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Ever since I had the rear spring replaced in 1994 on my '64 convertible - 300HP, 4 sp, posi - it has ridden much higher than it should, in my opinion. Is there a ride heighth spec for the backend with a new spring? Not knowing where the 9 leaf spring was acquired, should I just get a new one? The posi is out of the car for rebuilding, so now's a good time to solve my ride heighth dilemma. Thanks.
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Re: 64 rear leaf spring
If you had spring bolts where the cushions go that had more threads (aftermarket) you might be able to adjust the height more to your liking. The factory bolts can only be tightened so far. -
Re: 64 rear leaf spring
Exactly which bolts are you referring to, the single bolts to the trailing arms or the 4 bolts for the diff carrier mounting bracket? Thanks.Comment
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Re: 64 rear leaf spring
Rick -
Many aftermarket replacement rear springs result in excessive ride height, and a common "fix" is to replace the outer link bolts with longer bolts and Nylock nuts to compensate. A better solution is a correctly-made 9-leaf spring - Eaton Detroit Spring (www.eatonsprings.com) makes the closest one you'll find to an original.
The measurement to determine whether or not the ride height is within specs (which is independent of tire size) is the "D"-height, which is shown in your assembly manual in section 4, sheet B5.00. Takes less than a minute.Comment
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Re: 64 rear leaf spring
I recently purchased such a spring made by Eaton. My ride height is two inches to high per the AIM spec. On my 1970, Eaton suggests having some of the arch taken out of the spring . The spring is becoming very expensive. Plus the time and effort.Comment
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Re: 64 rear leaf spring
John, since I just ordered the manual today, could you tell me what the "D" height is for my car? I will check out Eaton for a possible replacement. Are these supposed to be the 300# strength springs? Thanx, RickComment
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Re: 64 rear leaf spring
Bob, if you do get the spring arch reduced, where will you take it? Have you priced that repair yet? So Eaton said too bad, get it fixed yourself?
Thanks, RickComment
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Re: 64 rear leaf spring
Rick --- I meant to say that which ever way it takes to correct the ride height of the new spring that its an added cost to the my orginal purchase. My responce to you is that you ask them up front how that they would correct the problem if it were to happen.Comment
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Re: 64 rear leaf spring
Bob, thanks for the info. RickComment
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If memory serves...
the specifications for '63 and later Corvette rear leaf springs aren't published in Noland Adams Vol 2 book while the specs ARE published for the front coil springs...
My crib notes show I'd found the info at one time and for the standard 9-leaf spring, the free arch measurement spec is 10.0 inches. That's the distance between a straight line through the outer mounting holes up to the bottom center of the spring when it's relaxed, off the car...Comment
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GM spec for free arch is 10" +/- 1/8" *NM*
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Re: If memory serves...
Jack, thanks for the ride height spec. I'll check my spring. RickComment
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Re: If memory serves...
I just measured my springs Old 10 1/2" New 8 3/4"Comment
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Free arch for non-GM springs
Bob,
If the new spring has thicker leaves, which they often do because some of the spring stock from the '60s is no longer available, then the new spring will be stiffer and then it will need a smaller free arch in order for the ride height to be the same. The free arch measurement needs to be considered along with the spring stiffness before one can determine if ride height will be correct. And I know of no easy formula to do that. My only point is that with a non-GM spring, the free arch may not be 10" and the spring may still have a correct ride height.
GaryComment
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Re: If memory serves...
Bob, You measured your new spring free arch height at 8 3/4" and its ride height is 2 inches too high? Must be some very stiff metal. Maybe I won't buy one from Eaton. Are there any OE GM springs available that you know about?
RickComment
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