Ride Height Mock-up

[SBC]

I see everyone using frame jigs to ensure final ride height.

How does that work without springs installed?
How do you account for spring compression/drop when the car is finally set on the ground?
How do you determine the final spindle/control arm angles and height for wheel and tire considerations?

[Dave Severson]

I use a tube with the appropriate ends welded on it and bolted in place to simulate the springs at ride height. Most of mine are coilovers and I keep a good selection of different spring rates on hand.... As for figuring what rate spring to start with, I use a set of scales under the car with all the components either installed or dummy weight in it's place, including the driver weight. Once you know the weight of each corner, determining the spring rate is easy.... As for the control arms, I start with the lower control arm parallel with the jig surface, and mount the rest of the suspension components accordingly..... Trial and error along with lots of practice is still no guarantee of selecting all the correct springs and component positioning the first time around. I don't final weld anything other then the frame rails and crossmembers until I have the entire car mocked up for the first time.... Then make my changes and mock it all up again. It takes a lot of time to do it right, but if it was easy, everybody would be doing it.....and I would have to get a real job....

[Itoldyouso]

I keep lots of little pieces of lumber around to shim it up with, and guess a lot. Sometimes, I actually get it right.

Don

[SBC]

Thanks -

Its the front end that's hurting my head.
Seems like most of the spring rate is used up just installing the spindle.
Can't get a handle on how much more it will settle when lowered onto the tires.

I guess that's where all those spare springs comes into play . . .

Also - with as many cars as you have built, you probably have a log book that gets you real close to start.

[Dave Severson]

If you're using coilovers on the front and running a small block, start with about a 350 pound spring, big blocks need about a 450. Just remember to start with your lower a-arms parallel to the ground at ride height. When mocking things up, don't forget to check the bump steer. It's probably one of the most critical items to set up, and the most often overlooked in any suspension set up!!!!