View Full Version : Rebuilding an automatic trans

03-17-2011, 07:31 AM
Who here has done this?

Im seriously considering trying to do this to a ford 5R55E. I located a good source for a factory repair manual and parts for it, but Ive never done one. Does anyone know if there are any special tools required?

The transmission I want to rebuild has all forward gears operating perfectly so I know fluid flow is ok, but the reverse band is suspected to be broken. Im guessing I have to disassemble a number of sub assemblies to get to it, but seriously? how hard could it be?

edit: this is otherwise a throw away transmission, so I plan to take it apart at least just to see whats all involved, but if I cant get it back together, no big deal.

Hipster Lawrence
03-17-2011, 12:22 PM
I've rebuilt a c4. But that's a really simple trans.

You may need special tools. Maybe talk to a local trans builder and see what he thinks.

03-17-2011, 01:47 PM
Do it

03-23-2011, 10:06 PM
It's usually a bit of a PITA.
Lots of small parts to keep track of, that need to stay in the same place.

Clearances are very important, have to keep the clutch packs in order.

Tension on the bands also is a big deal.

And you will probably need some special tools, though my experience is limited to Toyotas.

For someone like you it's definitely doable, but IMO not worth the hassle.
Taking it apart is the easy part.

03-24-2011, 03:22 AM
After doing tons of research and reading several manuals specific to the transmission model, and looking at some good picture diaries of someone else doing it, Ive decided it should be quite doable for what I would want to do. I wouldnt be doing a full rebuild. The only special tool I would need is a clutch spring compressor. Band adjustment looks to be quite easy (torque to a value then back off so many turns).

But Im still undecided if I want to bother. I probably will do it later this summer when its nicer out and I actually want to be in the shop. Right now I have zero motivation.

03-26-2011, 05:42 AM
Might as well make this a diary of the process since I went ahead and dove in head first like I always do.

So, it took me a little over 6 hours to get the trans out of the vehicle. Part of the problem was that everything was stuck fast and the exhaust was pretty rusty. Rather than making more work for myself down the road by having to pull manifolds and drill broken studs I took my time, used plenty of Blaster and worked all my exhaust bolts out without breaking anything. It was quite a relief actually.

After that it was fairly routine but still it seemed like everything took extra effort to free up for removal. It doesnt help I dont have a lift and Im working on cold concrete with a near 50yo body, but...she came out!

http://a5.sphotos.ak.fbcdn.net/hphotos-ak-snc6/190409_193658144006911_100000881806029_438439_8183 456_n.jpg

That was yesterday, so today I cleaned up the outside of the trans. Easy off oven cleaner FTW! I then mounted it to an engine stand, an idea I got from the explorer forums and set to taking it apart:
http://a2.sphotos.ak.fbcdn.net/hphotos-ak-snc6/190413_193872790652113_100000881806029_439807_7173 970_n.jpg

I dedicated a work area and table to the job so I could keep everything in order, clean and organized. I have pretty good light in this spot as well.
http://a1.sphotos.ak.fbcdn.net/hphotos-ak-snc6/199134_193872830652109_100000881806029_439808_5116 091_n.jpg

So skip ahead to most of the day taking my time, being careful to note how everything came apart and which was was up...I came to the reason for this repair, the broken reverse band. Ive seen this exact same failure on others pictures. Seems like a weakpoint, but what do you expect at 300K miles.
The tab that the reverse servo pushes on to constrict the reverse band was broken off.
http://a7.sphotos.ak.fbcdn.net/hphotos-ak-ash4/188602_193872847318774_100000881806029_439809_5577 018_n.jpg

At the end of the day, this is where I stood, transmission torn comepltely down, everything bagged and/or tagged and all I can do now is wait for my rebuild kit to arrive. (note the laptop for the teardown manual on hard drive for assistance as needed). Man I love technology.
http://a4.sphotos.ak.fbcdn.net/hphotos-ak-snc6/199754_193872873985438_100000881806029_439810_3356 900_n.jpg

The guts of the beast. Everything looked really good coming out.
http://a6.sphotos.ak.fbcdn.net/hphotos-ak-snc6/196342_193872897318769_100000881806029_439811_2166 937_n.jpg

Parts should arrive early next week.

03-26-2011, 03:52 PM
Awesome like all ways.

03-30-2011, 10:30 PM
I was more involved in getting this thing put back together ranther than taking pictures along the way so all I have is two to share.

the cause of the problem next to the solution:
http://a3.sphotos.ak.fbcdn.net/hphotos-ak-snc6/206035_194820297224029_100000881806029_445111_6951 720_n.jpg

and the completed animal:
http://a1.sphotos.ak.fbcdn.net/hphotos-ak-snc6/188610_194820323890693_100000881806029_445112_1620 521_n.jpg

Assembly went pretty much as expected. I was worried I would drop a small piece in deeper and have to fish it out, but that didnt happen. Im confident this transmission will work fine after this.

Since I had it out anyway I also decided to tear apart the transfer case. I was a little worried when almost no fuild came out of it after pulling the drain plug. Once inside I also found everything coated in a sticky dried ATF residue...not good. Tearing it down though I really dont see anything wrong with it. The bearings all feel/sound good, nothing looked cooked or scored or anything. Ive decided to just clean all the parts really well and put it back together as is and put fresh fluid in it and see if that fixes the "clunk" it was giving me. Im a little sorry I didnt run the 4WD while up on stands and get under it to see where the sound was coming from. Its easy enough to take back out if I need to though, so I will re-evaluate after I have the trans working right.

03-30-2011, 10:38 PM
So do you completely understand automatic tranmissions now? I get the theory, but I cant wrap my head around it till I break one open.

03-31-2011, 02:32 AM
No, to be completely honest I have done the followup reading on theory to help explain what I have now had my hands on. Certainly alot more things make sense like one way bearings, planetaries, bands/drums, clutch packs, etc. All the hard stuff makes pretty good sense, but how the valve body and fluid flow works to make it all happen is still pretty much lost on me. Im good with stuff I can see. If I can see something broken, out of line, worn, etc., I can fix it. Its the same reason Im not very good with electricals.

Small update: Is there really anything more satisfying than that last little bit of wiggle that makes it just slip right into place? I couldnt help but shout, "Oh yeah! you're my BITCH!! I OWN YOU!"

(yes, Im still talking about the transmission here)

trans is in and a seal kit is on its way for the T/C. Im probably going to put this back together as is though and do the T/C seals later.

03-31-2011, 02:45 AM
That last 1/4" is allways the worst, when it finally goes your like FUCK YEAH!!!

03-31-2011, 05:13 AM
oh yeah I was totally like...

http://a5.sphotos.ak.fbcdn.net/hphotos-ak-snc6/206869_195028023869923_100000881806029_446421_7974 599_n.jpg

04-01-2011, 07:17 AM
Ok so finished this job up today, and took her for a spin. Everything works perfectly, just as it should. Well, except for the 4WD system which still has a nasty clunk in it, but Im positive now its coming from the front axle. Thats something for later.