I have an 04 evo and the driver side rear upper control arm went bad. This was discovered at my inspection today. I found an oem replacement....but should I do both. If I should why?

Also is it worth getting aftermarket replacements? I could not seem to find them online just the bushings.

Any help would be greatly appreciated. Thank you

 

There are no aftermarket replacements. You don't have to replace both arms either.

 

Why not both is there a reason?

 

There's no reason not to. Just saying you don't have to.

 

Thank you

 

Be aware that one of those bushings is bonded to the shaft that goes thru it. This is done intentionally by Mitsu. It acts as a spring in rotation to both limit the travel for geometry reasons and help stiffen the rear in spring rate. The other bushing is replaceable and simply has a pivot bolt going thru it.

If you replace the bushings on the bushing with shaft ( whiteline superPro ralliart or whatever) you must replace them on both arms for that reason. You may need to go slightly stiffer in spring rate as well.

What is wrong with the arm and how did they discover it ? Are the bushings torn? Loose? ball joint bad ? If they are just saying that one bushing is seized, that would be incorrect as , like i said they are bonded from the factory. If the ball joint is bad, you have to get a replacement arm. If the replacement one is used, check the play on the ball joint...there should not be any at all. If there is , the only fix is to get new ones ( yes if that was the case then 2 new ones from Mitsu. )

I had trouble with passenger side rear trailing arm...the ball joint went bad and clunked everytime I went over bumps. That ball joint also is not replaceable so ended up sourcing 2 replacement arms that the joints were in good shape, replaced the dust boots, installed ES trailing arm bushings and all was well again.

Hope this helps you out

 

When you say trailing arm, are you talking about the one connected to the lower ball joint. I have a damn noise in the rear that is driving me mad. It sounds like something broke in the diff but it only make the noise at low speeds and going through bumpy uneven parking lots or when I hit the brake. I can get on the high way and do 80+ for 25-30 minutes straight with no issue so I'm not thinking its in the diff.

 

The rear trailing arms are sort of banana shaped. Yes ....ball joint on one end and goes from axle hub to the body mounts in front of the rear tires.

Mine used to make the clunk going over small bumps at low speed ( clunk rattle ), backing out of my garage etc, then it started getting worse and ended up that you could feel it clunking over minor bumps when turning left ( loaded up the passenger side arm that way ) little scary i hafta say to feel the rear suspension moving and rattling as it loads up

Only way to diagnose is a big bar to move it around... And that clunk rattle will drive you nuts Bad enough wear could make the joint fail so bear that in mind.

See my post about the joint not being replaceable. Def better to replace in pairs, so either get 2 new ones or make sure 2 used ones are in great shape. Mitsubishiparts.net will sell the joint boots to you so if they are punctured or torn, ask RussellM and he'll take care of it for you.

Hope this helps

 

Update: This thread was a lot of help. I got my wheel off and started prying and it turns out it the upper control arm bushing with the shaft made into it that is making all the racket. This all kinda makes since now because I recently installed a WL swaybar in the rear and new links so im assuming the stiffer sway bar made the noise more pronounce.

Anyways, you say to replace in pairs, are you talking about driver and passenger or upper and lower? I'm just going to do the one for now because Ill most likely buy it knew and they aren't cheap.

To the op, thank for starting this thread, that dang noise was stressin me out.