What caused forward clutch to fry?

[joeschwartz5150]

Hello all, thank you for taking the time to read this post.

I have a '99 Explorer with the 4.0L OHV and 5r55e transmission. Like many others I have had my share of slipping, shift flares, etc. Thanks to this excellent site I have been able to do many repairs myself and am grateful to have found such a great community of enthusiasts for this vehicle. I recently (less than a year ago) replaced my valve body to resolve an ever escalating slip/flare between 2nd and 3rd and problems getting forward any gear engagement. I planned on rebuilding my old VB but found a new and upgraded one on Ebay with the bonded sep gasket and other mods. Once installed the problem was gone and she shifted fine. However, I still had some forward engagement issues, it was better than it had been but it still persisted. It gradually got worse until I lost all ability to use any forward gear.

Feeling emboldened by the advice and information found on these forums I decided to attempt my first automatic transmission rebuild. I've always tried to do as much of the work on all of my vehicles through the years. I am mechanically inclined and like to learn what I can, when I can. So I've torn in to my 5r55e and found that the forward clutch is completely fried and found some fine hair-like metal shavings in the immediate surrounding area.

My question is what caused it to fry. The vehicle has 174K but it turns out that my trans is from a 2000 not a 1999. Not being the original owner I have no idea why the trans was replaced, nor do I know how many miles are on this transmission. Since the symptoms were there when I replaced the valve body was the low pressure the cause of the clutch going? Would it have continued to degrade even after correcting the pressure issue and was therefor just a matter of time. Could there be another cause, like a weak pump or bad seal. Will simply replacing the internals of the forward clutch assembly be enough. Or do I need that whole drum? I dont want to have to pull it out a year or two down the road to find its occurred again. Any suggestions or advice or anyone who has had the same problems insights are welcomed and are appreciated.

Once again thanks for taking the time to read and/or respond.

Joe S.

 

[crunchie_frog]

You might want to try posting this on the transmission section of the forum, if you have not already. There are some experts there who may can answer your questions. I rebuilt a 4R70w that burned the clutch plates for the OD and the seal on the piston had flipped over on a small section preventing any pressure from building so it could not hold the pressure on the plates. I bought the vehicle used so I am not sure what caused it but the seal was definitely leaking. My own two cents would be to go ahead and rebuild the entire thing now that you have it out and since you have metal shavings in there who knows where they all went. You probably can pick up all of the parts you need for a few hundred dollars. I would be sure the tolerances on your pump are in spec if you already had a low pressure problem.

 

[joeschwartz5150]

Thank you for reply. I did post in the transmission section and am working with all of the advice given so far. The general consensus is to replace everything. so that is my plan. Thanks again, every bit of info and experience is relevant!