Autocross and Road Racing Technique There is more to life than a straight line

*THUNK* in rear suspension! POS!

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Old Oct 4, 2002 | 12:57 PM
  #1  
Geoff Chadwick's Avatar
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Angry *THUNK* in rear suspension! POS!

I recently got the 4 shocks/struts replaced, and it made a huge difference for my 138,000 convertible, but the rear wheels still slam and thunk at potholes. Not as bad, but still. Perhaps it's time to upgrade the LCA's, Torque Arm, Panhard rod? Any other things I can do? I'm pretty new to this huge rear axle thing.

Also the rear suspension when under compression kinda squeaks like an old bed but a deep squeak, if you know what I mean. It does this when the weight transfers in turns and stops and rather unlevel pavement. I can even park the car, get out and push down on the trunk and "squuueeka" I got the struts changed a week from Monday and it just started last night, the shocks/struts *should* be good me thinks. I actually think the spring is doing it, but it seems to come from the whole thing/center of the axle, so it'd be both springs or something else. Torque arm? Any thoughts?

(Edit)

I just went out and looked at the LCA's, panhard, Torque arm. They *look* okay and not gone to crap, but... they're really crappy! My god! Tiny assed stamped steel things. I knew they werent good but jesus. They need to be replaced or I'm just going to go batty otherwise.

(Insert)

What about just getting new bushings for the suspension and all? Might that help? Anyone?

Lastly, I'm working on gathering parts for the TT project, and I'd just assume a max of 600 crank HP, so might as well buy the things I'd need for that now. LCA relocation brackets? (But how to also make the rear end less twitchy at the same time, a new anti roll bar back there?) And might as well get a new Torque arm that'll handle it - and I've got a case of Vibra-shaft. I dont mind the money I put into it, it's the 5 or 6 different squeaks/rattles that drive me nuts. I'm ordering a new e-brake assembly cause this one rattles, the center console does too, the top dash piece does a little in the front passenger area, the rear suspension, somewhere in the passenger door, the cowl, and lastly, the rear of the driver door. Ack!

Last edited by Geoff Chadwick; Oct 4, 2002 at 02:43 PM.
Old Oct 5, 2002 | 09:13 AM
  #2  
V6Bob's Avatar
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Be careful. You can make things worse than they are now. For example:

"(But how to also make the rear end less twitchy at the same time, a new anti roll bar back there?) "

A bigger anti roll bar in the rear will make the rear more twitchy.

"What about just getting new bushings for the suspension and all? "

Poly bushings in the LCAs will make the rear more twitchy.

You need to know more about suspension and to understand exactly why the above things are true. A suspension professional could give better advice than random amateurs (like me), but you still need to understand this stuff.

If I had a 95 convertible the very first thing I would do is add subframe connectors and a strut tower brace to stiffen the chassis. A coupe has a much stiffer chassis to start with and a chassis gets looser with age/mileage.
Old Oct 5, 2002 | 10:05 AM
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I agree with the subframe connector suggestion. If you don't have them already, it's about 7 years too late, so get them first. As far as the squeaks, I suppose it just takes time to find them one at a time and elliminate them. It sounds to me like your major one is the rear springs. Do the springs have the rubber isolators on the top? Do you have a section of hose wrapped around the bottom? If not, I'd do both. I doubt it's the shocks.

Dave
Old Oct 5, 2002 | 10:31 AM
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What kind of shocks and springs did you buy?
I installed new shocks on my car and everything was fine.
Then I went road racing. A couple of days after the race I noticed a squeak in the rear end, just like the one you described. I figured it was the poly bushings, so I removed and lubricated every poly bushing in the rear end. Well, that didn't get rid of the squeak. I finally found that it was the rear passenger shock that was squeaking. I lubricated the mounting bushing on the shock, but that didn't help. Then I told a friend, who's a mechanic, about the squeak. He said some shocks will squeak, and I could take it off and send it back to the manufacturer.
In short, it's probably one of your shocks.

Kurt
Old Oct 7, 2002 | 05:18 PM
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Geoff Chadwick's Avatar
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The shocks and Struts were OEM De-carbons

Yes I know the rear end can get more twitchy, but anyway, with the new shocks, it just hits hard, the "sqqueaak" is still there, it sounds like the springs, but still need to look. I'll take care of it. It's a really deep squeak, not a high pitch (hard to explain) but I do notice, when I think about it, that in bumps around turns the rear axle wants to break loose, and it feels like its sliding, but the actual rear end isnt, and this was confirmed by a friend, that the axle isnt quite under the car in a turn over a bump, so... anyone have a guess as to what I need? Atleast some new LCA's and a panhard rod are in order, because I'm guessing the panhard rod (last I knew) is what helped keep the axle where it's supposed to be.

Otherwise, I'm trying to find a 3pt strut brace (was told to get that) and I have heard of 4pt's - but never seen one. The only one I have actually seen is the Edelbrock 3pt, and that is so far, high on my list.

And for SFCs, which would I want for the convertible? You guys know a lot better then me, and most of the ones I see are NOT for convertibles... Hmmm... I'd prefer bolt in's, but I know weld ins work better. A 4pt roll bar is also in order for winter, so that must play some consideration. Anyone have any ideas?
Old Oct 7, 2002 | 06:45 PM
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Loud thunk when you hit bumps? Kinda like the rear axle is slamming the frame?


pop of your rear wheels and see if the factory rubber bumpsotp is there or not, mine rotted and fell off on my passenger side around 105k, Its a $15 part, and my car stopped thunking when I hit bumps, I think the GM replacement part looks better then the stock rubber one.

Serioulsy I would check this out before I blew mroe money on new components, I spent time tracking it down before I finally found it. And have heardd the problem on alotta other f-bodies, and the parts guy knew exactly what I was talkingabotu said it was pretty common to go out.
Old Oct 7, 2002 | 09:32 PM
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Geoff Chadwick's Avatar
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For $15 each, I'm gonna go take them off tomorrow at work and look! For if that's true...

Thanks for the idea (that might be EXACLTY what I'm looking for, considering it sounds like (and feels like) the axle is smacking the frame)
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