Thread: Suspension rebound - is this normal?

Originally Posted by Slunnie

It's more a shock problem than a spring problem. You will find that the oscillations are smaller with stiffer springs, but I wouldn't pursuit that avenue just yet. If the shocks are right to start with it will eliminate the problem.

Yep agreed, just trying to point out if RS doesn't know the spring rate (original and current kings) then no good taking a punt on a 3rd unknown spring rate.

Knowing the spring rate could also help tune the shock to suit.

I stand by what I've said. Here are Bilstein valving, I dont think they normally do bullnose curves for the road.

Originally Posted by uninformed

Yep agreed, just trying to point out if RS doesn't know the spring rate (original and current kings) then no good taking a punt on a 3rd unknown spring rate.

Knowing the spring rate could also help tune the shock to suit.

I had a set tested years ago, I think they were something around 240-270 or 240-300lb/in. I'm not sure what length the transition occurred though. The King Springs are at(were?) right at the soft end of the range for lifted springs on a Disco2.

Originally Posted by Slunnie

It's more a shock problem than a spring problem. You will find that the oscillations are smaller with stiffer springs, but I wouldn't pursuit that avenue just yet. If the shocks are right to start with it will eliminate the problem.

Stiffer springs make the oscillations smaller, but faster.

Unsure of the spring rate, Kings don't seem to carry the info on their site they are KRRR04, but from what I can tell they offer a KRRR04 HD if you are carrying 300 - 500kg's constantly.

This may be useful when I have the kids and trailer loaded (approx. once a year). Not overly concerned about a more harsh ride when I am by myself as I was used to driving lowered vehicles before the discovery, but don't want to trash the ride in the process.

The next question is what are the things I should be looking for for a less bouncy ride at lower speeds?

In what circumstances is a bouncy ride at lower speeds good, ie when I head off road?

If I have to replace some components just trying to make sure I do it once and try and achieve the mid range between harsh ride for towing, but not bouncy at low speeds.

Originally Posted by Slunnie

I stand by what I've said. Here are Bilstein valving, I dont think they normally do bullnose curves for the road.

Yours are custom, I can tell you that off the shelf HD Bilstein valving is jiggly, their off the shelf comfort valving uses a lot less low speed bump than the off the shelf HD valving.

You don't need a significant knee in the graph to achieve this, just less in that 0-4" sec range.
On most dampers it's just a case of opening the bleed a little.

If you graphed the OP's dampers, the rebound curve (the bottom line) would start from the 0/X axis at around the 50-100mm/sec mark, ramp up a little and then probably be fairly linear too.

I agree, it's all a damper/shock valving thing and any decent aftermarket damper that's valved specifically for a DII, eg. Bilstein, Koni, Delphi-de Carbon, whatever Ultimate Suspension sell, etc would be an improvement.

Originally Posted by Slunnie

I stand by what I've said. Here are Bilstein valving, I dont think they normally do bullnose curves for the road.

Thanks for the plot, do you know which bilstein valving numbers it is for?

I plan to build a shock dyno eventually. So force/velocity numbers on a plot like that are extremely helpful.

Originally Posted by Dougal

Thanks for the plot, do you know which bilstein valving numbers it is for?

I plan to build a shock dyno eventually. So force/velocity numbers on a plot like that are extremely helpful.

I helped heavily modify and rebuild the original BMC/Leyland/JRA dyno that dated back to the fifties so that we could plot and rebuild race dampers.

It was really interesting that it was all setup to measure medium/high speed shaft speeds, it just couldn't go low enough to do the critical low speed stuff, my mate Mark reversed the pulley drives around so we could get decent low speeds, I added a 3 phase variable speed drive, (10hp three phase motor) supplied and installed an LVDT, etc.

The original was an all mechanical plot on graph paper doing a displacement/force graph, the classic D shaped Koni graph.

It was a monster of a thing, god knows how heavy it was, but it was big enough to do fatigue cycle chassis twist testing on Perentie 6x6 chassis when the ADF was having chassis cracking problems in the mid/late nineties !