Originally Posted by gearman
The 4R100 trans is a very capable trans. Heat is the killer and 95% of drivers just don't know how to drive/use them. .....
It is a capable tranny, after all it was married to a very stout engine. But still that 'capable' is a relative word. And heat wasn't the R100's only enemy. How easy it was to heat the stock tran was also a downfall.
I would think however, that it is accurate to say that it was certainly the weakest link in that drive train.
I had Banks install their brake in my truck after Ford couldn't diagnose a 4R100 problem at 8,000 miles that effected my ability to tow in mountains safely. Ford had installed extra cooler, AND tranny guage, AND much deeper tranny pan upon me buying the new truck too.
(coast clutch problem diagnosed a month later, paid for by Ford but Banks already installed)
I probably could have gone straight to the aftermarket tranny builder I now have and saved myself some
I agree that many people have towed successfully for 150,000K+ miles with a stock 4R with no problems.