Main Shaft Dragging in Sleeve Gear?

MikeG said:

I agree, the shaft setup is fine as you are not measuring it against anything but itself. The sleeve gear on the other hand is being measured against it's concentricity and squareness in the case. Mounting the base as you have will not tell you that.

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You are correct and that has been addressed in previous posts. The dial indicator will not measure sleeve gear misalignment with the case. Please read the following posts. If some sort of device was mounted to the sleeve gear and a machined surface on the case was gauged that was perpendicular with the C/L of the axis of sleeve gear rotation between the bearings, then we could measure that misalignment.

concours said:

"However, the bearing could be misaligned in the case and still show .000: runout."

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Dan1950 said:

That is what I am thinking. When I get my sleeve gear and bearing back from the machinist I am going to very carefully install the sleeve and inner case bearings. I think the press will allow me to assure that both bearings are seated fully/squarely and the properly fitting sleeve gear will probably allow a slight bit of self alignment since the bearing is a single row ball bearing. With the .002" interference fit it caused a very slight amount of drag in the bearing itself. Not enough to be concerned with seizure, but still not 100% to spec and it certainly wouldn't allow any alignment tolerance IMO.

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Dan1950 said:

You are correct and that has been addressed in previous posts. The dial indicator will not measure sleeve gear misalignment with the case. Please read the following posts. If some sort of device was mounted to the sleeve gear and a machined surface on the case was gauged that was perpendicular with the C/L of the axis of sleeve gear rotation between the bearings, then we could measure that misalignment.

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The mag base on the sleeve gear, stylus on the mainshaft, orbitted around the fully mounted main shaft will ABSOLUTELY speak to the proper seating of the sleeve gear bearing in the case.

No need to SHOUT...just trying to help you out.

concours said:

The mag base on the sleeve gear, stylus on the mainshaft, orbitted around the fully mounted main shaft will ABSOLUTELY speak to the proper seating of the sleeve gear bearing in the case.

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Except it would be very difficult to mount my mag base on the sleeve gear. That would be the same as my suggestion of measuring a machined surface perpendicular to the C/L except you would be measuring the actual C/L axis via the mainshaft.

MikeG said:

No need to SHOUT...just trying to help you out.

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Bold is not shouting, I just wanted to make the text stand out among the rest.

ALL CAPS IS SHOUTING.

Dan1950 said:

Except it would be very difficult to mount my mag base on the sleeve gear. That would be the same as my suggestion of measuring a machined surface perpendicular to the C/L except you would be measuring the actual C/L axis via the mainshaft.

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I've done it, on my transmission. And hundreds of times on machine tools. Be aware of droop. A mini-mag base is good. Or a clamp type.

My gearbox needs seals and a drive side bush probably. Stories like yours make me hesitant to get the parts and do a minor rebuild and instead continue topping off the gear oil and fine hone my procrastination skills.

Any positive progress on your gearbox?

Schwany said:

My gearbox needs seals and a drive side bush probably. Stories like yours make me hesitant to get the parts and do a minor rebuild and instead continue topping off the gear oil and fine hone my procrastination skills.

Any positive progress on your gearbox?

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I have been waiting on parts from AN. The shipment is still MIA but I got enough of the parts from Greg to start assembly.

What I have learned:

1) Unless the bearings are loose in the case DO NOT use Loctite. If the case is heated it tends to set the Loctite immediately making it difficult to get the bearings seated fully and square. My sleeve gear bearing is a .002" interference fit into the case with both at room temperature. The inner cover bearing is a .0015" interference fit.

2) If the sleeve gear is an interference fit in the bearing, polish the surface of the sleeve gear for a snug slip fit into the bearing.

3) Do not attempt to remove the locating dowels in the case unless absolutely necessary. Mine where seated quite tightly and required a TIG welder, heat and a slide hammer to get them pulled.

I had the old tooth-worn sleeve gear modified to use as a holder to allow the (chilled) sleeve gear to be inserted squarely into the heated case. Heating the case and chilling the bearing should allow me to insert the sleeve gear bearing into the case with hand pressure. I will utilize my new press to assure the bearing is seated fully.

I should have an update in the next few days.

Waiting is annoying but I'm thinking that old Commando is still keeping you busy playing with other bits and pieces. Looking forward to hearing of your success with the gearbox.

I used to freeze bearings and heat the case but fairly recent advice on here was to leave the bearing at room temperature. I'm pretty sure this came from Jim Comstock. The reason is that the frozen bearing cools the heated case too quickly so the bearing can get stuck midway. (So I don't do that anymore.)
There was no need for a press when I did mine in the bike a few years ago.

batrider said:

I used to freeze bearings and heat the case but fairly recent advice on here was to leave the bearing at room temperature. I'm pretty sure this came from Jim Comstock. The reason is that the frozen bearing cools the heated case too quickly so the bearing can get stuck midway. (So I don't do that anymore.)
There was no need for a press when I did mine in the bike a few years ago.

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JC did mention that in a post once but is fairly common practice. (as in don't do that)
It is a good way to generate and introduce condensation also.

I can't see a Commando ever needing the two gear box bearings pressed in (including in a cracked case)
All they need at most is the case heated uniformly after the bearing bores are cleaned with Acetone and the bearings as is also cleaned with Acetone, they should be all but drop in.
The option is then there to use wicking Loctite (290) after everything is cooled.
The sleeve gear with an outer support tube can then be pressed in with minimal pressure.

