Rear suspension clunk, passenger side.

[Tight Lines]

Here is a video of problem clunk.
Gt500 suspension clank? - YouTube

All BMR suspension UCA, UCA mount, LCA's, LCA reloc. Brac's, panhard bar, Koni Sports and Steeda GT500 Sport springs. Only happens over sharp quick bumps. I went through the entire suspension yesterday and everything looks good. Re-torqued all bolts and looked for any wear indications on metal parts, didn't see anything. Checked trunk for loose items, nothing. I had a friend sit in the rear seat and its coming from the passenger side behind the rear seat. He did hear like a pressurized gas leak right before the noise. Any ideas, hope I have given enough info. Yes, I did talk to BMR and he was OK posting to hear other thoughts.
Thanks!

 

[PLATIADO]

Did you check if your panhard bar is not hitting your diff cover or the axle back?

 

[Tight Lines]

Axle backs are clear of hitting anything. Panhard looks to have plenty of clearance.

 

[me32]

Is the rearend centered?

 

[54First]

Whose panhard brace do you have? If it's a Steeda it's guaranteed to hit the panhard bar. BMR or factory is OK. Also, jack the car up so the axle is hanging. The standard thought is something's compressing but I had a problem at full extension. So check with the axle hanging. Do you have a panhard relocator? Check swaybar to relo clearance. If you have a cast diff cover, check panhard to cover. I think a prior poster already suggested that.

On a completely different tack, maybe your friend heard a shock blowing out.

Steve

 

[BMR Tech]

I am very, very curious to see what this is.

As I told the OP, this is something that I have never received feedback on. Of course, I have received feedback about clunks and clanks, etc....but nothing that replicates this. Typically, I can solve an issue in a matter of 1-2 phone calls and the customer going out int he garage to check things....this, not so much.

At this point, we are narrowing it down to possibly a shock issue, but I just can't - for the life of me, accept the shock making that noise?

I am fully confident in the OP having everything installed properly, as we have spoken numerous times and he is definitely up to par on the installation side of these components.

 

[BMR Tech]

Whose panhard brace do you have? If it's a Steeda it's guaranteed to hit the panhard bar. BMR or factory is OK. Also, jack the car up so the axle is hanging. The standard thought is something's compressing but I had a problem at full extension. So check with the axle hanging. Do you have a panhard relocator? Check swaybar to relo clearance. If you have a cast diff cover, check panhard to cover. I think a prior poster already suggested that.

On a completely different tack, maybe your friend heard a shock blowing out.

Steve

You, sir, Steve...are on point! :beer:

These are exactly the things we have discussed....and why I am just baffled by this situation.

I am really anxious to resolve this.

 

[Tight Lines]

Is the rearend centered?

If you are referring to centered with a panhard bar, yes.

Whose panhard brace do you have? If it's a Steeda it's guaranteed to hit the panhard bar. BMR or factory is OK. Also, jack the car up so the axle is hanging. The standard thought is something's compressing but I had a problem at full extension. So check with the axle hanging. Do you have a panhard relocator? Check swaybar to relo clearance. If you have a cast diff cover, check panhard to cover. I think a prior poster already suggested that.

On a completely different tack, maybe your friend heard a shock blowing out.

Steve

Stock panhard brace. I will check with suspension in full droop as I only checked clearances with suspension under load. Yeah, that's why I was leaning towards the shock being bad. I will replace with a stock one sometime soon and retest over the same road for comparison. Thx.

You, sir, Steve...are on point! :beer:

These are exactly the things we have discussed....and why I am just baffled by this situation.

I am really anxious to resolve this.

Thanks for chiming in Kelly. Don't want people thinking I'm posting first before talking to you.

 

[kozumasbullitt]

Whose panhard brace do you have? If it's a Steeda it's guaranteed to hit the panhard bar. BMR or factory is OK. Also, jack the car up so the axle is hanging. The standard thought is something's compressing but I had a problem at full extension. So check with the axle hanging. Do you have a panhard relocator? Check swaybar to relo clearance. If you have a cast diff cover, check panhard to cover. I think a prior poster already suggested that.

On a completely different tack, maybe your friend heard a shock blowing out.

Steve

Can you elaborate on the Steeda brace? I too have rear end noise but more of a squeak over bumps.

 

[Tob]

If the shock took a dump you'd sense a different dynamic quality than when the car didn't exhibit this issue.

