Safe low trans temp

madmikeismad

madmikeismad

So mad
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Dec 19, 2009
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Whats a good temp to reach before you make a pass? Can't remember seeing anything about it before. I'm only assuming it's like the engine where you cant just get in and make a full power pass without warming up a little. Oil viscosity and pressures, metals warming up and expansion and warping, etc....

EDIT: On further though, what about diff's? I can't recall anyone ever caring about minimum diff temps, but I'm sure at some level that becomes important?
 
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RDPsmoker said:
IOO
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That usually implies the thread is going to turn into a chit-show. Is this a stupid topic that everyone but me knows the answer to? I've never had the opportunity to race anything really fast, just streetable stuff, so I've always just ran at regular operating temperature. I'm curious about the really fast guys.
 
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No but I usually never make it on the first page of a good topic :hehe: so I never get to use it! Just leave me be haha
 
Lavon told me the cooler the better but I'm sure he didn't mean 40° out. Who makes passes when its that cold out anyhow :lolly:

Someone might remember but didn't Hellman have a dry ice cooler for the trans in his truck?
 
I will ask my trainer for the engineering side, but mine runs down the road at 140 or less, I would think 100 is a good round number. Something else to consider is, pan or line sensor. The heat latency of the different fluid mass will be different.

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The lower the temp(thicker the fluid) the higher the pressure you tend to see. So the Cooler the better


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My first pass of the day, the tranny temp is in the 130* range when pulling up to the beams. Warming up the engine/coolant temp to about 160 degrees usually has the tranny temp up in that 130 range. Of course after the first pass, then it's plenty hot for the rest of the day.
 
As far as the differential I'm curious as to what some say for temp, if it's as important as making sure the grease is covering the bearings and gears. At least for pulling this is important, not sure on how much different a racing application would be. We would always overfill the rear end to make sure of this (for pulling).

As a side note, my friends dad is a nostalgia super stock racer and said back in the 60s/70s guys setting records were running the minimum rear end grease. Basically a splash to make sure the bearings were wet. However this was in an application where longevity didn't matter as they were pushing every aspect of the car to the max just for a .01th to set national records.
 
I know cooler will net more pressure, but how cool can you go is what I was trying to ask. I think. LOL I'm sure the transmission itself has to be at a certain temperature before it's safe to operate without leaking or warping or just creating premature wear. Or does it not change a damn thing performance wise, so just run it at 130-150?

Also where is the better spot to pull trans temp?
 
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Doesn't really matter unless it's too hot. As Hobie said, cooler is better. I'd prefer <100F for every pass, but hot-lapping doesn't afford that luxury.
 
Y'all would hate the new Ford's....the trans thermostat keeps it just above 200*.
 
I'd get it just warm enough to have it feel 'normal'. I run a 200rpm lower than stock stall converter, and Case HyTrans (probably lowers another 100rpm. When it's cold (under 45deg or so), if I put it in drive, it likes to skip 1st gear, and if I manually put it into 1st, it damn near stalls the truck. When it's thick it feels like it is another 400rpm lower.
After fluid is moving a bit (like a minute), it gets back up to around how it normally drives.

I'm not saying it's bad to run it cold, but be ready to have a hard time spooling at the line!
 
Well this is great news. I was debating putting a 2nd trans cooler in the daily, and possibly a 2nd on the race truck (when it's running of course).

How much line/cooler can you run before it can't be pumped through anymore? I'd like to add one in the bed in a big loop with the front stock cooler.
 
madmikeismad said:
Well this is great news. I was debating putting a 2nd trans cooler in the daily, and possibly a 2nd on the race truck (when it's running of course).

How much line/cooler can you run before it can't be pumped through anymore? I'd like to add one in the bed in a big loop with the front stock cooler.
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The length shouldn't matter. The coolers aren't going to add much resistance. As long as you've got the system filled enough to not starve the pan, you should be good.
 
mathews8pt said:
The lower the temp(thicker the fluid) the higher the pressure you tend to see. So the Cooler the better


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This is not accurate

The viscosity on cold fluid virtually assures seeing high pressure, yes, but pressure is resistance, and pressure under cold operation doesn't mean fluid is flowing to and between rotating surfaces.
This isn't to say that there isn't a residual film from the last shut down.

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mathews8pt said:
Based on what?


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I edited, I was driving. I knew I couldn't do you that way.

As for Temps, hottest point is the TCC outlet.

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biggy238 said:
I edited, I was driving. I knew I couldn't do you that way.

As for Temps, hottest point is the TCC outlet.

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You are correct, I wouldn't want to race on a Trans that was 30*, but a converter makes a lot of heat and it doesnt take long to warm up fluid past 60*. If I could keep it under 100* like Brandon mentioned I certainly would.

There is a fluid temp(I think it's 60* F) that must be reached before the PCM will allow lockup. That would be the coolest I'd want to run one, but like i said it doesn't take long to get there.

Also, 47re/48 Trans temp(viewed by PCM) is taken from the transducer which is in the vb, for anyone wondering.


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