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King of Rear Clunks
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Discussion Starter · #1 ·
Well, another project (somewhat) done, once again thanks to some help from our buddy the HACK.

A couple weeks ago I posted when I noticed my RD sways were touching the drive axles someplace. I speculated that slightly longer endlinks than the stockers may solve this problem, so the HACK offered me an extra set of adjustable UUC links to put in.

Putting the car up in the air and taking the bar out, we noticed that the axle rub was occuring at full suspension extension, something that, luckily, doesn't happen very often. Still, I was uncomfortable with this happening so we proceeded with the work. I also noticed that I was, in fact, having the same problem that Ben Chou was having (on UUCs) with another part of the bar hitting part of a subframe mount. In my case, this was happening at full compression, as the bar swung forward, and there was enough contact over time that paint was worn in a sizable spot, and a small part of the mount was also bent. :thumbdwn:

With some rough guessing, we decided to adjust the UUC links to about 5mm longer than stock. We figured this would allow plenty of clearance in both offending areas. After installation, we checked and both areas looked good, however it now seems that at full extension, the bar may slightly tough the exhaust, but since this isn't a moving part, and the exhaust system has a little give, I decided to leave this alone for the time being. I'll also check later for bar/brake cable clearance, as we forgot to do that after putting the car back down.

Looking at the RD vs UUC bars, I think the bends in the UUC bar are greater, meaning possibly more stresses in the bar itself, but because of that it may have less potential of contacting all the other bits and pieces down in that part of the car. However any contact that either bar would make would be at the extreme ends of rear suspension travel, so I don't think its an earth-shattering big deal. That said, however, I feel better with the UUC endlinks (the ones RD used to ship standard probably would have worked equally well, but they are no longer standard fare).

Of course this does nothing for the blown rear shock mounts (at 11k mi) which still sound like rocks in a box. Since it doesn't seem like leaving them in for a little while isn't gonna kill anything, I'll leave its replacement for later. I could always have it replaced under warranty but would they put M3/Cic mounts (which wagons should get standard because of weight) + Z3 reinforcement plates in at warranty's cost? Probably not. For $50 in parts I think this will just be a future weekend project.
 

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My suggestion: Have them replace the shock mounts under warranty. This way, you'll a) get free spares, and b) they'll fix anything else that might potentially have gone wrong with them, too.
 

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King of Rear Clunks
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Discussion Starter · #3 ·
Yeah, but I just don't want some dealer monkey tearing up the car (and its tough to get to the shock mounts in a wagon) only for me to have to go in there and put better parts in myself.
 

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Hey Kaz,

Damn what an experience to go through. :( Now that you mentioned this, I am more eager to find out that funny clunk from the front. I don't, however, any from the rear, despite the enlarged Eisenmann connecting pipes. I am sure you saw that when we worked on the rear sway.

In any case, James have the UUC sways and he, too, have the Eisenmann muffler and connecting pipes (to replace resonator). But guess what? According to the shop, the connecting pipes get in the way of the UUC sways. Maybe like you said, the UUCs bend more. Hence, what the shop did was use back the stock connecting pipes without the resonator.

Btw, you coming up for AutoX on the 9th? :)
 

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King of Rear Clunks
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Discussion Starter · #5 ·
VinceTopasBlau3 said:
Hey Kaz,

Damn what an experience to go through. :( Now that you mentioned this, I am more eager to find out that funny clunk from the front. I don't, however, any from the rear, despite the enlarged Eisenmann connecting pipes. I am sure you saw that when we worked on the rear sway.
Your front noise HAS to do something with the front endlinks. Maybe its at the top, or maybe its bent from one of your auto-x sessions? :dunno:

As for the sways and the exhaust, yes, I recall yours having plenty of room, but I can easily see how some ofher combination of pipes and sways will make something hit somewhere.

As for the next auto-x, can I just come watch this 1st time? :D
 

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Front endlinks aye? :confused: Hmm....Will take a note of that. Certainly worth thinking about.

Do drop by at the AutoX. :) Remind me about passing you the mesh and the CCA stickers too. And a copy of Euro catalog?

Kaz said:


Your front noise HAS to do something with the front endlinks. Maybe its at the top, or maybe its bent from one of your auto-x sessions? :dunno:

As for the sways and the exhaust, yes, I recall yours having plenty of room, but I can easily see how some ofher combination of pipes and sways will make something hit somewhere.

