Rear Suspension Problem

Originally Posted by Aurora40

I'm not sure that is true? The spring should have a linear spring rate, so wherever it ends up shouldn't make it stiffer.

Just like any other spring, you change the angle or induce more tension, it has less room to travel.

That's interesting if the stock bolt only has one cotter hole? The FSM has a section on ride height, I wonder how they say to adjust it if you can't move the castle nut through a very wide range?

You have roughly maybe 5mm of adjustment with the castlel nut and cotter pin.

[flyin ryan]

Originally Posted by Aurora40

I'm not sure that is true? The spring should have a linear spring rate, so wherever it ends up shouldn't make it stiffer.

if your cranking pre-load into one side enough to raise the ride height, well...i'm sorry it's going to be stiffer by a bit. it's an I.R.S., if it was a solid rear axle, that's a different story, transverse or not. my Stingray in my avatar, i had it 60' a best of 1.325 seconds with the factory I.R.S. with out a trans. brake. my world revolved around I.R.S. stuff for ten+ years. in the I.R.S ¼mile drag world i'm considered an authority by many. didn't make them happy when i put a solid axle set-up in. just trying to provide correct information.

[HIZNHRZ]

Originally Posted by Aurora40

Scott, what do you mean by first level it, then lower it? If you lower it you will have to adjust the stuff again to re-level it. If you plan on going to lowering bolts, leveling it with the stock ones first would seem to just be time wasted.

I'm not yet convinced that I don't have a problem. I understand that many ZR1's may not sit level but are they more than an 1" off? More than an inch is a whole lot!

What I'm planning to do is level two cinder blocks on my garage floor. I was then going to jack the rear wheels onto the cinder blocks and take some measurements to the floor. I'm hoping to figure out "what" is out. I figured I'd do this with the factory bolts. I don't have the "lowering" bolts yet. It doesn't appear I'm going to be able to find them locally.

Has anyone seen the rear end out of level by over an 1"?!?!?!?

[HIZNHRZ]

Yes I know the measurements are very course but they do allow one to visualize the problem. The pictures are on a car with ~10K miles that until recently was a stock garage queen. The spring "adjustment" bolts are stock and the castle nut and cotter pin is in the same place on both.

Drivers side:

Passenger side:

[Aurora40]

Originally Posted by Jeffvette

Just like any other spring, you change the angle or induce more tension, it has less room to travel.

Presumably though the spring has enough travel for the whole range of suspension movement?

While I realize lowering/raising affects the suspension geometry, well he's trying to make them even. If the ride heights are the same but the spring bolts are not, does it matter?

Won't the spring rate still be the same on each side, meaning it will take X amount of lbs of force to compress the spring/suspension an inch (where X is the springs rated rate). If you tighten the nut up, you aren't compressing the spring more, rather it will raise up the car by the same amount, correct? So it's not getting pre-compressed or anything? Or am I thinking about it wrong?

Also, is it correct to say the spring raises the car from the middle (more or less), which is possibly why side-to-side it can have some variation?

[Aurora40]

Originally Posted by HIZNHRZ

Yes I know the measurements are very course but they do allow one to visualize the problem. The pictures are on a car with ~10K miles that until recently was a stock garage queen. The spring "adjustment" bolts are stock and the castle nut and cotter pin is in the same place on both.

Scott, you may want to look in the FSM. Ride height is not measured in terms of wheelwell gap. You should measure out the appropriate place on the side skirt and measure to the ground.

You can not take measurements there.

Proper measurements are taken from the frame rail to the ground. As body panels are not always applied or installed in the same position.

[HIZNHRZ]

Originally Posted by Jeffvette

You can not take measurements there.

Proper measurements are taken from the frame rail to the ground. As body panels are not always applied or installed in the same position.

I realize the measurements are not the correct way to diagnose
"a problem". I guess I am doing a poor job of providing information that might allow one to visualize the issue.

If it were your car and when it was sitting on a level surface the space above the rear tire on the passenger side was one inch greater than the same space on the drivers side, what would you do?

Thanks in advance.

Has the rear sway bar been off this car at all?

How did it look before you swapped the wheel/tire combo?

Originally Posted by HIZNHRZ

If it were your car and when it was sitting on a level surface the space above the rear tire on the passenger side was one inch greater than the same space on the drivers side, what would you do?

Coilovers

[HIZNHRZ]

Originally Posted by Jeffvette

Has the rear sway bar been off this car at all?

How did it look before you swapped the wheel/tire combo?

I'm not positive the sway bar has been off but Marc Haibeck just put 4:10 gears in it if that tells us anything. Are you thinking it might be flipped 180?

I never really noticed the problem with the 17 inch Amolds and Michelins or with the sawblades and GYs. I'm in the process of pulling out some old pictures to compare.