Bouncy H&Rs or bouncy Bilstein sports? Both?

EuroShark · Post by **EuroShark** » Feb 16, 2007 9:57 PM

Hey everyone

I just got my Bilstein sports and H&Rs installed this week. I like how everything feels, except I get the feeling that the rear end is very bouncy... At low speed like under 30, and around and over 60, depending on the roads, the REAR can get a bit bouncy and it just doesn't feel quite like I would expect.

Granted, it has been cold, like 17 - 30 degrees this week. Today it was in the mid 40s and it felt lots better, so thats one possible explanation I suppose. Also, I know my tires are cupped a bit, the rears (which were on the fronts) had a considerable (maybe 1/32 or a bit more) ridge on the inside edge, and they were only rotated about 100 miles ago. I can feel this, and I wonder if possibly it is adding to the bouncing issue.

I set the spring perches on the second from the top, but I have 6 spots for the perches... I don't know how common that is, but I have seen sets for sale that only had 3 or 4. I bought these shocks from a guy who removed them from an E28 M5. He said they had about 10k miles on them, and by all indications, I believe him... They appeared brand new and very clean. The ride height is virtually the same from RF to LF and from RR to LR, so I don't think either shock is bad.

My 6 series with the same wheels and tires didn't do this. It had Alpina suspension consisting of Alpina springs and Bilstein shocks. With the setup I have is a little bounciness normal? Thanks for the help!

Mless5 · Post by **Mless5** » Feb 16, 2007 10:01 PM

If I recall correctly it is a common problem and it has to do with billy sport valving.

BRRV · Post by **BRRV** » Feb 17, 2007 12:07 AM

It also happens with HD's. At least it does on mine, since I got them installed new in 2000. I'm on the top perch, IIRC. It's disconcerting but I've learned to live with it. It's more pronounced now than when they were new, but it's always been there. I'm wondering if general wear and/or mechanical issues at the rear suspension could exacerbate this - my rear suspension hasn't been touched and it's probably due.

lkfoster · Post by **lkfoster** » Feb 17, 2007 12:15 AM

HDs and Sports have the same valving, just different lengths or spring perch locations.

Bilstein will rebuild and revalve them to your specification for $65 each. I'm planning on doing this when I get back. I just need to figure out how much stiffer I want to go on the rebound setting. I'm thinking 25% stiffer, but am open to suggestions. Too much bebound and the rear end will compress on rough surfaces.

EuroShark · Post by **EuroShark** » Feb 17, 2007 1:14 AM

It almost seems like they need to be softer, but maybe I am thinking backwards.

If they need to be stiffer in the rebound, I'm thinking it's not by much.

Steve Haygood · Post by **Steve Haygood** » Feb 17, 2007 10:06 AM

springs control the rate of compression and rebound, in other words they moderate spring movement, if that makes sense. It's the Bilsteins. In it's worst form, with shocks removed, the car would bounce top to bottom every time you hit any bump and never stop ( in theory)

BRRV · Post by **BRRV** » Feb 17, 2007 11:44 AM

Steve, did you mean to say that "shocks control the rate of compression and rebound"? I would agree it's the Bilsteins. Problem is that this shock is very very good on the highway with factory springs; regrettably they exhibit this weird bounciness, along with very poor compliance characteristics at low speeds and/or on uneven or poorly maintained pavement. I'm considering replacing my front HD shocks with adjustable Koni Yellows while retaining original springs all around. I was going to have the rear Bilstein HD's rebuilt, but I'd like to consider an alternative, so long as I could get better low speed characteristics as well as lose the bounciness, which I swear lifts me off the seat ocasionally. Any recommendations, Steve or anyone? Boge TurboGas have been highly recommended by some, but I'm unsure they will be as good at high speed on the highway or appropriate for limited track work or autocross (these would be a distant secondary consideration).

KillerPM · Post by **KillerPM** » Feb 17, 2007 12:00 PM

Well this explains the bumpiness I get on my new Bilsteins.

I thought something was bad on them. Luckily I mostly drive highway Anyway.

GregATL · Post by **GregATL** » Feb 17, 2007 12:57 PM

I am running Boge turbogas on my car with Eibach springs.

I am not conscious of any irregular bounciness in my cars ride. They could in my opinion use slightly less stiction over small sharp bumps but are valved for compression and rebound nicely. Bear in mind there is room for improvement if minor.

As far as track/autocross worthiness they are fine. Certainly not coilovers but good nontheless.

I too am very interested in adjustable Konis but was under the impression they were NLA. If I am wrong about that please let me know.

BRRV · Post by **BRRV** » Feb 17, 2007 1:57 PM

Koni currently lists them as available on their website, and Tire Rack has them available too, albeit on a delivery status of 3-4 weeks. There are no rear Koni shocks available for our cars. I have not placed an order yet, though.

