no reverse!

[donaldthacker]

i all of a sudden lost reverse in my 99 sport 4x4. forward gears are fine. I changed the fliud and filter and all looked really good. a local mechanic told me he thought the reverse band was broken, that was based on what I described to him. anyone have any suggestions?

 

[Glacier991]

It could the reverse band, but this would be easy to check, because that band is also used for manual 1st... select manual first and see if the vehicle moves.... if so t'aint that. That is a robust band, and unlikely to have broken. So check that first, I am doubtful, but never say never... ok, assuming you have manual 1st gear... Let's run down the list of possibles based on your info (I'll be leaving out a plugged filter in your case since you just changed it and will assume your fluid level is proper - checked hot, on a level surface engine running in park).

Your transmission uses a "Transmission range sensor" that tells the computer what gear is selected so it knows how to shift. Yours could be bad, and it may not be telling the computer to shift into R. Probability - reasonably high.

A seal on the installed filter could be bad. Did you put the two O rings on the filter? Did you use the right bolt? Are you confident of the filter installation? Probability - medium based on your own confidence level.

Your valve body could have blown a sep plate gasket, or the screws could have come loose. Also possible sticking/stuck 2-3 shift valve, 3-4 shift valve or reverse modulator valve (bores 203, 204 and 205 - see Diary) Probability - high.

Your pump could be damaged or leaking. Could be determined with a pressure test. Probability - low

Reverse clutch could be burned, the check ball in the piston could be stuck, not allowing pressurization/actuation. Probability - low in my opinion but need more info on your symptom onset.

Your low/reverse servo *could* have a bad seal, but this should also show up in manual 1st.....

Hope this helps.

 

[BrooklynBay]

Maybe a shift fork in the transfer case? Did you try to change to other settings like 4 X 4 low, or anything else?

 

[BrooklynBay]

Check this thread: http://www.explorerforum.com/forums/showthread.php?t=159680

 

[donaldthacker]

thanks for the info
i tried all of gears manually and all worked fine. i did goo done the road at high speeds as I am concerned about possible damage. I drove it in my driveway and the explorere moves just fine in all forward gears. I also put it 4hi and 4low and all forward gears worked fine, just no reverse. When I changed the filter the fluid looked really good, no debris. I replaced the o rings and it went back together fine.
you mentioned the range sensor. I called my local napa store and they did not list that item. they had several sensors for the tranny but not that one. would it be called something else?
i do want to point out that a few weeks ago we got hit by a tropical storm and we had really bad flooding. I was in some deep water and was thinking that could have effected the range sensor

 

[BrooklynBay]

It is also called the DTR, or digital transmission range sensor.

 

[Glacier991]

Your FORD dealer should have one. If you want to send me your old one I can test it for you.

 

[BrooklynBay]

Make a mark on the sensor, and the case to realign it when you try to reinstall it.

 

[donaldthacker]

i tried a new sensor, no luck. I can pull the vb, but i really do not want to go much further than that. I build just everything I just tend to stay away from tranies. you mentioned a diary, what is that. I need to see what the vb is all about

 

[BrooklynBay]

The sticky above has the 5R55E valve body rebuild diary listed.

 

[donaldthacker]

i removed the vb and the sep plate did not have any gaskets.
mainly I wanted to know what the bore adjacent to the shift linkage bore control. I could not move the valve in the bore like the others. What does this control?

 

[Glacier991]

If you mean the one next door to the manual valve - and located on the SIDE of the VB as opposed to the end, it is the reverse modulation/boost valve. You may have located your problem.

 

[BrooklynBay]

You have the bonded gaskets, so they are part of the separator plate. In the 5R55E valve body diary, there is a diagram with the entire valve body mapped out, and numbered. You could also look in the photo gallery. Glacier has a diagram there too. It's actually the same diagram that was linked into the diary.

 

[BrooklynBay]

I was looking in Glacier's photo gallery, and found this diagram. I hope that it helps.

 

[BrooklynBay]

I was actually looking for this diagram. The previous one is for the bolt torque sequence. This is also in Glacier991's photo gallery:

 

[Glacier991]

Rebuild the VB and make sure you remove and clear the sticking reverse modulator valve. I'll bet you $5 you will get reverse back.

 

[donaldthacker]

the plug #59 was difficult to remove, it has some burrs on it. Also I am have trouble trying ot remove #62&63 and the spring inbetween. should these come out fairly easy.
I bought the superior kit and the ford parts listed in the dairy. all is done but the above.
also the superior kit ask to splice wires for the pressure riser. I read a lot on the is the diary and I seem to get mixed thoughts. do I need this?

 

[BrooklynBay]

If you remove #6, it should come out. You might also try some low pressure air to push it out, but be careful not to apply too much. It could shoot across the room!

 

[donaldthacker]

i finally got the reverse valve out, not easy at all. I found that the valve as well as the bore wall had a few burrs on them, thus keeping the valve from moving. I used a rat tail file to lightly clean the inside of the bore. I also used a very fine soft deburring bit to clean the valve. I got the valve to move with ease.

Now I have a concern about doing this, I cleaned the vb very good a put it all back together. During the deburring of the valve itself I removed a small area of the hard coating. what impact will this have?

I have the tranny back together and road tested it. Well I got my reverse back, all forward gears seem to work fine. I am going to put more highway time on it today. I used the parts that you recommended.
I am a little concerned that it seems to shift into reverse fairly hard. It seems a bit harder that before. I thought the superior kit would help with this.

any thoughts?

 

[BrooklynBay]

You could replace the low/reverse piston's O rings with the viton D ring kit.