Three link rear end alignment

[BB767]

Can one of you more experienced builders tell me this.
What are the best reference points to measure from to ensure the rear axle is centered?
How do you tell if the rear is lined up with the frame and tracking straight?
Moser three link with 17" FFR halibrands.
Thanks.

[GoDadGo]

I doubt if I've got more experience than you but I will tell you what I did.

1. I adjusted the car to sit at ride height. (About 4.5" Front & Rear)
2. Next, I measured from the frame at the shock mounts to each wheel/tire and adjusted the Panhard Bar until it was centered.
3. Then I took a few different measurements at different spots on each side of the car just to double and triple check my adjustment.
4. Finally, I checked my pinion angle to make sure that it was pointed about 1.5 degrees down compared to the driveline angle.

Hope this help, but like you I'm not an expert.

NOTE:.. I did shorten my wheelbase, getting shorter control arms made, so that I could better adjust my pinion angle.
............This change also allowed me to better center the rear wheels within the wheel arches so I did a lot of measuring.

https://youtu.be/IGYtX-3p7xk

[CraigS]

For centering the axle measure from a tire to the frame or upper shock mount bolts, whichever is easiest. As far as I know the lower control arms are not adjustable so you trust the FFR welded the mounts to the frame correctly. You could try to measure from a point on the axle out near the wheel to some point near the front of the car. I know that when I tried that, I wasn't real confident that I had an accurate measurement. Another method I used was this
IMG_20170419_160800746 by craig stuard, on Flickr
In actual use this gets laid down flat, slid under the frame, turned back to this position, and pulled out until the short vertical piece is against the inside of the main 4 inch frame tube. I lay a laser on the outside of the rear wheel on a piece of 1x4 wood cut to sit on the edge of the wheel and see where it hits the scale. I then move it to the other side of the car. There is an identical scale on the other side of this tool and so I see where the laser hits on the other side. Hopefully for you, it is the same left and right. I made this for aligning the IRS. For you w/ a solid axle, I would just trust FFR.

[NAZ]

A popular method used by race car fabricators is to carefully measure the center line of the chassis and place witness marks at strategic locations along this line. I typically drill 1/8" holes where there is no issue with compromising structural integrity or sanctioning body rules. The alternate method I use is center punch marks. These center line witness marks are important to setting up the suspension and determining the extent of race damage. A center line is an accurate datum and does not rely on measuring perimeter tubes or brackets that can vary as ALL chassis are constructed to a +/- tolerance and stacking these errors can lead to very inaccurate suspension settings.

If you're the kind that want's "accurate" setups you need to use the well established center line method. If you use "pick up points" off chassis elements you will realize some amount of error.

[BB767]

Ok, thanks.

[johnnybgoode]

Can one of you more experienced builders tell me this.
What are the best reference points to measure from to ensure the rear axle is centered?
How do you tell if the rear is lined up with the frame and tracking straight?
Moser three link with 17" FFR halibrands.
Thanks.

For centering I lay a two foot level (or other straightedge) on the rear tire horizontally at the midpoint and then measure from the inside edge of the level to the 4" round tube through one of the windows in the rear wheel (it's easy to lay a measuring tape on the flat side of the level and move up/down/in/out until you can easily hit the frame rail). Do the same thing on the other side, compare your measurements and adjust the panhard bar until they are equal. Rear end should now be centered to the frame. At least this is what works for me. Scott

[Driver_WT]

You should also measure the wheel base from the center of the front wheel/hub to the center of the rear wheel/hub on the rear. I set mine for 90" wheel base.

[TexasAviator]

I did as Steve (godad) did. You could also get a 4 wheel alignment at a shop later.

[gtrclark]

Can one of you more experienced builders tell me this.
What are the best reference points to measure from to ensure the rear axle is centered?
How do you tell if the rear is lined up with the frame and tracking straight?
Moser three link with 17" FFR halibrands.
Thanks.

Here’s what worked very well for me. The molding is just short enough to slide under the control arm but tall enough to hit the frame rail. As long as your frame rail heights are the same on both sides this should work really well. Just measure how much is sticking out past the level and make it even between both sides.

3AA586E0-98A5-4CD1-936D-E53EB75DCCFF.jpg

[rich grsc]

4 yr old post

[magicmarto]

Jeff Kliner says to center the rear end on the body, don't worry about centering to the frame
So one the body is on center it then
What is what I did with no issues. 6700 miles so far
Martin

[Jeff Kleiner]

Jeff Kliner says to center the rear end on the body, don't worry about centering to the frame
So one the body is on center it then
What is what I did with no issues. 6700 miles so far
Martin

Uhhhh, no. Maybe you misunderstood something Martin. Center the rear end on the chassis by measuring from the tire to the rectangular chassis tube under the upper trunk floor and adjusting the panhard bar as necessary. There isn't much side to side adjustment available to the body from the cockpit rearward but if you center the axle on the chassis the body usually sits pretty close to even in relation to the rear wheels. So I guess given that, by extrapolation we can conclude that centering on the body will have it pretty well centered on the chassis as well.

Jeff