Lift-All pump gears--reassembly advice?

zooeyhall · Mar 8, 2009

I had to completely dissassemble the Lift-all pump on my M. I am in the process of putting things back together, and had a question about aligning the pump gears and the pump body. I've used a good micrometer I have the correct shim arrangement giving the recommended side clearance. However there doesn't seem to be anything to ensure the "centering" of the gears in the pump body--no dowell pins or anything on the back plate. When I try to tighten the pump body bolts the gears become hard to turn. Is there some sort of knack to this? Any advice is appreciated!

47M · Mar 8, 2009

Where are you putting shims inside the pump? My Lift-All manual doesn't mention shimming anything. If clearances are too great to produce good pressure, you need to replace worn out parts--either the pump body, cover plate, or back plate.

The drive gear and driven gear have to be "thinner" (1.998 in. to 2.000 in.)than the pump body is thick (2.001 in. to 2.003 in), or the pump cover and backplate will pinch the ends of the gears when you tighten the bolts.

The driven gear stud and the drive gear shaft keep the gears where they need to be in the pump body, if the bushings for the gears are all in good shape.

Mitch

Anonymous-0 · Mar 8, 2009

The shims are to adjust end clearance not side clearance of gears to plate. Sounds like you need another light shim. As far as centering gears, just shove body against gears on pressure side. You want it as tight as you can get it and still turn it with a maybe a foot long bar,these are not real precision pumps. If it is really stiff, you just need to be gentle when you engage the clutch on start up, run it in a little at a time, it will free up readily. If all parts were perfect you would want it free on assembly but I am betting there is some grooving on both ends. If you have over about .008 clearance around gears it will probably not pump very well.

Anonymous-0 · Mar 8, 2009

This is typical when assembling a gear type pump. Myself last summer I did the same job as you with my super M. Assemble the pump loosely and tap the side of the pump housing with a hammer twisting the pump shaft at the same time. Tighten pump housing bolts even and in inkermits of 20 lbs.Tapping the housing with a hammer will line the pump shafts.

zooeyhall · Mar 8, 2009

Thanks everyone for the advice. I tightened the bolts to about 5 ft lbs, and then carefully tapped all around the pump body while turning the gears and seem to finally get it just right, where I could turn the gears with minimal effort. There is definitely a knack to getting it just right!

Got it re-installed and tested the pressure and it is just over 800 lbs.

Mine had some thin aluminum shims between the pump body and the back plate. They seem to be OEM.

Lift-All pump gears--reassembly advice?

zooeyhall

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47M

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Anonymous-0

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Anonymous-0

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zooeyhall

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