Thread: load = ride comfort = what spring rate?

what brand springs? May'be as low as 180pound, would be ok unladen, but loaded up may be a bit soft. i have 220 LRA spings in the rear of the disco, ride is fine with a bit of weight in it, a little, but only a little harsh unladen.

attached chart might help,
LR coil spring rates

go below the page to the bottom half, only rear 110 -130 springs will fit.

I use light rear springs & pump up polyairs for loads or towing, they dont affect the ride or articulation when they are deflated.

I'll be interested in how you go. I am in exactly the same boat with a shortened alloy tray and pondering the same question. Have you weighed it at all?
I was sort of thinking around the 250 mark, but maybe that is too heavy.
My standard ones are terrible at 330's....

Serg - air springs!

More comfortable than coils with no loss of load carrying ability!

I run 2''lifted standard rate nissan GQ Patrol rear coils in the back of my 110 ute they are pretty soft, they give a good ride and perform well in the bush.
They sag a little bit with a load in the back but not a huge amount

TIM.

Originally Posted by bitdist

[snip]

My standard ones are terrible at 330's....

Dampers/shockies have a huge bearing on this too.

Lots of low and medium speed bump valving can make the ride feel firm, even harsh, and standard LR dampers have a fair bit of low speed bump valving.
Bilstein have far more.

Serg took a 130 for a drive recently with rear dampers that have bugger all (IMO) low speed bump valving with 330lb rear springs to compare with his Koni's.

I think he found it interesting

Rick, do you think that the LR rate or amount of bump valving goes back to the earlier days of lighter spring rates?

as you know my King springs are 250lb, OEM 110 with LL are about 180lb rear and 150lb front...My fronts being 210lb, but the TDi is forward and the winch and bar add (yes id like to go lighter in the front also)

If I go down to a low rate of 180lb, will my Koni's with more bump actually be an advantge/better feel than lowering the Bump and getting say 220lb?

yes I know its all in my arse....the feel that is

hey Benny, no way on the air springs mate....got way to many unfinished projects on the go..and my TA are way up the list before air springs....

OK, lots of low speed bump valving serves two purposes.

(definition: low speed refers to anything under 4"/sec shaft speed, which has no correlation to the actual forward speed of the car)

1. It controls the rate of acceleration of the unsprung mass after hitting a bump.
Our wheels, diff housing and half the weight of the control arms have no suspension to control them at all, and our 4WD's unsprung mass is high (anyone that's ever lifted a Sals knows what I'm talking about) so you need more bump valving to control the diff housing and wheels than a car with independent suspension would use.

2. It controls or slows the rate or speed at which the car rolls during cornering, and the rate of pitch and squat under acceleration and braking.

Roll, pitch and squat, particularly roll are low speed movements for the shaft and piston in the damper/shockie, regardless of road speed.

High(er) levels of low speed bump slows the rate at which the outside damper bleeds down when cornering, it sort of props the car up, and through short corners gives the impression the car isn't rolling as much, but all it's doing is slowing the rate of roll.

In a steady state cornering situation, eg. driving in a constant circle the car will still assume the same degree of roll as a set of dampers that had no bump valving at all.
It's the time taken to get to that ultimate degree of roll that is controlled by the low speed circuit in the damper.

High amounts of low speed rebound will give a similar effect to lots of bump when controlling roll, except that in that case the inside damper is restricting how quickly it extends and therefore reduces the rate of roll.

Too much rebound and you may start pulling the tyre off the road. (a little like too stiff an anti-roll bar)
Too much bump and the tyre starts to skip.

What will work with what is why car companies and race teams employ test drivers to drive around and feel/see what works. We can theorise and calculate till the cows come home, but the only way to know is bolt bits on and try it out.
Road cars are such a compromise, as what give the best grip can often give a harsh ride, and what works in the dry is miles too stiff (in particular bump valving) in the wet.

Fast gravel requires totally different valving to fast bitumen too, I'm guessing the dampers need to be more compliant to let the car take a set faster to cut through a loose surface and generate grip.

Rule of thumb.

Bump controls the unsprung mass. (and you really feel it in ride comfort over bumps)

Rebound controls the chassis. (ie. the feeling of stability or float)