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Early Commando head bearings

Submitted by stephen_froggatt on Fri, 17/07/2015
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Commando

Hello all this is probably basic, fitting new head bearings to an early commando (71) tried taper rollers but did not like the Gap with the taper rollers being slightly larger, gone back to standard bearings with a spacer but the spacer is loose even with the bearings fully seated. when I originally stripped it, it did not have a spacer , do I need it , the forks are early forks, dominator I think

Cheers steve

Submitted by david_evans on Sun, 19/07/2015

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Hi Steve,

Your bike would have originally been fitted with cup and cone and loose balls with no spacer. The later 750 and all 850s have a pair of standard sealed ball races with a spacer. My 1970 Commando came from the previous owner with these sealed bearings but no spacer. In effect they were being used as a cup and cone type of bearing. Like you, I thought I should fit a spacer, but the standard spacer was not the correct length to do anything constructive. Fitting the sealed bearing without a spacer may be ok for you, (I rode my bike for years like this) but I have gone to taper roller and there doesn't seem to be any issue with gaps and the headlight brackets fit fine. Taper roller is the more satisfactory engineering soloution IMHO

Submitted by phil_hannam on Mon, 20/07/2015

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The Mercury frames also had a spacer between two headstock ball bearings. When I had my frame repainted 5 years ago and fitted new bearings the spacer then flapped around due to the thickness of the new paint. I was informed that this spacer has to be exactly the right length in order to do its job of splitting the bike weight loading between the two headstock bearings. Although, how this is achieved by the fitting of this spacer tube I do not fully understand. On the Commando the part number is 0700100.

Submitted by stephen_froggatt on Tue, 21/07/2015

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Thanks guys my commando being early, is different from the haynes and norton manuals but I have gone for no spacer ,it served no useful purpose and it seems fine, I purchase the bike from the states but it left London 7 miles down the road in 1971 ! the forks Dominator ? have two bolts protruding at the front any Idear what size type they are, dont really want to cut them off , what were they for

Thanks for your helpful comments

Steve

Submitted by david_cooper on Thu, 23/07/2015

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There is a lot elsewhere on this site on this topic. One factor is that most or maybe all Commandos had a coarser thread which makes them less suitable to adjust bearings which is why they are ( at least in theory) better of with the spacer.

 


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