WS6Guy25

iTrader: (1)

First let me start by saying I've owned this car since 2005 and it has 38k on it. But I've done suspension mods to it that I wish I never did. The car handles like absolute crap. Theres banging over bumps, sudden jerks, and it's frankly hard to control at times especially if the driver has never driven the car before. Below is the list of mods:

Eibach/Bilstein SLP package
SLP subframe connectors
Control Arms (forget the brand)
Double Adjustable panhard bar
Strut tower bar
18" wheels c5 zo6 (does that even matter?)

Let me start by saying I don't know if the panhard bar is adjusted properly. When I get under the car and look at the bar it is essentially parallel with the axle.

The car bangs and makes like a hollow thunking noise when going over bumps even small little potholes or minor cracks in the pavement.

I've come to the end i really can't handle how shitty the car rides. Ive considered getting rid of it but i just cant because it really is such a beautiful car and in pristine condition.

I'm beggin for help here anyone that can help me I would greatly appreciate it. Or in the alternative if you know of any shops in the new England area that specialize in suspension on f body's I would love to give them a call.

Thanks guys I appreciate anything you can help me out with.

lees02WS6

iTrader: (5)

Is this a street cruiser, an event car (drag, autocross,etc.), or some combination?

bufmatmuslepants

iTrader: (3)

Sounds like you could use an alignment. Is the bump/clank coming from the rear or front of the car? If its the rear you could take out the rear springs and cycle the suspension from the bumpstops to full droop and see if anything gets close to touching anything and make sure there is no binding.

The Batman

iTrader: (4)

What type of panhard rod do you have?

The Batman

iTrader: (4)

Also, what type of control arms do you have? If they are rod ends, they could need replacing. I agree with getting a 4-wheel alignment. Also get your wheels rebalanced

lees02WS6

iTrader: (5)

What is the current ride height? What tires are you running?

Pictures are helpful too. Pics of the rear suspension, front suspension, especially the control arms.

WS6Guy25

iTrader: (1)

The control arms are UMI I think Non-adjustable with poly
The panhard rod is a double adjustable UMI

I definately need an allignment for sure and I will probably get new tires soon so a tire balance is in order.

I am going to do the allignment and balance within the next couple of weeks.


The banging/thunking is coming from the rear. It is not the exhaust, because I have check that, it is on there tight.

lees02WS6

iTrader: (5)

The poly/poly LCA's aren't helping you either, they'll transmit more NVH. Are you're front control arms still stock?

The UMI PHB is it double adjustable with rod ends at both ends?

Are the Eibach springs SLP Eibach's, Prokit, or Sportlines?

SSickLS1SS

i think i may know your problem..is your panhard ends like ball joints that move around? a long time ago i bought lower control arms that had those ends and it was doing exactly what your describing and i swapped them out in like 2 days. ever since i put the solid LCA's in the noise went away. if i were you id change out that panhard bar for one with an adjustable piece in the center like this
http://www.bmrsuspension.com/?page=p...&productid=279

lees02WS6

iTrader: (5)

We haven't heard yet whether he has a rod end equipped PHB. IF he does, It could be the jam nuts are loose, or the rod ends have gone bad. Rod ends do make noise even when new. At the edge or their own travel (rotating side to side) they click, either against themselves or the housing they're in. When they loosen up they make even more noise.

http://www.youtube.com/watch?v=xvoZy...ature=youtu.be

Monsoon

I was having a strange 'thunking' noise in the back that I couldn't figure out for a while. It actually turned out to be the e-brake cable banging against the underside of the body where it routes over the rear axle. You said you checked the exhaust but did you check that cable?

Latch

iTrader: (8)

Start by swapping out the poly LCAs with stock ones with new rubber bushings in them.

UMI Performance

iTrader: (77)

The poly/poly control arms won't cause rattles like everyone is explaining. The only time they will transmit more noise is if the bolts are tight enough. Since you have SFC's make sure the front control arm bolt is TIGHT. Since the SFC's most likely wrap around the control arm mount it will take more force and pressure from the bolt to tighten the control arm properly.

If the rod ends in the panhard bar are wore out they can offer some noise.

But check those control arm bolts, the thud sounds like the SFC/control arm area not being tight.

I hope that helps,
Ryan

kyoytey1693

iTrader: (7)

Dont start changing parts until you find the problem. Tires and alignment will help the ride a lot but it does sound like something is loose. I had a bad trans mount on my 96 and I would have sworn it was coming from the rear end. You need to get under it (on jack stands) and check everything out. Use a pry bar.

lees02WS6

iTrader: (5)

His problems extend beyond just clunking if you read what I read from his post. So far, I have heard

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Other notes:

• "I've come to the end i really can't handle how shitty the car rides."
• "The banging/thunking is coming from the rear. It is not the exhaust, because I have check that, it is on there tight."

Modifications:

• Springs: Eibach ???
• Shocks: SLP Bilstein
• SLP subframe connectors
• UMI Poly/Poly Control Arms
• Some type of Double Adjustable panhard bar (What type, Rod Ended, Poly bushed?)
• Strut tower bar
• 18" wheels c5 zo6 (does that even matter?), Yes it matters, increased mass of any unsprung weight will reduce ride quality.
• Bridgestone Potenza ???/??/18

Call me crazy, but I don't think fixing just the a PHB or tightening bolts on the LCA's would address all those issues. We need more complete information.

We also need to know the use of the car? Daily driver, weekend toy, drag car, autocross, some combination?

UMI Performance

iTrader: (77)

I completely agree. I was just trying to correct the few people that mentioned poly control arms being the source of the noise and issues, quite a few mentioned changing them will fix the issue, I disagree. The things I mentioned are areas to check in which I have experience in regarding the UMI items on the car.

dr_whigham

iTrader: (49)

Here's my take- When was the last time the ball joints and tie rods were inspected / replaced? Those two by themselves will cause every symptom you've described.

WS6Guy25

iTrader: (1)

Very interesting. Mine is the one I have attached. I think you may be on to something here.


And yes I still have the stock control arms in front.

The springs are the SLP kit the valved bilsteins and eibach spring package.




Tire Size is 275 35 18 Front // 285 35 18 Rear

The car is garaged probably like 7 months out of the year. It's a weekend toy, but I do take it to the drag strip, but it's def not a drag car.

Driver_10

I can tell you right off where the "clunking and banging" is coming from. The 4th gens used foam bump-stops that wear down into nothing and become a nuisance when a car has been lowered. Replace them with easily modified, 3rd gen, f-body, rubber bump-stops and that should end the "banging" noise entirely.

The scraping noise that your getting in the rear end is an incorrect pan-bar adjustment. You will need to shorten the panhard bar until the driver-side tire no longer makes contact with the wheel well at full compression.

This happens to a lot of people with lowering springs and large tire combos. Its an easy fix.

As far as the "twitchy" handling is concerned, the wheel offset may be incorrect because of the larger wheels. This will cause the tire contact patch to bias towards the outside shoulder of the tire and ****** the tire about. The offset can be easily corrected with wheel spacers.

A final alignment job will correct any other problems after these things have been resolved.

hope this helps.

The Batman

iTrader: (4)

You have a rod/rod panhard bar. They tend to make a lot of noise, and can wear out quickly. I wouldn't be suprised if you have to replace both rod ends. If thats the case, I would replace them with roto joints.