Tranny Temps (how cool is too cool?)

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Old 06-06-2014, 07:56 PM
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Question Tranny Temps (how cool is too cool?)

After installing an FTI 9.5" 4k stall converter on my 69 RR, I had to address the cooling system because the first night out was kinda sketchy, hitting 190+ degrees on the highway


Earlier this week, I replaced the old cooler with a new 45,000 BTU unit, then today I swapped out my old deep pan for an even deeper 5 quart cooling pan


















Thing is, now I seem to have a new problem

I can't seem get it up to operating temp

It's a warm night here in Orlando and I just took her out for a 30 minute romp both in traffic and made a few happy passes on the back road

Kept my eye on the gauge and it didn't want to move above the first mark (like 120-125)

I thought maybe I goofed when I installed the sensor in the new pan, but how the hell could I f'up two wires

Checked the fluid and what was on the stick was still cool to the touch

In fact, I actually palmed the end of the stick and the fluid was just barely warm....

Put her up on the lift, hit the pan with my temp gun in all directions and the highest reading I got was 117*

Checked the ground for the sensor with my ohm meter and all is well.

Everything appears to be working fine (engages each gear firmly, shifts great at any speed, etc.)


I guess I'm being paranoid, but how cool is too cool?
Old 06-06-2014, 11:19 PM
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You may need to put a thermostat in the circuit. Swap back to the smaller cooler

Last edited by TVLynn; 06-06-2014 at 11:30 PM.
Old 06-07-2014, 03:12 PM
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That's great Snake, It's fine the cooler the better... What RPM does the car run on the cruise??? if it is above your 4000 Rpm stall it is not slipping... I always believe the cooler the better... If it runs hot it is slipping either in the clutches or the converter... My opinion is it is fine.. The cooler you put in is massive and the pan with cooler built in and extra fluid is doing its job quite well....Trust me if you get playing at the track the temp. will come up some but until then your fine...Bill
Old 06-07-2014, 04:27 PM
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IT's fine....
Old 06-08-2014, 02:47 PM
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OK, earlier today I went out for a cruise to see how high the tranny temps would get in warm weather.

It was 93* with 51% humidity when I left the shop and I drove around for about an hour in traffic keeping my eyes glued to the gauge.

As I was sweating my ***** off, every now and then I'd hammer it hard in 3rd gear from about a 40 roll to around 70 just to see if it would make any difference and this was the highest to gauge went.




Got to the highway where I was pushing about 70-80mph cruising and the temps actually went up instead of down (weird), but only slightly...



That's the highest I've seen the gauge go since installing the new pan and cooler

After 2 hours of cruising around and randomly beating the **** out of her, I went back to the shop and hit the inlet/outlet of the cooler with a temp gun...




I honestly don't know which one is in or out as the cooling lines kinda get mixed up under the headers, but either way, I guess I'm good to go

Any particular reason why it's running slightly warmer on the highway?

Lynn, the new cooler came with a thermal valve (little blue thing in the goodie bag), but I was told it would only work in extremely cold weather.

Also, my trans builder suggested not using it because he's seen a few of them fail, smoking the trannies in the process
Old 06-08-2014, 04:27 PM
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The reason it might be going higher (temp wise) is because when you are cruising at these speeds your rpm is not up to the stall speed of the converter...In other words it is not locking up because it is below (rpm Wise) the 4000 RPM of the converter... The temp. seems good the hotter it runs the more damage it causes...Heat is your enemy... Just a question why did you put such a high stall speed on a street driven car??? And did the converter builder do the formula to see what converter is best for your App. CRT transmissions could help you with that...They take the cam specs gear ratio tire size and other stuff and tell you exactly what you should run so you are not over convertered for your set up...Bill
Old 06-08-2014, 04:53 PM
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Originally Posted by pro-tech
The reason it might be going higher (temp wise) is because when you are cruising at these speeds your rpm is not up to the stall speed of the converter...In other words it is not locking up because it is below (rpm Wise) the 4000 RPM of the converter...
I kinda figured the temps would be higher in traffic since I was lugging around in 3rd gear most of the time with less airflow tot he cooler


The temp. seems good the hotter it runs the more damage it causes...Heat is your enemy... Just a question why did you put such a high stall speed on a street driven car???
Well, it's not just a street driven car

And apart from a little slip just to get her moving, it's not really much different than the stock converter during normal driving.

Well, except for the fact that I can hammer it in any gear and not bog the motor down

She just finds that sweet spot in the rev range and pulls away

In fact, had I known it would be this easy to drive around town with, I probably would've went with an even higher stall


And did the converter builder do the formula to see what converter is best for your App. CRT transmissions could help you with that...They take the cam specs gear ratio tire size and other stuff and tell you exactly what you should run so you are not over convertered for your set up...Bill
Yes, my cam actually calls for a 4000+ converter.

However, they recommend 4.10-4.56 gears while I'm running 3.91's with 29-30 inch meats.

We let FTI know this before building the converter as I wanted to stick with the 3.91's and they did what needed to be done.
Old 06-08-2014, 05:16 PM
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I put a 2800-3000 converter in my 408 small block Duster and I even told him it had 323:1 ratio and it in fact has 2.76:1 (soon to have the 323) and it woke the car up tremendously now if I can get it to hook up it would be great.. Its pretty impressive to be doing 30-40 MPH in 2nd and mash the go pedal and have it start spinning. I need to get some 15" rear rally wheels and some street slicks.. The comp TAs don't bite good as I think they should but they are also 14" just about as big as I can find... Its a lot of fun to drive though.. My car runs about the same temp as yours.. I am running the full synthetic fluid though. Which is to run a lot cooler so they say... .Bill
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