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Old 09-01-2015, 08:29 AM   #11
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Thanks for all your responses.

Might take into consideration where your temp sending using is too. Mine is in the pan. I forget where is the most accurate place to have it.
You have a pan filter and a spin on [that might be a retarder setup thing]...right?
My temp is taken right out of the converter which explains temp variations. I have an external filter and fluid/water cooler. I plan on putting a sender in the pan, that would tell how well the cooler is working.

Was it hunting gears, did you manually drop it? Did you aggressively climb the hill or just meander up it? I'll drop mine to 3rd and sit it about 2000 RPM. It will climb anything at that speed. I pretty much have the throttle backed to about 1/4 throttle to keep from going above that RPM. I figure no sense having things wound tight just to fight to go up hill fast. Especially with a 5 mile grade or so.
I may have been driving too aggressively, I drove a truck for 20 years, but it was std transmission and had the horsepower to pretty much climb anything at speed. Really high temps were seen when starting up hill and never got to 3rd, so no lockup.

That lead me to more research and I found this (taken from various forums and condensed)

Tom Johnson and I was the Transmission Fluids Engineer at Allison Transmission from 1990 until my retirement in 2009.

Don't worry about temperatures on TranSYnd. I've run it in the lab at 325F for 600 hours straight with not much change except for some oxidation. When I say the Allison will run all day long at 250F, I mean it. This temperature will do absolutely nothing to the transmission. Internal parts are designed to run at up to 350F.

Of course, running cooler is always better but the kinds of temps you all are seeing is not much. If you don't believe me, take oil samples and you'll see that temperatures up to 250F will do nothing to TranSynd or the transmission. So ...... stop worrying about it and move on to something else.

I would be concerned if you ran over 225F consistently. Really you should normally operate somewhere around 180-200F. Maybe even lower. The Allison is designed to take much higher temperatures but the fluid will degrade at a faster rate. General rule of thumb is that fluid life is cut in half every time you increase the temperature by 18 degrees Fahrenheit (10 degrees Centigrade or Celcius). Keep in mind that this general rule is based on chemical reaction times and TranSynd can take much higher temperatures for much longer periods of time
I think my first order of business is going to be change to synthetic fluid and install sender to oil pan, also change my driving habits. From what I have gotten from all of this is, if I change to transynd or equivalent, the higher temp right out of the converter isn't really that big a deal as long as it doesn't go high in the pan, and may not be at all unusual.
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Old 09-01-2015, 09:53 AM   #12
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TranSynd will deal with heat much better than the older Dexrons and such. But only to a point. Allison put out a chart a while back (I'm still trying to relocate) that spells out the expected fluid life based on running temps. Even the new gen fluids life gets dramatically reduced when run at temps above about 220. And even fairly short exposure to higher temps (like 250-280) can render it bad enough to call for replacement in pretty short order.

Effective transmission fluid cooling is critical to maintaining the trannies health as well as the fluids.
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Old 09-01-2015, 07:23 PM   #13
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Originally Posted by somewhereinusa View Post
I may have been driving too aggressively, I drove a truck for 20 years, but it was std transmission and had the horsepower to pretty much climb anything at speed. Really high temps were seen when starting up hill and never got to 3rd, so no lockup.
If you werent in lockup, that would have been a good part of your problem. Non-lockup is just a means to get to the next lockup without such a big jump.
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