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Transmissions, coolers, and gauges

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  #41  
Old 05-23-2016, 09:35 PM
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Originally Posted by dbbd1
Why I didn't think of that, I don't know.
It'd be unusual if you had thought of it, actually. The way most folks learn of it is in conversation after steaming a hood. It's somewhat counterintuitive to spool up an engine that's already threatening to overheat. You're in good shape unless it overheats when running north of three grand, but with just a 4,000 pound trailer on you shouldn't have any problems at all.

Should you find the temp gauges running in the nervous zone when you make the summit, just leave it in second gear until the temp gauges just begin to fall, then go ahead and upshift. It shouldn't be any more than about a half mile or so before that happens except in very hot weather and/or (relatively) very high elevations.
 
  #42  
Old 05-27-2016, 07:59 AM
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Thanks to the OP for starting this conversation. Next time I do a pan drop I might temporalily install a pan-out probe as well as a return line probe--I'm afraid I would watch my temperatures so closely that I wouldn't pay enough attention to the road.

I did take the advice of another poster and installed a Derale thermostatic switch after the external filter. As well I removed a secondary auxilary cooler that I had installed along the frame. Previously I had run all my filters on the return side of line, after the external cooler. For the life of me I can't remember why I had it installed that way, and it seems that my original installation could lead to the cooler getting clogged.

I removed most of the original metal lines to accomodate a driver's side cooler and ran the return line through the driver's side frame. For overkill I added a magnetic power steering type filter right before the fluid returns to the transmission.

https://www.dropbox.com/s/z010e7qagf...ilter.JPG?dl=0

https://photos-2.dropbox.com/t/2/AAA...00&size_mode=3

https://photos-4.dropbox.com/t/2/AAA...00&size_mode=3

https://photos-3.dropbox.com/t/2/AAB...00&size_mode=3

https://photos-4.dropbox.com/t/2/AAB...00&size_mode=3

I swear I'll get this attachment thing down one of these days...
 
  #43  
Old 06-12-2016, 05:38 PM
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So, in theory, you can never run a transmission too cool (except for getting it up to some kind of operating temp, say above 100*, so it goes into overdrive). Why do they sell those bypass valves set to 180*?
 
  #44  
Old 06-12-2016, 08:21 PM
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From what I have read, running too cool, is not quite as bad as running too hot, but, still bad......
 
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Old 06-13-2016, 01:28 AM
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Originally Posted by dbbd1
Why do they sell those bypass valves set to 180*?
To be sure the oil heats to normal operating temperature so the parts will expand to become the size the machine is designed for. That's why ya don't launch a cold automatic -- it makes the clutches go bye-bye.
 
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Old 06-13-2016, 02:19 AM
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Originally Posted by wjamesbass
For overkill I added a magnetic power steering type filter right before the fluid returns to the transmission.
Hmmm. Imagine that magnet is so powerful that no ferrous metal ever gets past it, and there's eventually just enough of that metal to plug that line up tight. I figure that at that point you'll wish the magnet were instead in the pan where the worst the iron could do is raise the sump level.

It might not hurt to put an engine oil filter magnet on a remote canister style filter, though. If the filter is upstream of the coolers the magnet might keep some iron from getting to them, and it'd be only an already dead transmission that could chuck enough iron down the pipe to plug the filter with the magnet on it.
 
  #47  
Old 06-13-2016, 02:03 PM
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Sorry, I'm still trying to nail all of this down.


So, if my RPM's are above the stall of the converter and/or it is locked, there will be less slippage, therefore less heat buildup?
 
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Old 06-13-2016, 03:32 PM
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That's the whole idea behind the locking converter. The "slip" you get from the converter (which is how it multiplies torque) generates a LOT of heat.
 
  #49  
Old 06-13-2016, 06:07 PM
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Originally Posted by dbbd1
So, if my RPM's are above the stall of the converter and/or it is locked, there will be less slippage, therefore less heat buildup?
The question is made confounding by the fact that there are two different things that can be called locked. One is the locked mode of converter operation, the other is clutch engagement which takes the fluid coupling completely out of the circuit.

In locked mode operation, the converter is still fluid coupled so still experiencing friction, but a lot less than when in torque multiplication mode. Generally, the engine will be turning a couple hundred RPM faster than the transmission input shaft, and adding more torque to it won't really change that speed differential. In torque multiplication mode, throwing more torque at it increases the speed differential and with it the torque multiplication factor, though the two aren't precisely linear in their relationship -- the energy lost as heat doesn't ever reach the input shaft, and the greater the differential speed the greater that loss.

In the clutch engaged mode, the thing behaves like a manual transmission. There's zero hydraulic coupling in the converter, as you've connected the housing and the output shaft by way of a mechanical clutch, so the oil is just going along for the ride and the only friction is that of pushing the oil up to the same speed as everything else -- it's just riding inside a spinning steel donut, doing nothing any more interesting than that.

That said, in the locked mode of operation you've got a lot less fluid turbulence inside the converter so there's a lot less friction, and a lot less mechanical energy being converted to heat in the process of overcoming that friction. The equation that determines whether the converter is locked or multiplying contains primary variables entirely outside of the converter, so it's a fairly fuzzy kind of thing. For the most part, though, all ya need to know outside of drag racing is that you're going to want to maintain engine speed north of stall speed if you're sustaining a hard pull. It's so happy a state of affairs that your rod bearings will thank you with their silence.
 
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Old 06-13-2016, 06:32 PM
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Originally Posted by UnregisteredUser
The question is made confounding by the fact that there are two different things that can be called locked. One is the locked mode of converter operation, the other is clutch engagement which takes the fluid coupling completely out of the circuit.

In locked mode operation, the converter is still fluid coupled so still experiencing friction, but a lot less than when in torque multiplication mode. Generally, the engine will be turning a couple hundred RPM faster than the transmission input shaft, and adding more torque to it won't really change that speed differential. In torque multiplication mode, throwing more torque at it increases the speed differential and with it the torque multiplication factor, though the two aren't precisely linear in their relationship -- the energy lost as heat doesn't ever reach the input shaft, and the greater the differential speed the greater that loss.

In the clutch engaged mode, the thing behaves like a manual transmission. There's zero hydraulic coupling in the converter, as you've connected the housing and the output shaft by way of a mechanical clutch, so the oil is just going along for the ride and the only friction is that of pushing the oil up to the same speed as everything else -- it's just riding inside a spinning steel donut, doing nothing any more interesting than that.

That said, in the locked mode of operation you've got a lot less fluid turbulence inside the converter so there's a lot less friction, and a lot less mechanical energy being converted to heat in the process of overcoming that friction. The equation that determines whether the converter is locked or multiplying contains primary variables entirely outside of the converter, so it's a fairly fuzzy kind of thing. For the most part, though, all ya need to know outside of drag racing is that you're going to want to maintain engine speed north of stall speed if you're sustaining a hard pull. It's so happy a state of affairs that your rod bearings will thank you with their silence.

So what you're saying here is ...... raise hell and praise dale?
 


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