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Lowered on coilovers - concern about noises?

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I have KW V3 coilovers and, although not slammed, it sits quite a bit lower than OE (lower about 1.25" front and 1.5" rear). When I am driving it in a rather, ahem, "spirited" manner and hit some big bumps I hear some pretty good clunks and clangs. I spaced my panhard brace down about 3/8" and I am not seeing anything hitting/scratching/scraping under the car so I can only assume that it is the over axle pipes and bump stops making the noises.

For those of you running lower springs or coilovers, what other things should I be looking for? Am I worried for nothing? I will probably crank the ride height back up another 1/4-1/2" to try to alleviate the noises. I never had any such noises on P springs, by the way.

Thank you in advance for your comments.

John
 
You shouldn't have any noises induces solely from a ~1.5" difference in ride height. Maybe if you were aired out on airbags/airride. Try to isolate where the noise is coming from. Front or rear? There was no noise that came from my KWs and they were about an .5-1 inch lower than you both front and rear.
 
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Hey thank you for the reply, Neema. It is coming from the rear. I posted my question on another forum and got this response from a shop that actually sells/installs KWs. And yes, I do have the gap that he speaks of.

"KW uses polyurethane bushings for the rear shocks (on the top). They are too short and often lead to noises in the back. Jack up the car and look at the top of the shock from under the car, you will see the gap above the bushing. You can swap the bushings off your stock shocks to eliminate the noise."

Seems to make sense and I will try that when I get some time. The noises occur when I hit a dip at a good speed. As far as I can see, the car isn't bottoming on the pavement. I trimmed the low-hanging exhaust mid-pipe bolts a long time ago so I don't think it's something actually making contact with the ground.
 
Champale said:
I have KW V3 coilovers and, although not slammed, it sits quite a bit lower than OE (lower about 1.25" front and 1.5" rear). When I am driving it in a rather, ahem, "spirited" manner and hit some big bumps I hear some pretty good clunks and clangs. I spaced my panhard brace down about 3/8" and I am not seeing anything hitting/scratching/scraping under the car so I can only assume that it is the over axle pipes and bump stops making the noises.

For those of you running lower springs or coilovers, what other things should I be looking for? Am I worried for nothing? I will probably crank the ride height back up another 1/4-1/2" to try to alleviate the noises. I never had any such noises on P springs, by the way.

Thank you in advance for your comments.

John
Hi John,
I have the same KW and a Magnaflow cat back syst. (3")
The axle hits it although I was aware of the problem and tucked it as close as possible to the chassis.
I guess the next step will be to fabricate a flat and wide portion of both tubes to clear the axle...
Patrick
gallery_12429_213_47630.jpg
 
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Thank you for that info, Patrick. Can I ask how you have been able to verify that it is the over axle pipes hitting so that I can look for the clues? So far I haven't seen any nicks, scrapes, etc on the OTAs, the panhard brace, or anywhere.

Thank you again, guys!

John
 
After the winter mods install (Kw's and many others) I test drove the car.
If I would hit a big bump I would hear a metallic bang coming from the rear
(It's a LS - - no seats and the trunk has lost all its insulation - battery and rear axle breather...so you hear what's happening there...like the fuel pump, etc...)
I lifted the car back and could see some tiny shiny spots on each of the exhaust tubes just above the axle.
I lifted and bolted the whole exhaust to the max and drove to the track the next day.
At the track all seemed fine but on my way back home I hit a big hump on the road and heard that noise again.
Once home, I could see one muffler was not centered anymore in its opening.
One of the tube had been hit by the axle and it angled the connected muffler...
Now I think I will go to a friend of mine who is an expert at metal fabrication + welding and expose him the case...
 
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Hah well I guess those were some pretty obvious clues! I will spend some more time poking around underneath my car because it seems like a metal on metal sound, although sometimes it sounds more like a thump than a clang so maybe I have multiple issues to deal with.

