Auto trans fluid for HPDE?

[PortlandWineGuy]

I'm wondering if I can/should use a high temp/racing transmission fluid in my daily driver that occasionally sees track days/nights; just 2-4 per year.

Details:
128i N51 ZF automatic transmission, 120k miles
Eibach springs, koni adjustable, continental extreme contact sport, aFe filter, high temp brake fluid, cool carbon brake pads.

I bought the car with 88k miles, no maintenance records so proceeded to replace all fluids including trans and diff fluid. Did 3 or 4 SCCA track nights in summer 2016 after purchase, and another 3 track nights (each with 3 20-minute sessions at full pace) so far this year. Although it never threw a CEL, the car would suddenly stop revving up easily and lose almost all power after 10 to 18 minutes of HARD (95-100% of limit) driving. Figured out that it's the auto trans overheating. Ran with electronic aids on trans turned completely off (press and hold traction button). Running heat on full blast with closed center vents and side vents pointing out windows kept it from happening until the 18th minute of my 20 minute sessions this summer. After cool down I could do another 15-19 minutes before it would happen, depending on heat of the track/day.

Now that I've boiled/overheated the trans fluid on each of these sessions and ran it 30k miles, should I replace the fluid now or wait until spring (40k miles), before my next track days/nights? I'll probably only do 3-5 track nights and days next year. If this keeps happening I might only do track nights. If I can resolve it I'd try a full day.

Should I try using a higher temp auto trans fluid (ATF)?

Before the trolls come a trolling: I'll buy a dedicated track toy as soon as I can afford it. Until then my DD serves dual use.

[WhatsADSM]

Honestly if it ain't broke don't fix it. I would use whatever the oem fluid is personally. The issue isn't really the fluid so much as the temp.

Have you considered adding a trans cooler of some sort? Not sure about how the ZF trans in the 128i is setup. Is there any cooler in there now?

[Taskmaster]

Originally Posted by PortlandWineGuy

I'm wondering if I can/should use a high temp/racing transmission fluid in my daily driver that occasionally sees track days/nights; just 2-4 per year.

Details:
128i N51 ZF automatic transmission, 120k miles
Eibach springs, koni adjustable, continental extreme contact sport, aFe filter, high temp brake fluid, cool carbon brake pads.

I bought the car with 88k miles, no maintenance records so proceeded to replace all fluids including trans and diff fluid. Did 3 or 4 SCCA track nights in summer 2016 after purchase, and another 3 track nights (each with 3 20-minute sessions at full pace) so far this year. Although it never threw a CEL, the car would suddenly stop revving up easily and lose almost all power after 10 to 18 minutes of HARD (95-100% of limit) driving. Figured out that it's the auto trans overheating. Ran with electronic aids on trans turned completely off (press and hold traction button). Running heat on full blast with closed center vents and side vents pointing out windows kept it from happening until the 18th minute of my 20 minute sessions this summer. After cool down I could do another 15-19 minutes before it would happen, depending on heat of the track/day.

Now that I've boiled/overheated the trans fluid on each of these sessions and ran it 30k miles, should I replace the fluid now or wait until spring (40k miles), before my next track days/nights? I'll probably only do 3-5 track nights and days next year. If this keeps happening I might only do track nights. If I can resolve it I'd try a full day.

Should I try using a higher temp auto trans fluid (ATF)?

Before the trolls come a trolling: I'll buy a dedicated track toy as soon as I can afford it. Until then my DD serves dual use.

Awesome, I love seeing people use their toys!

I would strongly recommend a transmission fluid cooler and possibly updating the software for quicker shifts (slips the transmission less) rjahl can provide you with the software upgrade and you can DYI the cooler.

[rjahl]

Originally Posted by TheAxiom

Awesome, I love seeing people use their toys!

I would strongly recommend a transmission fluid cooler and possibly updating the software for quicker shifts (slips the transmission less) rjahl can provide you with the software upgrade and you can DYI the cooler.

What makes the OP think the trans overheated? Did he get a warning on in the Kombi? I'm pretty sure the trans overheat will just lock you into a gear and throw a gear warning light without a power cut.

