Different methods of wheel alignment

[cavehamster]

Wowey batman, I'm really impressed by how quickly posplayr can type an essay on the string method! Nicely done man!

Regardless, on any method you use, it takes some care to make sure your 'beams' be they light or string or metal bars are lined up coaxial down the frame and not being deflected by anything. If I might add one minor suggestion to any method, I would suggest as a basic sanity check that you measure the distance between the beams near the source, and again at the other end of the bike. If they are equal, all you have left to do is correct any parallax and you'll have a straight jig you can measure off of.

I found it a lot easier to measure off the front wheel and get that locked in so I could scoot the rear wheel around and not have to re-do the jig a lot, but getting setup to do this is a pain anyway.

Anyone have any links to what the pro jigs actually look like? I'd much rather see a few pictures than a ton of descriptions, just so I could look at it and see what I could be doing better.

Interesting discussion though.

 

[posplayr]

In summary...... string if you want it near enough, straight edge or jig if you want it right

Cheers tone

Although I'm not smart enough, a person so qualified could probably measure the speed of light with a peice of string and a stick of bubble gum, that is to say the accuracy and utility of the string is largely dependent on how it is used.

Perhaps the FSSM (Fuzzy String Strum Method) is not common knowledge , but as I described it is has sub mm accuracy.

 

[tone]

Anyone have any links to what the pro jigs actually look like

Thats another minefield mate there are a ton of different types of jigs out there & ideas or variations for hundreds more, a quick google should throw up more pics than you can handle

To help you understand a little better, there are 2 basic designs of jigs for 2 basic jobs although there are countless variations

#1 a frame building jig which can be fairly basic mainly consists of an ajustable post to hold he headstock, an accuately marked centre line to measure off, blocks & chocks for holding engine etc & guides for locating swingarm pivots & rear wheel spindle, A good example of a more advanced version of this type of jig would be a eurocustom jig

#2 a alignment or straightening jig which is similar to the above with all the above mentioned stuff & more but much stronger to allow the use of rams etc to straighten a bent frame eg the frame is not always held by the headstock & a pointer is installed there which is used to measure any misalignment before & after the frame is pulled, a good example of this would be a motorliner jig

If you want to build a straight frame #1 is the boy for the job & if you want to check or straighten a frame #2 is the kiddie, although there can be some crossover of usage, having used both i must say i'd hate to have to build a frame on a motorliner

hope it helps tone

 

[tone]

Although I'm not smart enough, a person so qualified could probably measure the speed of light with a peice of string and a stick of bubble gum, that is to say the accuracy and utility of the string is largely dependent on how it is used.

Hey Jim i think you are plenty smart mate but as you say the accuacy is dependant on how string is used, to my mind some people will get reasonable accuracy with this method but most wont so see no reason to remove one more variable

Leave me alone in the gaarage with a ball of string & i could maybe knit you a vest but i'm too clumsy to measure my wheel alignment with it

 

[Charlie G]

Fuzzy factor

Fuzzy factor

Jim,

Nice write up on the various methods of alignment check. I used the string method a few years ago on my XT-350 Dual sport and it worked great. I was running about 8mm out. I used a "dental floss" like string that is used in construction for checking acoustical ceilings for straightness.

Charlie G

 

[posplayr]

Jim,

Nice write up on the various methods of alignment check. I used the string method a few years ago on my XT-350 Dual sport and it worked great. I was running about 8mm out. I used a "dental floss" like string that is used in construction for checking acoustical ceilings for straightness.

Charlie G

Thanks Charlie,
I was watching a show about the building techniques that the Egyptians are theorized to have used to build the Great Pyramids. I wonder how many Pyramids were build using Lasers? Does anybody think they used 1000 ft straight edges?

There was another story from ancient Greece I believe. IIRC, the people on an island were besieged and did not have any water on their side of the mountain. They needed to drill a hole through both side of a mountain so the water would flow through and still have them meet somewhere in the middle. Anybody think they used lasers? How about large T-squares? Think they understood error propagation?

These are all rhetorical questions as it is a matter of the user of the instruments (probably string and hoses) to make maximum utility by developing accurate measurement techniques with these simple tools.

