Wheel and chain alignment

[Minto]

My usual preferred method of getting the rear wheel running straight is not an option on my plunger A10 as you can't get the alignment tool onto the sprocket with it being a brake drum as well. My next choice would be to measure from the centre of the rear spindle to an exact reference point on either side of the bike (usually the centre of the swing arm spindle) ha, no s/a!
Is there another decent reference point to use on the plunger models, I thought maybe the front foot rest bolts but not sure how evenly placed these are.
Any other suggestions to save me messing about with a ball of string.
Thanks
Jase

[AdrianJ]

I messed around with two long pieces of wood, but that's probably not that helpful.
I have two long straight pieces of wood for sidecar alignment, it makes rear wheel alignment relatively simple.
Adrian

[Minto]

You found straight timber in Britain? Not from B&Q I presume! 😁

[AdrianJ]

It was given to me when I bought the sidecar!
It may not be straight now after a couple of years in my garage :-)

[muskrat]

G'day Minto.
I used to always use a string line. These days I do it by eye.
First eye down both sides of the front tyre and adjust so you see the same amount of rear tyre either side. Now move to the back and sight down the sides of the rear tyre till the front tyre disappears. Note how much of the front of the rear tyre you can see. Adjust rear wheel till same on both sides. It took longer to type this than it does to do. https://www.a7a10.net/forum/index.php?action=dlattach;topic=2408.0;attach=6453;image
Cheers

[Minto]

I'll give that a go Musky, though im sure my front mudguard obscures pretty much all of the tyre when viewed from the rear.
Cheers
Jase

[BSA_54A10]

Get a plumbob and with it mark the floor at the axel either side of the bike .
Do the same for the front wheel.
Move the bike
Join the dots to make 2 lines they should be parallel

[Jules]

couldn't the parallel lines be trapezoidal rather than rectangular though doing that? ie axles points are parallel but wheels/tyres are not (necessarily) parallel to the frame, nor to each other ????
I seem to remember lots of debate on this topic years past, so there should be heaps of data in old threads on this, I partic. remember Musky commenting on HD acceptance standards for (out of) alignment!

[Swarfcut]

You will be lucky to achieve true perfection when you consider some of the possible variables acting in this situation, and a fair compromise is about the best option.

 We are considering a frame which may not be perfect, fork yokes and legs not  true to original spec, wheels with run out, plunger units with springs differing in performance, for a start. Also any factor within the hubs and wheel rim which moves the  centre of each away from their design position....think incorrect rim offset on a respoked wheel, as an example.

 In an ideal world both wheels will track with the centre of their their vertical  planes in true alignment. A twist from vertical when viewed from behind produces a contact patch for the rear wheel offset to one side..... Suspension and/or frame problem. Rear wheel  vertical but running to one side "crabbing"  described by Jules as trapezoid, this is a matter of adjusting the rear axle each side fore and aft.

 This will affect the chain alignment, so maybe best to start by adjusting the rear axle so the chain lies in its  best alignment between the sprockets, in other words sprocket faces parallel as best you can, top run of chain leaving the rear drum parallel to the backplate.  Adjust the chain for the best running tension with the bike off the stand and loaded  as in use, setting the wheel by eye and giving it a go. Problem here is you need to be followed and observed by someone who knows what to look for, and a less than perfectly central rear mudguard can fool the brain.

   In practice, tensioning the chain and  matching the gap each side between the wheel rim and the lower frame member  a " does a finger fit?" test  is  the usual cheapskate way, and is adequate for everyday riding.  Certainly good enough until you get a second opinion. If it looks right, that's good enough.
   Footrest bolts as a datum you would think to be the same both sides, but beware of that bend from long ago and also the possible less attention to detail in 1950's Small Heath Frame Department.....may not have been "perfect " from new, but acceptable for the market.

Swarfy.

[BSA_54A10]

couldn't the parallel lines be trapezoidal rather than rectangular though doing that? ie axles points are parallel but wheels/tyres are not (necessarily) parallel to the frame, nor to each other ????
I seem to remember lots of debate on this topic years past, so there should be heaps of data in old threads on this, I partic. remember Musky commenting on HD acceptance standards for (out of) alignment!

Ideally you start with a strait line drawn on the floor then position the bike directly over the top and centered on it ( harder to do than it sounds ).
Then you drop the plumbob points & draw the axel lines in.
After which you measure from the point to the center line.
The measurement each side should be the same.
If you have one axel off set left / right to the other , no amount of axel adjustment will correct this situation because the frame is bent.

[Minto]

Nothing's ever straightforward is it. Thanks for all the wisdom and experience. Taking as much of this into account as I could I've done some measuring to try to find some reference points on the frame too assess alignment from.
Straight line on the floor, bike parked centrally along this. Squared off this central line both ends to give a point to measure from, plumb line from Axel's to floor, then from centre of both tyres to floor leading and trailing to check alignment. Then from various points on the frame to determine suitable measuring points for future. As it happens, it seems that on my bike the foot rest mountings are a pretty good reference, which is nice!
So, finished fitting a new rear sprocket of the correct type, not the one made of cheese with a massively undersize bearing housing from an eBay seller. What a difference, proper pleased with the results, the bike feels so much happier at higher speeds now. Just need to recalibrate the Speedo for warp!

[BSAmoto]

When I check new (to me) bikes for proper alignment, I take timing- and primary cover off. The bike is pulled up with my chain lift so that the wheels still just touch the ground. With a spirit level I check both sides of engine for being dead vertical, if they are, I can check the rear wheel. If it is, I can check front wheel. If it is dead vertical, it must point straight forward. So now I put the straight edge on wooden blocks and check wheel alignment. Should be parallel and the same distance both sides.
The reality is quite different as many swingarms are bent a little, engines hanging croocked in the frame and wheels respoked with the wrong offset. Not to talk about bent frames/headstocks.
So where to start?
I check that the engine/gearbox is fitted correctly to the frame and not crooked in any direction, then get the chainline correct and have engine and rear wheel dead vertical, wheel parallel to the engine covers - thus the rear end should be fine.
When front wheel is in the middle of the forks, dead vertical, it must be pointing straight ahead - the straight edge will verify this when wheel is compared to the engine cases. If front wheel is vertical and parallel but offset to the rear wheel, the rear wheel is off the centerline. If front wheel is parallel but not vertical, frame/headstock/fork/yokes are bent.
Make sure you turn the wheels 180 degrees and do every measurement twice, write down your findings, add up and half them - this will be the correct measurement if the wheels were dead true.
Lots of fun bending frames back in shape - once I hung a featherbed on a tree stump and pulled with my chain lift locked to my van. Sometimes the framework needs time to get back in shape so I have to leave it overnight under tension. A stubborn Commando needed two nights...
 

[olev]

Been doing a cleanup and came across this method for wheel alignment.
I used it a few years ago and it seemed to work.
cheers

https://www.motorcyclemetal.com/downloads/Harley%20Davidson%20Wheel%20Alignment%20Made%20Simple.pdf