Front Coil Spring = Rear Ride Height?
 

https://cimg8.ibsrv.net/gimg/www.cor...3b563ff329.jpg
Could this?
https://cimg9.ibsrv.net/gimg/www.cor...7bbe82391e.jpg
Cause this?
First photo is RH front coil spring sight hole. It appears I have the end of the spring about a 1/4" past the sight hole. In other words , NOT indexed correctly. Could that be the cause of the RH rear wheel opening so high? Floor to w/o measurement are R front 27 1/2", R rear 29 1/4", L front 26/ 3/4", L rear 28".

Your front spring is indexed close enough and the front height would have negligible effect on the rear height. Your rear height problem is caused by the rear spring or how it is mounted. Could you post a picture similar to the one below of your setup on the rear?

https://cimg0.ibsrv.net/gimg/www.cor...560ee5c3f1.jpg

The rear spring bolts are threaded to allow ride height adjustment. To lower ride height, install 8" spring bolts in place of the stock 6" bolts.

That's the stock 6" bolt. Replace with an 8" bolt to lower your rear.

Lets say the rear spring is a fiberglass 330lb spring
Let's say the bolt is swapped out, 6" for 8".
lets assume that each nut is threaded on until the nut is flush with the end of the bolt.

how much will that lower the ride height? The full 2"? Or something less?

Much less. Maybe 3/4" in my experience.

I disagree. It would lower it the full 2 inches. Please explain why it wouldn't.

Hey guys, I've been screwing around with suspension issues for almost 2 years now. The reason I asked about a incorrectly indexed front spring causing rear ride height problems is I seem to recall reading a couple of threads during one of my many searches regarding front springs that an incorrectly indexed front spring could indeed cause a higher ride height in the rear. I was hoping for a quick confirmation of that. Oh well, I'll just do some more searches. Thanks everyone.

Wish I could. Has to do with spring/suspension geometry somehow. I said 'in my experience'. I swapped from 6" to 8" and it lowered the rear about 3/4".

Alan 71
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Hi,
I believe because of the geometry used in the rear suspension design lengthening the spring to t-arm bolt DECREASES the ride height dimension by about HALF the INCREASE in bolt LENGTH.
I.E. A 2" LONGER bolt decreases the ride height about 1".

This may be why you see folks trying to use 10" long bolts to get the decrease they need.

Regards,
Alan

Post #26: https://www.corvetteforum.com/forums...cked-up-2.html

R front and L rear are very close to factory spec.
High R rear and low L front are not coincidental.
If you jacked the L front under the ca one inch I believe the R rear would lower by one inch. Something is off on your L front. Spring, shock, bushings.

No. A 1/4" off from a fully seated front spring in the upper pocket will not affect ride height. Kid Vet already pointed this out.

https://cimg2.ibsrv.net/gimg/www.cor...d9809122df.jpg
Left sight hole. Spring indexed correctly.

Thanks for the reply, mortgageguy. That makes sense to me. So, if I index the right front coil spring correctly, that will RAISE the left rear wheel opening. Correct? Would it raise it an inch to even out the rear ride height?

I have 8" bolts and a 330 LB spring and mine looks like this.....
It also settles about an inch or so when I'm in the car.



https://cimg5.ibsrv.net/gimg/www.cor...a06c3cc6ff.jpghttps://cimg5.ibsrv.net/gimg/www.cor...d479ecb1a6.jpg

Well I guess I'll have to crank the nuts up as far they go and see what happens. But looking at the rear suspension, I see no reason for the change to not be 1:1.

Are the front springs stockers or aftermarket ones? Correct for the car? (BB springs in a SB car or viceversa)

Some threads I've read say the 550 sport springs (gymkhana?) will provide a stock like ride, just shorter (lower) to the ground than regular OEM (stock) springs. I have no idea if thats true or not, just what I've read online (here).

I think if the spring isn't indexed correctly, yes it'll affect the car (think like a 4 legged table, with one leg 1" shorter). Now one thing would be HOW MUCH improperly indexed would it affect the rear (the opposite table leg in my example)? 1/4" off, like not much difference, 1/2 a round or 3/4 of a round out is a whole other ballgame, IMO.

The reason I'm curious is Im thinking or dropping the car 1" to 2", but by using new shorter springs (as opposed to heating and relaxing or cutting the coils) and using 8" (as opposed to 6") bolts in the rear.

The rear trailing arm has a Motion Ratio between the T/A bushing and the wheel hub and the spring bolt. My measurements give:
Rear Motion Ratio
Spring to t-arm pivot (a) 20.0
Hub to t-arm pivot (b) 16.8
Motion Ratio 1.136
Because it is reversed compared to a normal front coil spring setup, the spring moves more than the wheel.
So if the bolt moves the spring down 2 inches, the car should lower less or 2/1.136 or 1.76 inches.

When all else fails, using a shorter spacer on one side of the front sway bar will level it out.

Moog 5758 (474 lb.). Engine's a SB. I cut a half a coil because of the aluminum heads and intake manifold.