rear suspension? 4 link? caltrac mono leaf? street lynx?
I’ve owned a couple 850+ Hp turbo cars. Nothing this old. So I could definitely Use some guidance
I agree with Greg. I’m not sure it’s worth any upgrades right now if you are going to make that kind of power. You’d be spending money twice.
For what you want you need the best shock you can get, and it will probably take a couple of tries to get the valving right, and you’ll need a 4 link.
If you don’t have a chassis book, my two favorites are the very hard to find Chris Alston chassis book, which is pretty basic but it has some great info in it.
The other book I like is Dave Morgan’s Doorslammers book. You will learn how important shocks really are, and how to correctly lay out a 4 link. He did make one mistake though, which in late 2002 or early 2003 when he was the editor of the IHRA weekly magazine he corrected.
In his book, he claims that when you install the 4 link, you want the bottom bar parallel to the ground. This is not only wrong, it’s dead wrong, and he admitted this.
Dave’s theory was if the bottom bar was parallel to the ground, you could just raise and lower the top bar and move the Instant Center forward and backwards and not raise or lower the IC at the same time.
The problem with this install is that a parallel bottom bar almost always (99.99999% of the time its wrong) the IC will be too high, no matter where the IC is set relative to its forward postition.
I install/set the bottom bar so that if you draw a line through the bar, that line will intersect with the lower ball joint on the front suspension.
In that position, the bottom bar gets more leverage over the suspension, and you can use the upper bar to set the forward position of the IC.
As an example, in 1986 I converted my car from the worthless ladder bars to an Art Morrison 4 link. The Art Morrison default IC position is (I should say was as I don’t think they even do race car parts anymore, but they may, and I haven’t discussed this with them until I figured out how wrong it was in 1990) half the wheel base forward and cam high up! Holy crap...that will beat the hell out of the tire on even an honest 450 horse engine. And I fought that for several years. I couldn’t get a shock to control the suspension. I forgot, Art Morrison was also big on getting the bottom bar parallel so it wasn’t only Dave Morgan who taught this.
So...on my shop floor, in full size, I laid out all my 4 link positions. I was stunned at what I saw. I learned I needed to get the IC way further forward. With the bottom bar parallel to the ground like that, to get the IC forward to just under the front suspension (that was my best guess at that time...I was running a clutch so getting help on chassis was near impossible) which on my car was 106 inches out. Couldn’t do it. There wasn’t a hole position to get there, and keep the bottom bar parallel.
As I looked at the lines on the ground I realized the IC need to be lower, much lower than cam high. So...to make a long story less long, I moved the back of bottom bar up a hole on the axel, and the lowered the bottom bar one hole on the chassis.
Now, the IC can be any where I want it, as long as it’s not cam high. I can’t think of a situation where a cam high IC would even be close.
I ended up on my best chassis/clutch/shock settings the IC was about 112 inches out and about 3 inches off the ground, and the bottom bar was never parallel to the ground. The shocks (some Koni’s that were ok...nothing like what even a Viking is today) could now handle the speed of the axle movement, where before you couldn’t get the shock stiff enough in rebound or bump.
Ok, that’s my rant on 4 links and 4 link set up. Once you do a full scale layout of all the IC possibilities you can have with a 4 link, you’ll see why the parallel to the ground bottom bar is a horrible starting point.
That is some of what you’ll learn in the Morgan and Alston books.