Steve Haygood · Post by **Steve Haygood** » Feb 17, 2007 2:01 PM

Thanks, that was before my coffee this AM, exactly, shocks do control etc

BRRV wrote:Steve, did you mean to say that "shocks control the rate of compression and rebound"? I would agree it's the Bilsteins. Problem is that this shock is very very good on the highway with factory springs; regrettably they exhibit this weird bounciness, along with very poor compliance characteristics at low speeds and/or on uneven or poorly maintained pavement. I'm considering replacing my front HD shocks with adjustable Koni Yellows while retaining original springs all around. I was going to have the rear Bilstein HD's rebuilt, but I'd like to consider an alternative, so long as I could get better low speed characteristics as well as lose the bounciness, which I swear lifts me off the seat ocasionally. Any recommendations, Steve or anyone? Boge TurboGas have been highly recommended by some, but I'm unsure they will be as good at high speed on the highway or appropriate for limited track work or autocross (these would be a distant secondary consideration).

tschultz · Post by **tschultz** » Jul 23, 2011 9:14 PM

Not to thread ressurect, but any dieas why this might happen?

My car seems to be a bit bouncy in the rear. Any ideas? I have Bilstein sports with Eibach Springs

Kyle in NO · Post by **Kyle in NO** » Jul 23, 2011 9:22 PM

My Billie Sports with Eibach springs feels great out back, but you cannot put the spring perch on the lowest setting. It relaxes the spring too much and allows it to bounce. Raise the perch to somewhere in the middle and it should feel nice and planted.

Bimmerguy2002 · Post by **Bimmerguy2002** » Jul 23, 2011 10:55 PM

its bouncy because the rear shock valving sucks on the bilsteins. After i had bilstein revalve them with a stiff rebound the problem went away, although i have way stiffer springs, its no different. way stiffer than i thought Anyway.

JamusMcFamus · Post by **JamusMcFamus** » Jul 23, 2011 11:36 PM

sidenote - what ever happened to steve haygood after that whole debacle a while back?

m535is · Post by **m535is** » Jul 24, 2011 6:00 AM

Gentlemen,
If you use the search function at the top, this subject as been discussed to death. It has actually been a topic of discussion since at least the late '90s. Like previously suggested the only way to fix the problem is to spend the $65 to get them revalved. While you are at it, it might not be a bad idea to have the fronts softened a little, but that is just my personal opinion. I have run Koni sport yellows on my car for the last 10 years and to be honest I run them at almost full stiff all the way around. I did do a test at one point with the E34 Koni Sport Yellows in the rear and to be honest I could not adjust the ride height to my liking. Also you have a huge range of adjustment and I will tell you, running them on full stiff is like driving a drift car.

Hope this helps,
Rob

mcm97 · Post by **mcm97** » Jul 24, 2011 9:43 AM

Running H&R's and Billy Sports and my issue isnt bounce its that the car will "drift" right or left when you're driving in a straight line. Let me explain better - ok, you're going down the road and all of a sudden the car will jerk itself left of right. Not a violent jerking, just a enough to let you know something isnt right. Has this happened to anyone else?

shocka · Post by **shocka** » Jul 24, 2011 9:52 AM

Yes, ive had this. But most likely has nothing to do with shocks/springs, you need some front end work. UCA's etc..

Frybrid 524td · Post by **Frybrid 524td** » Jul 24, 2011 10:16 AM

mcm97 wrote:Running H&R's and Billy Sports and my issue isnt bounce its that the car will "drift" right or left when you're driving in a straight line. Let me explain better - ok, you're going down the road and all of a sudden the car will jerk itself left of right. Not a violent jerking, just a enough to let you know something isnt right. Has this happened to anyone else?

That sounds like an alignment issue or something not being right with your steering linkage and/or control arms.

mcm97 · Post by **mcm97** » Jul 24, 2011 11:27 AM

would worn trailing arm bushings make the car do something like that?

tschultz · Post by **tschultz** » Jul 24, 2011 12:29 PM

Thanks for the info guys. I don't care enough to have them revalved right away, but i'll keep that in mind if it gets worse.

Kyle in NO wrote:My Billie Sports with Eibach springs feels great out back, but you cannot put the spring perch on the lowest setting. It relaxes the spring too much and allows it to bounce. Raise the perch to somewhere in the middle and it should feel nice and planted.

Mine is actually set second from the top just like the OP.

Post by **Jeremy** » Jul 24, 2011 1:58 PM

mcm97 wrote:Running H&R's and Billy Sports and my issue isnt bounce its that the car will "drift" right or left when you're driving in a straight line. Let me explain better - ok, you're going down the road and all of a sudden the car will jerk itself left of right. Not a violent jerking, just a enough to let you know something isnt right. Has this happened to anyone else?

Stop threadjacking. It's most likely the subframe bushings, nothing at all to do with springs or shocks.

1st 5er · Post by **1st 5er** » Jul 24, 2011 2:42 PM

I get some of that with my HDs and Eibachs.

mcm97 · Post by **mcm97** » Jul 24, 2011 3:44 PM

Jeremy wrote:
mcm97 wrote:Running H&R's and Billy Sports and my issue isnt bounce its that the car will "drift" right or left when you're driving in a straight line. Let me explain better - ok, you're going down the road and all of a sudden the car will jerk itself left of right. Not a violent jerking, just a enough to let you know something isnt right. Has this happened to anyone else?
Stop threadjacking. It's most likely the subframe bushings, nothing at all to do with springs or shocks.

