I have a chassisworks eliminator II 4 link that i am getting close to install on a backhalf car. Before welding it in place, i layed everything out on the floor and set everything up at the instructed measurments. I noticed that the arc of holes on the frame bracket (upper set of holes and lower set of holes) only line up in a perfect arc with 1 lower and 1 upper hole of the axle bracket. The other axle adjustment holes upper set and lower set throw off the arc on the frame bracket that i would have to adjust the length of the links to travel through those arcs. I hope i’m making sense with how i’m explaining this. Is this normal? I am thinking it is because lifting or lowering the pivot point at the axle would change the arc at the frame bracket. Just want to make sure this is what you experience also before i install.

Thx

All the 4 link kits I have installed use different length link bars, so the arc of the bracket holes should be a little different top compared to bottom, if I understand your question. If it was my car I would run some numbers and measurements through a 4-link calculator program. I like the one from performance trends. But the height of the frame brackets will be critical in getting you the most adjustment close to the sweet spot. If you get the bracket too high or too low, you most likely will have a few holes that work, but no near as many as if the brackets are in the right spot.

https://www.bing.com/videos/search?q=Free+4+Link+Calculator&&view=detail&mid=ADBB08D2ADEE69766A44ADBB08D2ADEE69766A44&&FORM=VRDGAR&ru=%2Fvideos%2Fsearch%3Fq%3DFree%2B4%2BLink%2BCalculator%26Form%3DVDRSCL%26%3D0

Thanks for replying and for that information. Actually, what I was trying to say was that if the lower bar is in the lower hole on the axle bracket, the bar can be swung up and lines up perfectly with all the lower adjustment holes on the frame bracket. Thats great. But, if I raise the lower bar to a higher position on the axle bracket, the bar does not line up with all the holes swinging up thru the arc. Even after adjusting the length of the bar so it aligns with one of the frame bracket holes, the arc is no longer correct for the holes on the frame bracket. Does that make sense? So every height adjustment I make on the frame bracket, i would have to adj the length of the bar. It’s not a big deal, i just want to make sure this is common. I am welding in the brackets at the exact dimensions and heights that chassisworks specifies. So it should work as they intended for the plot of I C’s.

I understand your question. Imagine drawing and arc (the front mount holes). There is one central point for that arc (the one hole on the rear mount). If you change the central point then the arc changes completely. There is no way you can have more than one central point for any given arc. You can easily do this on paper with a compass to see the results of moving the rear point.

Ok. Great. You confirmed my suspicuon. Thank you. Now i can set up the rear axle and weld on the axle brackets in place and move on. Thank you.

The 4 link is a system. Not a collection of random brackets. The brackets should come as a set from a manufacturer that has designed them to be compatible and/or drawn up the correct locations.

You bought a complete deal. There should be information telling you the proper heights to install the brackets in order to maintain the desired geometry. I would call the people if there are any questions.

The bottom bars control square and wheelbase. They probably won't need to be adjusted if moved. The top bars will likely need to be fiddled with for pinion angle and preload.

Geometry has changed a bunch over the years. Brackets installed 20 years ago are all wrong now. Pay attention that you are getting up to date parts and not some street rod junk.

There have been some teams that would carry 4 link bars made for specific locations so they could just swap bars at the track when making a change and not have to check anything.

Years ago I made up all my brackets so both bars swung in an arc to not change their length or pinion angle. I laid the whole thing off on a 4x8 sheet of plywood, chassis, rear, tires, shocks and brackets-bars at the ride height I wanted. Then plotted most of the ICs on the board. After I got car completed and weighted I could transfer the points from the board. Check your bar length as that could change the equation (example like 20” and 25” long bars)

Thanks. As M Callister stated, this kit has exact dimensions where the brackets have to be installed to work as designed. I will install it exactly as they spec. They give pages and pages of ICs for all the given link bar hole combinations.

The housing brackets go where they go. Height from the ground is determined by tire size. That dictates where the chassis brackets go. The chassis has to be built to the suspension mounts, not the other way around.

That works, until you move the bar location on the housing. Or the ride height.