Ran a search, but didn't find much. School me on some possible upgrades to the 4R70W. I've done some towing with it ('97 f150) and plan to do a lot more of it in the future (building a trail rig). I can't complain about the tranny to much, I've got 165k miles on it, with only regular fluid changes. Problem is about a year ago, I hauled a CJ7 about 400 miles and since then, it's been slipping. The use of some Lucas oil :grinpimp: has kept it going as a DD, but I know it won't hold when the trail rig is finished and I'm making regular trips.

Are there any good upgrades to clutches and bands that will let me tow up to 8500 or so lbs without causing an issue? Other than the obvious, good cooler and gages, what can be done to make it a stronger tranny?

Thanks for the help.

http://www.becontrols.com/tech/tech.htm

The 4R70W has what is known collectively as the "J-Mod". This mod stems from one of the Ford engineers who helped BUILD the 4R70W (His name was Jerry, hence the J-Mod). It basically is just telling you where to drill for a free shift kit to increase flow as needed. This combined with buying some new springs and such, and you can have your 4R70W shifting like a manual having its clutch sidestepped almost. To read more about that, I'd go to www.tccoa.com/ and go to the articles section under transmission. Its a Thunderbird/Cougar/Mark VIII site, but it applies.

As said, big B&M 24K cooler and SYNTHETIC FLUIDS. Mercon V I *believe* is recommended now for that transmission. Go read, but it is one that if you have shudders and such it is recommended, but you can change anyways i'm pretty sure.

Do a search over there, or look around - they've got lots of help for you. There are also renowned rebuilders over there, as well as some guys that build custom parts for them, and there are ALOT of guys that run their parts. The 4R70W is a good transmission.