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      09-14-2012, 02:18 AM   #1
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AT Transmission Mods

Hello dear co-addicts,

I've read a few threads about level 10 tranny upgrades, so please dont send me there. Instead, if anybody has knowledge(or even better experience) in AT transmission strengthening mods, please, do share. I'm not looking to spend 4k+ for the level 10 kit, and have my car down for a month. If you have any ideas as far as strenghtening the AT tranny to handle close to 500rwhp, please share!

Thank You

Last edited by Sick335; 10-28-2012 at 09:34 PM.
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      09-14-2012, 02:50 AM   #2
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Are you having issues with your AT with 500whp?
Cheap way would be to keeps AT oil temps under control with an oil cooler.
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      09-14-2012, 03:47 AM   #3
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Quote:
Originally Posted by enrita View Post
Are you having issues with your AT with 500whp?
Cheap way would be to keeps AT oil temps under control with an oil cooler.
Not yet i'm not, but after doing some research it would be nice to get some reasurance. Getting RBs installed soon. I already have the stock oil cooler, and also putting in CPE oil cooler when doing the rbs install.
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      09-14-2012, 04:55 AM   #4
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i am talking about AT oil , not engine oil
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      09-14-2012, 06:19 AM   #5
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Quote:
Originally Posted by enrita View Post
i am talking about AT oil , not engine oil
I've been thinking more and more about this recently. I don't see why it wouldn't be possible to bypass the ATF/water heat exchanger and mount a dedicated ATF cooler in front of the drivers wheel. A thermostats such as Earl's 501ERL could be used to keep the temperature in the operating range. I don't know this for certain, but I would have to assume the engineers at ZF designed the transmission to operate with the fluid above ambient.

My car did not come with an oil cooler so I plan to retrofit one as outlined here:
http://www.e90post.com/forums/showthread.php?t=525795

This same approach should work in front of the drivers side wheel for an ATF cooler.

I agree the best thing to do to protect the auto tranny is to keep the fluid temp n check.
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      09-14-2012, 07:06 AM   #6
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Quote:
Originally Posted by enrita
i am talking about AT oil , not engine oil
Did you ever figure out how to set one up?
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      09-14-2012, 10:23 AM   #7
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After reading some more, I have an idea.

The stock "cooler" setup is an ATF/water heat exchanger. During warm up, the coolant is warmer than the ATF, and heat flows from the engine coolant to the ATF to bring it up to operating temperature faster. Once the engine is hot, the ATF is warmer than the coolant, and heat flows in the opposite direction.

So my idea is to place to an axillary cooler before the stock heat exchanger in the ATF cooling circuit. This way, cold ATF would flow through the aux cooler, then to the exchanger where it would pick up heat from the water on its way back to the transmission. Once everything is warmed up, hot ATF would flow through the aux cooler first, lower its temperature, then it would flow through the heat exchange where one of two things would happen. If the ATF was still hotter than the coolant, heat would flow into the coolant. However, as long as the cooler is sized properly, the ATF should be below the water temperature, in which case the ATF would be brought to the coolant temperature and return to the transmission.

Regardless, the ATF would transfer less heat to the coolant with an axillary cooler placed before the heat exchanger in the cooling circuit. The greater temperature differential between the air/ATF with the aux cooler compared to the coolant/ATF heat exchanger should result in improved cooling of the ATF, as well. This depends on the size of the aux cooler, but with the aux cooler before the stock heat exchanger, you shouldn't be able to make it too big, even in northern states.
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      09-14-2012, 10:50 AM   #8
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Last edited by N54_Fan; 10-25-2012 at 07:59 PM.
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      09-14-2012, 11:36 AM   #9
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From what I can find, ATF has a specific heat half that of water. Of course not all ATF is created equal, but this estimation is better than nothing.

http://books.google.com/books?id=Mp4...20heat&f=false

http://www.engineeringtoolbox.com/sp...ids-d_151.html

Looks like 0.5 Cal/gC is 0.5 Btu/lb.F from two different specific heat conversion calculators I tried.

Maybe one of the aftermarket shops who works on the zf transmissions would know the flow rate of the pump.

You would still need to know the temperature differential between the hot fluid and ambient air to calculate BTU/hr through an air oil cooler, right?
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      09-14-2012, 12:06 PM   #10
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Last edited by N54_Fan; 10-25-2012 at 07:59 PM.
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      09-14-2012, 12:11 PM   #11
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Quote:
Originally Posted by N54_Fan View Post
I am working on getting data on the ATF temps but suspect they are only a ~10 C hotter than the water temp at normal driving. I may know the answer to this during this weekend. Water temps are between 97-102 C with daily driving. So I think ATF will be about 107-112 C. Even spirited driving with some WOT pulls gets my water temps only up to 108 C.
I think using 'M' mode produces the most heat, from what I have read at least. If so, this is the use case we should be targeting with the cooler upgrade.

