The BSA A7-A10 Forum

Technical => Frame => Topic started by: Jules on 27.05. 2011 09:20

Title: front wheel offset in forks
Post by: Jules on 27.05. 2011 09:20
Me again, I've assembled the front wheel into the forks so that I can check frame/rear wheel/front wheel alignment and note that the front wheel is closer to the RHS fork than the LHS fork ie not central. The bike is a 1956 A10 with full width hub and a spindle clamp on the LH fork ie spindle passes right through to a nut on the RH fork and is then clamped in position by the LH fork. The spacer seems to have the right protrusion that locates into the RH fork but it means that the brake hub is basically right up against the fork (whereas the rear has a spacer) - no spacer is shown anywhere in the books and the hole for the tommy bar is in about the right location relative to the left fork, so I can only assume its correct, but it looks wrong  *conf*.
Does anybody have any practical experience of this please? cheers
Title: Re: front wheel offset in forks
Post by: muskrat on 27.05. 2011 14:50
G'day Jules,
               first make sure the forks are straight and parallel. Easier to do this with the sliders off. Fit the wheel and tighten the nut. Now pump the suspension a few times then tighten the clamp. The rim should be central in the forks. If not spoke adjustment will be made to do so.
 I have checked mine to be true but the hole is partially covered. I can't remember how close the brake plate is to the slider, will look in the morning.
Cheers
Title: Re: front wheel offset in forks
Post by: bsa-bill on 27.05. 2011 16:29
Yes and if you have to move it across (the rim) it takes very little on each spoke, a half turn slack off  each spoke on the nearest side and a half turn tighter on the furthest side moves the rim probably as much as you need, now how do I know this *whistle*
Title: Re: front wheel offset in forks
Post by: muskrat on 28.05. 2011 23:49
G'day Jules,
                brake plate against slider. A few pics.
Cheers.
Title: Re: front wheel offset in forks
Post by: Jules on 29.05. 2011 09:12
thanks Muskrat, I must say that it does look like mine, but then why would the wheel be laced up offset, seems very strange... I've attached some pictures too. It looks like I need to move the wheel across to the left about 10mm, I guess I could just add a spacer to the RHS? Would be interested in your (further) thoughts, if you have any, cheers
PS also started another thread because I've found that I have one leading and one trailing fork leg ie the two legs are angled forward at different angles   *sad2*.....
Title: Re: front wheel offset in forks
Post by: muskrat on 29.05. 2011 20:36
G'day Jules,
                looks like the PO didn't measure the hub to rim offset before they unlaced it and didn;t bother to correct it. I don't like the spacer idea and may create other problems. If the gap is 10mm larger on one side the rim needs to move 5mm. 1 1/2 to 2 turns on each nipple should get you close (give them a good dose of WD the night before), and might get away with not removing the ryre just let the wind out. BUT there is a chance a spoke could puncture the tube.
If I understand your other ? right it means either the triple clamps or fork legs are bent.
I like the short seal holders. Do you have internal springs?
Cheers
Title: Re: front wheel offset in forks
Post by: Jules on 30.05. 2011 07:36
Hi Muskrat, thanks for the feedback and sorry to disappoint you but the short seal holders were the work of the butcher who had the bike years ago. He hacksawed off the shrouds (presumably because they were rubbing through due to the bent legs) left the springs exposed and chromed everything, then proceeded to bush bash the bike and totalled the forks (and I mean totalled them !). I have replaced the legs and fitted new bushes and hard chromed the legs, they slide very nicely now but have reassembled them using the old seals and yoke bearings just to see if I need to get other parts like shrouds and things sorted/painted before I do the final assembly to avoid damaging the new parts......any other thoughts welcome (like where's the best place to get some shrouds, I thought I had found some but they appear to be RR ilo Flash), cheers
Title: Re: front wheel offset in forks
Post by: Angus on 19.01. 2014 21:21
Hope its Ok to reopen this thread, think I have a similar problem.
1960 A7 with full width hubs and groove in axle and bottom clamps to hold front wheel on.
Have run for 14 months with very old tyres (still soft and no cracks) but it was worrying me particularly as I still want to ride but it never really dries out.
Anyway it was fine. Bought new tyres same size, same manufacturer but different model (Avon AM20).
This tyre rubs on the mudguard right hand side when looking at the bike, the old tyre must have been close (unless I am missing something) but did not rub.
The wheels where rebuilt in the 1980’s with new rims and spokes but not used until rebuild Oct 1012, so I assume it can not be anything but the offset (about 15mm gap on right hand side).
I have check the A10 and that front wheel looks even in the forks.

Confirmation or other options would be good before I contact a wheel builder to look at it.
Title: Re: front wheel offset in forks
Post by: 1959superocket on 19.01. 2014 21:57
I remember reading somewhere that the front wheel on a FWH 58-62 A10 does have an offset so should not be laced up central to hub.
I cannot remember what the offset is but BSA familiar wheelbuilders will know and I thought it was only about 5mm which might be to compensate for the nut that holds the brake plate?

