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I am slowly trying to identify and eliminate some of the clonks I get from the rear of the car. I know that there is nothing touching anything it shouldn't but I still get several noises I shouldn't from the rear somewhere when going over rough surfaces.
Have any of guys had this problem and identified the source?
Cheers
PS the front seems relatively well sorted except for the odd ting when going over a surface that is bumpy in sympathy with the natural resonance of the mudguards...
My driver door is rattling a bit which I need to sort out.
At the back my shocks did squeak but that because they are ball jointed not bushes. A bit of WD40 every 6 months sorts it out.
I'd have a look round your arb links if your using them at the back.
You getting a metally noise or a squeak? Squeaks could be the tub rubbing on something. I've used small amounts of foam padding between fibreglass and metal parts where they are not solidly bolted.
I am slowly trying to identify and eliminate some of the clonks I get from the rear of the car. I know that there is nothing touching anything it shouldn't but I still get several noises I shouldn't from the rear somewhere when going over rough surfaces.
Have any of guys had this problem and identified the source?
Cheers
PS the front seems relatively well sorted except for the odd ting when going over a surface that is bumpy in sympathy with the natural resonance of the mudguards...
I get the occasional 'clonk' when something bottoms out. I have put it down using standard shocks and shortened springs but not actually proved that.
I guess taking out a rear spring and moving the suspension up and down with a jack you might locate somthing thing making contact?
Do you get it both sides or just one?
I get the occasional 'clonk' when something bottoms out. I have put it down using standard shocks and shortened springs but not actually proved that.
I guess taking out a rear spring and moving the suspension up and down with a jack you might locate somthing thing making contact?
Do you get it both sides or just one?
...peter
It's both sides. I have had a good look arround and there is nothing obviously fouling. I was very carefull when I assembled the car to make sure the suspension arms had full movement with any problems,
My springs are a bit soft - I wonder sometimes if it is bottoming out rather often - although the ride height looks fine when it is static. Rather than getting new springs I was thinking about trying some grayson spring assistors. They are a rubber "thingy" that fits between the coils on the spring.
I was wondering about the top shock mounts. I re-used the original BMW ones as they looked fine. But as I recall they can be a source of clonks on the E30.
Top shock mounts - I followed Patricks advice and replaced mine for new E30 Cabriolet ones. Apparently they're a bit more resilient.
Also - did you fit the standard e30 drop links on the rear ARB? I know that this could be a source of clunking, as they can foul on the chassis at full travel. Again, following Patricks lead I swapped the exisiting E30 ones for shorter ones - E36 compact, I think? (Not had my coffee this morning - brain still foggy... )
Our car did bottom out with two people, the GAZ shocks are adjustable so just made them 4 or so clicks stiffer and it's been fine since.
The BMW Part number for the e46 vert top mount is 33526754096 - I got it from E30zone if you search there you can confirm. I think some part numbers have changed in time due to upgrades - those top mounts have always been an issue.
It's both sides. I have had a good look arround and there is nothing obviously fouling. I was very carefull when I assembled the car to make sure the suspension arms had full movement without any problems,
Cheers
Robin
That knocks my theory on the head!
I took a quick look on eBay and there are lots of e46 top mounts for sale with a variety of prices from about £10 to £129!!
Eurocarparts have e46 SKF mounts for about £20 a pair. (I wonder who makes the BMW OE?)
What's the theory on which bit clonks? Is it the top of the shock mounting hitting the metal mount?
If the rubber softens or tears then the shock will bash into the top of the tower.
There are aftermarket top mounts but I've only seen those in the states. BMW were using those on warranty replacements. I've got a set on my daily to go with my Koni yellow / eibach suspension setup. They come with a plate that goes on top of the body work to strengthen it - not an issue in the Sportster as the metal looks substantial enough to me
After I uprated the suspension on my old Sport (following a rear spring break) it used to eat these mounts so I will be very interested to see how you get on.
Well I fitted the new top mounts for the rear dampers. Still got the same noise - DOH!
While I was at it I noticed that the large nuts that screw onto the large stud that forms the upper spring plate are very slack on their threads. It's possible that dropping down into a hole and then coming out of it again causes the nut to move slightly in a vertical plane against the studs. So now I am looking for some more nuts to act as lock nuts which will eliminate this problem. Does anyone happen to know what the thread size is (other than ginormous)? It seems to be 25mm but I am not sure that M25 exists....
Thanks Chris. They seem to be 24mm. The next problem is where to get them from. They are
way bigger than anything Namrick supplies and most of the on-line shops that do stock them will only sell a minimum of 100. Hmm
Yep, Wentin is the bee's knees. I got all my stainless M6 dome headed bolts from there. If they won't send you any let me know and I could pop in next Saturday and post them on.
Thanks Chris. They seem to be 24mm. The next problem is where to get them from. They are
way bigger than anything Namrick supplies and most of the on-line shops that do stock them will only sell a minimum of 100. Hmm
Robin
Hi Robin,
I always thought it was odd not to have a lock nut or 'grub' screw to lock the spring seats in position. I think you might have fallen out with Mark on said subject?
I've often wondered if they are likely to rotate and move up due to vibration but if yours are loose after only a relatively few miles then they clearly need locking in place.
Are you sure they are M24? If yes, then there's a few sellers on ebay selling small quantities of M24 nuts for a couple of quid plus postage.
I checked over the w/e and it seems the thread has a 3mm pitch which fits in with the standard (coarse) pitch for M24. I ordered some nuts from Ebay so I will soon know if I am correct!
Well I fitted the lock nuts - so I did get the size right!
While I was at it though I think I may have found the root of the problem. When I removed the springs there were some signs that they have been binding - that is collapsing enough for the coils to touch. Fortunately when I moved the lower spring plates I also made the lower bump stops adjustable. So for a quick fix I can tweak these up a bit so that the bump stops come into play before the springs bind.
Long term I have two options:
1. Get some new springs of a different rate made.
2. Use the new Marlin springs which I believe involves chopping the top part of a standard spring off and welding the remainder to the upper spring plate. I think Jason has these. Jason - any feedback as to how well they work? Any pictures?
They work fine - I've not had any issues with them, and no odd noises that I'd attribute to the springs.
Marlin cut the springs down and then collapse the top most coil only, to form the upper spring seat:
Before:
After:
Spring Seats:
Painted and on the car:
As you can see, they're not welded to the upper spring mounting 'cup'. I cut the old rubber pads that the upper springs sat on (the witches hat one) so that It fit the cup, and I had the pointy middle section on the threaded stub
) 
