Bump Stop Rubbers

[mark030358]

Have just bought some Spax bump stop rubbers for rear suspension on my S4. The car is fitted with 2.25" springs and AVO shockes. However, they are much shorter than combined length of the two standard items fitted as origional, I guess the length of the Spax units is approx 60mm......
So is this a problem? and do I need to double up on them??
cheers
Mark

[rgh0]

You need the orginal length bump stops in good working order. If not the car can get very tale happy on the limit. personally I prefer to run with a spacer of about 22mm thickness so the bump stops come into play earlier than orginally designed as i find this improves stability on the limit with modern sticky rubber.

It sound like the spax items you have are just a generic bump stop designed to minimise the impact at the end of shock travel. In the Elan the bump stop at the rear is a critical part of the suspension design producing an effective rising rate spring system over a signficant part of the suspesnion travel.

cheers
Rohan

[mark030358]

Rohan,
How did you get the standard bump stops to fit into 2.25" springs?

cheers
Mark

[frearther]

There are no bump stops at all in the rear of my S2. Of course, it's not running yet, so there's no handling problem. What should I be adding to the damper to give the proper bump stop and (as Rohan suggests) the rising spring rate? I also have 2 1/2" springs in back (courtesy of DPO).

[rgh0]

I use 70mm ID 90mm O/D springs at rear so the orginal size Aeon rubber springs fit inside OK. Aeon springs are made by a company called Timbren now. You can look them up on the web and see the range they make at the following link http://www.timbren.com/aeon-rubber-springs.htm.

With a bit of research you should be able to find a suitable one in terms of length and load rating to replace the orginals with an O/D that will fit inside your springs.

cheers
Rohan

[frearther]

Thanks, Rohan. That's a big help.

[mark030358]

Thanks to alll for your help

cheers
Mark

[steveww]

My S4 has 2.25" rear springs and I have fitted the SAF005 bump stop from http://www.powerflex.co.uk/

This is also a progressive bump stop / spring helper. From the limited testing I could do is appears to have a similar spring rate to the original.

You definitely need some form of progressive stop or the bump over steer is a bit of a shock when it happens.