Trans Cooler - temp setting?
 

I'm hooking up the electricals to my trans cooler. I'm using a Hayden adjustable thermostat, and I've clipped the sensor to the side of the differential housing, out of convenience more than thanything, but from what I'm told, the diff gets very hot, so it works for me.

At what temp should I set the pump to come on? My first WAG at setting it has it coming on @ 240F, and it goes off about 220 on it's own. I'm using an IR gun to test temps and an electric heat gun to simulate the thermal load.

I'll post pix later of the completed setup.

I think your target range is too high. I think you want to be in the 180 range, similar to the engine.

I've been seeking good data on temperature vs. life expectancy of both engine and manual trans and haven't found good quantitative information.

The following link is a piece on Automatic trans life vs temp. They are suggesting 175 range. I think it is reasonable to think a manual trans would be similar.

http://autos.yahoo.com/repair/results/ques123.html

Well, it's easy enough to adjust. Thanks for the hint.

Here's the completed system:

http://vintagebus.com/howto/trans-cooler/legend.jpg

What did you use for nozzles?

Engine oil starts to break down at 250 degrees. Gear oil starts to break down at 200 degrees.

unlike engine, tranny is working pretty fine with lower oil temps, you only loose some efficiency, so i would suggest adjusting down thermostat somewhat.

P.S. How are you going to deal with metal particles going into the pump/cooler?

hmm...looking into your picture, i recognize one potential problem.

Tranny is only half-filled (to filling-plug) and pump is raised high above casing. When pump starts to operate it is going to cavitate/suck some air first before it starts filling whole oil-cooler and pump-cavities, effectivly decreasing amount of oil in the transmission. You either need to fill transmission somewhat more to compensate for that or possibly have pump under waterline...

also, some clever magnet/filter -arrangment to prevent particles being sucked into cooler/pump would be good thing.

Have you tried to operate pump in this setup?

More pix and whatnot at http://vintagebus.com/howto/trans-cooler

I'm using the term 'nozzle' rather loosely - they're 1/4" NPT/-6 AN fittings.

The pickup fitting is a 3/8" NPT/-8 AN fitting; the pump output is a 'manifold' with 2 -6 outputs.

Thom,

I figure you might know this answer since you have been doing so much with your transmission recently...

Do you know the best fitting/sensor to use for a transmission temperature gauge?

Is it really as easy as clamping one to the diff housing as you did, since I won't be able to really calibrate my gauge.

Would putting one in the place of the fill plug be easy and effective?

If so, what is that thread size and pitch?

Thanks in advance,

Olivier

Thats one beefy looking side plate, Very nice! Did you happen to get an installed weight on that puppy? Just monkey curiosity. Someone also did a very nice job on the clutch cable bracket.

Keep in mind that the IR case temp will be lower than the internal temps. I would target ~200F&deg as an average fluid temp.

Thom,

Here is a page with some sending unit options. Which would you recommend for a relatively easy (non-invasive) but reliable indicator of the trans oil temp? Would one of these fit in the drain or fill hole (fill seems safer, but may not contact the fluid)

Sending units

Thanks again,

Olivier

BTT

Thom,
The setup looks very compact and neat. However, I'm wondering whether the pump might live longer if you plumb it before the cooler so it receives unrestricted (but hotter) oil directly from the transaxle sump. This will pressurize the cooler for perhaps better fluid heat transfer. Unfortunately, this means making up some new braided lines which isn't inexpensive. On the other hand, if the present setup is working okay, keep it the way it is.

$.02
Sherwood
http://members.rennlist.org/911pcars

Actually, the release notes (Ok, so I'm working too hard) suggest that you should put the pump after the cooler, so the pump doesn't get as hot.

Bump... This is cool (and very old, I know). Nice job Thom. Did you ever change anything? I was wondering whether it would be possible to put actual spraying nozzles into a setup like this...

TIA

edit: and also, how often do you change your fluid now, and how does it come out?

edit #2: I did not realize that JackOlsen had done something like this as well, before Thom. Researching that now....

Not to steal this thread, but where do you get an "outy" fill plug like that. I've posted this before but we never found a good source. Some say 77 911s have these...but when you order from a dealer you get the "superceded" part....an "inny" ... just like I already have on my 85 :(
--Wil

http://www.pelicanparts.com/catalog/shopcart/911M/POR_911M_tranny_pg4.htm#item13