5R55S Servo Bore Wear
This information might help everyone on the Servo Bore wear on the 5R55S/W. I'm going through it right now.
I've got an 03 Explorer 5R55S and when accelerating from a stop to about 30mph the 1-2 shift starts, although it tries to shift and lags and the rpms go
up and up until about 5K and then eventually it catches and completes the shift. Also, no overdrive and the OD light flashes.
I knew that the Servo Bores could be worn and I didn't want to half disassemble the transmission while still in the truck to figure that out. I decided to do a rebuild myself and removed the transmission and inspect everything on the bench.
Removing the transmission wasn't to hard. The hardest thing was removing some broken frame bolts where the transmission mount cross member connects to the LH frame rail due to rust and one bell housing bolt on the top passenger side. Can easily do this with normal tools. You will need an impact driver for some of the frame bolts as they use loctite and you'll need a 12pt 12mm socket for the drive shaft bolts.
The only special tools I needed to completely disassemble the transmission were: Slide Hammer which you can rent from most parts stores $40 but I get refunded when I return it. OTC 307-397 Front Pump Removal Tool. Basically clamps onto the pump shaft and use the slide hammer to remove the pump assembly. Then everything else comes out after that. I bought the OTC tool from Ford because I have a discount, it was $110 but I've seen it online for $125. You absolutely need it!
After disassembling the transmission (145K on the Odometer) the only thing that was worn was the Low/Reverse Band Assembly, the friction material was getting really low in some edges. That was basically it for the internals within the case.
The valve body didn't look to bad after disassembling that either.There was some minor wear on the Cooler Bypass Valve but that was about it. Have to install a new bonded separator plate during rebuild too, like a gasket.
Removing the Servos was another story. I removed the Overdrive Servo and found that it was cracking but didn't look like it went all the way through. Poured some water in the servo itself to see if the water went through the crack and it did. Cut the pin off the Servo since I wasn't going to reuse it anyways (Both servos are like $20 each from Ford, Buy new Ones if you're removing them). Put the pin itself in the case bore to see how badly worn it was because you can't really tell when you shove the whole servo in (seals take up the slack), just the pin in there and there was some huge slop, up and down, no side to side slop. It was pretty clear that I had some good leakage there and from the cracked servo itself too.
Talked with two transmission shops. Said when the bores where out, the pins get stuck in grooves and it puts added pressure on the servos themselves, then they start to crack. They said they do at least 2 Servo Bore jobs a week!!! So I knew from the start that it was a fluid leakage problem. When the tranny fluid was cold, it would shift okay but when the fluid got warm it had real trouble. Cold fluid is thicker then warm/hot fluid so it took up some of the slack.
So if you got issues like my Explorer has, plan on taking your time and removing the transmission from the truck. Pull the servos out (you can remove the snap rings easier) cut one of the pins off one of the servos and slide the pin in the bore and check for slop. If it does have major slop, do the rebuild from there because you have to completely disassemble the transmission to do the machining work. I budgeted $800 to do my full rebuild. $280 for the master overhaul kit from Ford.
By the way you don't have to buy the Servo Bore or Sonnax Kit to do the bore reaming and sleeving. That's like $350 to $500, I'm having a transmission shop repair my case for me for $125! Easy and it's done correctly. Just call some shops and tell them what you got.
I haven't started on assembly yet but have most of the specialty tools. The ATSG rebuild manual found on Ebay or TransmissionParts.com is a necessity for rebuild $25. I should have my rebuild done in a few weeks, In a couple months if anyone is interested, you can buy my specialty tools from me.
Also got a couple of Sonnax upgrades coming too.
You guys got questions email me
mcrawley@live.com