I have a beefed up 700R4, still set up to shift automatically, 2800 stall lock-up converter, and an aftermarket tranny cooler in front of the radiator and condenser. The fluid goes through the aftermarket cooler, then the stock cooler, then back to the trans.

On a normal 60 to 100 degree day all is perfect. Part throttle is fine, WOT blasts even on the spray all is fine, as long as I don't do more than 2 in a row from a dead stop.

On a cold day (45 to 50 or so degrees), I have to drive for about 10 miles before it will shift into overdrive. 1-2 and 2-3 shifts are fine. Converter locks up like normal, just won't go into OD. I use a switch to unlock the converter for a while and that seems to heat up the fluid quicker and lets it go into overdrive a little sooner but it still takes for ever.

When hot, like after a couple back-to-back 1/4 mile runs on the spray, the shift points go WAY up. Instead of shifting at 6200 or so at WOT, it won't shift till 6500 or so. I've also seen it not go into OD when the fluid is this hot. After a 10 to 20 minute or so cool-down, it's fine again.

I'm not overly worried about the hot condition as I rarely make back to back runs without some amount of cool-down time and almost never do on a very hot day, and I don't autocross or anything. I know a bigger tranny cooler, or eliminating the factory cooler, would probably cure this. But I think that would make it worse on the cool days for not going into OD for such a long time.

Question is, is this the norm for a beefed up 700-R4 that can stand up to running mid 10's in the 1/4 mile, or is there something that I can do to alleviate the problem? I'm thinking maybe synthetic fluid (I just have cheap regular fluid in there now), or that B+M Trick Shift (have never used it so I don't know what it will or won't do). Running a tranny cooler in hot temps but not in cool temps really isn't an option since here in central PA it can be 70 degrees one day and 45 the next in spring and in fall. What do you guys think? Synthetic fluid help? Any other ideas?

Well, I'm not sure if it's normal or not, but that not able to shift to OD while trans temp is still low, is same on mine. I do however have stick shift so I can't say about shift points raising depending on trans temps.

I just installed a B&M Supercooler on mine and the instructions that came with it said to plumb the cooler into the return line coming out of the factory radiator/cooler. So mine is mounted after the factory cooler. Yours is mounted ahead of the factory cooler. Is your aux. cooler doing much good in front of the factory cooler? I'm not sure here as I have seen people place them in both locations, but I'm not sure of the actual results from one location to the next. I'm going to install a temp guage in the next month or so to get some data on what's happening there.

I installed mine before the factory cooler in hopes that, when cold, the factory cooler will actually help heat the trans fluid up a little before going back into the trans. If I install the aftermarket cooler after the factory cooler my problem will be worse.

2 things to add....the trans has acted this way since I installed it so there is no sudden change or anything....and, I spoke with the guy who built it, he said possibly the synthetic fluid will have less viscosity change with temperature change and it is OK to try it but doesn't know if it will solve the problem. He knows nothing about the B+M Trick Shift fluid other than that it may make the shifts more firm. That would be fine, the stall converter eats up the shift firmness anyway.

So, I'm just wondering if I should try synthetic fluid, B+M Trick Shift fluid, or if there is anything else I can change that might solve the problem. I can live with it but I don't like to, I'd rather fix it somehow but not if it involves removing the trans from the car!

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If you are talking about a 4+3 trans, the OD is controlled by the computer, by monitoring coolant temps. The coolant temp setting that is required to be reached before OD will engage may or may not be tweakable in the tune, not sure there. If you are talking about a full manual trans I have no idea.

I'm talking about 4L60 (700r4) that I've converted
to stick shift operation.

Link to my thread

Pete, have you ever seen this problem of not going into OD when cold? Is there any type of temp sensor or anything in the trans that controls it? I'm almost sure there isn't and it is just the viscosity change in the oil due to temp that is causing it. What do you think?

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I have not.Lock up yes, but overdrive no. OD is the result of tv and governor as it related to pressure and temperature. I would first suspect an incorrect seperator plate, or valve body gasket.

Is there anything else that can be done with TV cable adjustment other than the normal method? I am afraid to play with it and have trans slippage and eventually burn it up.

At this point, if nothing else is found, I'm considering using Redline synthetic type F fluid. I am afraid DexronIII compatible synthetic will let it slip too much. I'm thinking synthetic for more consistent viscosity in temperature changes, and the type F so it doesn't have the friction reducing additives that can contribute to slippage. Any thoughts on this?

Every trans I have worked on that used synthetic fluid, killed the planetary gearsets, or other hard part. Why this is, I don't know.