Hi,

I am looking for some information and ideas for installing some extra cooling capacity for the tiptronic transmission of my NA 996 C2. I am tracking the car and want to be sure everything stays cool to reduce wear to a minimal.

As the tiptronic transmission of the 996 NA an Turbo are based on the same 722.6 Benz transmission I am putting the question here. As the Turbo tiptronic gets tuned and modified more regularly to cope with possible big increases in hp.

I will need to get my tip tranny rebuild soon. Got some overheating last time. And think I got some extra wear and tear on the clutches and torque converter. Will do some minor upgrades on friction plates and the valve body will be modified with other solenoids for improved pressure and shifting.

At the same time I want to install some additional cooling for the atf. Just to keep things cool in case.

Is there an easy upgrade for the existing water/oil cooler? Like a bigger cooler with more capacity which replaces the existing one.

Adding an extra air/oil cooler is the most standard solution I suppose. But I am not in favour running long lines to front of the car and back. Is there a solution to fit an additonal cooler underneath with i.e. an air scoop, right next to the existing one. That should be perfect

 

Isn't there already a Tip fluid cooler located behind the center radiator?

If the Tip is due to be rebuilt/refreshed that should help it run cooler as the clutch bands will slip less and generate less heat.

 

No, there is only the water/oil cooler next to te transmission. Allthough the NA 996 tip cars have standard the 3rd radiator in the front. This is to add extra cooling capacity for the coolant, due to the transmission cooler. I suppose it is also the case for the turbo cars with a tiptronic.

In the 997TT forum they make reference to some cooler kits that some tuners sell. One of them ESmotors. I have contacted them but did not get much info.

 

maybe something like what pwdrhound built for his manual.

https://www.6speedonline.com/forums/...il-review.html

 

That looks indeed very promising.

 

With the stock water to liquid cooler, you will never see trans temps much below engine temps, I would suggest adding an air to fluid cooler by tapping the trans cooler line that goes to the passenger side of the trans. This is the fluid line that takes the fluid back to the trans after the factory water to liquid cooler. Placement of this cooler would have to be in front of the center radiator, as I really don't think you will get it under the car with an air scoop. There is a diverted valve by the factory cooler, you want to make sure that is opening, or the trans will overheat.

You could also separate the factory trans cooler and put it on its own circuit, this is much harder and complex, so I would highly suggest the air option. There are also trans line thermostats that make sure you don't run the trans too cool if you are driving in cold winter climates

 

That setup above would work well, you would definately have to run it in series with the factory setup, as running it alone would get trans temps hit in traffic and at low speed for an auto trans. The 722.6 has an internal sensor that will allow you to look at trans temps, so if you have a diagnostic tool you can read this.

 

I put this in front of my center radiator to keep my freshly rebuilt 6sp cool on the track.

 

That's clever nicely done.

 

I maybe missing something here, but trying to pump 75w90 gear oil though the confines of the added radiator doesnt seem like it would work. at operating temp the gear oil is 90 weight. Thats super thick. I wouldnt think that it would move fast enough through the system to really do much. Does anyone have any flow rates through the added radiator? The oil cooler pictured above looks like it could handle auto trans fluid with ease, but 90 weight gear oil I am skeptical.

As for the OP, I think that the added radiator would be of much benefit for a torques converter based auto trans.

EDIT: Had a brain cramp and got weights backwards. CDK pointed it out for me Thanks!

 

Yes you are missing the fact that oil does not get thicker as it gets hotter. The weight ratings are difficult at best, but the simple fact remains that oils are "thinner" at higher temperatures.

 

I had a brain fart there for a minute i guess, thanks for the correction :/ Even still though at 75 weight, that is still darn thick to try to pump. It would be good to see the pressure and flow rate after going through the added radiator posted in the pic. I did some searching on Summit and the best on I could find was 60 psi flowing 1-2 gallons per minute. It would make sense that the radiator would restrict the flow significantly b/c of the geometry of the cooler. It would be good to get some empirical data to see.

https://goo.gl/vL4hHG
I am assuming that the flow and pressure are for 75w-90 gear oil since it is design to pump diff fluid.

 

The transmission 75/90 at 200. F is pretty thin oil. I would guess that some manual trans temps exceed that easily, and probably are closer to 250 when pushed hard, and with no cooler. I agree that cooler is more suited to 20w auto trans fluid, but may work if the pump was wired to a switch to be turned on at hotter temps

 

I know we got OT here, but am i reading this wrong. It appears that the oil does gets thicker as temperature increases. i.e. it would be 75 weight (75winter rating) and then goes to 90 weight when it hits 100 degs C.

http://www.upmpg.com/tech_articles/motoroil_viscosity/

 

Disregard. After reading it more thoroughly, i get it now.