4r70w has reverse but no forward

[whlr]

Ihave a 97 F150.It goes in reverse fine but does nothing in drive.what could the problem be?

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[dirtyd0g]

Probably stripped out the hub on the forward drum or something like that.
Alan

[whlr]

Thanks for the reply.Is there any possibility of it being electrical?

[puki01504]

I have the same issue. What else besides stripped forward drum could it be?
There seems to be a lot of selonoid issues....what is common to all forward gears but would allow reverse to work?

[dirtyd0g]

Reverse is hydraulic. It could be electrical I suppose but even if you disconnect all of the electronics the transmission will be in 2nd which is a forward gear. The common link to 1st 2nd and 3rd gears is that they use the forward clutch. This transmission has a generally stacked pattern. 1st uses the forward clutch, 2nd adds in the intermediate clutch and 3rd adds the direct clutch. OD exhausts the forward and engages the od band while holding direct.
Alan

[projectSHO89]

Originally Posted by whlr

Thanks for the reply.Is there any possibility of it being electrical?

No, it's either a hyraulic or a mechanical problem.

Even if all the electrical connectors were unhooked, the transmission would still operate, although with no line pressure control and with limited gear selection.

A set of pressure test results might help pinpoint the fault, but the tranny, will, in all liklihood, need to come out for repair/rebuild.

Steve

[puki01504]

My 4R70W has only 41K on it, most of that is in an empty vehicle, never towed anything heavy. What's the likelyhood of this still be a stripped forward drum? The pressure test would provide what expected result in this case?

[dirtyd0g]

Strippage of the forward drum is not a result of weight. The general cause for the forward drum to strip out is when these transmission goes into overdrive they must release the forward clutch and instantly the reverse drum (which houses the overdrive band) must apply causing the mass of the transmission to whip around and start spinning the opposite direction. This load is placed on the direct stub shaft and the forward hub. Whichever one gives up first. That is why it is such a bad idea to allow these transmissions to go into od at wide open or even heavy throttle and suggested not to tow in overdrive.
Alan

[puki01504]

I got a chance to start the pig up again and move backward and try forward again hoping that devine intervention took place and the problem went away.....it didn't......

Anyway, if I were to go on the expert advice that I received here on this post and take this to my local x-mission shop, what exactly do I need to have done and more importanty, what do I NOT need?

Again, your time and effort is much appreciated. May I return the favor in some way in some other forum that I am knowledgeable in!

Steve.

[dirtyd0g]

If it doesn't move at all I would bet the hub in the forward drum is stripped out. Either way it has to be a forward clutch problem, the unit will have to be rebuilt.
Alan

[slimshady0479]

Originally Posted by puki01504

I got a chance to start the pig up again and move backward and try forward again hoping that devine intervention took place and the problem went away.....it didn't......

Anyway, if I were to go on the expert advice that I received here on this post and take this to my local x-mission shop, what exactly do I need to have done and more importanty, what do I NOT need?

Again, your time and effort is much appreciated. May I return the favor in some way in some other forum that I am knowledgeable in!

Steve.

i had the EXACT problem a few months back. i had to get it completely rebuilt and the shop that did it said nearly all the teeth on the inside were stripped. say hello to a $1600-$2500 tranny bill

[MikeHartsock]

If you guys feel bad about having 41k on your tranny and it not worling i had the same problem with my tranny at 500 miles.