I will probably start by re-installing that OE upper shock bushing and I may remove my Bob's axle overflow tank to rule that out, too.
 
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By the way, Patrick, have you considered maybe wrapping the offending part of your exhaust with some muffler wrap/tape to at least soften the noise?
 
I upgraded suspension this winter -- 302S LCA's resulted in some clunks on street, but not audible on track, other than low speeds around paddock.....

Stiffer rear UCA increased Diff whine, in spite of reseting pinion angle. Rear axle hop and stability much improved at the expense of street NVH...
 
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Patrick - I hear ya, good luck and hopefully you can adjust the exhaust to get rid of it.

Black Boss - I have Steeda Billet poly/spherical LCAs, Steeda UCA and adjustable bracket, adjustable panhard, panhard brace, an axle overflow reservoir, alloy driveshaft, so there is a lot of stuff for me to point my finger at but I never had these noises until I recently switched from the P springs to the KWs which I have set up even lower. The car feels absolutely superb now and I just hope to figure out where the noises are coming from.

Oh and as for your diff whine, I also had it when I installed my UCA/bracket and was expecting it to get much worse when I put my Dynotech driveshaft on but the whine diminished to almost nothing (my car is an LS, also).

Thank you guys for all of your postings.

John
 
Black Boss said:
I upgraded suspension this winter -- 302S LCA's resulted in some clunks on street, but not audible on track, other than low speeds around paddock.....

Stiffer rear UCA increased Diff whine, in spite of reseting pinion angle. Rear axle hop and stability much improved at the expense of street NVH...

Did you remove your axle weights/harmonic dampers? I've heard they can subdue a lot of the axle noises transmitted into the cabin
 
1,022
97
Exp. Type
HPDE
Exp. Level
10-20 Years
Texas
One other thing to think about…This is something I experienced when I lowered my car on Eibach Sportlines. One thing you have to look at is the alignment of the bump stops. When you lower the car it twists the axle which turns the bump stops so they are no longer aligned properly. This causes metal to metal contact when the suspension articulates and fully compresses. Instead of the rubber bump stops hitting the axle contacts the body of the car. Get under your car and you will be able to see if they are aligned properly. It's easily corrected with an adjustable upper control arm.
 
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FlyboyGSXR - That is an interesting point, although my pinion angle is within spec (and I already have the shorter Steeda UCA for lowered cars and bracket with additional adjustments). I'm going to try to spend some "quality time" under the car this weekend and see what I can figure out.
 
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Update: it was my Bob's axle overflow reservoir setup. I was running it off the driver's side axle hole and it was smacking the exhaust, so much so that it actually cracked the fitting. When I first got the kit, I tried installing the fitting on the top of the diff, but there wasn't enough clearance between the fitting on the top of the diff and the reservoir itself which led to me position it on the axle.

I may go back to the ineffective turkey baster or maybe try the JLT setup which only mounts on one side of the UCA.
 
Champale said:
Update: it was my Bob's axle overflow reservoir setup. I was running it off the driver's side axle hole and it was smacking the exhaust, so much so that it actually cracked the fitting. When I first got the kit, I tried installing the fitting on the top of the diff, but there wasn't enough clearance between the fitting on the top of the diff and the reservoir itself which led to me position it on the axle.

I may go back to the ineffective turkey baster or maybe try the JLT setup which only mounts on one side of the UCA.

I'd recommend this:

b775bea5-201f-4412-a624-e14ade2bb0df_zps3f896521.jpg

No more expensive ;) and no clearance issues :)
 
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Hah yeah I have seen guys running that setup and if I it was a track car, I would do it. I do occasionally put stuff in the trunk, though (the horror!).

I looked at the JLTs a little more closely and I think I can fit it up so that nothing is anywhere near contacting. The Bob's is overly large for my needs (does anyone really need such a huge reservoir?)

Thank you for all of the help and comments, guys.

John
 

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