Regards

Stuart


Title: Re: front wheel offset in forks
Post by: muskrat on 20.01. 2014 07:26
The rim should be central in the forks. That is assuming the triple clamps and stanchions are straight. The hub could be anywhere.
Cheers
Title: Re: front wheel offset in forks
Post by: KiwiGF on 20.01. 2014 09:20
 i have a 56 a10 with ariel hubs, just a little tip, make sure the left hand leg is not under any stress caused by being pulled over when the axle is pulled through. If the axle catches on the leg it can pull the leg to one side and cause the forks to jam or be very stiff. In one of your pics it looks like the leg might be actually too far to the left as the tommy bar hole is partially covered by the leg?

I agree with othe comments that the wheel seems to have been laced with incorrect offset, albeit I suspect there is little if any offset on the ariel hubs, the centre of the rim should sit in the middle of the 2 spoke flanges?
Title: Re: front wheel offset in forks
Post by: Angus on 20.01. 2014 14:13
Thanks for the feedback.
The forks etc are all OK so must be the offset. I spoke to the friend who rebuilt them in the 1980’s and he remembers doing it and says he did not put any offset on either front or rear. He did offer to fix them but its not what he does anymore so I will take them to a wheel builder. I assume the rear needs an offset too difficult to see as the chainguard stops measuring against the swinging arm.
Title: Re: front wheel offset in forks
Post by: terryg on 20.01. 2014 15:03
Hello Angus - I'm in a similar situation to you but for different reasons.  My SR is in pieces and I have just laced the new rims and spokes but left them untensioned.  As the frame is apart for painting, my plan is to set the front wheel rim central in the forks (by adjusting any required offset) upon reassembly and then align the rear rim centreline with the front, by setting the necessary offset.  In my case, as both rims are WM2, checking alignment will be a little easier than with a wider rear.
Why didn't I measure offsets before removing the hubs?  Because the bike has an unknown history and going back to basics seemed a better option.
Title: Re: front wheel offset in forks
Post by: bsa-bill on 20.01. 2014 15:16
If the wheel is still true then it's an easy job to move it to centre of the forks.
Start at the valve and go right around the wheel slakening off the spokes on the side that too near the forks by only a quarter turn, starting at the valve again on the otherside tighten the spokes one quarter turn, (if you have to stop on either side mark the spoke you are upto (done) so you don't lose your place)
 check the wheel for centre, you might have to go around both sides again but it's amazing how much a quarter turn will move it  across.
Job satisfaction is good and if you manage to put it out of true "then" you can take it to a wheel biulder
Title: Re: front wheel offset in forks
Post by: Jules on 28.01. 2014 07:54
Hello all, I'm glad my earlier observation prompted some more discussion on this topic because since getting my headstock sorted this is one of my next jobs to do..... however, just a prompt for Terryg regarding aligning the wheels. I plan to do the same after setting up the front, then aligning the rear, but I noticed that my front and rear rims are actually slightly different overall widths due to a difference in how the rim has been rolled over (see my earlier post on this), hence I will need to take this into account with the alignment - worth a check Terryg?
Title: Re: front wheel offset in forks
Post by: terryg on 28.01. 2014 08:49
A valid point Jules re. the rims being identical widths or not.  Mine are both brand new CWC stainless WM2, consequently I 'expect' them to be identical in width; as they will, I assume, have been rolled on the same tooling.

BUT - I learnt a long time ago that 'assume' makes an ass of u and me!  I'll make sure I check the alignment from both sides.

What's the other saying?  Measure twice, cut once - measure once, cut twice!
Title: Re: front wheel offset in forks
Post by: Angus on 28.01. 2014 16:58
Right did not want to do it myself as wanted it right to ride so wheels to wheel builders. He confirmed 5mm offset on front towards brake plate and none on the back. Got them back after two days and now fitted them both. Front dead centre in the forks, back as it was before and fine with the new tyre.
'Fram Motor Cycles' (Framlingham Suffolk) did not charge me much and quick and helpful  *smile*
Now some just need dry weather to scrub the new tyres in and continue enjoying riding her.
Title: Re: front wheel offset in forks
Post by: Jules on 04.02. 2014 06:48
Ok then, I'm going to have a go at centreing the wheel myself, then remembered that it probably needs a tool of some sort that fits well onto the spokes - where do I get something like that that works ie doesn't round out because of the poor material?? any thoughts or practical experiences welcome.... *welcome*
Title: Re: front wheel offset in forks
Post by: bsa-bill on 04.02. 2014 10:11
readily available from most of the usual suspects