My suggestion...pull the rear seat bottom out. Have your friend place his hand in different areas, such as the UCA bolt atop the driveshaft tunnel. You can do the same elsewhere, such as a location near where the front of the LCA mounts to the chassis, down by the rocker.

If you have a one piece driveshaft I'd be checking that very carefully as well.

On Edit...I just noticed something Troy posted elsewhere...

FYI, I did have to weld in the BMR LCA relocation brackets (latest revision). I know they are a weld free design, however, I was experiencing bracket shifting and weird noises while driving. At first, I thought it was the endlink type on the 021 adjustable LCAs, so I removed them and reinstalled the stock arms. The stock arms are quieter, but I still had occational metal shifting clunk noises.

This morning, I welded in both LCA relo brackets, and now it's stock quiet. Soon I will reinstall the adjustable arms to see if I can tolerate the noise from them.

 

[rjm-1]

Okay, This is just a shot in the dark, but I had a similar problem of a clunk in the rear that I could not find the cause of. I too had installed BMR panhard, LCA's and FRPP lowering springs. After months I finally found that it was a FRONT sway bar bolt that was a little loose! The sound was telegraphing through the car and I swore it was coming from the rear of the car. Tightened the sway bar bolt and the noise was gone! My advice is to check everything over under the car, even those things you didn't touch. Good luck.

 

[54First]

Can you elaborate on the Steeda brace? I too have rear end noise but more of a squeak over bumps.

The Steeda brace shape doesn't play well with the BMR panhard. Nothing wrong with either part, They just weren't made to go together. And they would clunk, not squeak.

My first guess on the squeak would be suspension bushings.

Steve

 

[wingsnut]

UCA arm to chassis bolts not tight? The rearward facing bolts on the LCA relocation brackets tight? Driveshaft hitting something? Rear bump stops bottoming out? I developed a clunk going over bumps once the lowering springs settled in about 3 months after installing them. Turned out to be the bump stops, but your's sounds a bit more metallic than mine did. Did a rear shock or sway bar link come loose?
Chip

 

[Nsssane1]

Just double check you put the rubber isolaters inside the car on shocks. I have forgot them before, somehow.

 

[Tight Lines]

Thanks guys for all the ideas. I have given up for the night. I still have a few things you guys mentioned to go over but nothing yet. I will try a couple more things tomorrow night after work. Please keep any ideas coming or I hope someone out there had the same clunk and has a fix. Whatever comes about it I will conclude this thread, either fixed or go back to stock.

 

[Tight Lines]

Just a few things off the check list and the noise is still there.
Replaced shocks (stock)
Checked springs
Rubber bushings were in
Tightened sway bar end links

I will go at it again tomorrow.

 

[barspen]

Sway bar links

Just a few things off the check list and the noise is still there.
Replaced shocks (stock)
Checked springs
Rubber bushings were in
Tightened sway bar end links

I will go at it again tomorrow.

I noticed a similar sounds after swapping the stock rear sway bar links to FRPP. First time I had a loose bolt on the passenger side end link (on frame). Plan to lift it up this weekend to see if I can find any loose bolts and re-grease the bushings.

Keep us posted on what you find.

 

[54First]

When I first installed my BMR UCA and bracket, I had a clunk. It didn't sound a lot like yours, but at this point it might be worth mentioning. The bolt on top of the diff is a bitch to get torqued to 129. I used some combination of u-joints and extensions. After thinking about it I figured that I wasn't getting an accurate torque reading due to u-joint angles and twist in the extensions. So I tightened it to an indicated 150. Problem solved. That was five years ago. It's still OK.

But yours sounds like something long and tubular banging. (I have dog ears) That points to panhard or exhaust or sway bar (even though it's solid).

Steve

Edit: I just noticed Tob's post. The driveshaft is also tubular.

 

[Tight Lines]

Steve, thanks for your ideas. I can say that I am pretty positive it isn't the UCA. Torqued properly, it's not hitting anything and I had my friend put his hand over it from the inside by the bolt, nothing was felt. It is oming from below the downside of the trunk passenger side. It's the area around the square in the picture.

I totally agree about the bar/tube sound. I am taking a break for awhile as I am pretty frustrated. Coming home from work, wrenching, sleeping and doing it over for a week. My wife is also frustrated that I did this work to a rather expensive car and it sounds like this.
My plan next is to put a Gopro under the car and see if I can find something that way. I'm also want another set if eyes as everybody including BMR is stumped.
Thanks again to everybody for ideas and opinions. If I do figure this out I will post the outcome.

 

[Snapp]

Every figure it out? (from the dead)