I am looking for a lift kit for my JK Unlimited Diesel comparing USA made kits like AEv and RE v's Aussie kits like ARB and others. The AEV kit seems to be getting a great wrap for on road performace, and as this is my daily driver, this is important. Aussie kits are simply springs and shocks and rear trackbar relocater, Any extras are from the US. It seems that most US springs are progressive rate, where the Aussie springs are Linear. I have found in the past that aftermarket suspension on Izusu and Toyota 4WD to be stiff harsh riding and wobbly. i would like to here some feedback. I personally think that Aussie suspension is made for heavier trucks with heavier loads for longer outback travels. What do you think?

 

Hey Tom, I know what you mean. I just switched from a Pro Comp to AEV's Progesive spring and if made a world of difference. I'm not sure what type of spring pro comp uses but it was really harsh for my liking. I find that the new springs have brought my ride closer to stock. I don't buy any of the ads that say better than stock ride. I have never experienced it with any lift on my last 6 Jeeps, but this is close. Good Luck

 

Thanks, did you change the shocks to the Bilstein as well. The Bilstein shocks included in the AEV kit appear to be very long approx 27.75 inches, and inch or 2 longer than most. At first glance one would suggest to long. And I am think that maybe 3.5 inches may be a little to big for 33 inch tyres, which is about all we can legally put on over here.

 

I have had both progressive and linear springs. The progressive springs ride better IMO. They have a much softer spring rate on the upper 3 coils to help your Jeep ride better on the road.
Another added benefit is that the progressive coils are a little longer than the linear coils, which helps them stay seated when you are at full flex.

 

THe roughness in ride can most always be sourced back to the shocks of a vehicle unless you are using a spring with a VERY high spring rate. IMO I believe linear rate springs are superior and in conjunction with the proper shock they can ride just as comfortably and even more confidently then proggressive springs. When it comes to shocks almost all of the ones we use are designed with a 50/50 compression/rebound dampening rates. This is not really ideal because the rate of dampening needed on the compression stroke is not nearly as demanding as the rate required for rebound. Capturing energy during compression is why the spring is there, controlling the release of that energy during rebound is why the shock is there, although there is benefit for the shock to play some roll on dampening of the compression stroke as well.

IMO, the better question to ask is what are the compression/rebound dampening rates of my shock? The ideal shock allows you to make adjustments to both rebound and compression at rates that are independent from each other, or slightly less ideal than adjustable rebound/compression but still good a shock, one that adjusts at a rate that is more influential over the rebound. For instance a shock thats dampening rates that are closer to 35/65 compression/rebound. That being said I don't know of any that do this but only from a lack of research.


In the case of linear springs the initial coils have more potential to capture energy than with a progressive coil (they have the same helix top to bottom where as the progressive springs have tighter helix on one end and more active coils) IMO there is less of a demand for compression dampening and MORE of a demand for controlling your rebound when using a linear coil so the standard off the shelf shock which adjusts rebound/compression at the same rates is going to screw your ride. With the added resistance from the spring you are going to suffer in one of two ways.......you either turn the shock up to control your rebound properly and create extra and unneeded resistance from the shock over dampening compression causing a teeth rattling, feel every bomp in the road ride or you turn the shock down so you have a smoother, less jarring ride but now it's bumpy/bouncy cause the shock is not adequately controlling the release of all the springs captured energy.


The progressive rate spring is a band aid for less competent shocks, but this is only my opinion of course.

 

Good info. Anyone else have opinions?