Bluefire

I have an '03 A4 Coupe that I do HPDE's in. I have ~420 rwhp, 2800 stall, and I've also installed a 25 plate Setrab cooler (bypassing radiator).
Last Monday I was at PIR for an HPDE event. Normally, I would leave it in 3rd around the track, and pop it into 4th (OD) on the two straights. This time my instructor suggested that I go to 2nd gear for two of the turns to get better exit speed. It works great. I never redlined it but, at the end of the session my trans temp was 235 degrees (ambient temp was 88 degrees). My three questions are:

1.) Are there any issues with manually downshifting to 2nd on the track?

2.) Is 235 degrees too hot? (Never seen a DIC message

3.) Will adding a fan on my trans cooler help? ...or a vented hood?

Thank you in advance.

Dirty Howie

When I had mine I used 2nd gear no problem. I had a separate stand alone tranny cooler which I think is a MUST HAVE !!


DH

Bluefire

DH,

Thank you for the response. I'm currently running a 25 plate Setrab cooler in front of the AC condenser (bypassing the radiator). Should I do something different?

Dirty Howie

Sorry didn't notice that. So you have stand alone oil and tranny cooler, right? My tranny cooler was a one off (have no idea what it was) and very large. I also had a built RPM tranny. You will know if your temps are too high when your tranny gives up the ghost


DH

TKOGTO

1.) Are there any issues with manually downshifting to 2nd on the track? - other than higher temps (slightly, moderately - not sure) I don't see any. I run Lime Rock in 3rd gear for the whole track except for a brief stint in 4th on the main straight so identical to how you ran PIR. (2010 GS A6).

2.) Is 235 degrees too hot? (Never seen a DIC message - I was close to 260 last week with ambient about 80 and I have a B&M HI-Tech trans cooler so I wish I was @ 235. ECU sends car into limp mode @ 270 so 35 degrees below that is no cause for concern IMO. BTW - I did not know the C5 has a trans temp gauge. Does it?

3.) Will adding a fan on my trans cooler help? ...or a vented hood? I suspect both will. Considering the latter but cost of a good one, fitment of a less expensive one and the change in the aero that I have no means of quantifying keeps me looking for another solution. For now, a cool down lap in mid-session will have to do.

randomus

I agree with DH, you have to have a standalone cooler, I added mine in to the radiator loop which I thought might give better cooling.

Before I did that I would get to 250-260 easily and the DIC would start yelling.

In my 2001, the biggest problem downshifting was making sure you were going straight or hanging on when the shift actually happened. I spun a couple of times early on when I wasn't quite ready for the shift.

Bluefire

I've always wanted a vented hood (cuz they look badazz ) but, I'm feeling relatively good now with the 235 temp after reading the temps you're seeing.

I figured this out on Monday. I didn't spin (just a little tire bark and a wiggle) but, I wasn't far from making a seat stain.

Thank you both for your insight. With this and DH's response (Thanks Howie!) I'm more at ease continuing with the cooling solution I curently have. Even after my fourth session last Monday, it never got higher than 235 when I was on the track. Off-track/ hood open it quickly dropped to ~170 after ~ 20 minutes.


Bluefire

jaa1992

I teach my more advanced auto drivers - when you under the hardest braking going in to a corner drop it into 2. You do not want the transmission to shift by itself in the middle of the turn!
If you are going to do this alot you need the trans cooler!

Supercharged111

He has a trans cooler. I'm thinking bigger radiator. How hot is your coolant getting? Cooler coolant will make the radiator's trans cooler more effective, though to what extent I do not know.

Rookieracer

Add a fan to your existing cooler. Your average temp is 235, but there are places in the converter and trans that are much hotter.

TKOGTO

I think I may be missing something here. You indicated "when you under the hardest braking going in to a corner drop it into 2". I think you mean before a corner, correct? I do all my threshold braking in a straight line. If I need to brake more for an entry speed corner, I trail brake. I have been instructed never to do my hardest braking while turning.

