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Simple rear wheel alignment gauge

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MetrickMetal

MetrickMetal

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Joined
Nov 7, 2007
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Location
Antelope Valley CA
First Name
Scott
Last Name
Brown
I finally designed up a simple to use measuring gauge that allows me to easily check and adjust the rear axle so that it is parallel to the swing arm pivot on my 07 Bandit.

There is no clearance problem on the left side of the bike, but on the right side, the exhaust makes it difficult to design an alignment gauge that can span the distance from the swing arm pivots to the rear axle, and to get an accurate measurement, it pretty much need to run behind the exhaust pipe.

After sitting down next to my bike and seeing what would fit behind the back side of the exhaust, I discovered that one of my 24" rigid Starrett scales slips right in between the muffler, and the 24" Starrett scale is the perfect length and stiffness.

I had already made custom billet swing arm pivot caps for my bike, and after taking measurements, I determined that I could leave them in place and just machine up a special billet cap that would slip over the swing arm pivot caps that has a slot machined into the face of it to allow my 24" scale to slip into, which positions the end of the scale on the center of the swing arm pivots.

I machined the special locater cap for the swing arm pivots so that the end of the scale is exactly on the centerline of the swing arm pivots.

I then machined up close fitting slip in plugs for each end of the rear axle, that I drilled a very small center drill hole into the end of them, which I then filled in with black paint. I made all three pieces so that when in place, the scale sits flat against each of the special axle plugs, so I am assured of getting an accurate measurement.

All I have to do now to check my wheel alignment, is to slip the plugs into each end of the axle and place the locater cap over the swing arm pivots, I then slide the scale in place and note the measurement on one side of the bike, then compare it to the measurement on the other side and make any necessary adjustments to make them both equal. :rider:

ecd7c2253d50329205bb2bf4592a7de40_large.jpg


8209e1ff1ac72afe76fa295eed3912770_large.jpg
 
Pretty darn crafty. :clap:

I'm curious how accurate the swingarm marks are. They are notoriously always off if you ask for a general opinion, but on my 2nd gen SV, every time I took the effort to actually measure it out, the swingarm marks were dead on...

inquiring minds need to know!

trey
 
treybrad said:
Pretty darn crafty. :clap:

I'm curious how accurate the swingarm marks are. They are notoriously always off if you ask for a general opinion, but on my 2nd gen SV, every time I took the effort to actually measure it out, the swingarm marks were dead on...

inquiring minds need to know!

trey
Click to expand...

Were you accurately measuring the distance from the center of the swing arm pivots to the center of the axle?
 
El Bandito said:
Were you accurately measuring the distance from the center of the swing arm pivots to the center of the axle?
Click to expand...

Well, that was my goal... who knows how accurate I really was. I was using the "string" method and think I was doing as instructed... always came out right where the marks were anyway.

trey
 
i stopped by elbanditos, and heres a couple more pics of the way he can check rear wheel alignment.

img0179fc7.jpg


and detail of the rear cap in place, (even tho the wheel is off)

img0180wb6.jpg


now if we can just get him to measure the axle adj marks on his bike and see if they are straight. i would think if his are, then they all are.
how bout it el bandito?
 
suzukijo said:
i stopped by elbanditos, and heres a couple more pics of the way he can check rear wheel alignment.

img0179fc7.jpg


and detail of the rear cap in place, (even tho the wheel is off)

img0180wb6.jpg


now if we can just get him to measure the axle adj marks on his bike and see if they are straight. i would think if his are, then they all are.
how bout it el bandito?
Click to expand...

No problem Joe, for as soon as I install the back tire tomorrow, I will check the axle alignment and post up how accurate the marks on the swing arm end up being. Thanks again for your help today. ;-)
 
One of the "poor boy" ways to check a scoot's wheel alignment is to place an eight foot flourscent light bulb on each side of the front and rear wheel simultaneously. Of course it takes some measuring but it is fairly easy to tell if the rear tire is tracking properly behind the front tire, as it should.
And then there is the white flour method. Hardy
 
Hi Guys:

What about a simple caliper like this one measured from each side of the swingarm squared off and measured to the edge of the rim. I have not looked into this yet, but in theory this should do it. You would use the bottom end of the caliper where it extends out for measuring. If the swingarm is equal thickness on both sides and is built unifomrly, one would think this would work, eh?

caliper.jpg


Scratch this - swing arm is not universally shaped - should have looked before I wrote. - DOH!!
 