Sorry, I thought we were having a convo about H&R springs and Billy shocks.

Subframe bushings not U/LCA? Is there a quick check for that?

rodpaine · Post by **rodpaine** » Jul 24, 2011 3:51 PM

1st 5er wrote:I get some of that with my HDs and Eibachs.

I was struggling with rear end bounce, back in 2004-2007 when I was trying various spring, shock and anti-sway bar combinations. There is a good article in the October 2011 issue of Bimmer on page 57, 'The ultimate handling machine', based on TC Kline's work, with various spring, shock and bushing configurations in a 128i and earlier BMWs, such as an E30. He suggests people are using too much spring rate and not the best shock damping. This is what I found worked best in terms of what I was looking for, when I was trying all the various combinations and wound up using the stock springs and revalved Billy HDs. Check out the article.
FWIW,
-Rod

Post by **Jeremy** » Jul 24, 2011 4:02 PM

mcm97 wrote:
Jeremy wrote:
mcm97 wrote:Running H&R's and Billy Sports and my issue isnt bounce its that the car will "drift" right or left when you're driving in a straight line. Let me explain better - ok, you're going down the road and all of a sudden the car will jerk itself left of right. Not a violent jerking, just a enough to let you know something isnt right. Has this happened to anyone else?
Stop threadjacking. It's most likely the subframe bushings, nothing at all to do with springs or shocks.
Sorry, I thought we were having a convo about H&R springs and Billy shocks.

Subframe bushings not U/LCA? Is there a quick check for that?

That's what the conversation is, but your problem is not related, even if your components are the same. What you describe is the classic "rear steer" associated with bad rear subrame bushing and/or bad dogbone links in the back. Particularly if the rear steer direction switches direction based on whether your accelerating or decelerating, your symptoms match perfectly.

http://www.mye28.com/viewtopic.php?t=17643

1st 5er · Post by **1st 5er** » Jul 24, 2011 5:21 PM

rodpaine wrote:
1st 5er wrote:I get some of that with my HDs and Eibachs.
I was struggling with rear end bounce, back in 2004-2007 when I was trying various spring, shock and anti-sway bar combinations. There is a good article in the October 2011 issue of Bimmer on page 57, 'The ultimate handling machine', based on TC Kline's work, with various spring, shock and bushing configurations in a 128i and earlier BMWs, such as an E30. He suggests people are using too much spring rate and not the best shock damping. This is what I found worked best in terms of what I was looking for, when I was trying all the various combinations and wound up using the stock springs and revalved Billy HDs. Check out the article.
FWIW,
-Rod

October 2011? Is this a typo?

I'm not a subscriber, but maybe this will push me over the edge if that back issue is available.

On a side note, my DD 535i, Snob, has got cut stock springs; 1 coil rear and 1½ front, with HDs and don't have this issue.

rodpaine · Post by **rodpaine** » Jul 25, 2011 7:41 AM

1st 5er wrote:October 2011? Is this a typo?

I'm not a subscriber, but maybe this will push me over the edge if that back issue is available.

On a side note, my DD 535i, Snob, has got cut stock springs; 1 coil rear and 1½ front, with HDs and don't have this issue.

Not a typo, it is issue #101 for October 2011, came last week.
I am not a fan of cutting springs, even though I've done it in the past, I've never really been happy with the results, including driving other cars with cut springs, except one E30 with only 1/2-inch removed from its springs, running Sport HDs. To each his own, of course.
-Rod

mooseheadm5 · Post by **mooseheadm5** » Jul 25, 2011 1:29 PM

m535is wrote:Gentlemen,
If you use the search function at the top, this subject as been discussed to death. It has actually been a topic of discussion since at least the late '90s. Like previously suggested the only way to fix the problem is to spend the $65 to get them revalved. While you are at it, it might not be a bad idea to have the fronts softened a little, but that is just my personal opinion. I have run Koni sport yellows on my car for the last 10 years and to be honest I run them at almost full stiff all the way around. I did do a test at one point with the E34 Koni Sport Yellows in the rear and to be honest I could not adjust the ride height to my liking. Also you have a huge range of adjustment and I will tell you, running them on full stiff is like driving a drift car.

Hope this helps,
Rob

You can't get Konis any more for the e28.

tschultz · Post by **tschultz** » Jul 26, 2011 11:34 AM

Thankf for the info guys! Sounds like I need to go back to a softer springs (such as the original) or revalve the shocks.

For now I will deal with it, just wanted to make sure it wasn't something to do with the perch height or other suspension components.

MyE28.com

MyE28.com

Bouncy H&Rs or bouncy Bilstein sports? Both?

Bouncy H&Rs or bouncy Bilstein sports? Both?

Fronts only