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Steering Head Race Spacing
#790159 11/15/19 7:18 pm
Joined: Aug 2018
Posts: 48
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Upon re-assembling my 70 TR6C forks I noticed a 1/8 in. gap between the fork shroud and the upper lug. Thinking that I had not fully seated the steering head races I tore the beast down, polished the race recesses and re-installed. Still a 1/8 in. gap. There is no specification in the manual for the correct spacing, just drive them in to a "tight interference fit". I dug through every photograph I could find of '69 or '70 vintage TR6C, T120R and found many with gaps like mine and several with what appeared to be a spacer to close the gap. Before I tear down again I thought I would ask this group if they have encountered a similar issue. I can't see where it would hurt handling, though it does very slightly change front steering geometry. I hate to keep beating the races out to fix a cosmetic problem that may not be fixable.

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Re: Steering Head Race Spacing
TrophyGuy #790161 11/15/19 7:38 pm
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Its about normal. Some people add an O ring to fill the gap.

Rod


New, Genuine Lucas Motorcycle parts!

Insist on something else.
Re: Steering Head Race Spacing
TrophyGuy #790169 11/15/19 9:12 pm
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Maybe an automotive engine freeze plug of a size to fit OVER the top headlight mount shroud, but bored open inside to clear the top of the fork tube, will close the gap.
Many of those freeze plugs are about 1/8 inch in thickness.

Painted the color of the headlight shroud, it would hardly be noticeable.

Re: Steering Head Race Spacing
TrophyGuy #790421 11/18/19 5:11 am
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Very normal

Some will have a smaller gap

The nature of handmade parts!


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Re: Steering Head Race Spacing
TrophyGuy #790438 11/18/19 12:18 pm
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I am guessing you are using taper roller bearings??? If so this gap is normal. the taper bearings are a little thicker. We just install an oring in the top of the headlight ear to fill the gap.

Re: Steering Head Race Spacing
JakeH #790456 11/18/19 6:30 pm
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Originally Posted by JakeH
I am guessing you are using taper roller bearings??? If so this gap is normal. the taper bearings are a little thicker. We just install an oring in the top of the headlight ear to fill the gap.


Using the old fashioned ball bearings. I did replace the races and balls. The replacements are dimensionally identical. I felt guilty after beating the races out, and wanted to renew them. Overly cautious as I thought powdere coating had fouled the head tube recess. Those races are brutal to beat into an interference fit, way tighter than necessary to stay in place. These are big bearing races for the load compared to the wheel bearings, so I could see no advantage to tapered roller bearings. IMHO simple ball bearings have better line contact angles, and better load reaction geometry (axial and radial) than tapered rollers in this application. I am going to use O-rings to cosmetically seal the gap, a clever trick. Thanks to all for the suggestion.


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