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Tranny temp and AutoMeter rant

PotvinGuy

PotvinGuy

Well-Known Member
Staff member
I have long questioned the need for tranny coolers in our buckets. Consider: we have lightweight cars that spend most of the time cruising. We don't haul big trailers, we don't race for extended periods.
Our trannys are loafing! I've never had a cooler on my TH400. But wondered what the tranny temp was. So I installed an Autometer 3451 mechanical trans temp gauge. Here's the rant: the sender is a big bulb with a 1/2" NPT adapter fitting. No trans pan has such an opening. I called AutoMeter and all they could offer was a weld adapter. So I bought this to mount the sender. I drove for an hour, fast and slow, up and down, WOT, lots of stomping. The trans temp got to 180°. Tranny makers have many opinions re "ideal" temps, but they all say below 200 is fine.
 
Ted Brown said you don't need one.
I made a loop with my line about 8" long and have pulled the enclosed trailer for The bucket as well as an 4x8 trailer for my motorcycle to Daytona Beach .
Have had the no problems.

OPINIONS:)
 
PotvinGuy said:
I have long questioned the need for tranny coolers in our buckets. Consider: we have lightweight cars that spend most of the time cruising. We don't haul big trailers, we don't race for extended periods.
Our trannys are loafing! I've never had a cooler on my TH400. But wondered what the tranny temp was. So I installed an Autometer 3451 mechanical trans temp gauge. Here's the rant: the sender is a big bulb with a 1/2" NPT adapter fitting. No trans pan has such an opening. I called AutoMeter and all they could offer was a weld adapter. So I bought this to mount the sender. I drove for an hour, fast and slow, up and down, WOT, lots of stomping. The trans temp got to 180°. Tranny makers have many opinions re "ideal" temps, but they all say below 200 is fine.
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I agree. You will be hard pressed to keep the trans cooler than engine temp anyways. My only thought is to consider a trans cooler in the grand cooling system scheme, but I agree that it’s likely unwarranted. I imagine a finned or tubed transmission pan would provide ample cooling, if that’s even a real consideration. Now, how do I keep my clutch on my three pedal bucket from overheating? Lol.
 
PotvinGuy said:
Tranny makers have many opinions re "ideal" temps, but they all say below 200 is fine.
Click to expand...
I've always read that 175°F is the ideal temp. Even this chart starts at 150°F, but shows 175°F to give the longest life. What was a guy like you doing using a mechanical gauge ??? :rolleyes:

Ted Brown can do what he wants (did he ever measure the temp), but after I spent over 6 months building my trans and doing several modifications including high stall speed converter I'm going to use a nice cooler on mine.

I guess it all depends on how long you want your trans to last ?

upload_2022-10-25_12-43-31.png

Optimal Transmission Temperature: Updated 2022
 
Indycars said:
I've always read that 175°F is the ideal temp. Even this chart starts at 150°F, but shows 175°F to give the longest life. What was a guy like you doing using a mechanical gauge ??? :rolleyes:

Ted Brown can do what he wants (did he ever measure the temp), but after I spent over 6 months building my trans and doing several modifications including high stall speed converter I'm going to use a nice cooler on mine.

I guess it all depends on how long you want your trans to last ?

View attachment 23234

Optimal Transmission Temperature: Updated 2022
Click to expand...
Just out of curiosity, did you measure before and after temps in your bucket? I’m just wondering how much variance there is. The high stall converters are heat producers. Lots of variables to consider. I plumbed a spin on filter into the cooler lines on my z28 when I rebuilt it. Just as a precaution because I had a catastrophic converter failure that destroyed the previous transmission by filling it with debris. Of course once it goes through the pump, damage is likely imminent.
 
fletcherson said:
Just out of curiosity, did you measure before and after temps in your bucket? I’m just wondering how much variance there is. The high stall converters are heat producers. Lots of variables to consider.
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I would have answered yesterday, but I had to go back and find my notes.

When I installed the Derale (#51908, 19 row, stacked plate cooler) trans cooler, I was measuring fluid temps in the output line to the trans cooler. This fluid doesn't travel very far after leaving the torque converter and entering the output line and is therefore at the highest temp. The temperature dropped from 230°F to 205°F or about a 25°F drop. If I'm on the highway and manually lockup the torque converter the temperature drops even further, probably another 15° to 20°F. But you have to remember, this is in the output line and not in the pan where temps are even lower.

FP01_AN90DegSwivelFitting_6171.jpg

https://www.summitracing.com/parts/der-51908
.
 
Okay, that’s significant. The converter lockup differential is quite revealing. Awesome that you kept detailed notes. It’s nice to get real results to help compare, but wasn’t necessary for you to dig them out to reply to me. I was just interested. Another thing to think about in a t bucket is the temperature in the passenger tub. Irregardless if the temperature is too high for transmission longevity, reducing it would likely help keep the interior temps down since you are basically snuggled in with the transmission... thoughts? Thanks for the data!
 
fletcherson said:
Irregardless if the temperature is too high for transmission longevity, reducing it would likely help keep the interior temps down since you are basically snuggled in with the transmission... thoughts?

Thanks for the data!
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With my floor being 3/4" plywood, it doesn't conduct heat very well. So if the car is moving, I don't think the transmission temp is making much of a difference inside the car. Now if you are in stop-n-go traffic that would be a different story. Also it would depend on the amount of holes going thru the floor, until I put a rubber cup holder in my console I had a pretty good size hole coming from underneath with nothing to stop the heat. That I could feel for sure.

Your welcome !
 
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