Guys, I went for a drive in my Chevelle last weekend, weather was great here. Picked up the boy from baseball practice, and we all three (me, the wife, and Brandon) went to dinner. Car ran great, except I had a serpentine belt issue, but that’s totally unrelated to this question. Got on it a couple good times, taking it to rev limiter in first twice, which is 7800. Car is putting 616 hp/525 tq to tires currently on a poorly done street tune, again that’s a different sermon, for a different day.
Anyhoo, I get car back home, washed, dried, and back up on lift in shop where it stays with a cover on it, and I’m doing a visual underneath the car. To my surprise, my upper rear control arm bushings at the 12-bolt are both destroyed. I’m talking virtually gone. Looks like they exploded? They were poly, along with all my other rear control arm bushings. My question here is: I’m guessing I’m binding back there, but where? I’ve searched the net for similiar situations and I can’t find anybody dealing with this. My rear control arms are CPP, and of course it’s all new stuff. Is this a setup issue? Anybody ever see this before? I did read over on TeamChevelle that maybe I should go rubber bushings up top, if I’m running poly lowers, to keep from binding. I just don’t understand the binding part. When I was building the car, in mock-up stage, I cycled the rear through its motion up and down, with coil overs off, and just bare housing, and it sure didn’t feel like anything was binding. What am I missing here?
Well guys, after doing more research today, it turns out that with the A-body rear suspension setup, which is an inverted 4-link, you can not run a poly bushing in the upper rear control arm bushings. There is a inherent amount of binding that is naturally in this type of system due to the two different arcs that the uppers/lower arms are moving in, and there MUST be a small amount of movement at the upper rear joint due to binding. Using poly bushings in all 4 pivot points will not allow any movement, which is why my upper bushings literally exploded. I will either go rubber bushings, or to a “Johnny joint” type setup on my rear upper pivot at the 12 bolt, which will allow a tiny amount of movement. Hope this helps somebody out there.
Well...I have the Roto-joints with my CPP tubular uppers...which came with the poly bushings for the 12 bolt by the way... After much reading up on other similiar situations, apparently the Roto-joint simply allows for misalignment, but doesn’t allow movement front to back. The Johnny-Joints (at the 12 bolt pivot) are supposedly going to allow the pivot to have a small amount of movement front to back?
Or just perhaps this was just a scenario of big power and sticky tires?
Any input here from you guys would be awesome!
Ridetech just released a press in version of the patented R-Joint specifically for the A & G Body rearends. They will allow the needed movement getting rid of the roll bind and stiction and do not require any maintenance. The RTX-10 material we use never needs lubricated and the spring loaded design eliminates the need for adjustment. We also offer a simple tool that makes removal and installation super easy.
Brian Hobaugh SCCA National Tour June 2014
First Hemi 'Cuda Convertible Ever Built
Short clips: Goodguys Pleasanton autocross and pit videos
Upper rear control arm bushing help
Hybrid Mode