I agree with "You do not want the transmission to shift by itself in the middle of the turn!" but in my car the shifts are so slow it is unavoidable. I brake @ my brake point @ the end of a straight, downshift to 3rd then simultaneously turn in and start trail braking. ~1/4 to ~1/3rd of the way in the entry the tranny finally gets around to the shift. Balance of the car has to be modulated with the brake.

Supercharged111

i believe Jaa is talking about the downshift. Do your downshift as you're braking in a straight line approaching the corner. you're getting hung up on verbiage. If you're upshifting in the middle of leaving the corner, you probably should reconsider that downshift. No need to slow down just to accelerate, it's wasted time.

Bluefire

I D/S in braking zone (straight line only )

Coolant gets to ~220. However, I chose to bypass my radiator. My understanding is that the primary reason to route through the radiator was to "pre-warm" the ATF. I can't imagine routing the ATF through 220 degree coolant will dissapate much heat. I may be wrong though.

I set my shift times to 200 milliseconds. There are only three turns on this course that the trans could possibly D/S to 2nd. Those are the turns that I ensure I manually D/S to 2nd before the turn starts.

I'm at least 150' past the corner before I U/S to 3rd.

Thank you all for the insight.

Supercharged111

If your trans fluid is 235 all said and done, that 220* coolant might actually be doing something good. I don't think it'd hurt at all, because the fluid coming out of the trans is definitely hotter than 220. My truck (4L60E) has fluid hitting the radiator cooler, then the aux cooler. In the winter time, it takes damn near 10 minutes for the trans to get hot enough to allow the torque converter to lock. IMO with it running around 100*, that's too cold. Not necessarily cold enough to hurt things, but I think my winter MPG might go up a little were the fluid to stay at 150*. You live in OR, so I'm inclined to thinking you get some nippy winter air as well. Is your cooler a tube and fin or plate design? Got any pics? The charts I've seen have indicated that the max ideal temp for ATF is 180*. That being said, there are plenty of neglected cars running around coolerless that have had their transmissions going for 200k likely cooking around 220* in town, but after 1 season of HPDE (5 events) my ATF was cooked in my M12 and that's a manual. Take a sniff of the fluid, if it doesn't have an almost sweet smell to it you're getting it too hot.

I don't want to step on the toes of those who do track automatic cars, because most of what I've said is theory/good practice. If you've survived 5 years of tracking your car at 230*+, then that says something too. From all my research, ATF is one fluid you don't want to get super hot because it breaks down very quickly.

Bluefire

The cooler type I have is the plate type (25 plates). Here's a pic of the install.

http://forums.corvetteforum.com/auto...mp-update.html

I am also considering having the trans power flushed with synth ATF (Royal Purple, Redline). That should lower the temp another 10-20 degrees.

speedmon

235 isnt bad....especially when you're working it.
If you can smell it burning....thats bad.
Fluid should always be clear ruby red.

4L60E will last longer when you keep the temps under 200.

I've always routed through the radiator first then to the external.
....and a 160 T-Stat....and fan reprog....kept around 190.
Liquid cooling is much more efficient than air cooling.

And find a hose between sessions and run water over the external cooler while engine is running.....been there done that...works really well though....water cooled!

Boo383

I have tracked my A4 C5 quite a few times at VIR, and 235* is about the hottest temp I've seen.

blkbrd69

1.) Are there any issues with manually downshifting to 2nd on the track? NO

2.) Is 235 degrees too hot? (Never seen a DIC message A bit hot

3.) Will adding a fan on my trans cooler help? ...or a vented hood? YES

Some good reading for your auto.

http://forums.corvetteforum.com/auto...-course-t.html

Bluefire

Great thread! Thanks for the link.
I'm considering adding a SPAL fan on top of my external trans cooler. I would electrically tie it into the low side fan circuit.

Thanks a bunch.

Bill Dearborn

A club member went through a lot of that when tracking his S/C'd 99 that he drag races. Finally, he programmed the TCC to stay locked up while on the track and he shifts the tranny manually with the TCC locked. Don't know how it works with the TCC locked but he has been successful with the setup compared to ruining the tranny twice before changing the programming.

Bill