how does heat affect trans life?

[shogun]

Interesting stuff from European Transmissions, they even have a cooler kit with inline filter.
http://www.bimmerboard.com/forums/posts/290531

[winfred]

theres been a lot of talk about heat and lifespan of slush boxes on the diesel board, basicly the useful life of the tranny drops by half every 25* over 175* modern trannys with lock up converters don't make nearly the heat while locked up, so most of the diesel guys run a switch to control the lock up and get it locked faster when hauling and when using a exhaust brake, one guy wrote a article about driving his 30' dodge cab/cummins powered motor home to the top of pikes peak and a combo of a locked converter when he wanted it a kit that lets you run the 4wd transfer case in 2wd low range and a exhaust brake let him get it to the top and back down without roasting the brakes or tranny, he said in previous attempts the tranny fluid would get in the 200s in no time unlocked and take a couple minutes at a fast idle to get it down below 175* on the side of the road with the converter unlocked

[Alexlind123]

My torque converter only has a chance to lock up for a few minutes of my drive. Maybe i need to drive faster...

[winfred]

not a big deal in a car, it becomes more of a issue with a load and fluid sheer in the converter roasts the tranny

My torque converter only has a chance to lock up for a few minutes of my drive. Maybe i need to drive faster...

[repenttokyo]

heat is probably the greatest enemy of automatic transmissions. that and traction.

[Russell]

Synthetic atf fluid help? This is one reason I went to Mobil Dexron III synthetic atf. Supposed to handle higher temps well. Also my daily commute is 60% open road with converter lockup. That is good.

[repenttokyo]

fluid can help, but as to whether synthetic is a universal solution, I can't say. On my last auto car, with a ford 4r70w, I replaced the mercon iii with mercon v as per a ford tsb and it made a great deal of difference. The thing I find is to research your specific transmission.

What can be considered a universal solution to the heat problem, other than a cooler, is reducing slippage. Most auto trannies slip between shifts for comfort, but slipping creates a lot of heat. Any shift kit that can radically reduce or eliminate slippage will do a lot for extending the life of your transmission. The shifts will be not necessarily harsh, but no longer invisible, depending on how extreme you go with your kit. I find a noticeable shift is preferable to wear, and it's also fun to break the rear wheels free on the 1-2 upshift

[winfred]

till you shatter a drum or planetary set

Any shift kit that can radically reduce or eliminate slippage will do a lot for extending the life of your transmission. The shifts will be not necessarily harsh, but no longer invisible, depending on how extreme you go with your kit. I find a noticeable shift is preferable to wear, and it's also fun to break the rear wheels free on the 1-2 upshift

[Russell]

Not same but. I had a 70 mustang with a 351/300 hp big valve engine and 750 Holley/traction lock diff that ate auto tranys until I put a shift kit in it with street setting. Never a trany problem after that. I assume it was related to fimer shifts with less slipping. Sold it for my first BMW. Wish I had it and the BMW back.