New rear shocks rebound at very different speed - Bimmerfest - BMW Forums



Go Back   Bimmerfest - BMW Forums > BMW Model Discussions > 5 Series > E39 (1997 - 2003)

E39 (1997 - 2003)
The BMW 5-Series (E39 chassis) was introduced in the United States as a 1997 model year car and lasted until the 2004 when the E60 chassis was released. The United States saw several variations including the 525i, 528i, 530i and 540i. -- View the E39 Wiki

Reply
 
Thread Tools Display Modes
  #1  
Old 12-05-2018, 11:05 AM
javarithms javarithms is offline
Officially Welcomed to the 'Fest
Location: WA
 
Join Date: Oct 2015
Posts: 315
Mein Auto: '13 E92 M3, '03 530iA
New rear shocks rebound at very different speed

I'm planning on doing a full suspension rebuild on wife's 530i and I decided to go with Bilstein B4 shocks and struts since they are very close to stock setup on there now.

I got the B4s in yesterday and I decided to test the rebound speed on both the fronts and rears by compressing each one and timing how long it takes for it to rebound. The fronts are within 1 second of each other which I think is reasonable BUT the difference between the rear shocks is 10 seconds.

Does this indicate that one of the rear shocks (the slow rebounding one) is bad? Is my test even valid?
Reply With Quote
Sponsored Links
Advertisement
 
  #2  
Old 12-05-2018, 03:56 PM
Chedley Chedley is offline
Officially Welcomed to the 'Fest
Location: Beaverton, Oregon, USA
 
Join Date: Oct 2016
Posts: 1,330
Mein Auto: 2001 E39 540i
So, why do you wan to replace the original stock shocks (they are Sachs I think, not Bilsteins). ?

I would not touch the shocks, but I would replace the other more important suspension components: control arms, bushings, links, tie rods...etc..
__________________
<=E39=>
Reply With Quote
  #3  
Old 12-05-2018, 04:12 PM
javarithms javarithms is offline
Officially Welcomed to the 'Fest
Location: WA
 
Join Date: Oct 2015
Posts: 315
Mein Auto: '13 E92 M3, '03 530iA
I replaced the original shocks (Sachs) on my 530iA sport and all except for 1 (on the rear) were completely blown (would not rebound), and my car had 130K miles when I replaced them this summer. Wife's car has 170K miles so they are long overdue. The original shocks are probably bad after 80K miles and that's probably being generous.

But yeah, I'll replace everything while I'm in there.
Reply With Quote
Sponsored Links
Advertisement
 
  #4  
Old 12-06-2018, 05:54 AM
rdl rdl is offline
Officially Welcomed to the 'Fest
Location: Ontario, Canada
 
Join Date: Jun 2010
Posts: 2,135
Mein Auto: 530i 2003
Quote:
Originally Posted by javarithms View Post

...

Does this indicate that one of the rear shocks (the slow rebounding one) is bad? Is my test even valid?
The lack of consistency between shocks sure doesn't sound right. It could be loss of pressure in the slow shock, loose seals in the the fast one, tight in the slow, or, or, or.

I'd get in touch with Bilstein with the rebound times you've measured and ask them for an opinion.
__________________
Regards
RDL
Reply With Quote
  #5  
Old 12-06-2018, 09:16 AM
atobe atobe is offline
Banned
Location: Socal
 
Join Date: Apr 2018
Posts: 151
Mein Auto: 00 528, 01 540
Were the shocks standing straight up? Sometimes there's a little bit of air in them. But 10 second difference doesn't sound correct.
Reply With Quote
  #6  
Old 12-06-2018, 03:51 PM
javarithms javarithms is offline
Officially Welcomed to the 'Fest
Location: WA
 
Join Date: Oct 2015
Posts: 315
Mein Auto: '13 E92 M3, '03 530iA
Quote:
Originally Posted by rdl View Post
The lack of consistency between shocks sure doesn't sound right. It could be loss of pressure in the slow shock, loose seals in the the fast one, tight in the slow, or, or, or.

I'd get in touch with Bilstein with the rebound times you've measured and ask them for an opinion.
I called Bilstein and the rep was kinda of short saying that you need expensive equipment to test the shock and the shock was probably fine but if I didn't like it I should return it to the place I bought it from and get another one (although he said there is no guarantee the new one won't behave the same way).

Quote:
Originally Posted by atobe View Post
Were the shocks standing straight up? Sometimes there's a little bit of air in them. But 10 second difference doesn't sound correct.
The shock was upside down, I pushed down on the rod til it bottomed out and then let go of it until it rebounded while timing it. Is the right test to stand them up and push down on the rod? I guess I can try it when I get home and see if it makes a difference.
Reply With Quote
  #7  
Old 12-06-2018, 04:02 PM
528iAut 528iAut is offline
Officially Welcomed to the 'Fest
Location: Moraira, Spain
 
Join Date: May 2016
Posts: 2,264
Mein Auto: 1996 528i
Why not just get a new one, would be strange if that is slow also.
But maybe you should try again, they might behave differently after some movement.
__________________
E39 528i Steptronic 1996, Comfort seats, Rear sunshade, Focal amplifier and front speakers, Oxford Green.
Reply With Quote
  #8  
Old 12-06-2018, 04:23 PM
javarithms javarithms is offline
Officially Welcomed to the 'Fest
Location: WA
 
Join Date: Oct 2015
Posts: 315
Mein Auto: '13 E92 M3, '03 530iA
Quote:
Originally Posted by 528iAut View Post
Why not just get a new one, would be strange if that is slow also.
But maybe you should try again, they might behave differently after some movement.
Well, I don't want to replace it if it's not an issue or my test is invalid. Yeah, that's what bilstein rep was saying is that it's been sitting and it needs some cycling to "wake it up" again. I just don't want to redo the work since the rears are a lot of work.

