My tranny has been getting very hot lately. I took the trans (powerglide)& convertor out early in the year as I was concerned about my 60' times falling off. Tranny has been apart 4-5 times with new parts replaced this last time. New blue clutches & steels, new racing pump, new servo, and new kevlar band. Convertor opened 5 times and freshened up. Stall was set at 5600. I don't know what the stall was before. Trans temps reach as high as 260-300 degrees. Installed different convertor this morning and found stall to be at 5800. I know that's too high and will remove tomorrow. I'm not sure what the stall really should be. I've had this combo in the car for the past 5 years with no issues. 60' times are worse and car will not run where I know it should. I have a System 1 filter in line with a large cooler as well. All cooler lines have been flushed and cleaned each time tranny was removed. I'm past frustration and am getting a litle pissed. What have I done wrong and where should I be looking for a potential problem?

The overheating and 60 ft falloff I'm thinking converter issue. The lines/cooler are clear/flowing correct?

All cooler lines and the filter and cooler have been flushed and cleaned each time the trans has been out of car. I'm beginning to feel the 5600 stall is too high. It's just that I don't know what the stall was initially. I wonder if I have the stall lowered to say 5000-5200 if that will remedy my problem. On a different note, is there anything that could be wrong inside the trans that could create that kind of heat?

yes I missed that the lines/cooler were flushed & was debating whether to edit my post. Tranny heat pretty much comes from the TC and not the trans itself. That (stall) speed is very high which is what is generating the heat

yes, whenever the trans is in gear and the engine rpm is below 5600rpm, you will have a lot of slippage and a lot of heat generated by that slippage.

Could I expect a significant drop in temps if I lowered the stall to say 5000-5200? I'm going to do some checking to see if I have a flow problem. I don't think so because the temp probe is in the return line near the inlet on the tranny. Any other ideas?

It again depends on how much time you spend driving in gear below the stall rpm.

If you drive for 20 or 30 minutes below 5000 rpm, you will still generate a whole lot of heat. If you drive for only 2 or 3 minutes below 5000 rpm, things will be much cooler. In reality, I'd think with 5000 rpm stall, you are going to have little, if any street use, only good for racing.
And if you are racing only, you may want to post this issue over on Unlawful's race section, they probably have more experience to help you there.