Upper Control Arm CLUNK - This may be your problem!?

hotpony

Founding Member
Feb 26, 1999
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38
Lee County, KY
Ok so this clunk finally drove me to near insanity so I went out and took the upper control arms off (I had suspected these to be the issue), and what did I find? The HPM Megabite JR. Upper Control Arm spherical bearings had worn themselves into oblivion! Take a look, I have contacted HPM to see if I can just get the replacement bearings but I'm waiting to hear back.

In searching for the same issue I've found a LOT of people complaining about clunking in the rears of their SN95 mustangs, so check these guys. Oh and another thing, to test them you can just disconnect them from the frame and jump up and down on your trunk (with the lid open of course) and see if you get the clunk or not. That's how I concluded this to be the problem, well besides the fact the bearings are totally shot!.
 

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These are HPM Megabite JR. double adjustable upper control arms for 79-04 mustangs, they lasted about a year and a half. I know spherical bearings don't last all that long dealing with everyday driving, ie: potholes and bumps, so I'm really not that surprised, might have been a better idea just to get some reinforced or heavy duty motorsport ones with bushings on both ends instead. I'll just replace the rod end bearings on these guys though since I already have them, and it'll be more cost effective that way anyways :) I'm assuming there was some sort of teflon bushing in the housing that wore away first as you can see in the pictures it's only on the top and bottom and has completely worn from the front and rears allowing metal on metal contact which caused the grooves.

I'd also have to quote that the year and a half was about 4500 miles and that the roads here in Hawaii are really poor condition because of all the rain and soft foundations we have around here. On the mainland the roads are a bit better and less rain of course (no snow or salt though) and so they'd probably last a lot longer depending on climate.
 
Lubrication?



maybe not. the rear upper axle housing bushing is the same from 1994 to 2000 on Mustangs and 2001 up Mustangs use a different part # and I believe a different OD, so using the wrong one in the housing would cause a "clunk". most of these after market companys make a part that they claim fits ALL models/years but its not always the case. also from Ford there are 2 different upper arms listed depending on year. the difference is in lenght of the upper arm, some models are 237mm c to c and some are 242mm c to c and what this does is change the pinion angle and pinion angle is very importon as how your suspension works and how the car will ride
 
Now that's good to know!

But shouldn't the spherical ends be lubricated for longevity? Those pics look like the joint is dry.

well that depends on the type of hime joint(s) used, as some have a teflon liner that do not need tobe lubed (and some dont.) the one in the pic looks like it did have the teflon liner but maybe it broke-up due to them being cheap($) hime joints, improper install, something not tight/straight, rear not being square wth the chassis, bad or improperly installed lowers, wrong pinion angle and prob somemore I could think of if I had more time:D
 
These did have a teflon bushing, they're not very cheap as you can see on HPM's website, and the lowers were installed by probably the best mechanic on the island (besides me :) ), Henry of Honolulu Ford. Pinion angle is set perfectly as well. It's probably a combination of things really, from the weather here in Hawaii to the harsh road conditions, speaking of that, I was out driving today and just noticing how many potholes and rough roads are here makes me not want to drive so much. Camoflauged speed bumps are just as bad, I went over one about 15mph today, hammered my exhaust (Bassani X-pipe), I got out and cursed out the speed bump for a few minutes, made me feel a little better.. Haha... Also this car used to be a Honolulu Police Officers highway patrol car so I'm sure he got quite a bit of use/abuse out of it.

I tried to contact HPM to see if I could just order the bearing ends but they haven't replied, I'll try calling them tomorrow, maybe their internet is down :notnice:

Anyhoo, if I would have been the one purchasing the suspension, I would have just gone with some heavy duty motorsport ones, the spherical bearings aren't that great for street use.. Period.
 
So would this explain the clunking sound that comes from my trunk? The thing is my car has been making that sound since it was 1-2 months old. I took it to Ford about 3 times to fix this problem and whatever they did it the sound went away for a few weeks at best. One explanation I heard was my exhaust pipes were heating something up and causing them not to grasp on properly.. not sure what part he was talking about though as this was a few years ago.
 
Can you personally reproduce the sound? What if you open your trunk and bounce up and down on the back, will it knock? In your case I'd doubt those would go bad after only 1-2 months but you never know, could be a bad bushing. Can you see any wear marks from your exhaust? I'm really not sure what your exhaust could be heating up enough to make noise, I really doubt that's an issue..

And again, if you disconnect them from the frame and bounce the rear end you can isolate them to the upper control arm bushings, or not. Just have to use process of elimination most of the time when chasing clunks and rattles.