55R5W Reverse Problem 2003 Explorer.

[Dapped]

Hi Guys,

Need some advice here. I'll keep this in point form for easier reading.

Problem:
Select Reverse and instantly feel a bit going in but not fully engaging.

Bring up RPM and it bangs into gear then releases then bangs in gear then releases, this will continue to do this until I back off on the throttle. Have to watch were I pull into so I don't have to give throttle for reverse, just easing it for now.

Conclusion:
Not getting full reverse.

History:
Transmission was rebuilt at 180 K, now 205 K
Servo Bores were done with brass sleeves on the OD and Intermediate Bores.
New Solenoid block installed.

All gears from 1st to OD work fine and shift smoothly and seem to shift at the correct RPM.

I have read and read and read and found nothing similar to my condition.

I'm thinking it may be the reverse valve in the valve body and was thinking to order a new valve body online and trying it but sure would appreciate the opinions here before doing so. I could be on the wrong track here.

Thanks and hope to hear from you.

Regards
Don

 

[ronwc]

trans

Go the easy way first and make sure fluid is full.

 

[JK080]

I think you are on the right track.

If the fluid is full I would remove the pan and check the filter first, making sure its the correct one and that the seals are in place and tight. Then remove the reverse servo, making sure the piston and seal are intact and not damaged (Watch out for a big spring). With the servo off you can check for a damaged band, it may be hard to see if its lost the lining but that should be in the pan and filter.

Then its valve body time, I would give it a check for the obvious signs of damaged gaskets and stuck valves. If everything is checking out visually then there are two valves that can wear, these can give you reverse problems. I would say less than 1/3 of these I get my hands on have issues with one or both of these valves, but it does happen.

Here is what I use for these valves, they do require the use of reamers and a holding fixture, these items I have and they are not cheap. If this is where it comes down to then I would just get a replacement valve body with the updates already done or just one that is not worn.



http://www.sonnax.com/system/announcement/56947J-23K.pdf

http://www.sonnax.com/system/announcement/56947J-29K.pdf

 

[Dapped]

Problem occurred basically overnight about 2 months ago. I know one should not assume but I have concrete driveway and never a sign of a leak. Also added a few liters back a while just in case.

The effect is like something is kicking fully into and out of reverse every 1/2 second, equal time in and out. When I hold the break and do this at 1500 RPM the truck gets a rocking...have not done it for too long, more for test purposes, don't want to screw up planetary or other bands and things.

I would think low oil would have effect on forward gears and as mentioned before, everything is correct there with all gears and shifting from 1st to OD. All forward gears and shifting are smooth.

 

[Dapped]

Would like to add I am not sure both Servo bores were done, I was told they were and I know for sure the OD bore was done because they forgot to drill it out and I go the bang shift from 1st to 3rd when backing off the gas and no OD... took it back in and they drilled it out..

With that being said, does the intermediate servo bore have anything to do with reverse?


Thanks "JK080" for answering my PM and hopping on board here. Not sure what reverse servo you are referring to here "Then remove the reverse servo, making sure the piston and seal are intact and not damaged (Watch out for a big spring). "

Thanks Guys
Regards
Don

 

[JK080]

Problem occurred basically overnight about 2 months ago. I know one should not assume but I have concrete driveway and never a sign of a leak. Also added a few liters back a while just in case.

The effect is like something is kicking fully into and out of reverse every 1/2 second, equal time in and out. When I hold the break and do this at 1500 RPM the truck gets a rocking...have not done it for too long, more for test purposes, don't want to screw up planetary or other bands and things.

I would think low oil would have effect on forward gears and as mentioned before, everything is correct there with all gears and shifting from 1st to OD. All forward gears and shifting are smooth.

This trans has a long filter inside with seals on both ends, so lets say if the rear seal for the filter is not sealing it will pick up air when moving backwards because the fluid has shifted towards the front.I use to catch this a lot in the A4LD transmission because someone left the seal off or damaged it when changing the filter. So, if you haven't changed the filter recently then I doubt you have to worry about it anyway.

This still could be a reverse servo problem, maybe the band but I doubt it.

Valve body problems like weak or broken springs, but it sounds more like a internal fluid pressure leak. You may be able to see it with a gauge but I would just jump on in the pan and look around.

 

[Dapped]

Thinking back when they did the rebuild, they were not sure what was wrong and I know they had the servo pack in and out along with the valve body more than once before realizing they forgot to drill the brass sleeve, the new ones come pre-drilled but this was 3 years ago when mine was done. Maybe the drilled it with the trans being installed just not sure here, tried to spy as much as I could but of course I was shewed out of the shop a few times..

With that being said, I think they reused the gaskets when doing so, perhaps I have a failed valve body gasket or perhaps servo pack gasket failure... I think your right JK080 maybe I just have to hop in and see, just would be good to have an idea as parts will have to be ordered and I will be down waiting, as for now I can still use it.

