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Dura max won’t downshif t

Yahoo Message Number: 17158
I do not think leaving OD switch on would cause a gasket to go bad.
I did use the OD switch to keep rpm's up so engine would not lug on hills.

Best
Ron Hall

Re: [SuperCrvgroup] Dura max won’t downshif t

Reply #1
Yahoo Message Number: 17159
We have a 34ss and tow a jeep Liberty.
I have learned the limits of the engine/5 speed transmission the hard way.
Leaving Needles going to Barstow is a long grade on I40.
I wanted to use the horsepower curve so I turned od off and ran the engine at about 2900.
The engine didn't go to the red zone, but the transmission did. I guess the input shaft got hot enough to damage the seal. The hot fluid smelled up the unit. I now have a sometimes recurring problem with transmission fluid odor. I have lost a modest amount of fluid over the last 20,000 miles or so. I think I need a new front trans seal.

If I turn the od off and run 2400 - 2600 rpm the temperatures are manageable for extended pulls. If the trans shifts down, I only let the engine run up to 3000 rpm for a minute or less, depending on the transmission temp. The trans temp guage lags the temp at the input shaft or trans hyd pump.

Wish I would have known.

Ralph




Re: [SuperCrvgroup] Dura max won’t downshif t

Reply #2
Yahoo Message Number: 17160
Thanks for the comments, I have never even seen my trans temp gauge move from the far left.... Maybe its broken? Anyone else's never move..

Re: [SuperCrvgroup] Dura max won’t downshif t

Reply #3
Yahoo Message Number: 17161
Mine hadn't moved and I was wondering that also, until I had to drive up a 2000 ft elevation change driveway in W VA. Found out it will move !!!



 

Re: [SuperCrvgroup] Dura max won’t downshif t

Reply #4
Yahoo Message Number: 17164
I'm a former transmission engineer. The purpose of the OD cancel switch is to avoid "shift busyness " when you're at a speed and load close to the downshift point. Whenever possible drive in overdrive