2000BSME

I'm looking at this kit:

http://www.lgmotorsports.com/catalog...oducts_id=2210

and so far it looks like preload isn't adjustable, but ride height is? Am I thinking about this correctly? Is preload adjustment undesireable?

John Shiels

call LG they will be happy to help

ZR1 MK

Preload for the bars is adjusted with the connecting links. Jointed connectors are adjustable. If using stock connectors, shim.

Ride height for the coilovers is adjusted with a Spanner wrench that usually comes in the kit and the large nut at the bottom of the coilover.

Bill32

No preload adjustment on those coilovers because they are directly attached to the A arm, when you change the rideheight by moving the spanner nut up and down, you do affect the preload but it's not separately adjustable.

On cars with a bellcrank/coilover suspension (open wheel/sports racers) and some GT cars, the ride height is adjusted bu the link to the bellcrank. On these you can dial in preload on the coils and then adjust the rideheight independently.

gkmccready

Pfadt's coilovers get around this by offering both overall length adjustment and spring perch adjustment...

WKMCD

You can adjust the height and preload on the LG GT2's.

mgarfias

Those two things amount to the same thing: height adjustment. Preload comes from droop limiting unless you've got a cantilevered suspension like an open wheeler.

gkmccready

I think I need more explanation. You've got a fixed spring perch at one end, and one that moves at the other end... if you make that distance shorter you're adding preload to the spring no matter what your suspension configuration is, no?

mgarfias

only if the spring is shorter than that distance. And, by definition, your shock is at full extension, thus droop limited.

If you want to try it cheap, go down to one of the local r/c places, buy a single damper that has an adjustable perch, and try to add preload to the spring while keeping the damper from being at full extension.

gkmccready

I'm not trying to be an *** here, but I must be missing something basic. I have a 9in long spring and the distance between the perches is 9in to me this is 0 preload and you'll get whatever ride height you get based on the corner weight. So if the ride height is too low you shorten the distance between the perches to 8in... now you have 1in worth of preload, don't you? So moving the spring perch adjusts ride height by changing preload? Given that if you make the distance between the perches greater than 9in you're not adding preload to lower the car, but people generally don't like their springs rattling around at full droop, either, right? (Yes, yes, 0 rate helpers, etc...)

I suspect we're in agreement but just not seeing it clearly. :-)

ZR1 MK

For our purposes, take coilover preload and throw it out the window.

JDIllon

Ride height is adjusted by screwing the shock body in and out of the lower mount! Preload or corner balance adjustments are made by using the locking rings to increase or decrease preload on the springs. JD

mgarfias

I think you're confusing preload with the position of the spring on the damper.

You need to de-couple the perch from preload, they're not the same thing. I've tried a few times to explain it, and just erase what I've written because I can't come up with something that I'm happy with.

The easiest way for you to "get it" will be to get an r/c damper thats 2.5" long, and experiment with different spring rates/heights coupled with damper lengths. I cheated, I raced those things for years until I could afford to play with real cars.

But, I'll try again: basically the only way to load the spring beyond what it will see via corner weight is to compress the spring before it sees corner weight. How do you do that? By limiting droop travel.

In my oh-so-extensive experience (sarcasm there FWIW) the only reason you'd want to run a spring preloaded is when you've got lots of downforce and need to keep your ride heights from getting stupid in slow sections of the track where you don't have that download.

mgarfias

Nope. While screwing the damper body in and out of the lower mount does change ride height, changing the spring perch doesn't necessarily add preload to the spring.

You can change the perch height and still have the chassis compress the spring with the car at rest at its normal ride height. Preload is loading the spring BEYOND the normal loading it would see from the chassis normal corner weight.

Ask yourself why gary @ hardbar sells his coil overs with that helper spring?

gkmccready

I'm with you now. For it to be considered "preload" you have to compress the spring (with the perch) more than the corner weight such that the spring won't compress when corner weight is actually placed on the spring, which effectively means no droop travel.

My mind still says any time you compress a spring to less than its free length you're adding preload to the system in order to adjust ride height, though. But now I understand what you're saying. :-)

mgarfias

Well, in that sense you are, but, whats the point of that if the corner weight will load the spring more than what you've done with the perch? It'd be just as effective a suspension change to put ricer stickers all over the car.

JDIllon

I don't agree, and I could be wrong!, but it is my understanding that Gary's dual springs create a dual rate spring. And any tighting of the spring perch does create preload. And if you check with Pfadt, corner balancing is done by adjusting the sring perches or lengthing or shortening the shocks. Suggested preload on the Pfadt's are one to one and a half turns of the of the spring perch. JD
Note: I would suggest we get Gary or Aaron or Randy to jump in here and explain the facts! I get the feeling that we are all saying the same thing and non of us know for sure.

mousecatcher

Many confusing / misleading posts here.

No, as you now seem to understand. However, also (as you were originally questioning) in an inboard/pushrod suspension design, or a design like pfadt's where you can change the length of the shock body, the ride height and preload are independent. You change the ride height by changing the length of the shock attachment points, which doesn't affect preload.

Where you can't change the length of the shock attachment, your minimum independent ride height adjustment range is essentially (corner weight divided by spring rate) divided by the motion ratio. You can go lower than that, but now you are also adding preload.

mousecatcher

That's not my understanding. I thought Gary's design had stacked springs. If that's right then the lighter spring is just there to take up the slack at full droop. If they are concentric, then yes it is there to have a progressive rate.

not as preload is understood by vehicle dynamics guys, and as stated here by others. you need to compress the spring beyond the static ride height to have "preload". my guess is this is generally undesirable for a car like the vette.

mousecatcher

I looked it up, and the springs are in tandem but are still progressive rate. The smaller springs are not at full bind at static ride height. Probably one of the better coilover setups out there.