Regards
Don

 

[JK080]

Sure I understand about having everything you need ahead of time so you wont be down long, but that can be expensive and troublesome if you are wrong and don't need the parts. I would get the reverse servo piston itself and the rubber seal for the housing and wait on the valve body.

What I would do is to remove the pan, remove the reverse servo and inspect the servo and band. If all is well you can put it back together and drive it until you get a valve body.

Going back to the rebuild, I have had to drill those hole before after a rebuild and it sure is nice to have the new bushings with the holes . The servos for the intermediate and overdrive bands will not cause this problem in reverse. The valve body gaskets in these things are a great gasket, I have had them off and back on without issue, so I wouldn't suspect that.

The reverse servo is held on by the "G" bolts, there are four just remove them to inspect the band and servo

This is the servo apart, you will have to twist the top to get it apart and then you will see the big spring, its not a big deal just if you don't know its there it can send parts flying.

Also check the valve in here to make sure it moves freely.

 

[Dapped]

Thanks JK080.. This is exactly the guidance I was looking for and I thank you very much for taking the time to help me.

I will do exactly as you have suggested. It may take me a bit but I will post back how it goes.

Looking at this part I can see there is an internal O ring, if this has failed I can imagine the piston pushing on the band and when it gets close to the end of it's stroke and it is pushing on the band it would create a back pressure, this pressure could then cause the piston to go off center and lose the seal on the outside of the piston, thus retracting back, then when it returns it centers the piston again to push out once again. This could explain the cyclic action that is going on.

I think for piece of mind I will order a new piston or a complete servo just in case. Hopefully this will be the problem.

As this servo is a low pressure activation, any leakage would most likely cause it not to go into gear which is what is happening until I hit 1500 RPM thus increasing the pressure......and giving it what would normally be there....

Maybe I think too hard!!!

Thanks again JK080
Regards
Don

 

[Dapped]

Found one of the best Service Manual Download for the 5R55W and 5R55S, thought I would share....

http://downloads.bustedfingermotorsports.com/Ford%20Transmission%20Manuals/5R55W.pdf

 

[Dapped]

I did some test last night and triple checked everything.

Is the "Low/Reverse Servo" used by both forward 1st and reverse gear?

If it does and my 1st gear works fine, which it does, would this not eliminate the possibility of this " Low/Reverse servo" being messed up ?

I can get a "ford factory tested Valve body" for 39.99

Regards
Don

 

[JK080]

I did some test last night and triple checked everything.

Is the "Low/Reverse Servo" used by both forward 1st and reverse gear?

If it does and my 1st gear works fine, which it does, would this not eliminate the possibility of this " Low/Reverse servo" being messed up ?

I can get a "ford factory tested Valve body" for 39.99

Regards
Don

The low reverse band is supporting the low reverse sprag, and it is not applied in regular drive 1st or 2nd only in manual 1st and 2nd. The low reverse sprag is holding because you wouldn't have 1st and 2nd if it was broken.

If the the sprag is broken it wouldn't move in "Drive 1st" but if you use manual low it puts on the low band and it does the same job as the sprag, therefor allowing the vehicle to move in low 1st.

So just because it has 1st and 2nd does not mean that the band and or servo has to be good, but you are definitely are doing some good diagnosing skills.

 

[Dapped]

OK to clarify it...

Drive 1st to 5th (OD) work fine.
Manual 1st works fine.

Then still could be "Low/Reverse" Servo?

Regards
Don

 

[Dapped]

I hope these pictures come in here.
I took off the reverse servo and there was shrapnel and shards of steel flakes laying on the top side of it. The broken ring or spacer was laying on top as well. EDIT: no idea where it came from and what it's for? EDIT 2: The band seem to look OK, perhaps the shards inside were stopping the piston from hitting it's max extension, beyond me at this point.

What do you think?
Regards
Don

 

[Dapped]

Cleaned everything out and found some fine needle bearings.

Looking at:

http://www.makcotransmissionparts.com/mm5/graphics/Catalog-pdf/5R55N.pdf

Could be low sprang bearing? in the reverse hub #261 again not sure..
I am going to re-assemble and put ATF fluid in and drive it till it pukes I guess. I don't think there is much more I can do here unless I remove tranny. It did still work somewhat so hopefully still will.
I'll keep you all posted!

Regards
Don

 

[JK080]

Well thats not what you what to see, that is what is left of a thrust bearing.

It doesn't really matter where it goes, it will have to be completely disassembled and inspected to find the extent of the failure.

 

[Dapped]

I agree JK080. Just beyond my means as I have no hoist.

I did set out and did what I could with a set of ramps.

May look at buying a rebuilt transmission with all the updates or a used one at a wrecking (recycle) yard.

Thank you for your help and expertize, was much appreciated. Like I mentioned, it is much better than before.

Regards
Don