coobah

Hello,

I hear knocking sound from my front right (passenger) wheel suspension when driving thru a lot of small holes or harsh road in general (eg. the wheel is "vibrating" up and down quickly).

The sound reminds me of a worn sway bar links sound (in my previous cars). Maybe it sounds a bit "thicker".
Two shops were searching for it but they said they found nothing and they even did check all of the bolts and blah blah (which doesn't mean that I trust them fully of course)

Some time ago I hit a pothole with right side of the car. (but I'm not absolutely sure if it's related as knocking sound showed up a few weeks later)

And now the strange thing. The problem dissapeares (or at least weakens a lot as I won't drive like nuts thru a bunch of potholes just to check it, or at least not yet) when I switch the Airmatic to raised position... WTF????

Dokus

I had the exact same issue on my e500. It were the swaybar bushings. Try to spray them with a good amount of silicon lube and see if it goes away. They sit in the middle of the swaybar in the chassi of the car. Before i found it i replace most of the bushes and balljoint only to be saved by the lube. The sound made me miss diagnose.

coobah

Now that kind of info is possibly worth a lot Cheers. Will definitely try that out (actually I'm having a set of polyurethane swaybar bushings laying on a shelf so maybe I'll just fit those...)

JT1982

Funny, I had a very similar issue and it turned out to be a bad Arnott front shock. Same thing--no issue when fully raised. Mechanic replaced the shock and problem went away.

coobah

No, thats surely not funny...

StarvingArtist

Sway bar bushings are molded on to the sway bar, and hold it in place. You can tighten them up with some bicycle inner tube around the outside in the clamps, or buy a new sway bar. Poly mounts will take some doing. Check the steering rack end bushings. I'm guessing air strut though.

gheorghe

I'm in the same exact boat as you are. I too have a light clunk when going over pot holes and found it to be the ball joint on the control arm where the sway bar end links bolts to.
I'd suggest to unbolt the sway bar end links and take the car for a spin to see if this is the area where the noise is coming from.

Lower control arm

Dokus

It could be any of those things but OP, spray the swaybar first and see were that gets you before replacing any parts. I had the exact same problem going over bumps, went away when rised. Changed the ball joints, arms and so on and were just about to buy struts when i found it

coobah

Thanks a lot for sharing the info guys.

So...ATM I'm not in good conditions for testing suspension components but I jacked up the car and checked the sway bar. It's surely not good that the suspension was in fully extended position when I did it and I did not find any play (in the links nor in the bar itself) but... the links made me suspicious. There's no play but I'm able to move the links a bit to the sides with just bare hands. Again there's no "free/knocking play" but AFAIK those things shouldn't be that soft. Oh and the rubbers in top bushings look a bit torn (little pieces of rubber sticking out)

Picked up a set of two links and two ball joints from Lemforder today. Will also take my poly bushings from the shelf and mount all of it when I'll have a chance (most probably this weekend) I'll also do a better check of everything else too. Keep your fingers crossed

Dokus

Spray baby spray... that lube

kiluminati616

what kind of spray do you guys use? i have a similar issue with a creaky right rear suspension. my shop gave it a once over and didn't see any issues. they suggested just dealing with the annoyance instead of throwing money at different parts trying to find the culprit.

Dokus

Any silicon spray made for rubber. Locite among others makes them. Do not use wd40 or similar which dries out the rubber.

coobah

I'll surely grease the bar bushes if they'll look good but I'll just replace them if they'll show any bad signs. I'll replace the links and ball joints anyway too. It's very common for them to fail here where I live (I mean in all cars). They aren't expensive and my ones surely show some wear.

Don't know if you have the brand called Mannol in your countries but I've checked a lot of silicone sprays at work and this one (of course it depends on what you need in particular situation) appeared to be the thickest. It's almost like a grease. Leaves the thickest film... and smells nice too ... and is not expensive by the way.

In a Jeep world you use a lot of poly bushings. They tend to squeak and should be greased with silicone grease (not spray). At least that is what you get in the package from polyurethane manufacturer). The grease is lasting a lot longer than spray but I don't know any brand which makes one because... accidentaly I found that marine grease is a lot better for those things (it's deisgned to resist water). I always used the Quicksilver 2-4-C marine grease under my Jeep and it lasted for years not having an easy life (more mudding than rock crawling here). I'd recommend trying that stuff if looking for a long term squeaky suspension solution. The only disadvantage is that you should dissassemble the parts to grease them fully

Rovel

I had blown air strut. Replaced with Arnott and the knocking/ thumping sound developed. Would not make the sound when raised. I contacted them and they sent me a replacement. No issues since then. Good thing I did the labor myself.

jbaker1121

Did you contact Arnott directly or who you bought them from? I just put Arnotts on and have a thump.. argh

Rovel

I bought them from FCPeuro. However, FCP charges you for the return shipping which isn’t cheap due to the weight. So I contacted Arnott directly and they gave me free return label to their address. I got a replacement at first from them which was couple dollars cheaper than FCPeuro. Then I shipped the old one out and got reimbursed. I liked their customer service, but it sucks that despite advertised thorough inspection some of their struts have this issue.

jbaker1121

That's where I got mine from too. I'll do the same then. Thank you. Very annoying to have this issue. If I would have known, would have just went bilstein for a few hundred more (but I like their lifetime warranty)

thanks

coobah

So... as said before those were not expensive parts so I did replace both swaybar links and their ball joints. Actually they didn't look that bad (one rubber bushing was torn). Doing this I found out that I need to drop the subframe to get to swaybar bushings but as they looked very good I just did spray a lot of silicone lube in there while turning the bar up/down.

Results... nothing changed - still knocking ...just removed the struts today and sent them for a rebuild. Will report back soon.

EDIT: Forgot to mention that in the meantime I also went to "diagnostic shop". We tried the front on the "shock absorber test machine" (I mean those two pods that shake a lot after you drive your whells on). At first we couldn't feel anything (car lowered/comfort), but when we stiffened the suspension you could feel the knocking with your hand on top of the strut.

Dokus

Did you use the lube?

coobah

Yes sir. Half a can of thickest lube I know

coobah

Did rebuilt the front struts. No knocking anymore.