6AT and mods

[IDriveACamryNow]

So I thought I would post up my thoughts regarding the reservations I have regarding the longevity of the Auto transmission with modding and tracking. This no doubt has little interest to 6MT drivers.

At the recent EC track day, after a dozen or so laps (mostly at map 2/270rwkw) my transmission was practically toast. It didn’t throw any codes but was slipping and there was a clear power reduction to the point where it was pointless to continue. So now I want to explore what I can do to sort this out. Obviously an additional oil cooler for the ATF would assist in keeping the temps down and the fluid from cooking itself but there are a few things that I have found out that might also help.

The AT we supposedly have according to realoem is the ZF 6HP19Z. The 6HP19 is reportedly built for 400nm of input torque and was used in up until 09/2007. Since then, ZF’s 2nd generation transmissions such as the GA6HP21 came with massively lower shift times and input torque rating of 450nm. Supposedly, BMW is using the 6HP21 in our 2008+ cars but with the internal handle of 6HP19TÜ. Confused yet?

As additional input torque can stress the transmission, apparently additional weight for it to pull can be comparatively as stressful. Now the current F01 740Li uses the N54 (240kw tune) and current 6HP19TÜ but weighs an additional 490kg than the 135i and even the X6xdrive35i (similar setup as 740Li) weighs an additional 570kg!! The difference between us and them is the torque converter – we use the TC model A111 (#24407584406) whilst they use B111 (#24407584541). The older 6HP19 such as found in the pre-lci E90 3 series was the G99.

So, my assumption is that swapping over the torque converter to the B111 should make our ATs that much more bullet proof, so as to continue to push out much more power. I am sure that there is more to it than that (always is) but thought I might get some input from the rest of you.

[pavo335]

I recall you mentioning temps were a major issue, perhaps this was the cause of the loss of power? Might be easier to get the advan stage 1 oil cooler a go and take it from there?

[BBK]

Interesting... I personally haven't had any drivetrain issues so can't really add anything to the discussion. I don't think I've read about any issues besides this?

[RaihaX]

Originally Posted by BBK

Interesting... I personally haven't had any drivetrain issues so can't really add anything to the discussion. I don't think I've read about any issues besides this?

Quite a few guys in the states pushing their car with upgraded turbo had to upgrade their transmission.

[BBK]

Fair enough, but that is 300kw+?

[RaihaX]

Originally Posted by BBK

Fair enough, but that is 300kw+?

yeah and from the sound of it they go to the drags every second day!

[JB4-335]

Originally Posted by Drawn05

So I thought I would post up my thoughts regarding the reservations I have regarding the longevity of the Auto transmission with modding and tracking. This no doubt has little interest to 6MT drivers.

At the recent EC track day, after a dozen or so laps (mostly at map 2/270rwkw) my transmission was practically toast. It didn’t throw any codes but was slipping and there was a clear power reduction to the point where it was pointless to continue. So now I want to explore what I can do to sort this out. Obviously an additional oil cooler for the ATF would assist in keeping the temps down and the fluid from cooking itself but there are a few things that I have found out that might also help.

The AT we supposedly have according to realoem is the ZF 6HP19Z. The 6HP19 is reportedly built for 400nm of input torque and was used in up until 09/2007. Since then, ZF’s 2nd generation transmissions such as the GA6HP21 came with massively lower shift times and input torque rating of 450nm. Supposedly, BMW is using the 6HP21 in our 2008+ cars but with the internal handle of 6HP19TÜ. Confused yet?

As additional input torque can stress the transmission, apparently additional weight for it to pull can be comparatively as stressful. Now the current F01 740Li uses the N54 (240kw tune) and current 6HP19TÜ but weighs an additional 490kg than the 135i and even the X6xdrive35i (similar setup as 740Li) weighs an additional 570kg!! The difference between us and them is the torque converter – we use the TC model A111 (#24407584406) whilst they use B111 (#24407584541). The older 6HP19 such as found in the pre-lci E90 3 series was the G99.

So, my assumption is that swapping over the torque converter to the B111 should make our ATs that much more bullet proof, so as to continue to push out much more power. I am sure that there is more to it than that (always is) but thought I might get some input from the rest of you.

I think the ZF boxes can handle 300wkw (translates to approx. 340 crank kw) no problem IMO. It is a tough box and will be fine for 99.99% of guys running FBO + meth. You may have an isolated issue with your box.

[IDriveACamryNow]

Pushing the car hard on a race track like eastern creek and driving in traffic with the occasional squirt of power isn’t the same thing.

I would like the option of both of the above and want it also to be bullet proof. After looking at some pics of guys ATs that are 300rwkw+ and their fluid they drain out of it is brown (should be yellow) because it has started to cook. Also, its not the rwkw that is the measurement it is the input torque.

Who really knows what the consequence of high input torque stress is on the AT i.e. does the converter just stop delivering more power above a certain point and just start boiling the fluid?

[IDriveACamryNow]

Originally Posted by ianf

Tried a AT oil change?

Not yet. I have read of people swapping over the ZF lifeguard ATF for redline and other such 'performance' ATFs and having terrible shifting as a consequance.

11 litres of zf lifeguard would be some serious $$$ I would assume.

[RaihaX]

Originally Posted by ianf

Tried a AT oil change?

How often are you suppose to change the transmission fluid?

