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Matt

E30 bouncy rear

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Hi guys,

Need some advice about my suspension. When I drive over bumps the rear of my car is bouncing and wallowing around heaps. It feels like there's hardly any damping so the rear springs just keep bouncing up and down. If I push down on the back when the car is parked it seems to bounce around more than it should as well.

The car has brand new bilstein sport shocks and brand new H&R sport springs (Plus powerflex bushes, new shock mounts, and factory rear swaybar). This is a pretty common setup so I don't know why I would be having this problem.

IS it likely that the shocks are sitting to close to the limit of their travel so aren't able to provide enough damping? If this is the case, what can I do about it? Any other possibilities? I would hope a brand new pair of shocks haven't gone bad.

PS. It seems to get a lot worse when I've got people sitting in the back of the car. I'm not having any problems with the front end of the car, that feels perfect!

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Just went and checked that actually. Answer - Nope! Both sides the rubber bush has blown out of the bracket, so my shocks are basically hanging free at the top.

I guess it happened yesterday when I hit a pothole, only really noticed it from then, but it also happened to be my first big drive with the new suspension.

Can they be pressed back in and reused or do I need to get brand new ones (again). Kind of annoying because they're brand new shock mounts too. I even got the e46 ones because they're meant to be stronger <_<

Edit: Pic for reference...

Posted Image

Edited by Matt

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Just went and checked that actually. Answer - Nope! Both sides the rubber bush has blown out of the bracket, so my shocks are basically hanging free at the top.

I guess it happened yesterday when I hit a pothole, only really noticed it from then, but it also happened to be my first big drive with the new suspension.

Can they be pressed back in and reused or do I need to get brand new ones (again). Kind of annoying because they're brand new shock mounts too. I even got the e46 ones because they're meant to be stronger <_<

Edit: Pic for reference...

Posted Image

If those top mounts are genuine BMW then there is a two year warranty - check it out with the company you bought them from.

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They are OEM parts but I got them from Pelican parts. While I'm sure they're still covered by warranty it is probably more hassle than it's worth to go through it with them.

I'm going to try and press the bushes back in tonight but if I'm not successful I'll just get new ones from BMW tomorrow. At least it isn't a hugely expensive part but I'm pretty disappointed they only lasted a few weeks.

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i would think the shocks are the wrong ones for your setup. there are two main types of Bilsteins for E30s, are you using Bilstein Sports or Bilstein HD (Heavy duty) shocks with your H&R springs? The Billysports are a shock designed only for lowered setups, and the HDs are for standard, and neither should not be used in the place of the other. If they are sports then im stumped, but i have seen this happen on E30s stateside when they used HD in place of sports on lowered setups thinking they were essentially the same thing. Was ebaich springs iirc but all the same as far as this is concerned. has something to do with the valving on them

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^ Andy, are sports and HD lengths different then? i.e sports are already shortened to match the lowered height?

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They are definitely bilstein sports. It happened while I was driving on metal roads and hit a deep pothole which I didn't see in time. I guess this setup just isn't designed for those kind of roads haha. Oh well, lesson learnt.

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^ Andy, are sports and HD lengths different then? i.e sports are already shortened to match the lowered height?

They are definitely bilstein sports. It happened while I was driving on metal roads and hit a deep pothole which I didn't see in time. I guess this setup just isn't designed for those kind of roads haha. Oh well, lesson learnt.

both correct

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When I got my bilstein sports, I still shortened them 50 mm and my old standard top mounts have held up fine, How low is your car?

Iirc the sports are only 20mm shorter than standard , so they may need to be shortened more for your setup.

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As Ron said...your missing the disc washer that acts as a thrust pad under the shock mount on the shock shaft.

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Thanks guys. Is that picture for E30 or E36, Ron?

Looking at this pic below from realoem I am missing 4, 5 and 6. I will order them all today.

Posted Image

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The picture I posted is for an E36 because they look like E36 mounts not E30 mounts but Glen would be a better judge on that, my guess is the OE E30 mounts have been superceded with the E36 mount.

If you are going to re-do them use the HD/ M3 mounts available on trademe via Milland

Which ever you do make sure you have the correct bits to go with the mount you will use.

They are actually e46 mounts which are supposed to be the best of the oem ones from what I've heard. I also heard they are a direct swap into the E30, so I assume you can use the original plate underneath. Although searching realoem the plate seems to be specific to e30, e36ti, and z3. May need Glenn to chip in here with what I actually need though... Same for what goes underneath the plate (I currently have nothing).

Cheers for the help so far Ron.

Edit: Woops, didn't see your post Glenn. Cheers for the input. Do I get those other 2 E30 parts as well??

Edited by Matt

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Give me a call. I'm real busy and typing it all takes to long 2722546

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