This is the type you want though
Amazon here http://www.amazon.co.uk/KiWAV-Motorcycle-spoke-wrench-spanner/dp/B00F3XBUCQ/ref=sr_1_1?ie=UTF8&qid=1391508577&sr=8-1&keywords=motorcycle+spoke+spanner (http://www.amazon.co.uk/KiWAV-Motorcycle-spoke-wrench-spanner/dp/B00F3XBUCQ/ref=sr_1_1?ie=UTF8&qid=1391508577&sr=8-1&keywords=motorcycle+spoke+spanner)
Title: Re: front wheel offset in forks
Post by: muskrat on 04.02. 2014 12:52
Thats the sort I have.
Here's one in Oz  http://www.ebay.com.au/itm/Motorcycle-Spoke-Spanner-Tool-Wrench-6-in-1-Suit-MX-KX-RM-WR-YZ-YZF-CR-CRF-KTM-/151080580810?pt=AU_Motorcycle_Parts_Accessories&hash=item232d1ab6ca
Any bike shop would have them.
Cheers
Title: Re: front wheel offset in forks
Post by: Jules on 05.02. 2014 11:52
Brilliant, thanks for the quick feedback and links - just bought one from your Aust. link Muskrat, cheers
Title: Re: front wheel offset in forks
Post by: Jules on 09.02. 2014 06:25
Ok rec'd the tool, looks really good compared to my remembrance of the old type I had years ago! Good advice on the WD40 Muskrat, flooded them a few times and checked today, all cracked off ok except 2  *rant*. I must say that I was surprised it is only 2 when I looked at the state of the nipples  *evil*. I think I'll talk to Modak and (hopefully) get myself a few spares before I start, I suspect I might break a few....so here's the questions, if you can help please :
1. the parts book has the same spoke no. for front and rear but different nipples, 27 - 6813 front 27-6810 rear, any idea what the difference is and whether I can use either for front/rear?
2. the wheels are surprisingly true as is, just not centred, so I want to keep the trueness and just move the centre over 10mm at front and 5mm at rear - Muskrat suggested about 1.5 turns for the 10mm, but I'm sure I read somebody elses experience was much less than this. I really dont want to end up going back/forward so would appreciate your experiences...
3. finally, if I need to replace some spokes as I go around is this best done after I complete the move across (I'm assuming it will only be a few  *lol*) or as I go  ie move it across without interuption and complete the job so that (hopefully) the trueness remains as all the other spokes would be moved the same amount, leaving the new one(s) to just be fitted and "nipped"...
thanks for your thoughts, cheers
Title: Re: front wheel offset in forks
Post by: muskrat on 09.02. 2014 07:29
G'day Jules.
1: My book says the same re nipple #'s. I can't explain other than a typo in the parts list. 42-6813 is common to other hubs, go with it.
2: If you do it with the hub/rim in the forks give them 1 turn and check how far it's moved. Calculate how many turns to give you the desired movement.
3: Usually to replace a spoke most or all of the others must be slackened off (there goes you trueness). Outer spokes are easy but inner ones may need a few outers to be removed first.
Think of it all as a fun learning curve. Once done it's quite satisfying. I still remember my first  *whistle*.
Cheers
Title: Re: front wheel offset in forks
Post by: Jules on 13.02. 2014 09:45
Hi all, good advice Muskrat thanks - thought I'd feedback my experience for others too. I could only do 1/4 turn at a time because of the length of the spoke key, so ended up doing 3 rotations of 1/4 turn each, that got me the 10 mm offset fixed and recentred the wheel niceley in the forks and on the hub *smile*
Now I've checked the runout and its about 1.5mm horizontal and 1.5mm vertical (haven't identified the locations, just did a runout check). It doesn't look that good but I'm wondering what is an acceptable spec. please - I realise no runout would be ideal, but with old spoked wheels I cant believe that is (readily) achievable..... or is it  *eek*
Btw I'm only planning to use the bike as a club/coffe shop runs, no speeding/handling worries really......just as long as its roadworthy/safe, cheers
Title: Re: front wheel offset in forks
Post by: bsa-bill on 13.02. 2014 10:34
I read somewhere that in the UK it's 1mm, this might be different in Aus
Title: Re: front wheel offset in forks
Post by: muskrat on 13.02. 2014 11:31
I get mine down to 10 thou" = 1/4mm. You will find that where the rim is joined it's a bit flat or squashed. I try to beat it true with a mallet and then check it's the same width all the way round. If the joint is still out I disregard that section (may be 2 holes).
Cheers
Title: Re: front wheel offset in forks
Post by: MartinK on 28.07. 2017 17:10
If the wheel is still true then it's an easy job to move it to centre of the forks.
Start at the valve and go right around the wheel slakening off the spokes on the side that too near the forks by only a quarter turn, starting at the valve again on the otherside tighten the spokes one quarter turn, (if you have to stop on either side mark the spoke you are upto (done) so you don't lose your place)
 check the wheel for centre, you might have to go around both sides again but it's amazing how much a quarter turn will move it  across.
Job satisfaction is good and if you manage to put it out of true "then" you can take it to a wheel biulder

Thanks for the info. I am building a 1953 Gold Flash and the front wheel is offset to the forks. Now I have a way to sort it out, thanks.
Title: Re: front wheel offset in forks
Post by: MartinK on 16.08. 2017 11:26
On my 53 Gold Flash I had the same problem of offset front wheel. I adjusted the spokes and now it is correct. Just a little adjustment each time. slacken tight side and tighten opposite and you will see the movement.