Will 1/8 inch matter?

[Inferno]

Working on Phoenix (VLX bobber project) and straightening the frame. I'm using some pretty hi tech measuring devices and comparing them to Sally (VLX complete bike).
I'm working on the back end to align the swing arm to the rest of the frame.
I have it to 1/8 inch of perfect comparison to Sally. I can't see an easy way to get that last 1/8 inch with the motor in and the motor is part of the measurement process.
If I were to loosen up the motor mounts, the swingarm bolt will slide through the back of the engine and align both sides of the swing arm. If I tighten the motor mounts the bolt won't go through so easy but does with a little coercion.

The question is, does that 1/8 inch matter? It's front to back, not up and down, so in theory it could throw the rear wheel skew off, right? Can't that be compensated on the rear wheel adjustment?
It doesn't seem like the engine is out of alignment though I suppose it's possible.

It just seems like 1/8 inch isn't that big of a deal when all things are considered. Right?

[Motorchef]

Iferno,
Unfortunately it does matter. The bike will pull an 1/8 inch in the direction the bike is bent for each bike length traveled. That is a lot of pulling. Additionally, the bike will fight turning in the oposite direction and make cornering hell.

[still_bluenoser]

What did you measure the stock bike against to confirm that its perfect?


You could me measuring crap against crap.

[Inferno]

Originally Posted by still_bluenoser

What did you measure the stock bike against to confirm that its perfect?


You could me measuring crap against crap.

I measured in several places.
Most significantly I am measuring the distance from front points where the engine mounts to the rear where the swing arm mounts with the bolt that goes through the back of the engine.
Of course a final check will be done when I put the swing arm back in and I will mount laser guides along the swing arm and frame to see if it's in line properly.

My ultimate goal, of course, is to make sure the back wheel tracks true with the front wheel.

[93gc40]

You might be able to adust, via shims at the axels R and F for an 1/8" error. Chain drives are prtty adjustable for alignment.

[Lockman]

The main thing is wheel aliagnment, as long as both wheels are in line or running in a paralell line, even if the rear is offset to one side or the other (some are setup this way from the factory) you will be alright. Hope this makes sense.

[93gc40]

Originally Posted by Lockman

The main thing is wheel aliagnment, as long as both wheels are in line or running in a paralell line, even if the rear is offset to one side or the other (some are setup this way from the factory) you will be alright. Hope this makes sense.

Bikes are not built with an offset, 4 wheel vehicle ARE. The only bikes I have EVER seen with a front to rear offset are those that were built to run on a circle track.

[Lockman]

Measure a few.

[Inferno]

Originally Posted by 93gc40

You might be able to adust, via shims at the axels R and F for an 1/8" error. Chain drives are prtty adjustable for alignment.

I wouldn't even need to shim it. I don't even think t COULD be shimmed.
These wheels have the sliders and the gauge marks so all I would really need to do is have one wheel a mark in front of the other (and record that fact).
It's easy enough to get the wheel straight with this adjustment.

I wonder what the factory tolerances are as far as frame alignment goes? I can't help but think 1/8 might be in spec.

[Scrapdog2grand]

Originally Posted by Inferno

I wouldn't even need to shim it. I don't even think t COULD be shimmed.
These wheels have the sliders and the gauge marks so all I would really need to do is have one wheel a mark in front of the other (and record that fact).
It's easy enough to get the wheel straight with this adjustment.

I wonder what the factory tolerances are as far as frame alignment goes? I can't help but think 1/8 might be in spec.

That would throw off the alignment of your chain and sprockets.

AS far as specs see if you can get someone at a dealer to help you out with that, they should be willing to give you that info if they have it.