As a side note, do you know which line is which on the transmission? One supplies fluid to the heat exchanger, and one is the return back to the transmission. The realOEM and Tischer diagrams are ambiguous, in my opinion.
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      09-14-2012, 12:24 PM   #12
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maybe i got excited an missread topic, a firmer shift, if you have never been a car that shifts on time and firmer you are really in for treat. Im talking about scary almost out of control (can be) that should increase trans life because of less heat build uo (sliding in gear vs on time shift firmness) which translates to cooler clutches in the auto. i wish there was software out there to raise line pressure
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      09-14-2012, 03:59 PM   #13
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http://www.importperformancetrans.co...sion-4149.html

IPT, not Level10 for your AT needs. I know that's where I'll be going. Level10 fuqd with AT Subarus to the point someone had to spend 15k on top of the 4k just to get it right (Level10->Repairs->IPT).
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      09-14-2012, 07:50 PM   #14
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Quote:
Originally Posted by cityazndan View Post
http://www.importperformancetrans.co...sion-4149.html

IPT, not Level10 for your AT needs. I know that's where I'll be going. Level10 fuqd with AT Subarus to the point someone had to spend 15k on top of the 4k just to get it right (Level10->Repairs->IPT).
They still do not address the cooling issues though.

Amazing that after over 5 years this platform still has no cooling upgrades for the trans. There are many threads on the subject yet no vendor has taken the opportunity to develop something.
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      09-15-2012, 08:37 PM   #15
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Hi guys,

Nice thread, just to add some to the discussion, I have had the possiblity to analyse two ZF gearboxes with a AT diagnostic tool. Both came from a heavily tuned 335, one FBO mine was a FBO + RB's.

The FBO has 105000km and mine had 160000km tuned from it's birth.

The AT has memory that stores all kind of historical data, also a table with an operation temp range and the amount of time spend within each subrange.

I was surprised to see that the FBO, the car was never tracked, did not spend any time in the critical time range. Mine, a car that is tracked about 30 times on a racetrack (not 1/4mile), for more then 60 hours, did only spend about a hour within a temp range above the critical temp. (I thought this is is above 130 degrees celcius.)

Another thing I found was that the box temp is, during warm up, about 20 degrees celcius behind the engine temp, till the engine reaches 115 / 120 degrees celcius (Fully warmped up). The box requires a min temp of about 90 degrees celcius for max load, before that temp, high load is not recommend, so this means men should be carefull when you warm up your car, engine temp is not equal to the box temp, getting your engine up to 90 degrees is not sufficient for the gearbox.

Biggest problem for this AT is not the temp, it is the materials used for the clutchplates. Also for optimizing this box, real software adjustments are required. So far I have not found anybody outside BMW (Not ZF!) that has access to it and can adjust it.

In my gearbox, clutchplates 2-5 were completly gone. 1 and 6 in a pretty good state. This was after 150000km, while pushing the car most of the time.
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      09-15-2012, 11:33 PM   #16
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Last edited by N54_Fan; 10-25-2012 at 07:59 PM.
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      09-17-2012, 09:07 AM   #17
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I believe as the temperature of the ATF increases, the life of the transmission decreases exponentially. I read the entire chapter 2 out of the Google book (Handbook of Lubrication and Tribiology: Volume I Application and Maintenance) I posted over the weekend, and it was informative.

From what I've read, the "lifetime" fluids are designed to change very little in viscosity during their life. So a good indication of the health of the transmission may be to do regular UOA on the ATF to spot trends in the change in viscosity.

My reading also seems to indicate that oxidation of the fluid is very bad (sounds obvious) "with temperature being the key factor". Oxidation will cause changes in the viscosity characteristics, formation in insolubles (sludge, varnish, etc.), internal corrosion, and failure of seals.

I would say if your fluid spends any time above this "critical" temperature as read with the Bav Tech tool or others, it should be changed. Also, it looks like a trans cooler is a necessity for an AT car that is tracked to prevent these high temperatures.

Because the ATF is expected to do so much (transfer heat, lubricate, transfer power, prevent corrosion), the health of the AT is directly linked to the health of the ATF. So the easiest way to ensure your transmission lasts a long time may be to change the ATF regularly.

A second option would be the trans cooler if you plan to track the car, and if you decide to go pretty far to increase the torque output of your engine, an upgraded valve body or high performance clutch packs might be a good solution. Both Level 10 and IPT offer a service to upgrade your valve body, and both also offer rebuild kits.