As for the next auto-x, can I just come watch this 1st time? :D
 

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Rest in peace, Coach
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Kaz said:
Yeah, but I just don't want some dealer monkey tearing up the car (and its tough to get to the shock mounts in a wagon) only for me to have to go in there and put better parts in myself.
Yeah. The HACK monkey is much better than dealership monkeys.

Kaz, let me know when you got the shock mount parts...And if you need a hand with them. They're fairly straight forward but on the wagon can be a bit tricky.
 

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Rest in peace, Coach
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Kaz said:


Your front noise HAS to do something with the front endlinks. Maybe its at the top, or maybe its bent from one of your auto-x sessions? :dunno:

As for the sways and the exhaust, yes, I recall yours having plenty of room, but I can easily see how some ofher combination of pipes and sways will make something hit somewhere.

As for the next auto-x, can I just come watch this 1st time? :D
The front endlinks may have simply come loose. When I installed Raffi's sways, he came back the next week complaining of a clunk. We can hear it as I sat on the hood and rocked the car up and down (if the car's a rockin', don't come a knockin' as they say). It turns out the front PASSENGER sway link isn't 100% secure with the bar and was causing a light CLUNK as the suspension was compressed.
 

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Rest in peace, Coach
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VinceTopasBlau3 said:
Front endlinks aye? :confused: Hmm....Will take a note of that. Certainly worth thinking about.

Do drop by at the AutoX. :) Remind me about passing you the mesh and the CCA stickers too. And a copy of Euro catalog?

P.S.: Where's the sign-up sheet for the Auto-X?
 

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King of Rear Clunks
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Discussion Starter · #10 ·
Well, all is not totally rosy. The 'Ben Chou problem' has returned. There was some lateral movement of the bar in the last day (it actually seems better centered now), and now the bend in the bar that goes over the exhaust has shifted over enough so that its now closer to the rear diff mount (that's what it is; not a subframe mount). It really doesn't look like there's anything that can be done other than grinding a notch in the protruding lip of that mount.
 

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The HACK said:


Yeah. The HACK monkey is much better than dealership monkeys.

I can vouch for that. :p Dan is the man when it comes to fixing up/modifying cars!

There is no sign-up sheet for the autocross. You simply show up, it is first-come, first-served. They usually do sell out, so if anyone plans on participating, you should be there by 7 a.m. to ensure a spot. I think the event is limited to 60 people and it fills up very fast.

Later,
 

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The HACK said:


The front endlinks may have simply come loose. When I installed Raffi's sways, he came back the next week complaining of a clunk.
...
It turns out the front PASSENGER sway link isn't 100% secure with the bar and was causing a light CLUNK as the suspension was compressed.
Turned out to be a Raffi job, not a HACK job! :p
 

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After installing a brand new bar last week, things are much better but not perfect. It is much quiter now, and there is not much clunking except from the left side. Which I think, the bar is hitting the exhaust. I will have the left side adjusted up and the right side is a little close to the lower control are so I migh have it adjusted up. How much rooms do you guys have between the lower control arm and a UUC bar? Anyone done this? Is it ok to do? They would end up being slightly uneven in length.

The way I hear the sound is on the highway with those small divets put in to let you know the lane boundaries. If I ride on that with my left tires there is a clunking sound. If I do the same thing with my right, it is quite. Oh well.
 

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Rest in peace, Coach
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Ben Chou said:
After installing a brand new bar last week, things are much better but not perfect. It is much quiter now, and there is not much clunking except from the left side. Which I think, the bar is hitting the exhaust. I will have the left side adjusted up and the right side is a little close to the lower control are so I migh have it adjusted up. How much rooms do you guys have between the lower control arm and a UUC bar? Anyone done this? Is it ok to do? They would end up being slightly uneven in length.

The way I hear the sound is on the highway with those small divets put in to let you know the lane boundaries. If I ride on that with my left tires there is a clunking sound. If I do the same thing with my right, it is quite. Oh well.
You may want to check something else. What I have found so far with UUC swaybars, is that if EVERYTHING is properly tightened down, it's whispery quiet. Its usually SOMETHING ELSE that's causing the clunk or rattles. On my car it was a loose shock mount bolt. On Kaz's car it's definately a torn shockmount. On Raffi's car it was a loose lower control arm bushing. If you are certain all your nuts and bolts are tightened, then it should not be causing any clunks AT ALL.