I would not change to a high temp fluid. The transmission is designed for a specific fluid with specific friction coefficients and viscosity. Anything other than OEM fluid will not work correctly. In any case, it's the hi temps you need to avoid. I do recommend changing fluid every 50,000.

Before I modified anything, I would check to insure that the cooling system is working like it should. I'm pretty sure you have a trans cooler built into the radiator and take note that there is a thermostat in the radiator that controls the trans fluid temp.

Regarding the trans tune , I've learned a lot about the ZF transmission and one item of recent discoveries me is the Torque Converter Clutch operation. It seems like the TCC spends a crap load of time in a "modulated" mode where the clutch is only partially engaged. Any constantly slipping clutch can build up a bunch of heat that the cooling system will need to deal with. One of my next experiments will be to lock up the TCC sooner and try for a full time TCC lock up in manual mode.

Recent logs in my Z4 show the TCC never locked up through a full 0-80 MPH WOT run that included 7,100 RPM shifts. Normal driving in 6th gear have the TCC in modulated mode up to 2,500 RPM where it registers a full lock up.

[Taskmaster]

Originally Posted by rjahl

What makes the OP think the trans overheated? Did he get a warning on in the Kombi? I'm pretty sure the trans overheat will just lock you into a gear and throw a gear warning light without a power cut.

I would not change to a high temp fluid. The transmission is designed for a specific fluid with specific friction coefficients and viscosity. Anything other than OEM fluid will not work correctly. In any case, it's the hi temps you need to avoid. I do recommend changing fluid every 50,000.

Before I modified anything, I would check to insure that the cooling system is working like it should. I'm pretty sure you have a trans cooler built into the radiator and take note that there is a thermostat in the radiator that controls the trans fluid temp.

Regarding the trans tune , I've learned a lot about the ZF transmission and one item of recent discoveries me is the Torque Converter Clutch operation. It seems like the TCC spends a crap load of time in a "modulated" mode where the clutch is only partially engaged. Any constantly slipping clutch can build up a bunch of heat that the cooling system will need to deal with. One of my next experiments will be to lock up the TCC sooner and try for a full time TCC lock up in manual mode.

Recent logs in my Z4 show the TCC never locked up through a full 0-80 MPH WOT run that included 7,100 RPM shifts. Normal driving in 6th gear have the TCC in modulated mode up to 2,500 RPM where it registers a full lock up.

I don't know that the transmission overheat always throws a code. tetsuo111 had issues where his car would cut power without any indication as to why, and it's something I've seen a few 335i guys speak about.

[WhatsADSM]

Originally Posted by rjahl

What makes the OP think the trans overheated? Did he get a warning on in the Kombi? I'm pretty sure the trans overheat will just lock you into a gear and throw a gear warning light without a power cut.

I would not change to a high temp fluid. The transmission is designed for a specific fluid with specific friction coefficients and viscosity. Anything other than OEM fluid will not work correctly. In any case, it's the hi temps you need to avoid. I do recommend changing fluid every 50,000.

Before I modified anything, I would check to insure that the cooling system is working like it should. I'm pretty sure you have a trans cooler built into the radiator and take note that there is a thermostat in the radiator that controls the trans fluid temp.

Regarding the trans tune , I've learned a lot about the ZF transmission and one item of recent discoveries me is the Torque Converter Clutch operation. It seems like the TCC spends a crap load of time in a "modulated" mode where the clutch is only partially engaged. Any constantly slipping clutch can build up a bunch of heat that the cooling system will need to deal with. One of my next experiments will be to lock up the TCC sooner and try for a full time TCC lock up in manual mode.

Recent logs in my Z4 show the TCC never locked up through a full 0-80 MPH WOT run that included 7,100 RPM shifts. Normal driving in 6th gear have the TCC in modulated mode up to 2,500 RPM where it registers a full lock up.

Good point. I just took the OP at his word about trans temps.

There are quite a few nannies that can cause power reduction, oil temp, water temp, calculated brake over temp, etc. OP I would be sure it's trans temp related first.

