further word. (Nice, huh?) Changed trans and rear end fluids to eliminate them from equation. Next HDPE, warmer weather but basically the same trans behavior. By session 2 at 15 min point same behavior but at about 275° this time: No codes, or DIC messages, up-shifting on its own, got off track and idled the engine to keep trans cooler fan running until it shut off at about 240°. Car sat for another hour. Back on track, 15 minute mark, same problem. Got back off track. Cooled trans. Went home early. Half way home, check engine light came on. Two minutes later, heard clanking noise from rear. Pulled over. Stuck head under rear. Heard loud rhythmic clanking in "Park" that let me think something was going to fly through the trans case at any moment. Shut it off and had it towed to dealer. After sitting an hour waiting for the tow truck I could start it and drive it onto the flat bed truck and off again at the dealer without noise. Trans temp was at 240° when clanking first heard. It's at the dealer now.

Anyone else with similar issues (or solutions - like bigger,aftermarket coolers that will fit in the rear fender where it currently is located, or air scoops for air intake vents, etc)?

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old yeller

Sooooo, are they going to cover it under warranty since you were on the track?

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Desertdawg

Don't own a C7 but after just replacing mine in my 08 at 45k I had to try to figure out why it failed.

I've always had the trans temp on the DIC display and would see 200 to 240 temps even when just playing a little out on the road, a simple google search has tons of info. (See pictures below)

I also found out that 3 rd to 4the gear WOT shifts are very hard on the trans. I was probably doing 3/4 WOT shifts a few times a month. Living in the boonies there's plenty of opportunities to exercise the upper half of the speedo....., :eek:

transtemp.gif

trans_life_expectancy.jpg

FluidChart.jpg

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No knocking sound. But have had temp issues with auto transmission. I put a Dewits radiator in (it helped but) then jet coated headers to help engine compartment stay cooler. Finely I replaced the two fog lights and put black mesh over the openings. Then ran new steel braided lines to two newly installed oil coolers that looped the tranny to the radiator to add additional cooling for track use. That seemed to lower temps 15-20 degrees. Check my old posts for pictures below;

http://www.arizonacorvetteenthusiasts.net/topic/19646-installing-trany-cooler-venting-thru-fog-lights/#entry288736

SLAMMER

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Those bar charts are crap. The 100K marks should be 10 times as long as the 10K ones. lol

117K on my '08, with the majority having temps below 200 and never peaked above 235. I also avoid WOT with temps below 150.

Currently running a Hayden flat plate cooler fed into the OEM cooler. Since I swapped from a 3600 stall to a 4000, I'm hoping the change works. I'll know more when Summer is over.

Last year was the Hayden only and heavy low speed traffic got me to to the 220-230 area occasionally.

I may just need to go to a bigger or double coolers and put a t-stat inline.

One thing is very clear. When you push the engine coolant temps up, you're already in trouble without a separate cooler.

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Drewster67

This seems to be a common issue for the C7 -

I've seen it happen multiple times at the track - including a high end ride and drive I worked with ProAutoSports.

Dunno what the fix is other than something like water wetter or an additional cooler of some sort.

Good Luck

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