Where to measure ride height from?, Want to be able to compare to others. Options

[stugray]

So I just rebuilt my car, Pulled rear trailing arms, and added adjustable rear perches.

I added my drivers weight in the drivers seat and now I want to set my ride height all the way around.

What do others use for this measurement?

I can imagine:

Bottom of fender, or engine mount bolt, etc.

I will be setting the alignment all the way around by myself.

Any other starting measurements would be great (rear camber, front camber, toe, etc.)

Curious.

Stu

[Dave_Darling]

The factory measurements related the height of the axle to the height of the suspension pivot. That takes the wheel and tire size out of the question quite nicely.

A lot of people now use the height to the jacking donuts, or from the ground to a suspension mounting point, or similar. Fenders heights are usually not reliable, as they can (and do!) vary from side to side. And get even more wonky if collision repair is performed in a shoddy manner.

Stock alignment specs are basically zero camber in the front, 0.5 degrees negative camber in the rear. Caster 6 degrees (only has front caster). A little bit of toe-in both front and rear.

For more aggressive driving, add negative camber in roughly equal amounts front and rear. Max the caster out, subject to it being equal on both sides. Toe-in at the rear, a very small bit of toe-out in the front if you're autoXing. For higher-speed aggression or street driving, toe-in at the front still.

--DD

[stugray]

Thanks Dave!

This is for my race car and will be running hoosiers so I will go for the more aggressive stance ;-)

Anyone else? Cmon - nobody sets their ride height?
I will get measurements from my donuts underneath, but for now I am seeing:

~24 inches to the fender lip on the front & ~22-1/4" to the fender on the back.

with 195/60-15s on it now.

It looks a lot lower than my street car (hanger queen) already.

Stu

[r_towle]

Up front, lower it so the alarm is just above level by about 1/4 of an inch.
Measure both sides to make it even from the torsion adjuster, no from the fender.

Then take a level, set the rear to the rocker with a level on it shows about 1/8 inch higher across the 4 foot level so that the rear is higher.

Takes time to tweak it.

Then get it aligned and corner balanced.

Rich

[Dave_Darling]

The Hoosiers should have a known good working range for camber. If they're old-school bias-ply tires, that will actually be pretty close to zero. If they're radials, their best range is probably more negative camber than you can reasonably get.

I still prefer a bit more negative camber in the rear than the front, but there are folks that like it to be even all around or even the other way around from me. Tire temps will be a big help there. Tuning the balance of the car can be done with tire pressures, with alignment, with sway bar size or effectiveness, with spring rates. They all, to some extent, affect each other. Also your driving style. (We know more than one person who got a Super-Zoomy Race Alignment that made the car almost undriveable until you started pushing it much harder than that driver ever would.)

Toe-out at the front can be used to help give better initial turn-in response, especially at low (autoX type) speeds. It will make the car like to "wander", and you have to keep on top of it and always pay attention, even when driving in a straight line. It usually makes the car a bit unstable in higher-speed turns, which is one reason we usually don't recommend it for the Big Track. (Though it is one more tool.)

Toe-out in the rear is evil. It can be useful to get a FWD car to actually turn sometimes, but on our cars is is pretty much pure evil. And worse at higher speeds.

--DD