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Rear Suspension

M mickey356
As some of you may remember I have been working on the rear suspension for my Carrera Project. I was having trouble getting the rear shocks aligned to ride in the trailing arm/bottom mount cavity. Today my buddy and I finally realigned the upper mount so the shock no longer scrapes and bangs the edge of the cavity. I still get a pretty solid "bang" when I go over bigger bumps. It's not like the bumps are craters of speed bumps, just rises in the road or small depressions (sunken man-holes). It's not bone-jarring either, but enough to make me wince a little from the sound. I thought maybe it was the rear bumper brackets banging against the body from the rear clip sag so I took off the bumper, it got rid of a little but not the brunt of it.
So now I have no idea what the problem is. Is it the rear torsion bar/springs? I brought them up a notch when we did the rear narrowing so they're not dropped anymore. Is the car supposed to ride smooth over bigger bumps or is this common in pan based? I'm stumped and need some advice. Thanks.
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M mickey356
As some of you may remember I have been working on the rear suspension for my Carrera Project. I was having trouble getting the rear shocks aligned to ride in the trailing arm/bottom mount cavity. Today my buddy and I finally realigned the upper mount so the shock no longer scrapes and bangs the edge of the cavity. I still get a pretty solid "bang" when I go over bigger bumps. It's not like the bumps are craters of speed bumps, just rises in the road or small depressions (sunken man-holes). It's not bone-jarring either, but enough to make me wince a little from the sound. I thought maybe it was the rear bumper brackets banging against the body from the rear clip sag so I took off the bumper, it got rid of a little but not the brunt of it.
So now I have no idea what the problem is. Is it the rear torsion bar/springs? I brought them up a notch when we did the rear narrowing so they're not dropped anymore. Is the car supposed to ride smooth over bigger bumps or is this common in pan based? I'm stumped and need some advice. Thanks.
Gordon NicholsGordon NicholsMassachusetts 1993 CMC Supporting Member
It should be smooth over just about anything.

Possible causes:

Suspension set too low and the limit rubber snubbers are hitting.

Shocks are too short and either bottoming out or hyper-extending.

Spring Plate is hitting the bottom stop of the mounting casting on upswing.

Tires are hitting the top of the inner fender (more of a "Whoose!" instead of a bang).

Shock(s) not primed and clicking or banging from internal air.

Get someone to jump up and down in the back seat area while you look at what's going on from below (maybe on a lift or trailer?) to see where the interference is.

gn
FM Former Member
Mickey, Brian, please publish any findings.

I've had a hard left rear "clunk" for over a year, can't find anything amiss down there. Sounds almost like a big nut has backed off somewhere, and the attached parts are crashing into each other.

I only get it over pot holes and bad street repair patches. Great big whoop-de-doos that challenge the total suspension movement up and down doesn't cause any sound at all. Normal street driving doesn't cause any sound at all.

Nothing loose or obviously wrong that I can find. If something falls off, I'll post it here!
FM Former Member
mickey , check to make sure those big boxed trailing arms clear your rear subframe , i also had the same problems with shock alignment , the arms that should be used on the speedsters should be the the three tube version offered by blind chicken racing , they give you alot more room around the rear frame . ron
M mickey356
Ron,
Are you saying you ditched the "big box arms"? Geez, I'd hate to have to suck up $500 and have to get another set. I haven't had a chance to get someone in the car and up on a lift to check the travel situation back there yet. What location of the subframe was obstructing the movement of the arms?

I removed most of the interior the other day and had the car on the road today. It's amazing how much you can hear with no insulation. Anyway, there seems to be alot of things bangin around back there. It very well maybe the the arms not clearing the subframe. When I say alot of things I mean it sounds like things need to be secured better.
The shocks now seem to be able to travel freely so that's good. And the car seems to be a little more settled in, but there is still a pretty good bang on the bigger bumps. It almost sounds like it IS the subframe or the body banging into the subframe, I don't know. Can anyone guide me along as to where to look?
FM Former Member
Look for any unusually shiny metal -- torn, abraided, scuffed or dented pieces will provide clues, but anything that looks like is shouldn't. Worn pieces that used to be shiny don't count, and will probably be lightly surface-rusted.
Plan B, if you can't get a lift and it's really bugging you; get a drop-light and a palm-sized video camera. Turn on the drop-light, shove it under one side, aim the camera at the suspension from the ground and then jump in and hop up and down in the back seat.
The noise will probably coincide with something obvious happening on the video.
Just a thought. ...
Lane AndersonLane AndersonMt. Pleasant, SC Supporting Member
Just out of curiosity, you don't happen to have a Sidewinder exhaust, do you? I've noticed that large bumps will occassionally cause my Magnaflow muffler to come in contact with the side frame rail, making a heavy-sounding thump. I have less than 1/4" between the frame and the muffler, so it doesn't take too much flex in the pipes to make contact. I have a thick rubber mount at the leading end of the muffler because I figured I'd need some play due to engine movement. I may have to rethink that.
M mickey356
OK, now were gettin somewhere!

Lane,
I DO have a Sidewinder, so I'll check that out.

Ron,
I had to do it twice but I think I finally got the top shock mount placed where the shocks move freely through the arm. Though I do have to get under there and check to be completely sure. I'm almost positive the passenger side is good, but the driver side was a little close for comfort. If I have to I'll build a mount to get it right. As of now I just drilled a hole and welded a nut to the subframe to bolt the upper shock to. However if the subframe IS in the way of the arms it could be some "creative" reconstruction down the road.

Cory,
Good thinking. I'm pretty sure I can get it on Steve's lift in the next couple days.
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