Jump to content

Slow Speed Knock/rattle In Rear End Of Fg


ello678

Recommended Posts

  • Member
  • Member For: 12y 10m 6d

I've been in conversation with Sydney Shocks and they've been pretty helpful, they have just made up a 13.8mm bolt for the 14mm lower shock mount hole. So it seems that they think the problem is the lower bolt as opposed to the top. Once I have the bolts installed I'll report back.

  • Like 1
Link to comment
Share on other sites

  • Member
  • Member For: 18y 11m 17d

Ok so to throw a spanner in.....

My previous attempt with the longer bolt was not a fix, the knock was better but still annoying after more driving, so I removed it and put the factory bolt back in, I was not able to tighten the new bolt enough as I needed more washers, to stop the thread bottoming out, but I dont think is the bolt anyway....

Here is another 'theory' of mine lol, the opening hole on the body mount is quite large compared to the bolt and also the shock eye, so I wrapped the bolt with some electrical tape, several layers and then cut it back to a 1/3 of its width creating a 'collar' just behind the bolt head, then I grabbed my 450mm breaker bar and did it up tight, something I did has done something as it is much more quiet than it has been, still get a tap from it over the little stuff at low speed.

I think the bolt shank might touch on the body mount ever so slightly as it all flexes and that's where the little tap comes from, I think the mount may need to have the opening made smaller, the easiest way with maybe a 12mm washer welded on.......or some kind of rubber collar that crushes up as the bolt tightens, maybe a small piece of rubber hose, or a proper metal collar.....

I think the high speed damping of the bilstein in combo with small bumps is causing flex in the mount/bolt, before it translates into shock movement, when there is more weight on that side I.e passengers the shock is not able to overcome the weight and it wont knock, also when upto speed I.e 60kmh and above it is quiet over any surface, as I believe the shock damping cannot then react in the same manner as the car is moving over the ripples/bumps too fast.

Something else I have been thinking about is ride height, my static ride height with no one in the car is higher on the back left obviously due to settling of the springs, this would likely get worse when its just me in the drivers seat, also this would also be an issue with most cars id say... I have considered swapping springs to see what happens but need to get to a suspension shop for the hoist, bit hard in the driveway.

Or maybe that is all useless brain fart, and ello678's bottom bolt fix is the answer!

Link to comment
Share on other sites

  • Member
  • Member For: 12y 10m 6d

Ok just picked up the car, drove it home and it was near perfect! Sooo much better than before, im happy with the result, hopefully the noise wont come back. Apparently what they did was install a sleeve to increase the lower bolt shank diameter from 12.5mm to 13.8mm (thread diameter stays the same obviously) and it sounds like it has worked. It still doesnt explain why it didnt knock with the oem shocks. But anyway I would say to any1 with this problem to either try a sleeve or get a custom bolt made up, it should fix the problem.

Edited by ello678
  • Like 4
Link to comment
Share on other sites

  • New Member
  • Member For: 10y 6m 16d
  • Gender: Male

Ok just picked up the car, drove it home and it was near perfect! Sooo much better than before, im happy with the result, hopefully the noise wont come back. Apparently what they did was install a sleeve to increase the lower bolt shank diameter from 12.5mm to 13.8mm (thread diameter stays the same obviously) and it sounds like it has worked. It still doesnt explain why it didnt knock with the oem shocks. But anyway I would say to any1 with this problem to either try a sleeve or get a custom bolt made up, it should fix the problem.

Good to know it's sorted out. Keep us posted on how it goes after a couple of days. Also, if you don't mind me asking, how much did it end up costing you getting the car done today?

Link to comment
Share on other sites

  • Member
  • Member For: 12y 10m 6d

Well to be honest, it cost nothing as I let them know about the issue before the warranty was up, that was actually the third time ive been to the workshop. Even if yours is out of warranty I cant imagine them charging much for some bolt sleeves. Its a weird one because even though the problem wasn't directly caused by the bilsteins, the noise only happened with the bilsteins on the car.

Link to comment
Share on other sites

  • New Member
  • Member For: 10y 6m 16d
  • Gender: Male

Cheers mate. My suspension is still under warranty (only 3 months old) but it was bought and installed from a different place. I'll give them a call on Monday and see.

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Recently Browsing   0 members

    • No registered users viewing this page.
×
  • Create New...
'