Slipping, Whirring rev xcept for at high rev | Ford Explorer Forums - Serious Explorations

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Slipping, Whirring rev xcept for at high rev


Active Member
October 29, 2010
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Greets All,

Trying to wrap up this a4ld rebuild...not sure if I am going to have to pull it back out again?

Today I tried to test drive it, have forward movement in all forward gears, but it's like it slips as it accelerates, then makes "whirring" rubbing sound..and grabs..accelerates, then slips again, etc. I didn't want to damage it further so I only went a short distance, and did not get up fast enough to go past 2nd gear.

In reverse I have no movement, unless I revved it very high, then it grabs for just a sec, then nothing.. I drove around block, came back no reverse after I pulled into space...going from D to R, put it in park, then R ..revved high and it grabbed for a sec, then nothing, but when I went from R to N it wouldn't roll freely, like it was stuck?

If any of this makes any sense to anyone, please let me frustration level is getting high, I thought I rebuilt correctly, but maybe not?
Am going to recheck bands tomorrow... not sure what else to do?

If I cant find any external cause I guess I will have to pull it and look inside in case I can find prob there....

Thanks for any advice!


Prior to this I had no reverse on uphill slope, delayed engagement in low..other than that ran day I lost all movement in all gears at freeway speed , no noise eng just revved and nothing, had no pressure in any gear.
I pulled it and I rebuilt it completely (I thought).. replaced clutches steels, seals, washers, od and int med servos, replaced broken front pump gear which caused failure, bell housing bushing. Had wear on star washer and "castle" teeth on OD drum, replaced both, had wear on bottom of input shell, was stuck together, had to remove lockring on sungear to dissassemble, replaced shell and sun gear, high/rev clutches were burnt also.

I put it back in, and seemed to have a binding condition, I also had no rev, I disconnected driveshaft(rear), still had bind had to jack up front and turn wheel to release bind, I checked pressure and it was high in all ranges, super high in rev and bleeding down to 120 then soaring again... I dropped vb and started rebuilding it, got 3-4 backout valve hopelessly jammed in farthest back I bought a used valvebody same exact version as mine...rebuilt it, did transgo mods except I didnt drill pucks....reinstalled torqued w inch pound wrench, topped off fluids...took six qts.
Then took test drive today...and experienced symptoms listed above.

Thanks again for any help!

Just to keep everyone informed... I know you are all breathlessly awaiting news...

Dropped pan and checked manual valve positioning, really thought that might be it...but it seems good.

Replaced seals on low/reverse servo, I only have the o-ring type, and I checked with a screwdriver, stuck it up the low reverse bore, pushed against tang on Low/reverse band, it seemed to have spring back... also I went ahead and added a drain plug to my pan so I can add man valve index mod, and better seals to low/reverse servo later....with less hassle.

I have an air test plate that I had borrowed earlier, guess I am going to try and use a portable reserve tank, with a pressure limiting valve, and see if I can apply air to test ports, confirm whether drums, etc. are applying and releasing.


A4LD Rebuild tieing up loose ends.. Sonnax Governor Question?

Greets All,

My question is: Does anyone have any actual info on the changes in shifts that result from using the sonnax weight? i.e it used to shift at ** mph in ** gear, now it shifts at ** with the sonnax weight...

Just about ready to call this rebuild a wrap, only issue left is late 1-2 shift, slightly late 2-3 shift...sometimes it shifts almost normally, but other times it must go to between 3500 and 4500 rpms, then when I let off gas it shifts.

I replaced vacum modulator just in case, it wasn't leaking.. but the adjustment wheel was ****ed, so I replaced it just in case....

I am going to remove transfer case, pull and clean governor next...

Also, I have weak Reverse. Reverse is pretty good when cold just late engagement, but when Hot I have less movement. I have Man 1, and High Gear, I replaced orig seals with seals in kit, but they were standard O-ring type(both orig which also had issues, and kit seals were o-ring).. so I am going to order the improved vitron D seals and install them.

Other than that it runs sweet, all gears strong including OD.

Thanks for any help!