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Discussion Starter · #1 ·
Went to Thunderhill Sunday (9/30) for some open track/street school.
Beautiful day if a little hot (100 degrees):flaming:
I ran it hard at times, passing a viper and keeping up with a new porsche 911 turbo and a modified >400 hp camaro on race tires. The track is about 3 miles and I pretty much kept it in third except the main straight when using most of four.
After (or near the end of) each session a High Transmission Temp warning came on the DIC (all other gauges were normal - temp/oil/etc). This also happened to the other Z06 at the event.
Is this a common problem with the Z06?
I guess I'll need a transmission cooler. I've heard there is a GM setup - anyone put one in before?


Pete
technically challenged
01 black/black Z06 - all stock
 

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Pete,
I have not installed one but as my post above (Silver State) mentions, the Z06 tranny's do run hot. I have never had a high trans temp on a road course though. Let me know what you find out will ya? I might install one also.
Dave
 

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Dr. Z,

Just to add to your observations, I too have seen the High Trans Temp on the DIC about 4 times now. I frequently run a local road course and I'm also looking at the GM or other coolers. Usually by my second 30min run the Trans message is on. This past weekend I hit it on my second run, the airtemp was only 68F...but still got it. I've taken to 5 or 6 hard laps, followed by at least one cool down lap. That seems to keep the Tranny happy, but I'd prefer to get my money's worth outta my 30mins and run hard...just not hard enuf to cook the tranny. :)

BTW - I wonder why GM gave us an overtemp indication but not the acutal temp reading in the DIC??
 

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I have had that message also. It came on after about 30 minutes at BIR. I have since changed to Mobil 1 ATF, but I haven't been back to the track to see if that will add more minutes to a run session without the warning. Usually, my engine oil temp gets in the 280s and causes me to slow down before the tranny does. We should start a sub-group for those Z06 owners that have seen the high tranny temp message. With the design and purpose of these bad boys, I take it as a badge of honor.:lol:
 

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Dr. Z said:
Went to Thunderhill Sunday (9/30) for some open track/street school.
Beautiful day if a little hot (100 degrees):flaming:
I ran it hard at times, passing a viper and keeping up with a new porsche 911 turbo and a modified >400 hp camaro on race tires.

<snip>

Pete
technically challenged
01 black/black Z06 - all stock
Hey Pete,

It's a small World. Someone from another forum referred me to this site and while browsing the racing forum I found your post.

It seems that everyone on the track, including the low hp cars, passed the guy in the Viper. He must be just starting out.

I have some good video of you and the guy in the red Z06 that I'll try to convert to mpeg tonight.

It was great driving with you guys.

Pete, in the red TT
 

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Hi Trans Temp

Brian,
My high trans temp came on at consistent high speed with no shifting involved. As for the 911, 2 thoughts...I traded in my '95 this year and I can tell you that the Porsche is not in the Z06's league/ballpark/county or any other analogy we might use. My other point is the same one I've mentioned on this forum before, for $50,000 Chevy didn't get it perfect but they came pretty damn close. Personally I'm gonna wait to find out EXACTLY what the hi temp signal means. Is it STOP right now? Is it a heads up? Anyone know?
Dave
 

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I too have seen high transmission temp on road circuit.
After about 20 min of hard driving on third session of the day at Roebling Road in Savannah I got the warning. Interestingly, I didn't get it after four sessions the next day even though oil temp was hovering at 280 with same outside air temp.
I run Red Line D4-ATF so wasn't too worried about it, but did ease off and reset. It didn't come back.
I do heel toe downshift, but not sure if that helps or hurts.
FYI, the guys that built Heinricy's (sp?) car for T-1 have a differential and transmission oil cooler in their T-1 package. I would assume that it is legal for SCCA T-1, but I don't have a rule book handy.
Ffen
 

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The Cooler is legal in SCCA T1 Class for Road Racing... it is not legal in SCCA Autocross events. Which makes it difficult for those who race SCCA Solo 2... and enjoy doing Track events...

Peace,

Dave
 

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High Trans temp

I run SCCA T1 and the high trans temp comes on when the temp goes over 270. From what I've seen though, this primarily occurs when I get behind someone and have to slow down some. As long as I keep moving and driving hard, I don't have these warnings.

GM does make a cooler for it (and the diff) and most of the T1 have it installed...I don't...yet. I put a real good engine oil cooler on mine and if the high trans temp comes on again next year, I'll consider putting a cooler on it. The auto-Xers shouldn't have a problem with this warning considering the short runs.

Another problem with the high reading is that your tranny could be overfilled. Most of the racers run the fluid slightly lower than recommended to reduce drag (fluid drag) and reduce the total pressure in the tranny. Just an idea though. I'd just ensure that you check your fluid regularly, shift smoothly, and replace the fluid about once a year or so. You should be fine if you do that.
 

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Light triggers at 270 degrees !

