Ford 750/755 rebuild, tranny questions

750owner · Nov 25, 2015

Hi all,

I have a 750 TLB that I've been resurrecting, and right now I have the motor out for a sleeve job (it's got a cylinder wall cavitation pinhole).

My question is this: what if anything should I do to the torque converter and/or tranny while the engine is out?

It's hard to say since I don't have anything to gauge it against, but it seemed like I wasn't get much power to the wheels, certainly not as much as the engine seemed to be making. 1st and 2nd gear work, and 3rd is almost useless except on flat pavement or downhill. Uphill in 1st, on say a 20-25% grade, with the engine rev'd pretty high it moves but it's very slow. It digs alright though.

I'm not very familiar with automatic transmissions per se, but what if anything could be going on? Is the torque converter not transmitting power to the tranny? My understanding is that the transmission shifts by having various hydraulically actuated clutches "grab" the appropriate gear, and since the thing shifts okay, is that all it needs to do, or do these clutches somehow slip too?

I've filled the hydraulic oil reservoir and changed the filter.

Comments?

Thanks!

RM-MN · Nov 26, 2015

I think there are adjustments to be made on the clutches but I've never worked on one. You may have to get a shop manual to adjust them properly or find a mechanic that is familiar with them to help or give you pointers.

Greg_Ky · Nov 26, 2015

It sounds like you have a four speed power reversing
transmission. Get yourself a manual, a lot of parts for that
reverser are no longer available. Make sure you added the
correct oil if it was the oil and filter you changed in the
reverser, the wrong oil will wipe out the reverser quickly. I
have a 655A with that transmission.

Bern · Nov 26, 2015

Could be slipping clutches or a worn torque converter. A pressure test on the tranny would have been nice before the engine came out.

Torque converters can be evaluated for wear by an end play test of the internals. Most any transmission shop should be able to do this for you, as it takes a special tool to measure it with any accuracy.

750owner · Dec 9, 2015

Hi All,
Thanks for the input.

It's actually a 3 speed with fwd/rev clutch pack.

I have zero experience with these tranny's, though I do have the service manual (which isn't too helpful on the troubleshooting), but a few possibly dumb questions:

1) The machine does shift into the various gears and fwd/rev. I understand there are hydraulically actuated clutch packs that select the gears, but can they indeed slip enough to lose a lot of power? I had figured engaged was engaged.

2) To that end, it appears there is a pressure regulator on the transmission pump which I am told can be adjusted. Is this something to look at, or are there wearable parts in the clutch packs that might need replacing?

3) Can the torque converter actually significantly wear out? i.e. can the fluid significantly wear down the vanes? It sounds that way. I have no idea what the normal service life ought to be, or what the rate of performance deterioration is.

Thanks again!

750owner · Dec 10, 2015

4) Also, what about the "transmission dump"? Could that somehow be engaged and causing power loss? I admittedly don't know what it does.

Ford 750/755 rebuild, tranny questions

750owner

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RM-MN

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Greg_Ky

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Bern

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750owner

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750owner

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