Automatic C7 Trans Overheating on track
#41
Hopefully the "new" version of GM will be more responsive and willing to address overheating concerns but since only a very small percentage of owners are going to drive the A6 equipped C7 hard enough to create the concern I wouldn't hold my breath. If the A8 better manages temperature on the track I expect it will be even more difficult to get A6 issues addressed since from GM's point of view the problem won't be getting any bigger (since the A6 production run will have stopped).
A lot of guys jumped through a lot of hoops with GM starting back in 2004 when the new LLY revision of their diesel was introduced to meet new EPA standards and people quickly started experiencing severe overheating issues with both the engine and transmission when towing well within the rated specifications. The only real solutions were after-market and GM didn't solve the problem until the introduction of the LBZ third generation diesel with revised cooling for both the engine and transmission. I am very happy I skipped from the first to third generation and avoided the frustration.
If you need to kill some quality time in front of your PC here is a thread that links to the various twists and turns owners went through. I think the lesson learned from this is an aftermarket solution may well be the least frustrating and best solution. Hopefully those aftermarket products appear soon for the guys tracking their A6 equipped Stingrays. http://www.dieselplace.com/forum/63-...-problems.html
A lot of guys jumped through a lot of hoops with GM starting back in 2004 when the new LLY revision of their diesel was introduced to meet new EPA standards and people quickly started experiencing severe overheating issues with both the engine and transmission when towing well within the rated specifications. The only real solutions were after-market and GM didn't solve the problem until the introduction of the LBZ third generation diesel with revised cooling for both the engine and transmission. I am very happy I skipped from the first to third generation and avoided the frustration.
If you need to kill some quality time in front of your PC here is a thread that links to the various twists and turns owners went through. I think the lesson learned from this is an aftermarket solution may well be the least frustrating and best solution. Hopefully those aftermarket products appear soon for the guys tracking their A6 equipped Stingrays. http://www.dieselplace.com/forum/63-...-problems.html
#42
Melting Slicks
Got the car back and did a first effort mod on the air intake for the trans and diff. Here's the trans air scoop before sealing up the air leak at the inside rear. 1st opportunity to test it is next Sat and not a good one with a small track (.75 mile) at CAC and short lap count. Better test at Inde a week from Sat.
Last edited by slief; 05-20-2014 at 10:45 AM.
#44
Most autos for most performance cars have heat issues at the track. The Z51 improvements are not enough, it seems. MT or DCT for the track it looks like,
#45
Team Owner
All my previous Vette's have been manual's so I really never paid much attention to this.
Live and learn.
#46
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If you are trying to increase air flow to the coolers mounted in the rear of the car pull the grating out of the quarter panel inlet vents. When I was at Carlisle last August I spent a fair amount of time talking to the engineer that designed them. He spent a lot of time minimizing the air flow restriction caused by the grating. When I asked him how much they restricted the air flow he said about 25%. When I asked if the gratings could be removed he said yes but then you have to worry about items falling into the cooling ducts.
The cheap thing to try is to remove the grates and see if enhanced air flow through the coolers will help. I don't know whether that will help cooling an automatic since I don't think the auto trans cooling circuit uses those coolers.
Bill
The cheap thing to try is to remove the grates and see if enhanced air flow through the coolers will help. I don't know whether that will help cooling an automatic since I don't think the auto trans cooling circuit uses those coolers.
Bill
#47
Safety Car
If you are trying to increase air flow to the coolers mounted in the rear of the car pull the grating out of the quarter panel inlet vents. When I was at Carlisle last August I spent a fair amount of time talking to the engineer that designed them. He spent a lot of time minimizing the air flow restriction caused by the grating. When I asked him how much they restricted the air flow he said about 25%. When I asked if the gratings could be removed he said yes but then you have to worry about items falling into the cooling ducts.
The cheap thing to try is to remove the grates and see if enhanced air flow through the coolers will help. I don't know whether that will help cooling an automatic since I don't think the auto trans cooling circuit uses those coolers.