Last edited:
it seems so easy to align the chain. some doubt about the marks not being totally accurate, makes some want to be able to measure exactly.
the marks on the swingarm are deep and wide, so to accurately place the adj plates using them means you need to see exactly where in the deep wide notch, the other deep wide notch lines up on a plate that can twist somewhat.

using a ruler. to measure center to center assumes the ruler is not curved, or the distance measured is straight back, not at an angle, as the swingarm has some offset to allow the sprocket fitment.

one interesting feature, is the left side axle is smaller dia at the threads, than the dia of the rest of axle, it isnt untill the nut is nearly fully tightened that the adj plate rides up the ramp to the proper dia and then the marks would be correct. with the axle loose a few turns, it allows the wheel to move forward.

looking forward to what el bandito has to say about critical alignment.

having something to use, that can exactly tell axle alignment, rather than use a sighting method, is superior. you can see in this picture, the axle plate has twisted slightly, and the other side is not the same twist.
the depth and width of the marks are evident.

img0185bp5.jpg
 
I just finished aligning the rear axle to the swing arm using the speacial gauge I made, and with it lined up the rar axle to the swing arm to within 1/64" (.015) or less.

This made the front edge of the of the 3rd adjustment mark on the left side of the swing arm is flush with the back face of the axle plate, and on the left side, front edge of the 3rd adjustment mark is approximately 1/2 the width of the mark past the back face of the axle plate.

I then measured the distance between the back shoulder on each end of the swing arm to the front face on each axle plate where the adjustment screws bear against, and there is a .03 difference between each side now.

I think for giggles, I am going to generate a drawing in Inventor with the rear sprocket and axle and the front sprocket on the approximate center lines, and then I'm going to rotate the rear axle in .010 increments and see how much it moves a line drawn from the face of the rear sprocket off of the face of the front sprocket, just to see how it effects the alignment of the chain between the two sprockets.
 
So if I read you and this right, if I eyeball the marks, get them close, eyeball the chain and make sure the sprocket and chain look good and straight, then things should be closely aligned - if my marks and yours are the same......which they probably are.

It will be interesting to hear your results of the software'd up model version to project out mis-alignments and see what it all means.

Man! - I wish I had your free time!!!!
 
Whoevers rear axle nut that is should put a single wrap of electrical tape around it before putting tool on-will not give it the pipe wrench affect-All threads should be clean for proper torque-if you torque?????????????But i am anal with my toys




rworm
 
whew, no criticisms of the scratches on the bottom of centerstand....

i'm on my third set of tires now, and with a couple more chain adjusts, in there too, i'd guess i had the nut tightened ten times or so.
one of the little things about the chain adj, is the bolts that push the adj plates, are offset to the bottom, and the plates are not precision enough to not rotate in the slot in the swingarm, so both axle plates get rotated to the front at the top. its tuff to get the alignment right first time. my chain is stretched, and has tight and loose sections.

the bike has 9k mi now, and there are little knick and rock pitts here and there, and with me taking the bike apart in so many ways, i have given up on thinking the bike is still new.

i certainly try to take care of it keep it clean, and not mark it up.
i will take the advice of using tape on the nut next time.
thanks, rworm.
 
El Bandito said:
I finally designed up a simple to use measuring gauge that allows me to easily check and adjust the rear axle so that it is parallel to the swing arm pivot on my 07 Bandit.

There is no clearance problem on the left side of the bike, but on the right side, the exhaust makes it difficult to design an alignment gauge that can span the distance from the swing arm pivots to the rear axle, and to get an accurate measurement, it pretty much need to run behind the exhaust pipe.

After sitting down next to my bike and seeing what would fit behind the back side of the exhaust, I discovered that one of my 24" rigid Starrett scales slips right in between the muffler, and the 24" Starrett scale is the perfect length and stiffness.

I had already made custom billet swing arm pivot caps for my bike, and after taking measurements, I determined that I could leave them in place and just machine up a special billet cap that would slip over the swing arm pivot caps that has a slot machined into the face of it to allow my 24" scale to slip into, which positions the end of the scale on the center of the swing arm pivots.

I machined the special locater cap for the swing arm pivots so that the end of the scale is exactly on the centerline of the swing arm pivots.

I then machined up close fitting slip in plugs for each end of the rear axle, that I drilled a very small center drill hole into the end of them, which I then filled in with black paint. I made all three pieces so that when in place, the scale sits flat against each of the special axle plugs, so I am assured of getting an accurate measurement.

