5R55S Intermediate Servo Failures

To begin with - Moderators if you wish to combine this with my previous thread please do so.

Some of you have probably read my previous thread describing a 3rd gear failure in my 5R55S automatic transmission with only 9,500 miles. After doing considerable research using my Ford Service Manual DVD and pestering several transmission builders here is what I have determined. The root cause of the 3rd gear failures is the seal on the intermediate servo piston. By not continuing to drive the vehicle with this failure, the band is most likely not damaged. I spoke with a couple of transmission techs at 2 different Ford dealers and both said they replace 2 to 3 of these intermediate servo pistons a month for this exact reason.

So, I pulled the pan down on my 5R55S. No metal or clutch material and the fluid was not burnt. That indicated the failure may be as simple as a repair and not an overhaul. I investigated the possibility of replacing the intermediate servo piston with the transmission in the vehicle. This is not possible as the transmission is too close to the body. So I removed the transmission. Now here is where transmission shops offer differing opinions. Some shops say this CAN NOT be done without completely disassembling the transmission because when the servo piston is removed, the intermediate band anchor will fall down in the case. Yet others say they replace these components frequently without ever disassembling the transmission. I figured I had nothing to loose. I pulled the intermediate servo piston snap ring, cover, piston/seal assembly and spring. If you will look at the attached picture (the one that is very bright), you will see in the servo piston bore the anchor is still visible. This is good news as it would indicate that the band is not broken and the anchor did NOT drop down when the servo piston was removed. There is also a picture of a new servo piston, with the cover, assembled ready for installation in the case. Lastly, take a look at the piston I removed. Notice on the Small OD a 1.5" section of the sealing lip is completely gone. I now have the intermediate servo piston assembly reinstalled back in the transmission case.

While the transmission was out, I am replacing the TSS sensor as a while back I had a P0715 DTC for that sensor. I cleared the code and it never came back. But to replace the Input turbine speed sensor the transmission must be removed, now was the time to replace the sensor. Tomorrow I will adjust the intermediate and overdrive bands.

How much has this venture cost me - other than a whole lot of my labor:

(1) Intermediate servo piston (1L2Z-7D021-CA) $16.73
(1) Seal - intermediate servo piston cover W702969-S300 $2.60
(2) Band adjustment locknut (XW4Z-71000-AA) $3.60 ea.
Total parts investment $26.53

Now while the transmission is out, I am going to take advantage of this opportunity to install a 2,800 RPM stall converter. Keep in mind this is a daily driver and not a track vehicle.

In conclusion, will this fix my 3rd gear problem? Won't know for sure, but for less than $30 in parts I couldn't justify a complete overhaul yet.

Moral to this story: If your transmission looses 3rd gear don't continue to drive the vehicle.

At first glance my initial reaction was to combine this with your other thread. But after reading it, it fully diserves to be it's own thread.

Great information man!

Thanks for the info!!! Good stuff!

Hawgman said:

At first glance my initial reaction was to combine this with your other thread. But after reading it, it fully deserves to be it's own thread.

Great information man!

Click to expand...

Believe me I thought about combining it with the other thread. However, I wanted as many people as possible to get this information and thought it might not get read if I added it to the other thread.

Keep in mind I don't know if this issue is resolved, but for less than $30 I couldn't go wrong.

By the way, I am doing this by myself in my garage on jack stands using only a floor jack with a flat plate welded to the pedestal. A real PITA but it can be done!!

Did you check the clutches, band and such since it was out?

Great information. I don't think I am as lucky as you are, however. While my trans did break in 3rd, I have no gears at all, so for me I am thinking something more serious.

psfracer said:

Great information. I don't think I am as lucky as you are, however. While my trans did break in 3rd, I have no gears at all, so for me I am thinking something more serious.

Click to expand...

Paul do you think this is still something common even after Tony has ran through the transmission? I recently got my tranny back from Tony and hope that I have little problems for a good while! Guess you just never know.

If you haven't noticed by now, I have not posted any new information to this thread in about a week. Here's why:

Even though the intermediate servo piston can be replaced without disassembling the transmission, the damage to the intermediate band & drum had already occurred. The vehicle made 1 shift into 3rd gear and that was it - right back to where I started. Tony (Larry's Transmissions) I guess this is where you have every right to chime in with at least one "I told you so".

So fast forward until today. Transmission has been removed and disassembled. Intermediate band and drum are toast. Now here's what I wasn't expecting. Take a look at the input shaft and overdrive center shaft. Both are twisted. Keep in mind this vehicle only puts down 470 RWHP and has NEVER seen the track.

tmcolegr said:

If you haven't noticed by now, I have not posted any new information to this thread in about a week. Here's why:

Even though the intermediate servo piston can be replaced without disassembling the transmission, the damage to the intermediate band & drum had already occurred. The vehicle made 1 shift into 3rd gear and that was it - right back to where I started. Tony (Larry's Transmissions) I guess this is where you have every right to chime in with at least one "I told you so".