Bill
The cheap thing to try is to remove the grates and see if enhanced air flow through the coolers will help. I don't know whether that will help cooling an automatic since I don't think the auto trans cooling circuit uses those coolers.
Bill
I wouldn't place a scoop or periscope intake there like some have done because of drag and effectiveness and airflow disruption to the spoiler. Since the C7 Z07 package has adjustable aero bits, maybe they can offer a removable screened lid on this intake for race day.
#49
Melting Slicks
The manual trans Z51 has a cooler where the auto cooler is, non-z51 has no manual trans cooler.
Z51 option also has a differential cooler on the RH side.
#50
Team Owner
The Z51 has the same auto trans cooling as the non-z51. Appears to use the same engine oil cooler as well, but the Z51 has dry sump which should run cooler.
The manual trans Z51 has a cooler where the auto cooler is, non-z51 has no manual trans cooler.
Z51 option also has a differential cooler on the RH side.
The manual trans Z51 has a cooler where the auto cooler is, non-z51 has no manual trans cooler.
Z51 option also has a differential cooler on the RH side.
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911Hunter (11-24-2017)
#51
Melting Slicks
It certainly isnt a good track car for people that have tried and went into limp/trans overheat mode
But it may work for others, IMO if you seriously tracking a C7 the manual would be the way to go. Going to have to wait and see if the '15 A8 brings any cooling improvements.
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911Hunter (11-24-2017)
#52
Results at Inde
With the air scoops on at Inde (http://www.indemotorsports.com/site/...ction_thetrack) this weekend it lowered trans temps about 10° at the same ambient temps as in March when the problem was 1st noticed, same track (config 1CW), same track config, same lap times. When the track config was changed (2CW) on Sunday to add 3 demanding corners the temps got hotter, quicker than back in March with the same up-shifting on its own as before. Still no DIC messages and no codes.
Conclusion: No size air scoop other than something huge is going to fix the problem. It needs a second trans cooler (up in front?) since there is no room back there for a bigger one - or to correct the bad angle of the existing cooler that reduces air flow because of angular air flow.
Conclusion: No size air scoop other than something huge is going to fix the problem. It needs a second trans cooler (up in front?) since there is no room back there for a bigger one - or to correct the bad angle of the existing cooler that reduces air flow because of angular air flow.
#53
Burning Brakes
With the air scoops on at Inde (http://www.indemotorsports.com/site/...ction_thetrack) this weekend it lowered trans temps about 10° at the same ambient temps as in March when the problem was 1st noticed, same track (config 1CW), same track config, same lap times. When the track config was changed (2CW) on Sunday to add 3 demanding corners the temps got hotter, quicker than back in March with the same up-shifting on its own as before. Still no DIC messages and no codes.
Conclusion: No size air scoop other than something huge is going to fix the problem. It needs a second trans cooler (up in front?) since there is no room back there for a bigger one - or to correct the bad angle of the existing cooler that reduces air flow because of angular air flow.
Conclusion: No size air scoop other than something huge is going to fix the problem. It needs a second trans cooler (up in front?) since there is no room back there for a bigger one - or to correct the bad angle of the existing cooler that reduces air flow because of angular air flow.
Alternatively you could look into those massive ATF coolers they use on the big 2500 and 3500 series trucks - should provide some additional heat capacity, but finding the volume with the right airflow could be a problem. See: http://www.transmissioncoolers.us/ca...oolers-hd.html Where there is a will there is a way, but if you really want to track your C7 ALL DAY, the M7 may still be your best option.
Last edited by dcbingaman; 05-26-2014 at 06:01 PM. Reason: Update
#54
Snoreman, You monitoring this thread still? If so check your personal messages for an update on the A6 overheating issue. Everyone else will have to wait another 2-3 weeks or so for the resolution.