Think about the first attempts to measure the speed of light, this has always amazed me. They did not have a laser, but they did understand light.

http://en.wikipedia.org/wiki/Speed_of_light

Earth-bound techniques
See also: Fizeau–Foucault apparatus

Diagram of the Fizeau apparatus


The first successful entirely earthbound measurement of the speed of light was carried out by Hippolyte Fizeau in 1849. Fizeau's experiment was conceptually similar to those proposed by Beeckman and Galileo. A beam of light was directed at a mirror 8 km away. On the way from the source to the mirror, the beam passed through a rotating cog wheel. At a certain rate of rotation, the beam could pass through one gap on the way out and another on the way back. But at slightly higher or lower rates, the beam would strike a tooth and not pass through the wheel. Knowing the distance to the mirror, the number of teeth on the wheel, and the rate of rotation, the speed of light could be calculated. Fizeau reported the speed of light as 313,000 km/s. L?on Foucault improved on Fizeau's method by replacing the cogwheel with a rotating mirror. Foucault's estimate, published in 1862, was 298,000 km/s.

 

[Guest]

... How about the 8 foot fluorescent light bulb (tube) method they're pretty straight, a couple of them work... good enough for canada anyways....
..for lining up the wheels on my cycle, not building pyramids or measuring the speed of light or nothing, ....it's not rocket surgery ....jeez

 

[salty_monk]

just don't break one... Good idea though.

I have just done mine with some Alumnium angle. I cut part of it down so it also clamps to the rear sprocket & can be used for sprocket alignment.

Dan

 

[posplayr]

... How about the 8 foot fluorescent light bulb (tube) method they're pretty straight, a couple of them work... good enough for canada anyways....
..for lining up the wheels on my cycle, not building pyramids or measuring the speed of light or nothing, ....it's not rocket surgery ....jeez

Yes I heard others mention the 8" florescent light bulb method. As I don't have one I can't do it for myself, but how straight are they?

Lacking a 20 ton slab of machined granite, you could use a sting to see how straight it is . Tape two fixed size blocks to either end of the tube. Run a string over the blocks from one end to the other. Put the string to ether the left or right side of the light bulb. Take a caliper along the tube to see if the distance is consistent. That is the definition of parallel and since the string is straight (in the horizontal plane) you can measure any deviations of the light bulb.

While this is not Rocket surgery, it is Pyramid Science

 

[posplayr]

just don't break one... Good idea though.

I have just done mine with some Aluminum angle. I cut part of it down so it also clamps to the rear sprocket & can be used for sprocket alignment.

Dan

same question Dan, how straight is your aluminum angle? The 1/8" stuff I bought at the local home improvement center curved about 1/4-1/2" in 6 foot. I straightened it by screwing it to some OBS and verified with the "little ruler from the Pyramids", (i.e. a piece of string).

My combo OBS angle straight edge is about 1/16" in 8 ft.

 

[salty_monk]

Your angle is 1/8" on each flat side of the angle? Of course it won't be straight.

Mine is 1/8" thick & about 1.5" across the flats. Makes it much harder to bend & much more likely to be straight.

Measured with a laser level it comes out straight...... Measuring the swingarm to axle pivot centres also back up what I've done with it so far.

Should be good I could probably put it on Ed's flat table to really check it...

Ultimate test will be riding the bike & inspecting the sprockets as the rear is powdercoated so should be pretty easy to see if it's out one way or the other.

Dan

 

[posplayr]

Mine is 1/8" thick & about 1.5" across the flats. Dan

Mine is close to the same. Mine is 1" wide on a side, 1/8" thick material and it is square root of two on the diagonal.:lol:

And when you site down it it bends.

For chain alignment it is straight enough for wheel alignment, you had better pull out the "little ruler of the Pyramids".

 

[mighty13d]

http://www.jcwhitney.com/MOTORCYCLE...1027;0;100003;ProductName;7;0;0;0;2004177;0;0

for chain alignment

 

[salty_monk]

Those are only 18".. I needed something longer. Might pick one of those up though, they're cheap enough.

Dan

 

[mighty13d]

Those are only 18".. I needed something longer. Might pick one of those up though, they're cheap enough.

Dan

eight, not 18 so they're even shorter! but it's not hard to eyeball it after you have something longer sticking out. or maybe just fit a longer rod in there or to it??? I don't know. it was just a suggestion. I think i'm going to pick one up.

 

[salty_monk]

Made my own from some angle to reach all the way to the front sprocket. If I was just using it for setup rather than trying to measure sprocket offsets on my project 750 I would have gone for one of these.

Dan