Rear end alignment issue

[Rt Jam]

Assuming your tubular control arms have poly bushings it's not surprising you are having these alignment issues. The stock triangular rear suspension in G bodies rely on bushing deflection and control arm twist to prevent binding issues. Replace the stock pieces with stiff aftermarket tabular arms and single axis poly bushings of course you will get binding. In this case binding when putting the suspension back together. In short, stock rubber bushings deflect to act like balljoints, while poly bushings behave like a metal bushing with single axis rotation. The flexibility stock rear control arms act like they have a swivel joint in the middle, boxed and tubular arms don't which makes aligning the bolt holes more difficult due to binding.

Do you guys understand this? The stiff bushing also is hard on mounts even after you finally get the bolt in.

Picture articulation of the rear end housing. I know you are not rock crawling but even if it's 5 deg from going diagonally up the curb. That 5 deg NEEDS to come from somewhere. On a OEM rubber bushing, it can easily twist 5 deg. A poly fights that and I've seen this break mounts, oval eyelet and wreck the bolts. I'm not a fan of poly on triangulated 4 link for this reason.

Sorry to break off topic but threads like this are to educate. Rubber, roto joints or heims is the solution.

 

[Clone TIE Pilot]

Do you guys understand this? The stiff bushing also is hard on mounts even after you finally get the bolt in.

Picture articulation of the rear end housing. I know you are not rock crawling but even if it's 5 deg from going diagonally up the curb. That 5 deg NEEDS to come from somewhere. On a OEM rubber bushing, it can easily twist 5 deg. A poly fights that and I've seen this break mounts, oval eyelet and wreck the bolts. I'm not a fan of poly on triangulated 4 link for this reason.

Sorry to break off topic but threads like this are to educate. Rubber, roto joints or heims is the solution.

Thanks, I don't know how many arguments I had over the years about explaining these binding issues. Moreover the suspensions in these cars aren't precision mechanisms and need some give to compensate for wide production deviations from car to car.

 

[79 USA 1]

Do you guys understand this? The stiff bushing also is hard on mounts even after you finally get the bolt in.

Picture articulation of the rear end housing. I know you are not rock crawling but even if it's 5 deg from going diagonally up the curb. That 5 deg NEEDS to come from somewhere. On a OEM rubber bushing, it can easily twist 5 deg. A poly fights that and I've seen this break mounts, oval eyelet and wreck the bolts. I'm not a fan of poly on triangulated 4 link for this reason.

Sorry to break off topic but threads like this are to educate. Rubber, roto joints or heims is the solution.

I had experience to back this up. On my 79 Monte Carlo I just parted out , Many years ago I boxed the upper and lower control arms, added strengthening washers at the control arm mounts in the frame along with poly bushings and Lakewood No Hop bars. Ride quality went straight down hill and I had bad axle hop after two seasons of racing/street use. When I pulled the rear axle to save the No Hop Bars and the internals to swap into the current 79, the No Hop Bars are junk due to the upper control arm mount wallowing the mount on the bar and destroying the upper control arm in the process. A roto joint, heim or rubber bushings may have prevented it.