UMI Rear Suspension Comments

[ssn696]

I will be swapping the wagon's rear axle for the 3.73 / Auburn / LS1 Frankenaxle I've been working on forever. I pressed new poly bushings into the stock upper and lower control arms, but I am debating dropping some coin on some aftermarket solutions. UMI seems to be well-engaged with the G-Body Forum. They have literally 12 combinations of rear control arms. This car will not see the track much, but I might autocross it. I have read that urethane bushings cause the suspension to bind through the range of motion when pushed. I like their Roto-joint solution, but wonder whether having them only at one end of each arm (upper and lower) is adequate. What about the solid upper control arms with the urethane bushing, then pressing in loose Roto-joints into the axle's upper mount rings?
Any Forum members out there have this kind of setup - comments? Ramey, if you read this, your advice is welcome.

 

[pontiacgp]

I have the UMI conversion upper with one Roto Joint. If you have poly bushings with eh stock upper it will not bind on you. The stock upper control arm will flex when in a bind. One Roto Joint at one end is better than the stock set up. The Roto Joint has enough movement to prevent a bind. The stock lower control arm can be boxed and you can use poly bushings without a problem. I did get UMI lowers which UMI customized for me with a Roto Joint on the axle side to pick up the angle of the lower on my 8.2 rear. I have had that set up for a couple of years with no problem with the UMI products.

 

[565bbchevy]

For my Regal I was trying to keep it as budget friendly as possible so I bought the UMI fixed tubular rear control arms figuring I could upgrade later, the lowers went in fine but I did not like how the uppers were lining up with rearend upper mounts or rather were not lining up, so I spent the money to get the adjustable uppers with the Roto-joint these are very nice pieces and basically dropped in without any issues. I guess at least now I can adjust my pinion angle.

 

[liquidh8]

I have speedway tubular arms in the rear, using MOOG/1LE bushings. I will upgrade to the roto-joint in the housing later on.

these arms are in expensive compared to the others. May be a bit heavier, and non adjustable, but the work.