Level 10 also has some sort of software upgrade for sale. I wonder what exactly that is.
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      09-17-2012, 11:58 AM   #18
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Last edited by N54_Fan; 10-25-2012 at 08:00 PM.
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      09-17-2012, 03:08 PM   #19
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Quote:
Originally Posted by N54_Fan View Post
I have tried to estimate how much BTU thermal loss we should shoot for in an appropriate tranny cooler. There are 2545 BTU per HP. Therefore if we are running 200 HP over stock (lets say 500 hp) then we should want a tranny cooler that is rated to 500,000 BTU....wow!! It does not exist! When I looked at the various Corvette and Monster truck type of forums they generally ran as big a tranny cooler that would fit and have reported giid results. Some of the best ones out there are the Hayden Rapid Cool and the B&M Racing Universal Supeecooler series. I have narrowed it down to these two. They are both bar and plate designs which is most efficient.
I don't think that is the proper way to size the transmission cooler.

BTU's are energy, and horsepower is power. Power = energy / time. Most transmission coolers are rated at a BTU/hour value, which is also power (energy / time). Now your conversion factor of 2544 is correct for converting HP to BTU/hr, but your fault lies in your reasoning that all of your horsepower in excess of stock is going to be dissipated in the transmission.

The transmission has a certain efficiency rating, and this is how much of the engine's power that is lost in the transmission. This assumes you are in a gear and the clutch packs are not slipping. When the gears change, the clutch packs disengage and re-engage and in doing so slip. This generates a lot of heat very quickly. I think its a rapid change of gears that is causing the heat buildup in the transmission, and forcing the ATF beyond the critical temperature of 130 C. The toque converter also produces a significant amount of heat, but I am not sure when it is locked in this car. A locked torque converter should produce far less heat (maybe none) compared to an unlocked one.

We need to know how fast the fluid changes temperature over time to be able to calculate the size of the cooler. The only way to do this would be to measure the fluid as it exits and enters the transmission. This would depend on how you were driving. So if you wanted to size a cooler for a road course, you'd want to do a couple laps and log the temperature values. We know the specific heat of ATF and also the volume of ATF, so we should be able to calculate how much heat flows into the ATF over time once we have logs of how the temperature changes.

I personally do not have the means or opportunity to take these measurements. Also, looking over the calculations, I see things I remember from school, but my specialty is electronics, not thermodynamics. I would sooner say use the cooler size referenced in the link I posted in post #5 because it seems to fit reasonably well.
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      09-17-2012, 03:37 PM   #20
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I have also noticed that since my BMW dealer changed my ATF Fluid, on my request, my problems started.
This gave me the idea that the filling process in the factory might be different then somebody outsite of the factory can do. I'm thinking in the direction of filling under pressure/vacuum, minimizing things like the amount of oxygen in the box.

Might be an incorrect thought, but maybe usefull to share.
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      09-17-2012, 08:05 PM   #21
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Last edited by N54_Fan; 10-25-2012 at 08:00 PM.
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      09-18-2012, 03:48 AM   #22
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Quote:
Originally Posted by ajm8127 View Post
I believe as the temperature of the ATF increases, the life of the transmission decreases exponentially. I read the entire chapter 2 out of the Google book (Handbook of Lubrication and Tribiology: Volume I Application and Maintenance) I posted over the weekend, and it was informative.

From what I've read, the "lifetime" fluids are designed to change very little in viscosity during their life. So a good indication of the health of the transmission may be to do regular UOA on the ATF to spot trends in the change in viscosity.

My reading also seems to indicate that oxidation of the fluid is very bad (sounds obvious) "with temperature being the key factor". Oxidation will cause changes in the viscosity characteristics, formation in insolubles (sludge, varnish, etc.), internal corrosion, and failure of seals.

I would say if your fluid spends any time above this "critical" temperature as read with the Bav Tech tool or others, it should be changed. Also, it looks like a trans cooler is a necessity for an AT car that is tracked to prevent these high temperatures.

Because the ATF is expected to do so much (transfer heat, lubricate, transfer power, prevent corrosion), the health of the AT is directly linked to the health of the ATF. So the easiest way to ensure your transmission lasts a long time may be to change the ATF regularly.

A second option would be the trans cooler if you plan to track the car, and if you decide to go pretty far to increase the torque output of your engine, an upgraded valve body or high performance clutch packs might be a good solution. Both Level 10 and IPT offer a service to upgrade your valve body, and both also offer rebuild kits.

Level 10 also has some sort of software upgrade for sale. I wonder what exactly that is.
as far as i know only BMW - ZF - Alpina can flash the TCU . nobody else can.
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