LU-4 rebuild HELP!

[N1VSM]

I'm at my wit's end. (For the grammarians out there, yes, I only have one wit right now.)

I am trying to put the 2 rectangular keys on the main shaft to hold in the drum assembly. When I have the spacer in the correct place (between the drum & the keys), the keys are 1/8' too big - too much to overcome with a BFH. Without the spacer, there is plenty of room.

History, I am using the original parts which were installed correctly. Is it possible that the worm gear shimmied up the shaft by that much?

Any thoughts?

[MSeriesRebuild]

I'm at my wit's end. (For the grammarians out there, yes, I only have one wit right now.)

I am trying to put the 2 rectangular keys on the main shaft to hold in the drum assembly. When I have the spacer in the correct place (between the drum & the keys), the keys are 1/8' too big - too much to overcome with a BFH. Without the spacer, there is plenty of room.

History, I am using the original parts which were installed correctly. Is it possible that the worm gear shimmied up the shaft by that much?

Any thoughts?

My guess is the brass gear is pressed too far onto the shaft keeping the shaft from sliding through the the worm housing far enough for things to align correctly. Completely assembling & adjusting the gear box end will bring everything else into proper perspective for you I believe. It's a fine line as to where that gear rest on the shaft & everything working properly. Good luck.

[N1VSM]

What confuses me is that it all fit together when I took it apart, and as I put it all back together (without removing the worm gear) in the same order, it doesn't fit. I'll double check everything in the gear box, since in rebuilding I've taken out the "slop" of the movement.

[MSeriesRebuild]

What confuses me is that it all fit together when I took it apart, and as I put it all back together (without removing the worm gear) in the same order, it doesn't fit. I'll double check everything in the gear box, since in rebuilding I've taken out the "slop" of the movement.

Just tapping on the end of the drum shaft will move the gear as it doesn't press that tight. The wrong thickness cover gasket will cause the gear to move on the shaft when the cover is torqued down.

[Lifer]

I'm at my wit's end. (For the grammarians out there, yes, I only have one wit right now.)

Awwww! Ya went and spoiled my fun!

[N1VSM]

Just tapping on the end of the drum shaft will move the gear as it doesn't press that tight. The wrong thickness cover gasket will cause the gear to move on the shaft when the cover is torqued down.

Mine is stuck fast - funny since there are no signs externally of over-stress or abuse. I may try a press, if I can find someplace that has one AND is competent.

Question 1: Charles - for the record, what is the correct cover gasket thickness?

Question 2: Upon applying heat, the bronze worm gear will expand significantly more than the drive shaft. (I'll defer the physical/chemical proof.) In your collective experience, how much heat will get things to expand enough to get the gear to let go? Are we talking about propane? acetylene? plasma? fusion?

[MSeriesRebuild]

Just tapping on the end of the drum shaft will move the gear as it doesn't press that tight. The wrong thickness cover gasket will cause the gear to move on the shaft when the cover is torqued down.

Mine is stuck fast - funny since there are no signs externally of over-stress or abuse. I may try a press, if I can find someplace that has one AND is competent.

Question 1: Charles - for the record, what is the correct cover gasket thickness?

Question 2: Upon applying heat, the bronze worm gear will expand significantly more than the drive shaft. (I'll defer the physical/chemical proof.) In your collective experience, how much heat will get things to expand enough to get the gear to let go? Are we talking about propane? acetylene? plasma? fusion?

I wouldn't recommend applying heat in this case. A decent press should move it without a problem. You mentioned the bronze worm gear, the worm gear should be steel & the large gear on the worm shaft should be bronze. Be certain the bronze gear has a centered operating position as it meshes with the worm gear. Everything comes together here at very close tolerances. Cover gasket thickness varies, when all is in place correctly, slide the gear housing end cover onto the shaft & against the housing. Most likely it won't go all the way against the housing, measure the gap with a feeler gauge, use a material at least .025" thicker than your measured gap. It should compress out when the cover bolts are tightened & be OK. Be careful though, if you tighten the bolts & the gasket is too thin, you will break the bolt holes out off the cover plate. After tightening bolts, check to see the drum shaft rotates freely, if it's tight, you'll have to use a thicker gasket.

