The clunk many of us hear coming from the rear of the car after installing aftermarket rear sway bars appears to be the combination of three things:

1) The polyurethane bushings provided with most all aftermarket sway bars
2) The "sticky" grease provided in the kits
3) The OEM endlinks

First off, everyone says the problem comes from worn OEM endlinks. This doesn't appear to be true. Here's why. If my endlinks were worn, then why is it that when I've regreased the bushings trying to fix this problem, the clunk went away for about 2 to 4 days? The endlinks can't magically repair themselves. The sound you're hearing DOES come from the endlinks, but it's not because they're worn. When you mount up an aftermarket sway bar with tight fitting poly bushings and grease them with the provided sticky waterproof grease, the bar is very resistant to move in the bushings. The bushings require a lot of force to rotate the bar up and down (endlinks unattached). I'd venture to say that when bar is mounted and the bushings/mounts are torqued to spec, it probably takes over 80lbs of force to get the bar to initially rotate in the bushing. I'm a pretty strong guy, work out often, and it takes me a very healthy tug to get the bar to move downwards. With the OEM rubber bushings, it takes maybe 5lbs. I could make that bar move with my fingers.

When you initially do the aftermarket bar install, you've greased up the bushings nicely across the whole face of the bushing. You drive around for the first few days and there's no noise or clunk. Then as the days go on and the grease works it way off the outer edges of the bushing, which are smooth and in 100% direct contact with the bar, the bar starts to become very resistant to move in the bushing. This lack of movement or response in the bushing, as well as the force needed to move the bar, requires the endlinks to have to work overtime to lift up/push down the bar. Not only is the bar a lever to resist roll in the chassis, but the bar must be able to move up and down through the range of suspension travel. At slow speeds, usually under braking and on almost smooth surfaces, you start to hear this "clunk clunk". The clunk is most definitely coming from within the endlink itself as it tries to move the bar up and down slightly. The bar is slow to respond so something inside the endlink pops and the sound is transmitted to and through the bar because the endlinks have direct metal to metal connection. At higher speeds and on larger bumps, the suspension movement up and down helps the endlinks do their job hence the reason you rarely hear the clunking under these situations. Using aftermarket endlinks will most likely get rid of the clunk because the endlinks are far beefier and apparently can handle the lack of bar movement caused by the bushings.

The other and far cheaper option to a $150-170 set of endlinks is to grease the bushing with slicker and lighter weight grease and modify the bushing so that the bar can move easily. The fix is super simple.

The fix:

1) Remove the bar and remove the poly bushings. Clean the grease off the bushing.
2) Take a Dremel with the sanding wheel and grind out the inner portion of the bushing. Make sure to hit all areas of the bushing. Don't grind out a whole lot. About all you need to grind out is 1mm, maybe a little more.
3) Test fit the bushing and bar back on the car and test to see if the bar is easier to move once mounted and torque to spec. If it's still tight, remove and grind out a little more. The key is to go little by little because there's no going back.
4) Once the bar moves freely, regrease the bushing and remount everything.


I did this fix about 10 days ago and the clunking is gone.

 

thanks for posting this. i'm not sure if it will cure all the problems people have had, but its good to see someone is willing to try something new

 

Dave - The longest I went with no noise was using the grease that came with my Hotchkis sways. I have tried lubing them again with some normal suspension grease but the noise came back. Then I wrapped the bar with teflon tape and greased. The noise is back again. I think I am going to drop the $22 to get a tube of that sticky grease from Hotchkis and see if that helps. If not then I will be giving this a shot or perhaps ordering another set of bushing to try this with.

 

why not try 350Z endlinks or M35/45 end links. they maybe longer and stronger

 

i have the same type of clunking sound, but i dont have any after sway bars. but i did lower my car on z-suspsion. and that sound got a little louder when i got new tires =/. oh and i need to roll my fender but i can tell the difference between rubbing and the clunking becuase i had it b4 too but not as much. any help would be much appreciated.

sorry for the thread jack....

 

You might have worn end links. They wear out when the car is lowered, they make a clunk noise at low speed when hitting bumps.

 

^ Thanks. Do you think the OEM would be good enough for it, cuz those aftermarket ones are really expensive

 

I would try getting revised OEM from Riverside Infiniti. They are only $40 or so and while they might not last forever it is the least expensive way to figure out if they are really the noise makers.

 

what if you have aftermarket endlinks, and oem bushings and are experiencing this same clunking, should i try to do the method of sanding out some inside material?

 

i fixed mine over the weekend, I just loosened the rear most nuts on the mounts, still on there tight, car doesnt feel any different, just no clunking anymore.

I loosened them up, the retightened them to the point it require effort to continue, then I just backed them off about 1/2 a turn, viola!

Still tons of thread there to be safe. Next oil change I may get under there again and actually take them to a specific torque amount.