80 Series Spring Rates Measured. (1 Viewer)

[Dougal]

I don't have an 80 series. But a mate does and I have a computerised spring tester. He loaned me a stock front and rear coil to measure. I was honestly surprised how soft these are.

Like softer than Range Rover soft!
135 lb/in front and 129 lb/in rear.

A diesel classic range-rover ran 150lb/in front and rear.

 

[george_tlc]

Brand new OEM springs or old tired ones?

cheers,
george.

 

[Dougal]

Brand new OEM springs or old tired ones?

cheers,
george.

Used springs. The spring-rate doesn't change over time unless you've got serious rust.

 

[cahill]

Not trying to be argumentative but trying to learn. If spring rates don't change over time, how is it that older springs "sag" more than newer ones when comparing new vs old? Is the sagging springs being old just myth that is passed down in the hopes that new springs will give you more lift and a better ride?

 

[ppc]

In my opinion springs can sag somewhat over time because of reduced spring rate but I find that on this forum that is exaggerated. Just a good excuse to buy the latest offerings from the manufactures. Springs can easily be damaged by overloading/weight and driving under extreme conditions resulting in lower spring rates.

 

[Dougal]

Not trying to be argumentative but trying to learn. If spring rates don't change over time, how is it that older springs "sag" more than newer ones when comparing new vs old? Is the sagging springs being old just myth that is passed down in the hopes that new springs will give you more lift and a better ride?

I've never found a spring that sagged over time in my vehicles and some are approaching 40. It is possible for springs to yield and become shorter. This happens if they are compressed too far or made from steel that is too soft. If that happens then the free length of the spring measures shorter than it originally did. Lose an inch of spring length and you've lost an inch of ride height also. But the spring-rate remains the same.

This is rare because most springs are designed to not yield when fully compressed. For the spring rate to reduce you've got to lose metal. Either corrosion or cracking. This is also rare but both can happen.

IMO myth is the bigger player. Over time people add all sorts of extra weight to their vehicles and also don't have any original measurements to check ride height against.

I did spot an 80 series the other day which looked be standard height. Which was surprising as almost all that I see are sitting taller on aftermarket springs.

 

[MoJ]

If designed and manufactured correctly to begin with a coil spring will not sag unless it has been subjected to forces outside its original design parameters.

 

[MoJ]

I don't have an 80 series. But a mate does and I have a computerised spring tester. He loaned me a stock front and rear coil to measure. I was honestly surprised how soft these are.

Like softer than Range Rover soft!
135 lb/in front and 129 lb/in rear.

A diesel classic range-rover ran 150lb/in front and rear.

View attachment 2770864

Super cool you have a spring rate tester that can accommodate automotive coils. The linear nature is as expected per Hook’s law. The same straight line would be expected with “variable” rate springs where coil revolutions vary in pitch etc. as the deflection curve is a function of the average overall spring rate and generally wouldn’t reflect any multi staged design. In other words, variable rate is meh except for unweighted downward travel.

 

[Dougal]

Super cool you have a spring rate tester that can accommodate automotive coils. The linear nature is as expected per Hook’s law. The same straight line would be expected with “variable” rate springs where coil revolutions vary in pitch etc. as the deflection curve is a function of the average overall spring rate and generally wouldn’t reflect any multi staged design. In other words, variable rate is meh except for unweighted downward travel.

I tested some landrover variable rate springs the other day. The purpose of those is to keep the rear suspension frequency up as the vehicle is loaded up and the rear sags into firmer rate.

Basically vehicle handling suffers a lot when the rear suspension bouncing frequency gets slower than the front. Stock setup is almost always having the rear rear firmer/faster than the front unloaded and progressive rear springs mean when loaded to max GVM your rear frequency is still a bit faster than the front.

Basically it's to stop vehicles wallowing all over the road when they're loaded up while still giving a good ride when close to empty.

 

[MoJ]

I tested some landrover variable rate springs the other day. The purpose of those is to keep the rear suspension frequency up as the vehicle is loaded up and the rear sags into firmer rate.

Basically vehicle handling suffers a lot when the rear suspension bouncing frequency gets slower than the front. Stock setup is almost always having the rear rear firmer/faster than the front unloaded and progressive rear springs mean when loaded to max GVM your rear frequency is still a bit faster than the front.

Basically it's to stop vehicles wallowing all over the road when they're loaded up.

Let me guess, the force vs displacement plot from the variable rate LR springs is still a straight line…

 

[Dougal]

Let me guess, the force vs displacement plot from the variable rate LR springs is still a straight line…

I edited the above post with the graph. It's got a clear curve in there.

 

[MoJ]

I edited the above post with the graph. It's got a clear curve in there.

Cool. Thanks for adding it. I’d guess the spring was fully loaded at the point of inflection that created the curve…likely the turn/revolutions of the coil began to fully collapse and contact each other.

 

[Dougal]

Cool. Thanks for adding it. I’d guess the spring was fully loaded at the point of inflection that created the curve…likely the turn/revolutions of the coil began to fully collapse and contact each other.

Yep, when coils contact they make the spring shorter and stiffer.
I only tested the LC80 spring over 3" because it's a long flexy spring and I did not want that jumping out the tester at me. I had to test the LR spring to 6" to show the curve properly.

 

[MoJ]

Yep, when coils contact they make the spring shorter and stiffer.
I only tested the LC80 spring over 3" because it's a long flexy spring and I did not want that jumping out the tester at me. I had to test the LR spring to 6" to show the curve properly.

Thanks! Yep and once the revolutions contact each other it starts to behave like a solid piece of steel rather than a force absorbing suspension.