MCMLXIX
11-05-2009, 03:25 AM
OK. I had my frame (1967 Chevelle) modified to run coil over shocks on the front. I have SPD adjustable uppers and the lowers are from SC&C. Now they originally came with a spring bucket. That was removed for a flat plate and double shear mounts.
This is my question. - I hope I explain this correctly to get a response...
The LCA has 2 pivot points. They are in line with each other and when you put the arm thru is travel it created and arc.
Now when the put in the mount on the LCA its not in the same line with the 2 pivot points for the arm so I travels in a different arc.
https://static1.pt-content.com/images/pt/2009/11/DSC066781-1.jpg
Now the upper and lower shock mounts are in line with each other and the amount of suspension travel shouldn't be much with stiff springs....
Is this going to be a major issue?
JRouche
11-05-2009, 08:57 PM
Now thats an interesting Q. If Im seeing it right the pivot for the coil over is not paralell to the CA pivot? Just by the looks of it, it seems it would bind, no?
The lower mount for the CO? Is the bolt in the same orientation as the bolt that was there for the shock before? Looks similar to what I just did with my arms. I had TCI tubular arms that were setup for a coil spring and shock. I cut the pocket off for the spring. Welded in a flat plate to keep the strength then beefed up the shock mounting tubes for a shockwave air spring that will carry all the cars load like a coil over. I used the stock shock mounting tubes location which was parallel with the CA pivot. I even measured it, the straight line created by the CA pivot and the shock pivot, exactly parallel.
Why I see a possible bind is when I look at it from the front. Imagining the circle described by the CA as it moves through its travel.
At ride height where is the pivot for the lower coilover mount in relation to that circle? If its say at the 3 O'clock point on the circle for the drivers side looking from the front (lower mount all the way OUT, away from the centerline of the car), then its gonna tilt in slightly for all suspension travel. The lower mount will go from being all the way tilted out to tilting in a lil on both ends of travel. If the mount is parallel to the CA pivot it just pivots.
But your coilover pivot wants to pivot more fore and aft. So as the suspension drops or rises the lower coilover mount is wanting to pull in towards the radiator, not the engine. Shortening circle. If you have heim joints I dont see a problem. If you have stiff ploy mounts I do.
Ok, another visualization tool. Take it to the extreme and you can see the bind. Twist the coilover mounts even further off parallel from the CA pivot. You see, it gets tighter and tighter till you dont have any movement. So yes, thats why I see other than parallel you would have bind. Where is the cutoff point?? Prolly right where you have it :)
Thats was one of the nice things about working with the shockwaves. I could air them down and run the suspension through ALL the motions the suspension will ever see. I found some contact issues I was able to fix and was able to dial in some alignment numbers to see if I was close on my welded in points before loading the suspension to do a final alignment.
I dont know, just thinking about it. Picture it this way. What it you had a steel bar in there replacing the coil over. Tight pivots that didnt allow and deflection. Would the control arm be able to go through all of its intended travel?? If not, then you have bind. JR