[N1VSM]

I wouldn't recommend applying heat in this case. A decent press should move it without a problem. You mentioned the bronze worm gear, the worm gear should be steel & the large gear on the worm shaft should be bronze. Be certain the bronze gear has a centered operating position as it meshes with the worm gear. Everything comes together here at very close tolerances. Cover gasket thickness varies, when all is in place correctly, slide the gear housing end cover onto the shaft & against the housing. Most likely it won't go all the way against the housing, measure the gap with a feeler gauge, use a material at least .025" thicker than your measured gap. It should compress out when the cover bolts are tightened & be OK. Be careful though, if you tighten the bolts & the gasket is too thin, you will break the bolt holes out off the cover plate. After tightening bolts, check to see the drum shaft rotates freely, if it's tight, you'll have to use a thicker gasket.

Update- was able to nudge the bronze gear and have found the real problem. Talking about the main shaft: when the keys that keep the bronze gear in place are against the housing/bushing in the gear box (shaft assembly is all the way in), the drum is installed on the shaft, then the spacer ring installed, I cannot get the keys in: they are about 1/16" off. I can get them in if I shave them down, or try to nudge the drum bushing in a bit. Again looking for help - I don't want to break anything.

[MSeriesRebuild]

I wouldn't recommend applying heat in this case. A decent press should move it without a problem. You mentioned the bronze worm gear, the worm gear should be steel & the large gear on the worm shaft should be bronze. Be certain the bronze gear has a centered operating position as it meshes with the worm gear. Everything comes together here at very close tolerances. Cover gasket thickness varies, when all is in place correctly, slide the gear housing end cover onto the shaft & against the housing. Most likely it won't go all the way against the housing, measure the gap with a feeler gauge, use a material at least .025" thicker than your measured gap. It should compress out when the cover bolts are tightened & be OK. Be careful though, if you tighten the bolts & the gasket is too thin, you will break the bolt holes out off the cover plate. After tightening bolts, check to see the drum shaft rotates freely, if it's tight, you'll have to use a thicker gasket.

Update- was able to nudge the bronze gear and have found the real problem. Talking about the main shaft: when the keys that keep the bronze gear in place are against the housing/bushing in the gear box (shaft assembly is all the way in), the drum is installed on the shaft, then the spacer ring installed, I cannot get the keys in: they are about 1/16" off. I can get them in if I shave them down, or try to nudge the drum bushing in a bit. Again looking for help - I don't want to break anything.

Nothing should be hitting anywhere. Are the worm gear & the bronze gear tracking on center? Once you have achieved a perfect center at the gears, then you can accurately check out why other things aren't happening as they should. Check your keys & key ways in the shaft for burrs around the edges, doesn't take much to create 1/16" of interference. Everything has to be a tight fit with these keys so that all works properly in the end. If you start shaving things, you are likely to wind up with loose motion in the end, not good. As I already said, once gears are tracking on center, finding other small interferences usually is fairly straight forward. The reason why gear centers are so important is that when they rotate they will automatically pull themselves toward the center, if something is holding the gears from reaching that perfect center point, it won't let the shaft fall into the correct position so other things fit the close tolerences they have to for it to go together. It can be a rather pains taking process, just have patience & take your time. If it came apart & all is in good condition, it will go back. One other very important factor with the LU-4, when you get it assembled, BE SURE TO CORRECTLY ALIGN THE END HOUSINGS WITH EACH OTHER. If the housings aren't perfectly aligned with each other, it will leak oil around the clutch end housing oil seal no matter how good the seal is.

[N1VSM]

... once gears are tracking on center, finding other small interferences usually is fairly straight forward.

I think I fount it - one of the bushings must have been replaced at some point - it is sticking too far out of the drum. (Fortunately for me, the inside surface looks & feels beautiful - I still need to see if it is circular.) From here, I'll take it really slowly & check everything.

Thanks again!