Performance and Tuning Discussion forum for various performance tuning techniques and questions

How do bumpstops work?

Thread Tools
 
Search this Thread
 
Old 06-01-2001, 10:48 AM
  #1  
AudiWorld Super User
Thread Starter
 
Clues's Avatar
 
Join Date: Mar 2000
Posts: 3,335
Likes: 0
Received 0 Likes on 0 Posts
Default How do bumpstops work?

Do they affect rideheight at all?

TIA
Old 06-01-2001, 11:27 AM
  #2  
AudiWorld Super User
 
Žob's Avatar
 
Join Date: Mar 2000
Posts: 12,620
Likes: 0
Received 4 Likes on 1 Post
Default When the shock/suspension runs out of travel

It runs into the bumpstop.
Old 06-01-2001, 11:46 AM
  #3  
Elder Member
 
Bollinger's Avatar
 
Join Date: Mar 2000
Posts: 39,901
Likes: 0
Received 0 Likes on 0 Posts
Default they, they don't change ride height. and you don't want to be hitting them very often

It's very jarring and in the very long term bad for the frame.
Old 06-01-2001, 12:09 PM
  #4  
SKS
Junior Member
 
SKS's Avatar
 
Join Date: Mar 2000
Posts: 737
Likes: 0
Received 0 Likes on 0 Posts
Default They are actually a spring and can be used to tune a track suspension. They

come in all shapes,lenghts,hardnesses,with various fluted designs. Don't confuse these with the old leaf spring snubbers on big old American iron, they just kept the axle from hitting the frame. Our Jetta is lowered with Eibachs and with track tires in a turn we use them all the time.
Old 06-01-2001, 12:43 PM
  #5  
AudiWorld Super User
Thread Starter
 
Clues's Avatar
 
Join Date: Mar 2000
Posts: 3,335
Likes: 0
Received 0 Likes on 0 Posts
Default Thanks. Why would Eibach then claim that failure to use oem bumpstops

with their Prokit springs would affect ride height?
Old 06-01-2001, 12:54 PM
  #6  
Banned
 
ModifiedA4's Avatar
 
Join Date: Mar 2000
Posts: 34,209
Likes: 0
Received 2 Likes on 2 Posts
Default Dunno....I think it would only change travel limits...

EC had an article on Bumpstops a while back....
Old 06-01-2001, 01:24 PM
  #7  
Elder Member
 
Bollinger's Avatar
 
Join Date: Mar 2000
Posts: 39,901
Likes: 0
Received 0 Likes on 0 Posts
Default the bumpstops might also determine the top of the spring

Sort of the top perch height. I dunno. I don't know enough about the Audi suspension.

I wish Bentley whould ship the damn A6 service manual so I could look at diagrams and tell you.
Old 06-01-2001, 02:03 PM
  #8  
AudiWorld Super User
 
nick n's Avatar
 
Join Date: Mar 2000
Posts: 5,617
Likes: 0
Received 0 Likes on 0 Posts
Default My 2 cents..

the springs have to make up for the lack of a bumpstop if there is none. The bumpstops are 2-4 inches long (4" on the A4/S4). Eibachs are soft and they like to sag w/in time. I should know because I still have them on my car. You would definatly notice a difference in ride height w/o them since they're rubbber and they sit at the top of the shock body - not to mention they're 'cheap security' but on the flip side if you're hitting your bumpstops then there's a problem as the others have mentioned.

HTH
Old 06-01-2001, 02:48 PM
  #9  
Elder Member
 
ryoung's Avatar
 
Join Date: Mar 2001
Posts: 11,968
Likes: 0
Received 0 Likes on 0 Posts
Default Re: How do bumpstops work?

As mentioned earlier, they avoid bottoming the suspension ... or worse yet, bottoming the shocks, which often destroys them. With a properly designed suspension, bump stops have no affect on ride height.

The other benefit, especially on the track, is that when one corner bottoms out, the spring rate at that corner goes from 200 lb/in (or whatever) to infinity. The tire at that corner is immediately overloaded, taking load from the other tires. If this happens when cornering near the limit, you're off the track. A bump stop of correct length and hardness provides a progressive and controlled transition to the limit of suspension travel.

IMHO, bump stops are necessary on all high performance cars.
Old 06-05-2001, 11:05 AM
  #10  
Junior Member
 
eharleq's Avatar
 
Join Date: Mar 2000
Posts: 1,556
Likes: 0
Received 0 Likes on 0 Posts
Default Yes, and SKS is also correct...

The bumpstops provide additional spring rate when the strut/shock is near the end of the travel. Given the right shape and composition (I love celasto med.) you can use a milder spring with a long bumpstop (ala VW).

Old solid rubber bumpstops had really high rates and were just to protect the shock/strut from bottoming.

Short-travel suspensions (VW-GTI) engage the bumpstop all the time. I assume that is why the company tells you the ride height will change.


Quick Reply: How do bumpstops work?



All times are GMT -8. The time now is 05:49 AM.