Shock Absorbers difference: Leaf vs Coil Shocks

rob_macca67

Well-Known Member
Gents
I’m looking for some long travel shocks for my Coil 4WD. Unfortunately I can’t exactly find what I’m looking for but I did find a shock that meets the travel I’m looking for but it’s designed for for a rear leaf end GU Patrol.
I assume the valving in a coil shock would be stronger than a leaf sprung shock so I also assume it would be wrong of me to use a leaf spring shock in a coil sprung vehicle?
 

smitty_r51

Well-Known Member
Try talking to a suspension specialist. I had a lot of success with Nick at solve Offroad trying to sort shocks for a gvm upgrade on my pathfinder and keep travel and drivability
 

Chatty

Well-Known Member
Shock absorber valve rates are a function of how fast you want to dampen out the movement of the springs, so there's no such thing as "stronger" valving.
You really need a suspension specialist to advise on the correct travel and valve rates (compression and rebound) for your application.
 

rob_macca67

Well-Known Member
Shock absorber valve rates are a function of how fast you want to dampen out the movement of the springs, so there's no such thing as "stronger" valving.
Yeah I understand that... I just couldn’t think of the right wording at the time of writing but I assume people would understand what I was getting at...
I’m only talking about a weekend play 4wd here and not looking to spend big money, so I’m looking at options of shocks from other vehicle types. I assuming the valving in a Coil sprung vehicle shock would be valved in such a way that would that require more dampening/rebound than a shock on a leaf sprung vehicle?
 

Chatty

Well-Known Member
Yeah I understand that... I just couldn’t think of the right wording at the time of writing but I assume people would understand what I was getting at...
I’m only talking about a weekend play 4wd here and not looking to spend big money, so I’m looking at options of shocks from other vehicle types. I assuming the valving in a Coil sprung vehicle shock would be valved in such a way that would that require more dampening/rebound than a shock on a leaf sprung vehicle?
I think I see what you're trying to get at - but it's important to understand valving essentially allows oil within the shock absorber to flow at a particular rate as it compresses or rebounds - and for the record, compression and rebound rates are usually significantly different.
The other key item is the length of travel - which needs to be a little bit more than the spring travel so that the damper piston never impacts the ends of the damper.

But the rate isn't really a function of spring type - it more related to spring stiffness (sometimes called spring rate), softer springs require faster oil flow as they move more under load than a stiffer spring, which is why vehicles with softer springs tend to wallow more than those with harder springs.
But you can get soft and hard springs in both leaf and coils - so there is no general rule of leaf springs are harder (or softer) than coils.

Leaf springs and coil springs with the same rate (stiffness) should, in theory, require roughly the same damper (shock absorber) valving. It's not as simple as a straight coil-vs-leaf selection.
Having said that, for many years the philosophy was that leaf springs didn't require dampers at all as the friction between the individual leaves worked as a form of damping anyway.

In any case, if we start from a position that if we have two virtually identical vehicles, with the same spring rate (that is, for every X kg of applied load they deflect Y mm) and length of travel on both vehicles, but one with leaf springs, the other with coils, than they should both require similar dampers.

Hopefully by now you're seeing the problem - without knowing the comparative spring rates between your vehicle and the Patrol, it's impossible to say one way or the other whether these dampers will be suitable. And you're also hopefully seeing why dampers start to get expensive when you start having customised suspensions such as yours.

The problem for me here is that I could tell you all will be fine with those dampers - but I would only be guessing, and not even an educated guess. Get the dampers wrong and there's a good chance the vehicle will become outright unstable and dangerous on the road, especially as you've already said you've got long travel suspension which is inherently unstable on the road anyway - and that's not a risk I would be prepared to take.
 
Top