You may want to check your shock mounts as well, it sounds like your shock mount may be torn from your description. As far as my bars are concerned, I have the 3 hole design in the back and my links are adjusted to show only 2 threads, and theres a lot of clearance to both the drive shaft and the lower control arm.

Good luck.
 

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The HACK said:


You may want to check something else. What I have found so far with UUC swaybars, is that if EVERYTHING is properly tightened down, it's whispery quiet. Its usually SOMETHING ELSE that's causing the clunk or rattles. On my car it was a loose shock mount bolt. On Kaz's car it's definately a torn shockmount. On Raffi's car it was a loose lower control arm bushing. If you are certain all your nuts and bolts are tightened, then it should not be causing any clunks AT ALL.

You may want to check your shock mounts as well, it sounds like your shock mount may be torn from your description. As far as my bars are concerned, I have the 3 hole design in the back and my links are adjusted to show only 2 threads, and theres a lot of clearance to both the drive shaft and the lower control arm.

Good luck.
Hack,

You know the funny thing is. How come these clunks don't occur until after the sways are installed. I find that kind of weird, since if the shock mount or lower control bushing was bad then it should make noise regardless of what type of bar is on there. What do you think?

How can I check on the shock mounts?
 

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Rest in peace, Coach
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Ben Chou said:


Hack,

You know the funny thing is. How come these clunks don't occur until after the sways are installed. I find that kind of weird, since if the shock mount or lower control bushing was bad then it should make noise regardless of what type of bar is on there. What do you think?

How can I check on the shock mounts?
My suspicion is that the swaybars put more stress on the shock towers in the back. My wife's car does not have any aftermarket suspension work and the shock mount is as quiet as day 1. Kaz's car has 10,000 miles on it and the shock mount is already shot. All the cars I know of with shock mount problems have either swaybars or spring kits.

UUC recommends the reinforced shock mount with the Z3 reinforcement plate for cars with any aftermarket suspension work. My was loose since it wasn't tightened in the first place when I installed the reinforced shock mount. It's actually quite easy to swap it out, if you have access to a floor jack and a set of jack stands. The shock mounts sit underneath the rear trunk trim panels, you'll need to remove the trim panel, and you should see a gray plastic thingy covering the shock mount. Remove the plastic thingy, remove the 3 bolts holding the mount down, and the weight of the suspension should pull the mount free. Just install the new shock mounts, use a floor jack to jack the suspension parts back up, tighten with new self locking nuts and you're done. All the parts come out to be about $50 from Circle BMW.
 

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The HACK said:


My suspicion is that the swaybars put more stress on the shock towers in the back. My wife's car does not have any aftermarket suspension work and the shock mount is as quiet as day 1. Kaz's car has 10,000 miles on it and the shock mount is already shot. All the cars I know of with shock mount problems have either swaybars or spring kits.

UUC recommends the reinforced shock mount with the Z3 reinforcement plate for cars with any aftermarket suspension work. My was loose since it wasn't tightened in the first place when I installed the reinforced shock mount. It's actually quite easy to swap it out, if you have access to a floor jack and a set of jack stands. The shock mounts sit underneath the rear trunk trim panels, you'll need to remove the trim panel, and you should see a gray plastic thingy covering the shock mount. Remove the plastic thingy, remove the 3 bolts holding the mount down, and the weight of the suspension should pull the mount free. Just install the new shock mounts, use a floor jack to jack the suspension parts back up, tighten with new self locking nuts and you're done. All the parts come out to be about $50 from Circle BMW.
\

I can just check and retighten if neccessary right without replacing, right? I will have to look into it.

Thanks
 

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Rest in peace, Coach
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Ben Chou said:
\

I can just check and retighten if neccessary right without replacing, right? I will have to look into it.

Thanks
Sure you can. Make sure the bolt for the shock is tightened to 18 ft-lbs and the bolt for the mount is tightenend to 24 ft-lbs.

But if it was quiet before and it's rattling/clunking now, it means the center bushing is worn...That means replacement. If your car is still under warranty, try and sneak it by the service department and see if they'll replace it fer free.
 

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King of Rear Clunks
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Discussion Starter · #20 ·
My bar now has the potential of (and actually does hit 1) hitting 2 places: The diff mount under compression and the exhaust under extension.

Looking at the way the stock vs RD vs UUC bars are bent, I think the RD bars were designed without the movement of the suspension in mind. :p There are just too few bends at too small angles to miss everything under all conditions.

Knowing all this now, I would likely no longer recommend RD sways, although their performance is otherwise great.
 
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