The back of my car is sitting a couple of inches too low. The spring is flat at best, almost bending upward slightly. I plan on removing it to either have it re-arched or replaced. Regarding the former, is it just the main leaf that gets restored, or the others as well? As far as replacing, I'm trying to remember how many inches of free arch is an indication of a good spring. Thanks....
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Re: '66 REAR SPRING FATIGUE
The number one cause of low ride height is compressed spring link cushions. How old are yours?
What kills springs is corrosion. Corrosion slowly removes material, which reduces the spring rate and can cause sag.
If your spring has never been rebuilt, it would certainly not be a bad idea to remove and disassemble it. Inspect it for serious corrosion and treat it to a corrosion resistant coating, then assemble it with new spring liners, and install the spring with new link cushions.
New link cushions will also dramatically reduce rear ride harshness.
Duke -
Re: '66 REAR SPRING FATIGUE
Duke,
The cushions have never been replaced, so I'll start there and see how much of a difference there is. There doesn't seem to be much corrosion on the spring, from what I can see. The last spring I replaced was on a side exhaust car. I can see it will be more difficult with an undercar system.
Thanks, RobComment
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Re: '66 REAR SPRING FATIGUE
I'd be willing to bet even odds that new cushions will work wonders. As long as the link bolt nuts aren't frozen it's no more than an hour job, and four new cushions cost about ten bucks.
Most C2/3 Corvettes probably need this service. It's something that most owners completely overlook. I recommend that they be replaced every five years, whether the car is driven or not.
DukeComment
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THANKS FOR THE INFO DUKE... *NM*
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Re: '66 REAR SPRING FATIGUE
I replaced the cushions and lowered it back down. I'm already happy with difference in the height, hopefully it will stay where it's at and won't settle. That was a great suggestion and I'm surprised at how much it raised the rear end. Thanks....Comment
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Re: '66 REAR SPRING FATIGUE
Did you notice a reduction in ride harshness from the rear suspension?
I've been pointing out the spring link cushion issue on this board whenever someone is about to replace their "worn out" spring due to ride height issues for probably as long as I've been hanging out here, which is over four years.
Make a note to replace them again in five years.
DukeComment
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Re: '66 REAR SPRING FATIGUE
To be honest, our roads are so smooth here it's hard to notice a difference in the ride, but the height stayed the same after driving it for 20 minutes, so I'm happy. Thanks again. By the way, the engine has never been rebuilt or modified at all 327 (350HP). What's your opinion on octane booster and/or lead additives? It's not pinging, but occasionally will run on after turned off.Comment
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Re: '66 REAR SPRING FATIGUE
If it doesn't ping, it doesn't need any "octane booster" most of which are worthless anyway. Their "points" are 0.1 not 1.0.
Check your total idle timing, It should be the sum of initial plus full vacuum advance - 16 vacuum, plus whatever initial you are running, which should be in the range of 6-10 for L-79. The vacuum advance should be marked "236-16" for an OE Delco can or "B28" for a proper replacement, and full vacuum advance should be achieved at 8". Engine idle vacuum should be about 14-15" at 750 to 800 with the proper mid-twenties range of total idle timing.
If the igntion map is proper, just get in the habit of letting the clutch out in gear as you shut it off. If it has insufficient total idle timing, for whatever reason, it will have more tendecy to "run-on" after you turn it off.
Anecdotal evidence indicates that a lot of vacuum cans may be incorrect specfication, frozen, leaking, or otherwise manfuctioning. Few owners pay any attention to them, but they are a very important part of the engine control system.
DukeComment
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Re: '66 REAR SPRING FATIGUE
Rob-----
To the extent that the cushions become compressed beyond their original design compression specifications, the EFFECTIVE length of the spring bolts increase. Longer effective bolt length = lower ride height. It's as simple as that.
In the case of these bolts, it doen't take much difference in effective length to make a significant difference in ride height and, these cushions DEFINITELY DO compress an additional amount over time. Plus, there are TWO of them on each side, so it's a "double whammy" as far as compression is concerned. If the cushions get to the stage of cracking, even at the edges only, the additional compression is greatly increased.In Appreciation of John HinckleyComment
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