G.M only gives Z06 ( and all Corvette models sold overseas) a idiot light that comes on when temps have hit 270 degrees !

The exhaust pipes is the biggest issue dumping heat onto both trannie and transaxle which also helps dump heat into MN6.
Also the low height of the car does not help for little flowing air goes across the trannie case to help cooling.

Using ATF fluid in a manual trannie does not help either for it foams much easier then a thicker manual trannie fluid does and this ATF will expand, foam and is puked out the vent tube on top of the trannie.
I know how bad it gets for during an open road race of 120 miles, over half that distance the trannie was puking fluid onto exhaust pipes and sending a nonstop plume of smoke out the ass end.

I spent the almost $900 for the G.M Performance trannie cooler ( which by the way the paperwork says adding the cooler will
void trannie warranty :puke:

IMHO, go to like Earl's Performance and buy a pump and cooler and do it for half the price for all G.M is doing is OEMing a Weldon pump with a small Fluidyne cooler which you have to mount all the way in front of the car.
The kit comes with small diameter hose, A/N fittings are 90 degrees causing even less flow, wiring harness is wired wrong.

They have you wire it to a constant 12 volt souce so when you pull off a highway to get gas, pump is still going while your pumpig gas.
No oil filter, thus the MN6 produces metal shaving and is sucked into pump ( I lost my pump twice now due to that design flaw) and they have you install a thermal switch to a outer cooling fin of MN6 which kicks on at 190 degrees which means the inside of the trannie/fluid is much higher then the 190.

I have a 3.73 rear end gear and when pulling highway speeds during the hot summer temps through high highs ( like Donners pass or the grapevine) the pump comes on showing these MN6s don't need to be in a race condition to be running too hot.

During the ORRs I have done, every Z06 had their hot tranie temp come on and had to slow down to cool it down and you can't win races that way :eek:

I found that Mobil I syn ATF functions better and has a higher temp rating before foaming.

It does suck that non Z06 MN6 C5's sold in the USA don't even get the idiot light so they never even know the trannie if overheated until the trannie starts leaking due to gaskets getting fried and leaking as mine does ..

You'd think after the crap we went through with the ZF trannie on the C4s that they would have made sure America's only sports car had a decent manual trannie.
 

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I'm thinking....

If a lot of the heat build up is radiated heat from the exaust system, why not wrap the cat back and over axel pipes with a thermal barrier tape. Might keep the exhaust gas temps up, increasing flow and scavage and increase HP and torque also, as a side benifit.
 
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[QUOTEI've been thinking along similar lines.

I have used the stuff extensively on headers and it works well. You have to watch out for corrosion and the impact of keeping more heat in the pipes. A lot of people who've never used it doomsay the stuff, but my experiences have been pretty good. It does trap moisture against the pipes.

I don't think the heat or the corrosion would be a problem for the titanium system. Titanium is 100X more corrosion resistant than stainless in salt water testing. That's not to say there couldn't be a reaction with the binders, etc in the tape that doesn't occur with mild steel.

[/QUOTE]

Question I have is would the increased inside temps of pipes due to being heat wrapped have a ill effect to the downstream O2s and the cats themselves ?

Any idea how hotter the internal of pipes would be due to this wrapping ?

Thanks, John
 

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Given that for extended competition, the current setup needs cooling, for those of us running much shorter events, would RedLine help to protect longer under high temp conditions? If so, which RedLine product is recommended?
 

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Switch to Redline D4 ATF

As a start, I think the Redline D4 ATF is the way to go for you road racers. I would change it once a season.

It seems to have the highest flash point temperature of any ATF I've seen at 437 degrees. It also the lowest pour point temperature at -72 degrees. It seems like it is slightly lighter weight so there should be less heat generated from fluid sheer.

Good question why the general didn't let us see what the actual temps are on the DIC... seems like they are hiding something ;) .
 

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The 2002 Corvette brochure shows some sample DIC displays on page 19. TRANS FLUID appears to be available. Is this really true for the Z06?

The December Corvette Fever magazine describes the installation of the GM transmission cooler kit.


Has anyone tried to fabricate a metal heat shield to fit between the transmission and the exhaust system.


John Pease
 

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Having abused the car on the track all last year I only had it come on three times and here was why for each time.
Pulled in the pits mid-session and had to obviously shift come to stop and then power out
Stuck behind slower car for a while any everything got hot.
Pulled in pit's again mid-session and then went out after sitting for a minute.
I run almost evry track in third and forth gear and shift pretty minimally so it seems to be maybe exhaust heat and poor flow sometimes.
 

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FWIW, Chuck Mallet was involved with GM in Z06 development and he told me the original plan was to have a tranny cooler as part of the Z06 package. He also says that the ONLY way to cool tranny temps is with a cooler...I ran my heat blocker/wrap idea by him and he said "forget about it". :(
 
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