HELP: Clunk Noise after Coilover Install

HisStigness · 01-03-2017, 01:39 PM

Hey guys I really need some help, just got HKS Hipermax IV GT coilovers installed a few weeks ago that I brought brand new from CZP. Had my mechanic install them who has a lot of experience installing coilovers for various cars.

Under normal driving conditions and just normal size or small bumps, everything is fine even under cornering. But if I hit a really harsh bump or go over a sharp crest where the car first unloads and then reloads a lot on compression, I get a very loud clunk noise only from the back right corner, 100% positive that's where it's coming from, it almost sounds like metal on metal but hard to tell for sure.

This comes after I already took it back to my mechanic once and he thought the rear right might by bottoming out on the fuel tank tube that goes from the gas cap to the tank, so I stiffened the shocks up a lot more (4 clicks from full stiff front, 3 clicks from full stuff rear), it was fine for awhile after that but it made the sound again last night after a big bump on the highway. Never once did this with my stock suspension and I left the HKS's in their factory settings which was a 3/4" drop.

Really hope you guys can help.... Thanks.

kenchan · 01-03-2017, 03:15 PM

is it the spring or the damper making da noise?

on some cars I've done in da past, I had to rotate the spring in a certain orientation, otherwise it would rub the spring carrier making a loud clunk noise. not sure if datz da case here.

I would swap dat one damper to stock and see if u got a defective damper.

kenchan · 01-03-2017, 03:16 PM

another reason why I hate letting people install my bits.

Spooler · 01-03-2017, 03:43 PM

You need more pre-load on the rear. You adjust it by shortening up the rear shocks. They should have adjustments on them.

HisStigness · 01-03-2017, 04:43 PM

Really hard to tell exactly what part is making noise. He had an idea to swap the rear shocks side to side to see if the sound follows. And good idea Spooler, I'll look into that. It's just weird cause HKS always advertises a ton that their suspension for our cars arrives already properly adjusted.

kenchan · 01-03-2017, 06:38 PM

is the rear spring and damper setup or a strut? thought those were separates.

HisStigness · 01-03-2017, 07:36 PM

Quote:

Originally Posted by kenchan

is the rear spring and damper setup or a strut? thought those were separates.

It's the oem style so separate spring and strut yes.

OptionZero · 01-03-2017, 08:51 PM

You need thrust washers for the springs. Under compression or decompression they are trying to rotate, and there is a lot of friction with where they are sitting.

Swift makes them, pretty cheap. You'll need to take the fronts off to install them. Not sure if you have OEM or true type rears. True type needs to come off. OEM type just raise the car and slip them in after disconnecting the bucket.

You can also step up to thrust BEARINGS but I don't think that's necessary

01-03-2017, 01:39 PM	#1 (permalink)
HisStigness Base Member Join Date: Jan 2014 Location: San Ramon Posts: 64 Drives: 10 370Z Sport 6MT Rep Power: 11	HELP: Clunk Noise after Coilover Install Hey guys I really need some help, just got HKS Hipermax IV GT coilovers installed a few weeks ago that I brought brand new from CZP. Had my mechanic install them who has a lot of experience installing coilovers for various cars. Under normal driving conditions and just normal size or small bumps, everything is fine even under cornering. But if I hit a really harsh bump or go over a sharp crest where the car first unloads and then reloads a lot on compression, I get a very loud clunk noise only from the back right corner, 100% positive that's where it's coming from, it almost sounds like metal on metal but hard to tell for sure. This comes after I already took it back to my mechanic once and he thought the rear right might by bottoming out on the fuel tank tube that goes from the gas cap to the tank, so I stiffened the shocks up a lot more (4 clicks from full stiff front, 3 clicks from full stuff rear), it was fine for awhile after that but it made the sound again last night after a big bump on the highway. Never once did this with my stock suspension and I left the HKS's in their factory settings which was a 3/4" drop. Really hope you guys can help.... Thanks.

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01-03-2017, 03:15 PM	#2 (permalink)
kenchan A True Z Fanatic Join Date: Aug 2009 Location: N/A Posts: 76,801 Drives: N/A Rep Power: 141520	is it the spring or the damper making da noise? on some cars I've done in da past, I had to rotate the spring in a certain orientation, otherwise it would rub the spring carrier making a loud clunk noise. not sure if datz da case here. I would swap dat one damper to stock and see if u got a defective damper.

01-03-2017, 03:16 PM	#3 (permalink)
kenchan A True Z Fanatic Join Date: Aug 2009 Location: N/A Posts: 76,801 Drives: N/A Rep Power: 141520	another reason why I hate letting people install my bits.

01-03-2017, 03:43 PM	#4 (permalink)
Spooler A True Z Fanatic Join Date: Jun 2014 Location: Ga Posts: 13,512 Drives: 2013 Nismo 370z Rep Power: 2684391	You need more pre-load on the rear. You adjust it by shortening up the rear shocks. They should have adjustments on them.

01-03-2017, 04:43 PM	#5 (permalink)
HisStigness Base Member Join Date: Jan 2014 Location: San Ramon Posts: 64 Drives: 10 370Z Sport 6MT Rep Power: 11	Really hard to tell exactly what part is making noise. He had an idea to swap the rear shocks side to side to see if the sound follows. And good idea Spooler, I'll look into that. It's just weird cause HKS always advertises a ton that their suspension for our cars arrives already properly adjusted.

01-03-2017, 06:38 PM	#6 (permalink)
kenchan A True Z Fanatic Join Date: Aug 2009 Location: N/A Posts: 76,801 Drives: N/A Rep Power: 141520	is the rear spring and damper setup or a strut? thought those were separates.

01-03-2017, 08:51 PM	#8 (permalink)
OptionZero A True Z Fanatic Join Date: Apr 2011 Location: Sacramento Posts: 3,160 Drives: 15 370Z Nismo 6MT Rep Power: 203226	You need thrust washers for the springs. Under compression or decompression they are trying to rotate, and there is a lot of friction with where they are sitting. Swift makes them, pretty cheap. You'll need to take the fronts off to install them. Not sure if you have OEM or true type rears. True type needs to come off. OEM type just raise the car and slip them in after disconnecting the bucket. You can also step up to thrust BEARINGS but I don't think that's necessary