[desertman123]

You have a BMW scan gauge? Log some temps. I think Carly can do this

[PortlandWineGuy]

Originally Posted by rjahl

What makes the OP think the trans overheated? Did he get a warning on in the Kombi? I'm pretty sure the trans overheat will just lock you into a gear and throw a gear warning light without a power cut.

I would not change to a high temp fluid. The transmission is designed for a specific fluid with specific friction coefficients and viscosity. Anything other than OEM fluid will not work correctly. In any case, it's the hi temps you need to avoid. I do recommend changing fluid every 50,000.

Before I modified anything, I would check to insure that the cooling system is working like it should. I'm pretty sure you have a trans cooler built into the radiator and take note that there is a thermostat in the radiator that controls the trans fluid temp.

Regarding the trans tune , I've learned a lot about the ZF transmission and one item of recent discoveries me is the Torque Converter Clutch operation. It seems like the TCC spends a crap load of time in a "modulated" mode where the clutch is only partially engaged. Any constantly slipping clutch can build up a bunch of heat that the cooling system will need to deal with. One of my next experiments will be to lock up the TCC sooner and try for a full time TCC lock up in manual mode.

Recent logs in my Z4 show the TCC never locked up through a full 0-80 MPH WOT run that included 7,100 RPM shifts. Normal driving in 6th gear have the TCC in modulated mode up to 2,500 RPM where it registers a full lock up.

Thanks for the advice!

I'm not getting a CEL/gear warning light. I'll try pulling codes with my Carly but I don't think I can make it to any more track events before the rains/winter come. Maybe there will be some stored though. We tried pulling codes before and couldn't find anything using a scanner but my Carly found a few codes but I had believed unrelated to trans/overheating but could have been wrong. Any ideas which ones they might be?

Trans cooler is built in to radiator. Extra cooling systems seem to help a little or sometimes for some others facing this issue IIRC, but they cost $700+ (IIRC). If I could know it would help I might go this route but might rather save that money for a dedicated track toy.

The reason I believe it's overheating is that I read about these issues on the e90 forums, that the transmission won't shift easily nor allow power delivery when it happens on track, but returns to normal after cooling down (Sounds like TCC/clutch?!). By removing lower engine/trans plastic shield and running heat on full blast I was able to drive it harder, longer before issue occurred.

I'm very interested in a tune/TCC fix if possible. Details?

[WhatsADSM]

Originally Posted by PortlandWineGuy

Thanks for the advice!

I'm not getting a CEL/gear warning light. I'll try pulling codes with my Carly but I don't think I can make it to any more track events before the rains/winter come. Maybe there will be some stored though. We tried pulling codes before and couldn't find anything using a scanner but my Carly found a few codes but I had believed unrelated to trans/overheating but could have been wrong. Any ideas which ones they might be?

Trans cooler is built in to radiator. Extra cooling systems seem to help a little or sometimes for some others facing this issue IIRC, but they cost $700+ (IIRC). If I could know it would help I might go this route but might rather save that money for a dedicated track toy.

The reason I believe it's overheating is that I read about these issues on the e90 forums, that the transmission won't shift easily nor allow power delivery when it happens on track, but returns to normal after cooling down (Sounds like TCC/clutch?!). By removing lower engine/trans plastic shield and running heat on full blast I was able to drive it harder, longer before issue occurred.

I'm very interested in a tune/TCC fix if possible. Details?

CSF sells an upgraded radiator (PN #7046) for the automatic 135i/335i guys. I'm not sure if this is compatible with the 128, however it is very well reviewed by everyone that has it (myself included), and its relatively inexpensive as well (~$500).

[Dackelone]

On the 128i the trans is a GM French made trans. I think I would just do a trans service(ATF and pan filter change). I would contact Red Line oils and see which one of their ATF's they would recommend for HPDE's. Probably ATF-D6, but check with Red Line.

https://www.redlineoil.com/application.aspx


I think it's cool you are using your 128i for track use. As far as new SW for the trans... I don't believe there is any SW for the GM trans. Only for the ZF unit, that Alpina has hacked and offers their AT tune. That AT sw flash is out on the webs for free. But nothing for the 128i I am afraid.

Btw... you should also be changing your brake fluid, PS fluid and trans and diff fluids besides your engine oil.

Dackel