BSA Owners' Club Workshop Discussions

The BSA Workshop => Singles => Topic started by: Mark on 01 May, 2018, 21:04

Title: C15 Front hub spindle
Post by: Mark on 01 May, 2018, 21:04
Hello to all,

New front & rear rims & spokes ordered for my 1965 C15 hubs are to be blasted & painted first.
Upon strip down of the front hub I noticed some washers/shims on the spindle is this normal & should they be there?
Photos attached.
Thanks in advance for your help.
Regards Mark :)
Title: Re: C15 Front hub spindle
Post by: JulianS on 01 May, 2018, 22:35
Probably an attempt by a previous owner to align a wheel which could have been built with wrong offset , the shims behind the bearing would move the wheel towards the left.
Title: Re: C15 Front hub spindle
Post by: Mark on 02 May, 2018, 21:24
Thanks for the information Julian very helpful.

I measured the offset before I stripped the rims from the hubs as followed both front & rear from hub without front brake plate & rear sprocket fitted as follows measurements taken from these sides.

Front 4.5mm & I would need to correct this by the thickness of the shims I found in the front hub.

Rear 4.0mm with sprocket removed.

I just wondered if this is correct & if any member has a record of the correct offset?

Thanks Regards Mark
Title: Re: C15 Front hub spindle
Post by: AWJDThumper on 05 May, 2018, 07:59
Mark, I rebuilt a pair of C15 wheels a few months ago using data I measured when I took the old ones apart. I've thrown away the original data but the offset on the rebuilt front wheel from the end of the hub on the non-brake side to the rim is between 19 and 20mm. It would be interested to know how that compares with your front wheel.
Title: Re: C15 Front hub spindle
Post by: Mark on 05 May, 2018, 21:03
Thanks for the info AWJDThumper,

Hubs sprayed today then need to be lacquered I will be away working from Tuesday for a while as soon as I am back I will be rebuilding & will let you know.

Best Regards Mark   
Title: Re: C15 Front hub spindle
Post by: Dabbist on 06 May, 2018, 10:12
Rupert Ratio suggests a starting point of 1/8" for a C15 full width front hub (And the same for the rear) but does recommend a final adjustment with it in the forks.
Title: Re: C15 Front hub spindle
Post by: AWJDThumper on 06 May, 2018, 10:57
To work out the precise offset required, I would recommend trial fitting the rebuild front hub in place between the forks. If D is the inner distance between the fork legs, W is the width of the hub (68mm for a WM2), and d is the distance of the (non-brake side) end of the hub from the inside of the left fork leg, then the required offset on that side of the wheel can be calculated from:

   offset = (D-W)/2 - d
Title: Re: C15 Front hub spindle
Post by: AWJDThumper on 06 May, 2018, 13:28
Just measured my B40 fork/wheel dimensions (since C15 hasn't got forks fitted yet) and, after adjusting for the difference in fork spacing, the calculation is:

  offset = (118 - 68 ) / 2 - 5 = 20mm

This seems to confirm my C15 front wheel offset is about right.
Title: Re: C15 Front hub spindle
Post by: Mark on 23 May, 2018, 20:23
Hi AWJDThumper & all,

A Quick update, wheels now relaced using my original measurements of as described before (from the brake hub side) from the opposite side to the brake hub on both wheels the offsets dimensions are.

Front: 19mm

Rear: 26mm

see photos

I hope this helps!

Mark