In the meantime, I can tell you that sources that I cannot reveal tell me that the 2015 A8 will likely have the same overheating issues as the A6 - especially on the ZO6. So if you track buy an M7.
In the meantime, I can tell you that sources that I cannot reveal tell me that the 2015 A8 will likely have the same overheating issues as the A6 - especially on the ZO6. So if you track buy an M7.
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911Hunter (11-24-2017)
#55
My A6 Z51 Vert runs at +220 after 1 hour of just plain old driving. It is a bit disconcerting.
#56
They certainly manage to cool transmissions properly in other applications. The highest I have ever seen in my 2006 GMC pickup was just barely past the 200 mark towing a little over 10,000 pounds up to the Eisenhower tunnel in the summer running at the speed limit. Normal highway cruising is 160-170 during the summer months, goes up to 180 in heavy stop and go summer traffic and drops quickly back to 170 when the fan clutch engages.
#57
Scraping the splitter.
I've said it before, and I'll say it again...I seriously doubt GM is going to be able to control temps for the A8 in the Z06.
We've seen pictures of the Z06 cooler compared to the Z51 (I actually started a thread in that section), and it's only ~30% larger. They can lock the convertor and decrease some fluid temps, but considering the current A6 is already not capable of anything more than ~10-12 minutes on-track, I take GM's BS "track certified" comment with a grain of salt.
"Track certified" for whom? A novice driver on an easy track in ~50-60* ambient temps?
S.
We've seen pictures of the Z06 cooler compared to the Z51 (I actually started a thread in that section), and it's only ~30% larger. They can lock the convertor and decrease some fluid temps, but considering the current A6 is already not capable of anything more than ~10-12 minutes on-track, I take GM's BS "track certified" comment with a grain of salt.
"Track certified" for whom? A novice driver on an easy track in ~50-60* ambient temps?
S.
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911Hunter (11-24-2017)
#58
Maybe GM has decided that it is OK to run them this hot but it isn't rocket science to calculate the heat load of an automatic and put a cooler where it receives sufficient air flow to achieve a lower temperature. Saving the few pounds that a large stacked plate cooler with lines to mount it where it receives airflow isn't much of a gain when this weight savings results in a car that limps quickly when pushed.
They certainly manage to cool transmissions properly in other applications. The highest I have ever seen in my 2006 GMC pickup was just barely past the 200 mark towing a little over 10,000 pounds up to the Eisenhower tunnel in the summer running at the speed limit. Normal highway cruising is 160-170 during the summer months, goes up to 180 in heavy stop and go summer traffic and drops quickly back to 170 when the fan clutch engages.
They certainly manage to cool transmissions properly in other applications. The highest I have ever seen in my 2006 GMC pickup was just barely past the 200 mark towing a little over 10,000 pounds up to the Eisenhower tunnel in the summer running at the speed limit. Normal highway cruising is 160-170 during the summer months, goes up to 180 in heavy stop and go summer traffic and drops quickly back to 170 when the fan clutch engages.
There is plenty of unused room in the C7 engine compartment for one or even two additional coolers and two blocked off grill sections to feed it/them with air - exit air through side vents. Things I do not know is where to run the lines from the back. Space is at a premium -- and I don't know if the current pump would suffice. Maybe someone else more knowledgeable than I would know about those aspects.????
#59
Pro
Has anyone had at least some improvement with a different transmission fluid? If it overheats should you change it? Will a fully synthetic hold up under these conditions?
#60
Having said that, we are almost certainly NOT talking about a 30° difference as a result of changing fluid brand/types, which is what is needed in the A6 and the coming A8. And, more importantly, we never really have established what a sustained fluid temperature would be under sustained track runs since I don't know anyone who has made it past the 15 minute point. At that point, when the trans goes into limp mode and up-shifts on its own the fluid temp is still rapidly rising past 250-260°, etc.
Bottom line: not enough cooling designed into the car.
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911Hunter (11-24-2017)