How Much Wobble?

I am re-manufacturing a 1975 Mk III roadster, I am now doing logistics for the primary drive. The first item I have replaced is the bearing between the clutch basket and the clutch center. I purchased a Chinese made bearing, put it in using thermal methods (no hammering on the bearing). I let it cool/heat, I let it stabilize (thermally) and was awe struck as to how much wobble this baby demonstrated (over the stock 34 year old part).

I called another bearing supply place and asked (price independent) what was the best bearing they had. SKF was proffered as their best, I purchased it $27 (US). I installed it with the same thermal methods (heat the basket, cool the bearing---then heat the basket/bearing, cool the clutch center---no pounding). Still have wobble, less than with the Chinese bearing, but more than with the stock 34 year old relic. The wobble is less than specified in the Norton Tech Digest, but measurably more than the stock 34 year old part.

Is there something special about the Norton part number bearing? Any of you have any experience to share with me on this topic?

Regards,

RS

If your dealer were still around he would tell you that the wobble is needed to break the clutch plates loose. And in the day he may have been right with all that tranny oil on the plates. You are using the wrong yard stick to measure your Norton. Now if you were running a belt drive I might recommend a better tighter bearing and an outrigger to boot.

RoadScholar said:

I purchased a Chinese made bearing,

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Why buy cheap Chinese bearings in the first place?

RoadScholar said:

Is there something special about the Norton part number bearing?

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Yes, it is a special low-clearance "one dot" bearing (see factory manual specifications). http://accessnorton.com/norton_commando1629.html

Quote:
"The wobble is less than specified in the Norton Tech Digest, but measurably more than the stock 34 year old part."


According to Tech Digest it is "normal" with anything from zero to 3/16" wobble ??? What would be the "target" value?

I'm just about to re-shim the clutch position to get a better "line-up" for the chain and I'm changing the clutch bearing at the same time.

Cheers, Per

L.A.B. said:

Why buy cheap Chinese bearings in the first place?

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Or even: why replace good parts?


Hi guys, BTW.

Triton Thrasher said:

L.A.B. said:

Why buy cheap Chinese bearings in the first place?

Click to expand...

Or even: why replace good parts?
.

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I do the wobble test with the mainshaft not moving, the wobble is strictly a measure of the "play" between the bearing's inner and outer races.

I purchased the Chinese bearing because it was 34 years newer, I figured that it would be the beneficiary of updated materials, it was sealed on both sides and I didn't see the application as being particularly challenging. Live and learn; as far as I am concerned, from here on, China is the new symbol for bottom-of-the-barrel quality.

The original bearing, although tight, had plenty of "rough" spots.

The SKF bearing is the best commercially availabe, its properties far exceed the application's requirement. The wobble will be neutralized when the clutch pack is in place and the clutch is engaged; I concern myself only in the event that the wobble allows the basket to shift position with serial engagements/disengagements, setting up an errant vibration (?).

For anyone out there doinjg the same thing I'd advise you to go with the Norton part number bearing and save the tution money,and the wonder. I am about to start on assembling the engine, so I have plenty of time to bend over for part number bearing.

Thanks for all the input!

RS