Steering head bearing

htown16 · Jul 2, 2016

Getting ready to install sealed bearings in my 74 rebuild. The bearings are the same width however the recess in the bottom of the tube is deeper than in the top of the tube. Looks like the top set will be flush with top of the tube but the bottom set will set about an 1/8th inch up inside the tube. Is this correct?

L.A.B. · Jul 3, 2016

htown16 said:
The bearings are the same width however the recess in the bottom of the tube is deeper than in the top of the tube. Looks like the top set will be flush with top of the tube but the bottom set will set about an 1/8th inch up inside the tube. Is this correct?

Yes.

J. M. Leadbeater · Jul 3, 2016

Why ? Did AMC make a cock up machining the headstocks they supplied to Reynold so rather than scrap them they changed the drawing to suit?? Norton I believe did the same with the single flywheels and big end very early on .....they machined a pile of flywheels incorrectly so rather than scrap them they had the big ends made oversize to suit the flywheels and changed the drawings to suit......

kommando · Jul 3, 2016

The top bearing seat is the datum, the spacer tube sets the distance between the 2 bearings, the over lenght bottom housing let's the bottom bearing to be set by the spacer tube.

toppy · Jul 3, 2016

kommando said:
The top bearing seat is the datum, the spacer tube sets the distance between the 2 bearings, the over lenght bottom housing let's the bottom bearing to be set by the spacer tube.

Not that I'm a frame design person and of course it does work so it can't be such a bad idea but why not use the lower bearing as the datum?
It would seem logical as the weight of the machine and force of front wheel hitting bumps etc would not be able to over time dislodge the pair of bearings and make them raise up till lower meets step in tubing. It would seem a more failsafe way to have the assembly the other way up.

splatt · Jul 3, 2016

toppy said:
kommando said:

The top bearing seat is the datum, the spacer tube sets the distance between the 2 bearings, the over lenght bottom housing let's the bottom bearing to be set by the spacer tube.

Click to expand...

Not that I'm a frame design person and of course it does work so it can't be such a bad idea but why not use the lower bearing as the datum?
It would seem logical as the weight of the machine and force of front wheel hitting bumps etc would not be able to over time dislodge the pair of bearings and make them raise up till lower meets step in tubing. It would seem a more failsafe way to have the assembly the other way up.

Bottom bearing first and seated top bearing set by spacer tube

htown16 · Jul 3, 2016

Thanks for the replies. Got everything back together. Had some problems with the orings on the head light ears. Found out the only way to do them is put the fork tubes through the lower yoke, then the bottom two orings over the tube, then the ears, the top oring over the fork tubes then shove everything into the top yokes. My better half gave me an able assist as it takes more than two hands.

Steering head bearing

htown16

L.A.B.

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J. M. Leadbeater

kommando

toppy

splatt

htown16

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