romandian

your right, it will cancel out. (im always worried if i have to rely on something canceling out, but it will work.) i like how you seem to be precisely leveling the car. how do you transfer the horizontal laser beem to your measuring sticks on the floor?

cagotzmann

The mounting to the wheel is made from steel, the laser level has magnetic mounting base and projects laser lines like this.


This produces a vertical line at the measuring bar like this.


Again even if you have a lot of camber in the wheel it doesn't matter. We are looking for the difference from a reference point. If you want to increase precision & tolerate
more error then increase the distance between the measuring bar. I am using 48" rulers as spacers. If you have the space make the spacers/ rulers 60"

@ 24" x 2 spacers and with a 1mm difference ~ = 24x2 + tire ( ~ 13" ) = inv tan ( 1 / 1549.4mm) = 0.03698 degrees which is 1 / 64th inches total toe. This is already very good accuracy.
@ 48" x 2 spacers and with a 1mm difference ~ = 48x2 + tire ( ~ 13" ) = inv tan ( 1 / 2768.6mm) = 0.02069 degrees which is 0.6125 / 64th inches total toe. Very precise.
@ 60" x 2 spacers and with a 1mm difference ~ = 60x2 + tire ( ~ 13" ) = inv tan ( 1 / 3378.2mm) = 0.01696 degrees which is 0.502 / 64th inches total toe. Very precise.

So I would pick something between 24" & 48" so you can measure anything from 1/64th " total toe. Remember you suspension has more than 1/64th toe change due to ball joint play/ wheel bearings, control arm bushing etc.

Once you find a setup / alignment that is working for you at the track its important to have the same setup week to week. You don't really care what the numbers are just make them the same.
front 0-3mm difference total toe
rear 10-13mm difference total toe.

So for me once I get the setup I can quickly check the setup. To measure thrust angle / camber / caster / toe takes ~ 15 - 20 minutes. This includes using dry pavement vs frictionless surface to check suspension wear.

romandian

well, i will not talk about the precision of that downward projection. my point is this: using a lets say 5' straight edge on the tire and a plumb bob is fast, simple, nothing can go wrong and you get the precision you care for out of it.

fatbillybob

https://www.corvetteforum.com/forums...-measured.html

While you guys are at it I would like some confirmation on my early conclusion that rear bumpsteer in the C5 is a non-issue. Has anyone added bumpsteer kit to the rear of the C5 and Zero'ed out the bumpsteer or is the OEM toelink as good as my early work shows?

froggy47

I put front/rear Baer bumpsteer on my c5z when I lowered it. The Baer heims were junk so replaced with qa1, but the rest was good. Simply set the arms back to original measure of degrees from floor & never touched again, never had BS issues. How would you get the CA angle right with the toe link?

voda1

What brand level and model number? Think it's still available?

Can't seem to find one like pictured(cross line)! Could use digital readout also.

cagotzmann

"It still doesn't matter" if the projection is out by 1mm over 48" from the origin because its the same on both side. Even if the projection was a arc, it still works 100% because the laser projection is consistent or consistently out We don't care about the actual measurement just the difference to calculate a angle from a know reference point which is the center of the wheel /axle. This only matters when the distance front vs rear is not the same. then you would need additional math to calculate the angle to compensate for the laser error.

If you do all the math to correct for projection error / laser error you get the same answer. That's the nice thing about the process all the errors cancel out and the level you can measure at is much more precise than the suspension / steering tolerance for movement.

I have a spreadsheet I created to do all the calculations including laser error over distance and found out as well it doesn't matter.
Dark green is actual measurement / Light green is calculated based on laser error. Also included calculation based on tire size camber of the wheel etc.
Laser error was calculated on 2 axis. 1 mounting surface error. Does it project a pure 90 degrees over distance. And the error on the line projection based on distance from axis point 0,0.
The only error you get is if you don't position the laser 100% perfect to the center line of the wheel / axle. But I would say this margin of error is so small over a 5mm variance. The might vary ~ 0.0001 degrees.

cagotzmann

Here is the model I have.
https://www.ebay.com/itm/Craftsman-4...-/123557021616
The only part I use in the kit is the laser unit itself. But anything that has a magnetic mount and projects horizontal and vertical lines can be used.

fatbillybob

You have to measure the bumpsteer and change the shim/washer in the toelink end to minimize the BS. The thread I did measured stock C5 BS. It seemed so minimal that I did not add the heavy Bear toe-ends and play with them to see if I could make the BS smaller. It wasn't worth the 180 bucks if I opened the package. So I am still curious if I could do better than stock but it wasn't worth 180 bucks.