All I have to do now to check my wheel alignment, is to slip the plugs into each end of the axle and place the locater cap over the swing arm pivots, I then slide the scale in place and note the measurement on one side of the bike, then compare it to the measurement on the other side and make any necessary adjustments to make them both equal. :rider:

ecd7c2253d50329205bb2bf4592a7de40_large.jpg


8209e1ff1ac72afe76fa295eed3912770_large.jpg
Click to expand...

Hmmmmmm,nice. Wish you lived in Dalla,Tx.............I'd offer you a job.
 
the difficulty in the string method, is edging the string along the front edge of the rear tire.
you would think this is easy, but pulling the string tight enough along the back edge, allows it to sink into the rubber edge somewhat.
not much, but as the string is swung alongside the front edge of the rear tire, the actual point of contact, is magnified at the point past the front wheel.
of course, you are crouching in front of the front wheel at this time, and cant lay on the floor next to the back tire, to sense when contact begins or ends.
this is where the one tool, the 30 min time, is needed.

it is extremely accurate, but this method is similar to the use the notch on the swingarm method, it is the responsibility of the one 'seeing' to make minute adjustments that are accurately measured.

on the surface it seems easy to do, but in reality is extremely difficult to accurately run the string along the outside of the rubber tire edge to reflect in distance, the true edge alongside the front wheel rubber tire edge.


the other difficulty is in keeping the front wheel 'straight'.
every time you work the rear chain adjusters, you nudge the bike, and the lay of the front forks, in relation to the rear wheel, is disrupted.
nudging the front wheel, little by little, side to side to swing it straight again, is almost as frustrating as trying to tell when the string is actually nudging the front edge of the rear tire.

imo, this makes it no longer simple, but very difficult and time consuming.
 
terrebandit said:
Can't say that I've had the same troubles as you. Practice makes perfect, I guess.
Click to expand...


my point exactly, some just 'guess', and dont take the time to do it right, since you have not had the same troubles, thats you? right? el banditos endeavor is trying to eliminate 'guessing'.

how bout giving the list a detailed report, of how to do it, since your way has no trouble? please explain the 'I guess' part.
 
suzukijo said:
how bout giving the list a detailed report, of how to do it, since your way has no trouble? please explain the 'I guess' part.
Click to expand...

I'd be interested in seeing the how to's on the string method as well if'n ya' hav' the time.

Thanks.
 
PhilS said:
I'd be interested in seeing the how to's on the string method as well if'n ya' hav' the time.

Thanks.
Click to expand...

sure Phil,

First of all, you should read instructions at the link below:

string method

with that said, I've been using this technique for many years with success. It is very accurate because as it will align the front wheel with the rear wheel. I really like what el banditio came up with above but the string method will work on any bike without the need for fabrication of special pieces that mount to the frame. I just don't have the means or tools to construct those special pieces but doing what he suggests will work great too so long as your frame is perfectly straight. On a new bike, its probably safe to say that it is.

Basically all you need is some fishing line that doesn't stretch much (braided line works best, IMO). Position two heavy/stable objects (I use jack stands)about 3 -feet in front of the bike (one each side) Tie the string to one of those objects, wrap the line completely around the back side of the rear tire, and secure the other end to the other object up front. Some guys will duct tape the line to the backside of the rear tire to keep the string from moving but it seems to hold pretty well if you have good tread remaining on the rear tire. Important... Before positioning the line, put the bike on its centerstand and loosen the axle bolt slightly so that the chain adjusters will move the axle when you adjust them. Get the front wheel positioned (centered) exactly between the lines (front and back). I just use a small metric straight edge and measure from the wheel edge (not tiire edge) to the tight line on either side (front and back edge of front tire). You may have to change the position of the weighted objects up front or turn the wheel slightly to get it centered. Once you get the front wheel centered, look where the lines are on either side of the front edge of the REAR tire rear. When the wheels are perfectly aligned , the front edge of the rear wheel will be perfectly centered between the lines on either side. If the distance is greater on one side, simply move one adjuster bolt until its the same on each side. Once you get it where it needs to be, make sure you make note of where the adjusters are relative to the pre-punched marks on the swing arm. On older Bandit swing arms, its common for these marks to be slightly off. After you get things lined-up, all you need to do is move the adjuster bolts (in or out) the same distance and direction on each side to keep things in lined-up. The swing arm on my 2G bandit was about 1/2 mark off, on one side, whereas my 1G bike was spot on. Get in the habit of counting "flats" when you turn your adjusters to keep them the same.

Good luck.
 
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