It has to be remembered it is a flawed if not fragile design having ball bearings on clusters with narrow shaft centres and no doubt why Triumph used a bush superseded to a needle roller bearing due to no case material to allow two bearings.
Norton on the other hand elected to leave a paper thin divider between the two bearing bores and that to me is another reason to use proper holding tools on the primary and final drive sprocket that are independent.

batrider said:

I used to freeze bearings and heat the case but fairly recent advice on here was to leave the bearing at room temperature.

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When you compare the size change from the heat in the aluminium to the cold on the steel the difference is so large the cooling of the bearing adds nothing worth the effort, and as already pointed out, just adds contamination via condensation.

After installing a new sleeve gear bearing making sure it is seated fully and square in the case, I purchased a new inner cover with the mainshaft bearing already installed.

The mainshaft now rotates in the sleeve gear with a very slight amount of drag. Light finger pressure on the sleeve gear will hold it while the mainshaft is rotated. I consider this to be acceptable.

It appears that there was misalignment between the sleeve gear and inner cover bearing for whatever reason.

Thanks for all the advice.

BTW. I took the decision to replace some knackered gears recently. I also received a new sleeve gear from AN that wouldnt pass through the bearing. The old one goes through with a gentle nudge. I returned the sleeve gear to have it checked and was told that the bearing seat is within tolerance as stated in the original workshop drawings and it would fit when the bearing is heated to about 120°C. Never heard that one before. I just fitted the new bearings in the shell and now i am concerned that the plastic cage of the layshaft roller bearing will be damaged when i heat up the case again. I am considering to use dry ice which would cool the sleeve gear to -70°C (condensation would be the negative affect of course)

commandofastback said:

BTW. I took the decision to replace some knackered gears recently. I also received a new sleeve gear from AN that wouldnt pass through the bearing. The old one goes through with a gentle nudge. I returned the sleeve gear to have it checked and was told that the bearing seat is within tolerance as stated in the original workshop drawings and it would fit when the bearing is heated to about 120°C. Never heard that one before. I just fitted the new bearings in the shell and now i am concerned that the plastic cage of the layshaft roller bearing will be damaged when i heat up the case again. I am considering to use dry ice which would cool the sleeve gear to -70°C (condensation would be the negative affect of course)

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Do you have the tools to measure the interference between the sleeve gear and the bearing? I have just recently rebuilt 2 transmissions, and both only require a couple of taps with a soft hammer to drive them home.

120C should not affect the cage - Oil temperatures in some industrial gear boxes can hit 120C.

commandofastback said:

BTW. I took the decision to replace some knackered gears recently. I also received a new sleeve gear from AN that wouldnt pass through the bearing. The old one goes through with a gentle nudge. I returned the sleeve gear to have it checked and was told that the bearing seat is within tolerance as stated in the original workshop drawings and it would fit when the bearing is heated to about 120°C. Never heard that one before. I just fitted the new bearings in the shell and now i am concerned that the plastic cage of the layshaft roller bearing will be damaged when i heat up the case again. I am considering to use dry ice which would cool the sleeve gear to -70°C (condensation would be the negative affect of course)

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Mine was about .001" interference fit. I had a local machine shop chuck it up in a lathe and dress it down with Emory cloth.

Derek Wilson said:

Do you have the tools to measure the interference between the sleeve gear and the bearing? I have just recently rebuilt 2 transmissions, and both only require a couple of taps with a soft hammer to drive them home.

120C should not affect the cage - Oil temperatures in some industrial gear boxes can hit 120C.

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Unfortunately i dont have the tools. My outside-micrometer only goes up to 25mm. The digital caliper gauge (not that accurate) shows that the cylinder on the new sleeve gear is about 0.01mm larger than the old one. The old sleeve gear passes easily through both the old and new bearing.

commandofastback said:

Unfortunately i dont have the tools. My outside-micrometer only goes up to 25mm. The digital caliper gauge (not that accurate) shows that the cylinder on the new sleeve gear is about 0.01mm larger than the old one. The old sleeve gear passes easily through both the old and new bearing.

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Even if your digital calipers are off by a factor of 2, that is not much of a size difference. Heating/cooling should have it fit without too much issue.

commandofastback said:

BTW. I took the decision to replace some knackered gears recently. I also received a new sleeve gear from AN that wouldnt pass through the bearing. The old one goes through with a gentle nudge. I returned the sleeve gear to have it checked and was told that the bearing seat is within tolerance as stated in the original workshop drawings and it would fit when the bearing is heated to about 120°C. Never heard that one before. I just fitted the new bearings in the shell and now i am concerned that the plastic cage of the layshaft roller bearing will be damaged when i heat up the case again. I am considering to use dry ice which would cool the sleeve gear to -70°C (condensation would be the negative affect of course)

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Have you tried the new sleeve gear in the old bearing? Bearings are usually precise, but even they can have tolerances. A half thou too small bearing and a half thou to big sleeve gear and you have a small issue. The dry ice mostly likely will do the job and I wouldn't worry about condensation. Also, a little time with fine sandpaper on the sleeve gear might do it - it's possible the edge that enters the bearing has a burr or tiny mushroom.