Do stock upper rca's wear out? - Chevy Impala SS Forum
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post #1 of 13 (permalink) Old 10-26-2003, 11:58 PM
Aaron D
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I'm pushing 115K an am going to be replacing the lowers with some homemade billet arms sometime soon. I'm sure the upper bushings need replaced but how about the ams themselves? I want to go with poly bushings in all four arms and I've heard changing the bushings can be a beatch. If I'm not mistaken a new set of uppers is about $60. I'll just switch out the bushings unless someone says there is a good reason to change the arms too.

Later,
Aaron
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post #2 of 13 (permalink) Old 10-27-2003, 12:57 AM
Mike454SS
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I've seen the bolt holes in stock uppers wear into ovals...reason enough to replace the arms if you ask me.

For what it's worth though, due to the geometry of the suspension, I would put new rubber bushings into the upper side no matter what you put in the lower arms. And I wouldn't put anything other than stock uppers in too (unless you're going with extended lowers).
post #3 of 13 (permalink) Old 10-27-2003, 12:57 AM
AutocroSSer
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Will they be worn? yes.

Will they be "worn out"? Probably depends on the car usage.

FYI, my uppers have 112K on them now, and they are pretty toast. I am replacing them with a "temporary" solution this week until I can get the arms I want (which it looks like I'll need to build myself) in there.
 
post #4 of 13 (permalink) Old 10-27-2003, 01:00 AM
AutocroSSer
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Whoa, that was wierd (Mike and I posting at the same time [img]smile.gif[/img] ).

Also important to note is that in production GM used a total of THREE different length upper arms to fine tune the length for proper pinion angle. Not sure which of the three lengths you get if you just order new ones, or if they are even available in multiple lengths any more.
post #5 of 13 (permalink) Old 10-27-2003, 07:48 AM
bryante
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I didn't note any ovalizing of the holes on my UCAs when I swapped them out, but the bushing sure as heck needed replacement.

If indeed one wanted to refurb the stock UCAs, a few minutes with some washers, a welder, and a reamer would do the trick.
post #6 of 13 (permalink) Old 10-27-2003, 09:26 AM
Mike454SS
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Yeah that is wierd Ed...

Eric, I think the holes becoming ovals thing is something that will take a LONG time to happen on a normal street car. The cars that I'm thinking of that I've seen locally are both 9C1's with over 150K miles on the original UCA's (about 100K of police use in each case as well).

On the UCA length thing, I never bothered to research it, but I wonder if the different ride height cars have a different UCA part number that comes up as the default or if the 3 different part numbers really was just to correct for manufacturing tolerances. Seems to me that a 9C1 on curb hopping springs would probably want a slightly different arm than an Impala. Then again though, my 9C1 started it's life on those springs, and now it lives on Impala springs and I don't have any pinion angle issues.
post #7 of 13 (permalink) Old 10-27-2003, 08:22 PM
Aaron D
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Thanks for the info guys. Couple more questions.

Eric, could you explain in detail how you would go about refurbing the uppers. It doesn't sound too involved, but I'm not quite sure what you are getting at.

Ed, care to give any details on what you have in mind for your car? I'm all about making my own stuff if I can. I wouldn't mind making a pair of uppers. I would have already if I thought there was a better solution to the stockers. From what I learned before I made my lowers I might have a couple of useful ideas as well.

Later,
Aaron
post #8 of 13 (permalink) Old 10-28-2003, 12:40 AM
AutocroSSer
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Well, I'm taking a 2-pronged approach....

Temporary : picked up a set of BMR adjustable uppers. As soon as I get the bushing install tool I ordered (more on that once I use it myself and confirm it is "Da Bomb".....but have it on good authority that this tool rocks!), I'll swap them. I'm HOPING the tool arrives this week. Since the ECU is out of my WRX right now (sending off for an upgrade to complement the downpipe I threw in this weekend....I'll have a little 280+ HP sleeper of a station wagon later this week ) I'm driving the SS anyways this week and have it out of storage.

Back to the arms....I don't like Poly all-around up there (due to binding issues), but view that as better than the "play" that is there now. I suspect the bushings are long gone....you can FEEL the axle shifting around !

Longer term : take another set of stock uppers, and put spherical bushings in the frame end of them. Or if I can find the proper-sized spherical bushings for the frame end of the BMRs, I'll put them in those arms instead.

Mike : I can tell you (from personal experience on my SS and other SS's) that if pinion angle gets outside of a "range", it'll cause driveshaft vibration. And yes, pinion angle will change with ride height changes. I'm not sure if GM used different arms on cars with the same ride height (to account for production "slop" in the build) or if they used different upper arms only on different ride heights.

In my case, I have a driveshaft vibration right now only SOME of the time depending on how the axle has shifted in those loose upper arm bushings!

Onto "refurbing" the uppers : I think what Eric is referring to is replacing the bushings (both in the housing and in the arms) and them making sure the arms are structurally sound. You need to check both the bolt holes in the arms that go around the housing bushings, as well as the "ring" around the bushings on the frame end of the arms.

And check both carefully.....one of the local ROD members had the uppers on his SS (under 100K miles, but driven "hard" [img]smile.gif[/img] ) come apart by literally tearing completely apart in the ring around the frame side bushing .
post #9 of 13 (permalink) Old 10-28-2003, 01:48 AM
Aaron D
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Ed, you mentioned the upper CA tech "article" on GW's site not too long ago. Even w/ what amounts to spherical bushings in both ends, there are still binding issues due to the upper and lowers traveling in different arcs. The stock arms "remedy" this by actually flexing/twisting. Don't you think the BMR's w/ spherical bushings might suffer from the same issues?

Have you seen the "Johnny Joints" from Currie? It's basically a spherical design surrounded by poly all in a steel sleeve ($40 each) I'm using them in the fronts of the lowers I made. I'm thinking about cutting off the frame end of the stock UCA and welding the sleeve in it's place. I still haven't decided if rubber or poly on the other end is the way to go, probably rubber since the Johnny Joint doesn't have much give compared to a poly of roughly the same design.

Roughly how much for the spherical bushings you are talking about?

Later,
Aaron
post #10 of 13 (permalink) Old 10-28-2003, 03:49 PM
Lloyd
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Aaron, I thought the same thing concerning running spherical rod ends on the UCA's. From what I remember, the best approach was the stiffer OEM bushings (still available?) on the UCA's and GW lowers. The Jonnie-Joints have been brought up here a couple of times, I think you'll find the concensus to be that they have even less of a movement "zone" than the GW rod ends. I think reinforcing the mounting holes of the UCA's are a good idea if you will be putting that much stress and strain on them.

Either way, I'm sure Ed will chime back in to let you know his thoughts on why he's looking at running rod ends up there...
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