Transmission temperature -paranoid, How hot should it be? Options

[bugsy0]

I just finished a test drive after reassembling my tranny - shifts sweet, no noise, no problems. I drove it normally, with maybe 10 min. highway time. Outside air temp. is about 45F. Now the transmission case is *almost* too hot to hold my hand against.

Is it too hot?

[sean_v8_914]

trans can get hotter than teh engine. 150 is upper threshold for hand touching. engine operating temp is 180 to 220. you are OK

[pcar916]

Mine easily runs 180-195 even in the spring and fall according to the infrared thermometer and where I point it... hotter in the southern summers and on the track. North of 190 is too hot for dino-oil to stay stable for more than a couple of years and on the track 220 degrees and higher is why we run trans-oil coolers. Street cars have an especially bad time when the exhaust is pumping heat into the case while standing still at stop lights, and the ambient temp is in the 90-100 degree range. There is nowhere to quickly dump the heat after it's absorbed in to the box. The heat issue is even more of a problem with folks who have dropped high horsepower engines into their cars too. More energy into the transaxle makes for a lot more heat to dump... somewhere.

It's easier to get consistent oil temps from a gauge in the oil cooler circuit, but there aren't that many folks willing to install one in a street car for a system not that many folks need. It's cheaper to change the trans oil a bunch of times than to spend $400 to $1500 on a cooler circuit depending on how much you fabricate yourself (i.e. plumbing the case) and which equipment you buy. Coolers make a huge difference in the life of transaxle components (especially the R&P and seals) and fluid life.

I wish I had taken temperature readings when I had an open differential. That way I could have compared them to those now with a clutch-type LSD. In a straight line there would be no difference, but aggressive summer driving in the twisties and road track days would create considerably more heat with those clutches working hard.

Sounds like you're doing fine and in 45 degree weather, unless your fluid runs low or you don't change it often enough, you'll have to work awfully hard to make enough heat to worry about.

[bugsy0]

OK, thanks fellers
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