Rear upper FREAKING control arm bushings

[ootdega]

I have rubber in the diff itself on mine, the others are poly. I believe the rubber ones are Spicer brand but its been too many years for me to swear to that. I got them from the local auto parts store many moons ago.

Everyone seems to have different results with poly bushings... I don't think anyone has figured out why yet, either. There doesn't seem to be a consensus yet as to what makes them fail and what doesn't.

Actually that is not 100% true, the two upper diff-side bushings are different part number from the other 6, side by side I didn't really see any difference but it's not like I went for the measuring devices either. For all I know the dimensions are identical on all 8 and the two special ones just use a higher durometer material.

I have both types from Moog in the mail as of today, so I'll let you know. I imagine the diff bushings are a bit more stout. They do have different part numbers.

[sly]

Actually that is not 100% true, the two upper diff-side bushings are different part number from the other 6, side by side I didn't really see any difference but it's not like I went for the measuring devices either. For all I know the dimensions are identical on all 8 and the two special ones just use a higher durometer material.

This would make sense.

[gadget73]

Lower durometer would be more sensible. You want it to twist somewhere. Making the back end too stiff is liable to rip the arm mounts loose or bind the rear up. Thats why mine got rubber in the diff and poly elsewhere. For all I know the rubber is stiffer than whatever ES specified for the diff bushings though. Both cars have been that way for years and it hasn't caused me problems yet.

[turbo2256b]

The angles of the upper and lower control arms work against each other to keep the rear axle assembly centered. If they were parallel to each other such as the last years of the panther a track arm or watts link would be needed to keep the axle assembly centered.
Poly bushings work best in rotational situations were they are not compressed or twisted side to side.
So thats why in the control arm system in the older panthers work best combining both. Even in the sway bars I have had some issues with cracking the poly bushings on the ends of the sway bars but work great on the pivots mounting the bar to the frame.

[sly]

I may just leave the upper control arms the hell alone then. The bushings aren't even dry rotting (cracked) and are still pretty solid. The lowers were pretty good too, but the ES firmed things up a little so I can't complain.

[His Royal Ghostliness]

Should have said "different durometer", not "higher", as yes softer actually does make more sense in that particular location. This is also the only location I would leave rubber in. Oddly enough those two bushings can be both the easiest to replace with new rubber, or the hardest - if gas tank is out or the axle housing is dropped they're a piece of cake with the ball joint press, both axle and tank still in place tho fawk this shit!

[gadget73]

Even in the sway bars I have had some issues with cracking the poly bushings on the ends of the sway bars but work great on the pivots mounting the bar to the frame.

I haven't had them crack, but I've had them mash flat and become essentially useless. I think the last set I installed were a rubber-type material instead of the hard poly bushings that just smash.

[johnunit]

Would anyone leave rubber in one end of the lower rear control arms? I have the full kit and boxed lower arms sitting on a shelf

[turbo2256b]

I use rubber in one end of the upper and lower control arms. But my control arma are fully adjustable upper and lower using stock car parts and a differential end yoke from a edelbrock mustang adjustable upper

[His Royal Ghostliness]

Would anyone leave rubber in one end of the lower rear control arms? I have the full kit and boxed lower arms sitting on a shelf

Do you drive down crappy roads a lot? If yes, then maybe. For a car that's driven on mostly nice roads I'd do poly on both ends of the lowers for sure, as those bushings work mostly with rotation and do not see much bind (not like the ones on top of the diff). At the same rate the whole idea of boxing the arms is to make them stiffer, boxing them and using rubber would probably be about the same as leaving them unboxed and running poly on both ends - either way something twists, be it the arms themselves or the rubber. If you don't zoom around corners like an asshole, and/or you run stiff swaybars, as long as the rear suspension has no reason to flex much (one wheel goes up while the other goes down with respect to the frame) I'd think you you'll be just fine with poly all around.

[gadget73]

The poly does ride harsher on shit roads.

[His Royal Ghostliness]

Yup, sure does! But then again if the shit roads are shitty enough it hardly matters what bushings you got, tires would be more important there for ride comfort. And springs of course, but you already know where my allegiances lie there

[ootdega]

I haven't had them crack, but I've had them mash flat and become essentially useless. I think the last set I installed were a rubber-type material instead of the hard poly bushings that just smash.

Do you remember the brand(s) that happened with?

[gadget73]

Couldn't honestly say. I think its just a case of the material having been too hard and not so awesome for constant compression and flexing like sway bar end links see. The rubber ones I put on are boring old parts store brand, maybe Duraleast or something.

[turbo2256b]

Thinking about all this bushing stuff set up my new upper rear arm mounts for poly but cant remember if I bought a new set or hid them somewhere or planed on using the existing ones in Creamy currently.