Ride height, with or without weight?

[Quiny]

I just lowered my 818s down off the jack stands to check ride height. There was very little to no preload on the springs and it is at around 5 inches. Should the measurement be made with weight in the car? if so how much. I did not torque any of the rubber bushings yet so that's not holding it up. I also jumped on the suspension a few times to settle it out. It still seems like it requires very little preload on the springs to get the proper ride height. I would actually like to increase the ride height a bit since I will not be racing. What have some of the completed cars been set at? Thinking about go-karting next weekend.

[Rasmus]

Should the measurement be made with weight in the car? if so how much.
Ride height should be set at the weight the car would normally be driven. So full of fluids and a half full fuel tank, and "you" in the driver seat. So if you weight 200 lb. You'll need to go get 5, 40lb bags of salt and place them in the seat. If you don't have your panels mounted just grab another 40lb bag of salt and set it right in the middle of the car. Now, set your ride height.

[riptide motorsport]

I will also add that when you drive it, it will settle some more. Then you reset it and forget it....HTH Steven.

[C.Plavan]

I found on my R that once the car sits a bit on the springs, it lowered quite a bit after a month. The springs and everything else settled.

[billjr212]

I have a semi-related math/geometry based question (on a Friday afternoon, the nerve)

Would it be efficient to set blocks (eg 3 2x4's stacked) under the frame giving 4.5" ride height, put the wheels/tires on, and put the car down on the ground with NO springs/shocks in order to set up the rough alignment? In the back of my head, I'm thinking the springs/shocks should have no impact on the alignment, so removing them from the equation and limiting the contact pressure between the tires and the ground would make the alignment "easier."

This way, you can set the alignment, pop it back up in the air, add the springs and shocks and then you are adjusting only that factor in getting to your final ride height.

[Bob_n_Cincy]

I have a semi-related math/geometry based question (on a Friday afternoon, the nerve)

Would it be efficient to set blocks (eg 3 2x4's stacked) under the frame giving 4.5" ride height, put the wheels/tires on, and put the car down on the ground with NO springs/shocks in order to set up the rough alignment? In the back of my head, I'm thinking the springs/shocks should have no impact on the alignment, so removing them from the equation and limiting the contact pressure between the tires and the ground would make the alignment "easier."

This way, you can set the alignment, pop it back up in the air, add the springs and shocks and then you are adjusting only that factor in getting to your final ride height.

Bill
Your idea would work. One other thing you need to allow for is the compression of the tire.
I don't know how much, maybe 1/2" to 1".
Bob

[Rasmus]

I have a semi-related math/geometry based question (on a Friday afternoon, the nerve)

The 818's not a strut based car so I think that'd work just fine. Is it efficient? I don't know.

Usually when I set up my cars I:

Mount wheels
Eyeball adjust alignment so nothing looks goofy
Set tire pressures
Set ride height with bags of salt for "me" sitting in the seat.
Corner balance
Check ride height to make sure car's not listing left or right (e.g. NASCAR) and rake is correct.
Set Caster/Trailing Arm(s) Lengths
Set Camber
Recheck corner weights and run through 5-8 if needed.
Set Toe
Remove salt bags and vacuum
Test drive

[myjones]

Bill
Your idea would work. One other thing you need to allow for is the compression of the tire.
I don't know how much, maybe 1/2" to 1".
Bob

The website I found for spring rates/lengths said to allow 1/2" for tire crush when loaded. Overall tire height divided by 2 minus 1/2" would give a fairly accurate spindle or axle height was the way it was stated.
HTH
DB