If you look at the BMR and Spohn relocation brackets you’ll notice that the relocation holes are drilled at a slight arc, so the “one step down” holes are slightly forward of the stock holes, and the 2 step down holes are slightly forward of that.

Both bracket’s lower pivot point is 3” lower then the stock point, which turns out that if the LCA was perpendicular to the ground at the stock location would calculate out to needing to be about .22” further forward then stock to maintain the stock axle location (both LCA brackets don’t move it that far forward).

So here is the question… Any thoughts on where you really want to axle to be located? Anyone have a stock ride height/stock tire height car that can tell us what angle the stock arms are at (maybe measure front pivot to the ground and rear pivot to the ground)? From looking at the available brackets it almost looks like they just sorta picked a middle point and went with that.

 

No one has any thoughts on this?

 

You don't want your LCAs perpendicular to the ground. That would be bad.

You want them parallel to the ground. That's about where the stock ride height puts them.

When you put in the LCA RBs, you want the car's wheelbase to stay the same; i.e. the axle to be in the same place it was before.

Rather than outsmart yourself, look at the length of the LCA, which is of course the radius of the circle that the arc you're talking about is part of; look at the angle that you change it, with respect to parallel to the ground, or calculate it fromt he distance you mave that end of the LCA; and use trigonometry or other forms of simple high-school arithmetic to calculate that distance. I think you'll find that most all of the LCARBs on the market are roughly correct in their measurement. It's too easy to get it right. Not rocket science here.

 

Sorry, meant parallel, at 1something AM I’m surprised that I got that close

No, it’s simple to figure out, and that’s not my concern.

Maybe I am overthinking this, but with the car slightly lowered now, I would have to drill the pivot hole slightly further BACK to put the pivot point in a place where the wheelbase doesn’t change, and I would have to put the pivot point straight down from the stock location and in a location that would put the LCA parallel to the ground to get no wheelbase change from stock.

In other words, if I want to calculate an arc then it assumes that I am going to keep the stock ride height, if you drill the holes in an arc AND lower the car then you will end up actually increasing the wheelbase.

Does that make sense?

Also, as pinion angle goes negative and you use a lower pickup point the wheelbase will increase (not as big a deal since I figure that I’ll just pick a number in the 0-2* range and measure off of that, shooting for 0-1* makes sense in this situation since the only reason why you’d go more static is if you’re getting enough flex under load to push it into that range anyway).

Add those 2 factors together and you can easily be talking about a range of something in the ¼-1/2” range for the location of the pivot point and my question is, is there something that is optimum? Obviously, the LCA relocation brackets on the market just picked some situation and were sized to match that, and since the numbers stack like they do it probably does not match everyone’s situation. In my case since I’m welding up a set of axle brackets right now I have to opportunity to optimize if I can decide what exactly optimum would be.