Surprise at Rear Shock Mount with Questions

[sg000]

Background: 98 E36 M3, lowered, KYB rear shocks (came with the car)
Pulled back the covers to see if I needed to put in the reinforcement plates on the rear shock mounts and found two things.

First was 2 nuts. Perhaps this is where my unknown rattle is from.
2017-04-20 17.54.59_sm.jpg
The question: Is it possible those are the old nuts from the prior shocks? I can't see what else they may have come from under there.

The second was all the rubber around it that appears to be from the boot under the washer.
2017-04-20 17.54.18_sm.jpg
The question: How bad is this. Is this the shock or a separate piece that needs to replacing? How totally bad is this? Honestly, have no idea how long it might have been like this. I can move the peg slightly.
Followup: The rattle, occurred on small bumps in the rear during low speed <35mph most notably. Could the lack of this boot have been my rattle?

Thanks for the help.

[TostitoBandito]

Looks pretty beat. Should replace them, especially if there's play as you described. Don't think the nuts there are related to any damage. Someone probably just left them there by accident.

It's pretty straightforward to replace. Here's an article:

http://www.pelicanparts.com/BMW/tech...ock-Mounts.htm

Basically you just jack up the car, undo the bottom of the strut (while supporting the hub/rotor with something), then take out those two nuts on the shock mount. Now you have a shock with the mount attached. You can remove the mount from the shock via the retaining nut dead center on top.

For replacements, I strongly suggest something that is heavier duty and serves to reinforce the shock tower. I think the Ground Control mounts are very nice:

http://www.ground-control-store.com/...hp/II=7/CA=248

They have a built in reinforcement plate with the bolts welded on which drops in from the top and sandwiches the shock tower between the rest of the shock mount underneath. Saves you from having to get the reinforcement welded in, which should be mandatory if using OEM mounts. Added benefit is you do the nuts from underneath so you don't need to tear out you trunk carpet to swap out shocks or do work which requires the shocks to be removed.

[LockDots]

That rubber is from the shock mounts, not the shock itself. Cheap and easy to replace.

What Tostito said about the reinforcement plates is mostly true. I say mostly because reinforcements do not need to be welded in. Replacement shock towers do, but yours look fine unless your pictures don't show any cracks or rust forming around the holes where the shock mount bolts pass through (I just went through this myself).

The reinforcements are essentially Z3 plates that get sandwiched between the top of the shock tower (what you see in your photos) and the shock mounting nuts (also seen in your photo).

These are the reinforcements (good): https://www.ecstuning.com/b-ecs-part...002478ecs01kt/

Since you'll be replacing both shock mounts (recommended since they're cheap enough) which runs you about $40, plus the plates which are about $30 for a total of about $70, you might as well do the kit (better): https://www.ecstuning.com/b-assemble...521092362~kit/

The kit comes with both shock mounts (Lemforder is an OE brand and essentially the same as buying one with a BMW logo on it), two reinforcement plates, two gaskets (go between shock mount and shock tower underneath), and two sets of nuts for $66 and ships for free..... you'd think I'm an ECS sponsor at this point.

I'm leaving out a "best" because that's subjective. What I've listed is equivalent to being OE parts and quality with reinforcement. You can get more heavy duty shock mounts like the ones Tostito listed and ots of company make similar ones but they're typically harder and harsher on the shock towers than rubber. This may then require you to reinforce the shock tower further (Ireland Engineering rear strut bar comes to mind).

[kevinwilly]

Yeah, those big washers should be sitting down on the large part of the rubber bushing. Your mounts are totally toast. The center section has ripped out and is riding high now, which is where all the rubber is coming from.


New RSM's and reinforcement plates and you'll be good to go.

[sg000]

Thanks for the pointers and links. A little youtubing and got a better picture of what I'm dealing with. Didn't realize the replacement of the mount was so easy, that pushing the shock down didn't look difficult at all. Will order them up and put them in. As Lockdots said, whether to go heavy duty or OEM equiv is the big question now. The ride is already harsh as heck with the stiffer lower springs, I don't want to make it worse with a really stiff mount, but I can understand that the extra stress with the stiffer springs makes going with heavy duty a viable option.

--Scott

[A ///Monster]

Rear shock mounts fail. It's just something that you can expect. I would recommend the rogue engineering bottom mount RSM. It has a studded top plate for reinforcement and allows you to remove the shock from the wheel well, saving you time and the hassle of tearing apart your interior. Going with a bottom mount RSM makes shock mount replacement or even shock mount inspection a 10 minute job. Also, if you buy the Rogue Engineering bottom mount RSMs, the replacement rubber bushings for the mount are like $15 bucks. So it'll be cheap and easy to maintain your RSM's going forward. The Turner bushings also are a direct replacement for these Rogue RSM's, I just used them in mine.

http://www.bimmerworld.com/Rogue-Eng...0-E36-E46.html

[TostitoBandito]

You're not going to get much extra noise/harshness unless you buy solid/racing shock mounts. Obviously don't do that.

None of the aftermarket mounts with harder rubber or poly/urethane bushings should be noticeably different in feel from OEM, but should be more durable. Rogue, Ground Control, or various OEM+ options from ECS or Bimmerworld or wherever. And, I can't stress this enough, it's worth a few extra bucks to get one of the options which puts the nuts underneath the car instead of in the trunk. Removing carpeting and speakers to get at the shock mounts in the trunk is not my idea of fun.

[RRSperry]

Just buy the Rogue engineering mounts and call it a day. Your life will be better.

[RightYouAreKen]

I second (or fourth, or fifth?) the Rogue RSMs. They have been a godsend when adjusting my Koni adjustable rear shocks that need to be removed to adjust. I can have both shocks out of the car in about 15 minutes from start to finish now since I don't need to open the trunk and pull back the carpet. Just lift the rear of the car, remove the wheels (even this is probably optional), zip off the lower shock bolts, then remove the two nuts from inside the wheel well.