measuring the rear spring

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Jan 17, 2012 | 02:10 PM

Crahm

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From: Dallas TX

measuring the rear spring

I've searched the forums for previous postings but a known Corvette specialist in my area glanced at my rear spring and said it is time to replace it. I have new tires and think my car's stance looks right (car looks level to me although I haven't measured it).
But regarding the spring, if I took a straight edge from end of spring to other end of spring and measured the height to the bottom spring - is there a reference number range for what is correct? (measuring the height of the arc)
Thanks,
Charles Rahm

Jan 17, 2012 | 02:22 PM

MelWff

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Do you have an arch or is the spring flat? Are your halfshafts straight across or is the inside end higher than the outside end or vice versa? If you have the factory manual for your year, it gives the correct chasis height and you could measure that. Did you ask why he thinks the spring needs to be replaced? There is no arch measurement standard.

Jan 17, 2012 | 02:26 PM

Crahm

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From: Dallas TX

my spring definitely has an arch to it, but I don't know how much it is supposed to have. The specialist was doing a walk around the car shortly after I purchased. While looking underneath, he said it sits too flat and should be replaced. I don't know about the 1/2 shafts, I'll have to check whether the inside is higher than the outside.

Jan 17, 2012 | 06:08 PM

TheSkunkWorks

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From: Graceland in a Not Correctly Restored Stingray

I'd suggest you reference your ride heights against those listed in the AIM for your year/model; paying particular attention to the Z and D heights as they usually don't vary with non-OEM spec tires. What year? I might have the info already.

Jan 17, 2012 | 07:23 PM

Alan 71

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From: Westminster Maryland

Hi Charles,
I agree with Mel and SKW that you should use the dimensions given in the AIM to determine for ride height for bb cars.
I believe typically, with a full tank of gas and the spare tire in place, the spring is straight across or nearly so.
I don't believe it should have a negative curve to it.
Probably more than any other single thing the length of the bolts from the ends of the spring to the rear of the trailing arms affect both ride height, and the appearance of the arc in the spring.
Regards,
Alan

Jan 17, 2012 | 07:37 PM

Crahm

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From: Dallas TX

D - 1.63" as stated on page J184 of the 1969 assembly manual. This is the difference of bolt centers for the ends of the struts (rear).

Z - 1.95" as stated on page J177 for the front but I cant figure out what it is referring to?

Jan 17, 2012 | 10:44 PM

TheSkunkWorks

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From: Graceland in a Not Correctly Restored Stingray

"Z" is the difference in height between the centerline of the lower front CA shaft/bolt and the bottom most surface of the steering knuckle where the outer tie-rod end mates. Note factory tolerance is typically + 0.25". FWIW, I prefer to set D from between equal to Z to + 0.25" more than Z, and would discourage having Z at + 0.25" above spec with D at - 0.25" below spec. Hope that helps.