Transmission oil cooler? 1988- 911

[hunterpeaks]

Is there such a thing? I am thinking I need one.

I have re-built my G50 Transmission this winter, and it's still grinding gears from 2nd to 3rd, after about 30-45 minutes of hard driving on the track.
UGH.

Never happens when just driving around and won't happen in the first session of the day. But, always in the 2nd session of the day after about 30minutes of hard driving and lotsa gear changing. Then it's like the oil never cools after that and it will grind in the remaining sessions.

Can I buy one? Do I need to make one? Anybody help?

Thanks.
Hunter

[Bill Verburg]

According to the g50 afficianados on another thread g50s never have such issues

My first guess is that the trans needs a rebuild, as an interrim band aid you might try different fluid. What's in there now?

Yes, you can install a cooler. The install will be similar to that in a 915

something like this








This one uses another Setrab stacked on top of the 2nd engine cooler



there are also internal spray bars that can be added, again similar to a 915.

the ultimate would be a cooler/heater as used on the 996/997 tt/GT3/RS/RSR

[KTL]

Aficinados........ Oh ho! That's a dig right at me..............

That's not a pleasant feeling- still crunching after you spent the time & bucks to rebuild. Sorry to hear it. What did you actually do to rebuild? Because a fresh G50 should not crunch with the right fluid and right fresh components.

Still, a cooler is a wise investment because it goes a LONG way toward keeping the fluid cool and extending the life of the trans. Currently the only thing keeping the fluid cool is alloy heat transfer from the case. The cooler the fluid, the longer the life of the trans internals. Problem is, how do you practically install one? Most people install the cooler in the fender well and plumb a oil pump to it for circulation. Keep in mind your cooler location also needs airflow, via fan or vehicle motion air, to make the cooler most effective instead of the cooler simply being a radiant cooler in stagnant air.

Again, the problem is then finding a suitable place to install and supply oil to the pump. For a full-on track car, this is not a problem- cut and drill and mount things wherever its most convenient. If your car is a dual-purpose one, that's a decision you'll have to make. I've been debating this on my car for years. Just haven't yet spent the time to sort out where things can go to work effectively and efficiently- both the cooler & oil pump. Plus you have to decide where you want to feed the oil to the trans. Do you dump the oil on the ring & pinion or somewhere near the gear stack or both? This is typically done with a spray bar inside the case to get cool oil everywhere and not a basic do-it-yourself creation. Although I tend to think simply introducing cooler oil anywhere within the trans is a benefit. That's just my uneducated opinion.

Chris at Motodelta can give you some advice how to plumb an oil pump and cooler to the trans. His username here is cstreit.