So fast forward until today. Transmission has been removed and disassembled. Intermediate band and drum are toast. Now here's what I wasn't expecting. Take a look at the input shaft and overdrive center shaft. Both are twisted. Keep in mind this vehicle only puts down 470 RWHP and has NEVER seen the track.

Click to expand...

oh is that all?? Good luck with Tony your better off

Questions.

Servo:
Has an explanation been WAGed as to the cause of the seal failure? Could it be it was just poorly installed initially, or perhaps poor quality seals?

Shafts:
The 5R55W was designed for midsized trucks and towing initially. Are the shafts in the 5R55S softer then the W? I haven't heard much from the truck guys having this twisting problem.

Trans Operation:
Are you running a tune for the trans with raised pressures? If so does anyone want to WAG that the harder shifts and higher pressures could be causing both problems? Or perhaps the sluggish shifts of the stock setup could be causing anything?

Good info you provided to us. Now we just need to zero in on the possible causes.

Whats up guys.

tmcolegr said:

If you haven't noticed by now, I have not posted any new information to this thread in about a week. Here's why:

Even though the intermediate servo piston can be replaced without disassembling the transmission, the damage to the intermediate band & drum had already occurred. The vehicle made 1 shift into 3rd gear and that was it - right back to where I started. Tony (Larry's Transmissions) I guess this is where you have every right to chime in with at least one "I told you so".

So fast forward until today. Transmission has been removed and disassembled. Intermediate band and drum are toast. Now here's what I wasn't expecting. Take a look at the input shaft and overdrive center shaft. Both are twisted. Keep in mind this vehicle only puts down 470 RWHP and has NEVER seen the track.

Click to expand...

Hey sorry its been so long since I have been on here. First and foremost thanks to everyone for the positive PR I really appreciate it and you have all helped me with selling units Thank You. Now on to Todd......I have never been an I told you so kinda person so I can only say this..........and this....oh and this.....and last but not least thiscall me when you are ready to have your Tranny Built. You know Im just bustin your balls Todd. Good luck with the rebuild.

So are hardened shafts available for this tranny?

I have been selling hardened shafts with my builds because that is not the only weak link in the Transmission. I replace a ton of parts in this unit including the Overdrive Planet (This is the planet that the input shaft splines into) so putting a hardened shaft in without replacing this part and others is not helping your situation for example just changing the servo out.......LMAO I had to say it.

tlt05gt said:

I have been selling hardened shafts with my builds because that is not the only weak link in the Transmission. I replace a ton of parts in this unit including the Overdrive Planet (This is the planet that the input shaft splines into) so putting a hardened shaft in without replacing this part and others is not helping your situation for example just changing the servo out.......LMAO I had to say it.

Click to expand...

Tony, what did you change out in mine this past month?

tlt05gt said:

I have been selling hardened shafts with my builds because that is not the only weak link in the Transmission. I replace a ton of parts in this unit including the Overdrive Planet (This is the planet that the input shaft splines into) so putting a hardened shaft in without replacing this part and others is not helping your situation for example just changing the servo out.......LMAO I had to say it.

Click to expand...

Slightly off topic but do you also beef up E4OD transmission for say a 1997 F-150 4x4?

Would it be possible for you to list some of the thing you do to these trannies. Such as what type of clutch plate and steels you use and also what is done to the aluminum planitaries etc....

tlt05gt said:

I have been selling hardened shafts with my builds because that is not the only weak link in the Transmission. I replace a ton of parts in this unit including the Overdrive Planet (This is the planet that the input shaft splines into) so putting a hardened shaft in without replacing this part and others is not helping your situation for example just changing the servo out.......LMAO I had to say it.

Click to expand...

I still owe ya a coors It's the 4th I'll drink a few for you.


Trans is holding up great so far

06gt4rad said:

Slightly off topic but do you also beef up E4OD transmission for say a 1997 F-150 4x4?

Would it be possible for you to list some of the thing you do to these trannies. Such as what type of clutch plate and steels you use and also what is done to the aluminum planitaries etc....

Click to expand...

i have built a couple of E4OD units for a couple of Lightning Trucks and they seem to like them. There is a lot of work that has to be done to that unit with the valvebody and valve changes.

sevenleaf said:

I still owe ya a coors It's the 4th I'll drink a few for you.


Trans is holding up great so far

Click to expand...

Thanks Tim

don_w said:

Tony, what did you change out in mine this past month?

Click to expand...

Oh just the front pump seal..........Probably easier top tell you what I didnt change.

tlt05gt said:

Oh just the front pump seal..........Probably easier top tell you what I didnt change.

Click to expand...

LOL... Come on now, throw me a few bones here.