BTW, my wife and I would like to retire in Spain (she's partly Spanish) but are kind of scared of the wealth tax (plus other taxes) that would be levied on us.
Reply With Quote
  #9  
Old 12-31-2018, 10:33 AM
rdl rdl is offline
Officially Welcomed to the 'Fest
Location: Ontario, Canada
 
Join Date: Jun 2010
Posts: 2,135
Mein Auto: 530i 2003
javarithms

Did you ever get this problem sorted out?

Last night I stumbled across something that jogged my memory on a possible explanation and solution. (Something I should have twigged to on your comment that you'd compressed the shock while upside down) The B4 shocks are a twin tube gas pressure design. Twin tube shocks must be installed in an upright position so the the gas is kept in the upper portion of the outer tube that serves as an oil reservoir. However shocks are usually stored and shipped in a horizontal position and there is a chance for the gas to migrate into the inner tube. Whether or not the migration occurs depends on chance, i.e. the orientation of the valves while the shock is horizontal, or if it was upside down for some time in storage or shipment.

The correction for this problem is to stand the shock vertically in the correct orientation and cycle the shock full stroke for several cycles - minimum 3 or 4.
__________________
Regards
RDL
Reply With Quote
  #10  
Old 12-31-2018, 12:01 PM
javarithms javarithms is offline
Officially Welcomed to the 'Fest
Location: WA
 
Join Date: Oct 2015
Posts: 315
Mein Auto: '13 E92 M3, '03 530iA
Quote:
Originally Posted by rdl View Post
javarithms

Did you ever get this problem sorted out?

Last night I stumbled across something that jogged my memory on a possible explanation and solution. (Something I should have twigged to on your comment that you'd compressed the shock while upside down) The B4 shocks are a twin tube gas pressure design. Twin tube shocks must be installed in an upright position so the the gas is kept in the upper portion of the outer tube that serves as an oil reservoir. However shocks are usually stored and shipped in a horizontal position and there is a chance for the gas to migrate into the inner tube. Whether or not the migration occurs depends on chance, i.e. the orientation of the valves while the shock is horizontal, or if it was upside down for some time in storage or shipment.

The correction for this problem is to stand the shock vertically in the correct orientation and cycle the shock full stroke for several cycles - minimum 3 or 4.
You're absolutely right, my test was invalid. I tested them in the correct position and the rebound rates were very similar. Thanks
Reply With Quote
  #11  
Old 12-31-2018, 03:15 PM
Jason5driver's Avatar
Jason5driver Jason5driver is offline
Officially Welcomed to the 'Fest
Location: Middle of a corn field
 
Join Date: May 2007
Posts: 4,833
Mein Auto: E39 hamster w/ pin-wheel
Quote:
Originally Posted by javarithms View Post
You're absolutely right, my test was invalid. I tested them in the correct position and the rebound rates were very similar. Thanks
So, do you have the B4's installed on the 530i ?
If so, how do they ride ?
__________________
Reply With Quote
  #12  
Old 12-31-2018, 03:48 PM
javarithms javarithms is offline
Officially Welcomed to the 'Fest
Location: WA
 
Join Date: Oct 2015
Posts: 315
Mein Auto: '13 E92 M3, '03 530iA
Quote:
Originally Posted by Jason5driver View Post
So, do you have the B4's installed on the 530i ?
If so, how do they ride ?
No, not yet waiting for warmer weather and also have to get the rest of the parts for the full suspension rebuild in. I can do an update once I've installed them but from my research, the B4's are 10% stiffer than stock Sachs shocks.
Reply With Quote
  #13  
Old 12-31-2018, 06:28 PM
Jason5driver's Avatar
Jason5driver Jason5driver is offline
Officially Welcomed to the 'Fest
Location: Middle of a corn field
 
Join Date: May 2007
Posts: 4,833
Mein Auto: E39 hamster w/ pin-wheel
Quote:
Originally Posted by javarithms View Post
No, not yet waiting for warmer weather and also have to get the rest of the parts for the full suspension rebuild in. I can do an update once I've installed them but from my research, the B4's are 10% stiffer than stock Sachs shocks.
Are you installing them on OEM sport springs ?
I have read that the B4ís donít work right with sport or lowering springs .
__________________
Reply With Quote
  #14  
Old 12-31-2018, 08:04 PM
javarithms javarithms is offline
Officially Welcomed to the 'Fest
Location: WA
 
Join Date: Oct 2015
Posts: 315
Mein Auto: '13 E92 M3, '03 530iA
Quote:
Originally Posted by Jason5driver View Post
Are you installing them on OEM sport springs ?
I have read that the B4ís donít work right with sport or lowering springs .
No, they are going on wife's non-sport suspension. I installed koni yellows on my 530i sport.
Reply With Quote
Reply

See More Related BMW Stories


Forum Navigation
Go Back   Bimmerfest - BMW Forums > BMW Model Discussions > 5 Series > E39 (1997 - 2003)
Today's Posts Search
Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On



Forum Jump


All times are GMT -7. The time now is 08:33 AM.


Powered by vBulletin® Version 3.8.8
Copyright ©2000 - 2020, vBulletin Solutions, Inc.
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2020 DragonByte Technologies Ltd.
© 2001- VerticalScope Inc. All rights reserved.