Rear end sideways bump

[michael1972]

So what suspension parts might cause this? 1987 325e...replaced shocks and struts with KYB's and put in H&R race springs. The problem is this...when I hit small bumps like sewer covers and stuff with the rear it seems to want to bounce sideways like it shudders to one side. Also seems rather bouncy from the rear. I know I should of used a little better shock but was trying to be budget minded.

[Boris3]

First reaction is KYB is nowhere near enough shock for H&R race springs on an e30. Also a risk of blowing the shocks with the ride height drop and the race spring rate. Bilstein sports or koni's is a much better combination with the race.

[michael1972]

Yea I figured. I went the cheaper route on those. The fronts feel pretty good tho.

[michael1972]

Another question. I am looking at shocks on ECS site and they show a rear powerflex bump stop. I didn't have rear bump stops on the stockers so I did not install rear bumpstops on the new stuff. WTF! Do I need these?

http://www.ecstuning.com/BMW-E30-325e-M20_2.7L/Suspension/Shocks/ES2650407/

[patsbimmer1]

Yes you do.  It'll prevent your shocks from bottoming out and causing damage to the shock, mounts and body.

[michael1972]

So why were there none on the rear?

[michael1972]

Ok so here is where the bump stop issue is at. I called bavauto they say there is not a bump stop on the rear shocks on a e30. Looks like I need to get some new rear shocks. Anybody have any decent used ones laying around?

[Earl]

I'm going to be killed for this but 97 mustang gt shocks are stiffer than the KYB's and shorter than the Bilstein Sports. They're a good budget minded shock if you don't have the money for the Bilsteins. They're around $60 for a pair at the parts store and are a direct fit.

[michael1972]

I'm going to be killed for this but 97 mustang gt shocks are stiffer than the KYB's and shorter than the Bilstein Sports. They're a good budget minded shock if you don't have the money for the Bilsteins. They're around $60 for a pair at the parts store and are a direct fit.

Thanks Earl. I think I will throw some of those in and see how it rides. Am I looking for just stock replacement mustang gt shock?

[Rowleym]

I'm going to be killed for this but 97 mustang gt shocks are stiffer than the KYB's and shorter than the Bilstein Sports. They're a good budget minded shock if you don't have the money for the Bilsteins. They're around $60 for a pair at the parts store and are a direct fit.

What brand replacement would you get? You can get kyb's with adjustable dampening. NOt sure how much cost difference it is at that point though

[Boris3]

Take a look at real oem or bmwfans.info and you can find the parts schematics for your car. Useful sites.

Bilsteins have an internal bump stop so you wouldn't need to add one.

BAP was wrong about the e30. if you are using a shock w/o an internal bump stop you would need one on the fronts and rears.

Part number for rear: 33-52-1-125-078

What shocks were on on your car?

[michael1972]

No idea what shocks. Looked like oe BMW had a BMW sticker on them

[michael1972]

And how would I know if they did or did not have the internal stop? If they didn't why would they not come with a external bump stop?

[michael1972]

Well I called ECS who I got the KYB's from and the rears I have do have internal bump stops. Now my question for Earl would be, do the mustang shocks have the internal stops or will I need external stops to run them?

[michael1972]

Earl would these be what I would want to try?

http://m.advanceautoparts.com/mt/shop.advanceautoparts.com/p/monroe-sensa-trac-passenger-car-shock-absorber-5968/19710464-P?searchTerm=rear+shock

[Boris3]

A couple other things to think about. Did you replace the rear shock mounts? How did the rear towers look when you did the replacements (no tears in the metal)?

Did you put everything together correctly (esp the orientation of the cupped washers)?

http://www.turnermotorsport.com/pages/Instructions/rear_shock_assembly.pdf

[michael1972]

Well now you have me second guessing. But I took the stuff off the one and put it on the other same way.

[michael1972]

Was I supposed to reuse any of these parts? The KYB shock had a sleeve over the metal rod.

[Boris3]

That round rubber disk is your bump stop. The plastic sleeve will keep dirt and crap out of the shock and in the top of the sleeve is a metal cup washer open side down. See the Turner picture: which omits the bump stop and the sleeve.

Now all that said if the rear end wasn't dancing around when you got it the issue is the shock and spring combination.

[michael1972]

Ok so I got to the bottom of the problem thanks to Boris. Here is what happened total installer error on my part. See pic number one. There was a small metal sleeve spacer on the original shocks see pic 2 that I put on the new shocks bad idea as you can see. Also I took the bottom washer off that came on the kyb shock see pic 3 and put it on the top. Result no bottom washer and the top washer stuck on top of the small spacer instead of on the mount. Took the spacer out and put the washer on the bottom and other washer on the top see last pic. Went for a long bumpy road drive and it is way better now. Thanks for the help guys.

[michael1972]

Oh yea and my gaskets are totally rotted away. I am ordering some of the rienforcement plates asap.

[Earl]

Just stock replacements. I am not sure of they have internal stops. At your height you would never bottom them out anyways =) They are Gabriel Ultra brand

[michael1972]

That round rubber disk is your bump stop. The plastic sleeve will keep dirt and crap out of the shock and in the top of the sleeve is a metal cup washer open side down. See the Turner picture: which omits the bump stop and the sleeve.

Now all that said if the rear end wasn't dancing around when you got it the issue is the shock and spring combination.

Ok so now I think I still have it wrong. Am I supposed to reuse the washer thats in the sleeve on the bottom side of the mount or since the kyb has a metal sleeve on the shock do I not use a washer at all on the bottom. Because what I think I have going on now is 2 top washers. One on bottom and one on top.

[Boris3]

The PO on my 318is had kybs and reused the bottom stock cup washer under the mount (open side down like in the Turner diagram). The cup washers are the same top and bottom. The orientation on the install is the difference. See the picture.

When I put in the bilstein and h&r sports I followed the Turner diagram on assembly plus bought a set of stock rear plastic boots. Bilsteins don't have the Kyb metal sleeve and with a winter DD figured it would be good to keep the crap out of the shock.

Still think your bouncing has more to do with the RSM and/or the pairing of shocks and springs. Might help to have someone take a ride with you to figure out what's going on.

[michael1972]

The ride is way better now. I was just thinking I still had the washers wrong. I don't want to leave it like that if the ride is good but still have it installed wrong. If that makes sense. If the top and bottom washers are the same then I do have them installed correctly. The old washer thats in the plastic boot looks to be bigger tho.

[Boris3]

Good to that the ride is better.

As for washers being different sizes could be. As old as these cars are and the 'creativity' of POs and assorted hack mechanics you'd be surprised at what you find and don't find as you dig into the car.