[IDriveACamryNow]

Some zf tech documents state a change is required every 100,000kms/62,000 miles. Maybe with mods the time should be sooner?

[RaihaX]

Originally Posted by Drawn05

Some zf tech documents state a change is required every 100,000kms/62,000 miles. Maybe with mods the time should be sooner?

I would assume so if its anything like oil change/ spark plugs, would be good to hear someone that is in the know.

[IDriveACamryNow]

Turner sell the filter kit for our AT for $177 but this isnt inclusive of the ATF. From what I understand, to get in at least 90% fresh ATF you need to flush it twice and the capicity of the system is 11 litres.

[JB4-335]

Originally Posted by Drawn05

Pushing the car hard on a race track like eastern creek and driving in traffic with the occasional squirt of power isn’t the same thing.

Originally Posted by Drawn05

I would like the option of both of the above and want it also to be bullet proof. After looking at some pics of guys ATs that are 300rwkw+ and their fluid they drain out of it is brown (should be yellow) because it has started to cook. Also, its not the rwkw that is the measurement it is the input torque.

Your gonna need $20-$30k to make your car bullet proof. Gotta pay to play. Our engines produce their highest torque outputs approximately in the middle of the range, while the most torque is required when the vehicle is moving from rest or traveling slowly.

[IDriveACamryNow]

For those interested, I just pick up a 6HP21 Transmission fluid and filter change kit from ECS Tuning for $215. Its ZF branded and is about $100 cheaper than the BMW branded version - but same thing!

Should take about a week to arrive so hopefully Advan can acquire enough of the LifeGuard 6 to do a decent flush.

I am also negotiating a deal to get a E92 M3 rear axle + 3.85 M Differential, which will more than likely place more strain on the transmission, once installed. Once that is sorted out, I am turning my attention to replacing the AT radiator to a MT version ($400 incl. shipping) and having a dedicated ATF cooler installed on the passengers side duct.

[BMW86]

Originally Posted by Drawn05

For those interested, I just pick up a 6HP21 Transmission fluid and filter change kit from ECS Tuning for $215. Its ZF branded and is about $100 cheaper than the BMW branded version - but same thing!

Should take about a week to arrive so hopefully Advan can acquire enough of the LifeGuard 6 to do a decent flush.

I am also negotiating a deal to get a E92 M3 rear axle + 3.85 M Differential, which will more than likely place more strain on the transmission, once installed. Once that is sorted out, I am turning my attention to replacing the AT radiator to a MT version ($400 incl. shipping) and having a dedicated ATF cooler installed on the passengers side duct.

I'd like to go down this route for the radiator and ATF cooler too

[IDriveACamryNow]

Originally Posted by BMW86

I'd like to go down this route for the radiator and ATF cooler too

It would be a similar setup to what the F10 M5 (w/DCT) has, just a long oil cooler independent of the radiator/coolant.

What the F10 740Li (also N54) has though, is a bar/plate heat exchanger that is cooled by coolant from the main reservoir that is then sent to a secondary radiator in the left air duct that is then connected back to the main radiator. I am no engineer or mechanic but this might allow for better engine/coolant temps as well as stable atf temps, as too cold is almost as bad as too hot.

This is our setup




This is the F01 740Li setup - This has the advantage of not having the ATF coolant mechanism exposed to external damage i.e rocks and debris. Oil level is monitored by the dme but ATF is not, so you wouldn’t know if you had a leak until you literally grind to a halt.





I have been talking to Peter and Justin about this for a while now and, ultimately, I will go with what Advan can fab up for me but it is interesting to see what the 740Li has as it uses the same 6HP21 as we do, so the ATF lines would be the same (I assume). It also has the same water pump as we do so I also assume we could run an extra radiator and not have coolant flow issues?

[TimMc]

"I also assume we could run an extra radiator and not have coolant flow issues?"
Just like the extra radiator I have and that the 1M runs?

[pavo335]

Originally Posted by TimMc

"I also assume we could run an extra radiator and not have coolant flow issues?"
Just like the extra radiator I have and that the 1M runs?

Hey I forgot you got the ppk from SBM, all installed and fine?

[TimMc]

Originally Posted by pavo335

Hey I forgot you got the ppk from SBM, all installed and fine?

Nah, still working interstate

[IDriveACamryNow]

Originally Posted by TimMc

"I also assume we could run an extra radiator and not have coolant flow issues?"
Just like the extra radiator I have and that the 1M runs?

Going off the pics, the extra radiator is much, much bigger than the additional 135/1M version. It looks to be almost as tall as the main radiator!

ED: also, I was only using this setup as an example of what could be done for the 135i, other than a dedicated ATF cooler. Also, I think the 740li has a much bigger main radiator too.

[MrBlonde]

Steve I'd think your issues are heat related? My thoughts are:

1. Have your bleeder fully serviced ASAP
2. Increase your bleeder maintenance program significantly. Tranny fluid change after every track day?
3. Heat management! Do some research on what others (USA?) have done when circuit racing bleeders in terms of fabricating a tranny cooler somewhere on your rig. The airflow under the car to the back of the vehicle should be enough (with a tranny cooler) to make a huge difference.

Try not to reinvent the wheel, there are usually others who have blazed the trail for you. Being the first one means you bear the lion's share of R&D costs. Who needs that?

If you must trailblaze then try to partner with others in the same boat, or cut a deal with a workshop/fabricator to share the risk/reward in some way.