2004 Upper vs. Lower Control Arms - Should I do both? Advice please?
 

I get my subframe connectors welded in my 2004 GT this Friday. Full length UPRs with the torque box reinforcements. :D

I also have UMI Upper and lower control arms with the urethane bushings. My GT is a nice day driver/cruiser - not tracked or dragged - just a cruiser. I am trying to improve handling a bit but not make the ride to stiff. I plan to install the lower control arms for sure - I have read nothing bad about replacing those. I may also pull the quad shocks off - since I don't think they will do anything more with the nice beefy UMI lowers.

The question is do I want to install the uppers or return them. I have read some binding issues with the urethane bushings in the uppers - I have also read they will not help and possibly hurt the cornering.

Any thoughts on the Uppers/Lowers for me?

There is a lot more to it than I know and/or are prepared to speak on in a single post, and a lot of it having to do with "what do you want the car to do", but the short answer to your question is that I would definitely not install any upper control arm that uses polyurethane bushings.

For normal driving they are probably ok. For any sort of "spirited" driving - hard launches when the light turns green, actual track use of any sort, having a little fun on a twisty road, etc... They will introduce additional binding of the already poorly designed 4 link rear suspension and also possible torque box damage.

If looking to improve the upper control arms, replace the (probably well worn) soft rubber bushings with a new set of stock rubber bushings. Or go with a control arm that substitutes rubber bushings with spherical bushings/bearings. The upper control arms and their compliant rubber bushings are the one exception to the general rule of thumb on these cars which says that a less compliant material such as polyurethane is better.

If you haven't checked it out yet, scroll down to the Suspension subforum here and read "The Official Suspension Guide" thread. It explains just about everything you could ever care to know about these cars' suspension, how to make it better and what separates good parts from bad parts (especially the stuff about UCA's).

Good advise Z KLR