1999 4R70W maintenance and upgrades...

[skpyle]

Hello Gentlemen,

I am preparing to do some work to the 4R70W in my 1999 Explorer Limited 5.0L AWD. The trans has 127,000 miles on it and works just fine. The fluid is red, and was last changed in early 2010, about 38,000 miles ago.

My intent is to do the following:

-change filter, install NAPA filter kit ATP19751
-drain fluid from case and torque converter, refill with Mobil 1 Synthetic ATF
-add a drain plug to the pan
-install a remote filter
-install Baumann recalibrator kit RK-AODE-2
-install Baumann pressure regulator valve PR-2
-install Baumann bypass clutch control valve BCV-1
-have James Henson adjust my tune accordingly

So, here is my question: what else SHOULD I do?

I have searched:
"Baumann" 7 pages
"Sonnax" 16 pages
"4R70W" read 10 of 51 pages
"4R70W upgrade" 3 pages

I understand the 4R70W is a pretty stout and reliable transmission. What I have listed above should make it a happy animal.

However, I have read about:
-disassembling valve body
-Sonnax O-ring kits and plugs with O-rings
-replacing servos
-replacing accumulators

I have no problem disassembling anything, but don't want to if I don't need to. Make sense?
My Explorer is my daily driver. I drive about 50 miles a day, 90% highway.

Offer me advice and/or comments.

Thanks!

Seth K. Pyle

 

[arco777]

My experience is with the A4LD. Disassembling the valve body is going to be required for shift correction kits anyways and it's a good idea to clean out any gunk, valve/spool wear material, and so on. I did not find it difficult to do, although removing the bore plugs is a pain it's not too bad once you learn the tricks such as gluing a screw to the plug.

I have a few Sonnax parts in my valve bodies and like them a lot. The o-ring plugs are an option I passed on, as the stock bore plugs should re-install without issue. Sealing is not usually an issue with the stock plugs but if you were to do valve body work often you might consider it. Otherwise the stock plugs should be fine.

For servos, if you're happy with the way the stock servos perform, as long as their seals are in good condition and don't leak they should be fine. If you want more agressive servos that's another matter; a knowledgeable trans builder such as PATC should be able to give you advice on servos.

 

[skpyle]

Hello arco777!

Thanks for your perspective and advice, I appreciate it.

Seth K. Pyle