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Just purchased my first C3. '69 convertible 4 speed. Seemed to be in pretty good condition though I am sure there will be plenty of discoveries.
The car is sitting low on the driver side front. There is about an 1 1/4 inch difference to the top of the fender arch and about an inch difference when measured frame to floor. There is about a 1\2 difference when measured from frame to bottom of the lower control arm. I suspect its a spring issue but before I buy new springs I figured I would solicit some advice.
Thanks
Usually they would "wear out" more or less evenly. That's a fair difference, all kinds of things can go wrong, broken spring, high-side not installed into the pocket correctly would be the first two that come to mind. The other thing to look at is if the opposite side at the rear is high it will force the front low and vice-verse
Check and make sure you see where the problem is before throwing money at new springs
M
I generally don't help with tech, unless no one else is answering a question.
If the coil springs were designed properly to support the car weight, then generally no real expiration date, especially in performance models where the springs are heavier than was generally needed, but if someone has been running improper shocks and struts then those could have affected the spring set. It is rare that a coil spring snaps (breaks), but if you have bottoming, or clunking, then you definitely want to figure that out, to see if they have taken a different set, or other, and to restore, that would be a situation that would warrant changing them. I have not heard of anyone having to change like an F-41, seen the same set support the car from new in the 60s to the modern. We have cars autocrossed since the late 70s and 80s and even under those conditions, the springs seem fine, but we have went thru several shock replacements or rebuilds.
first measure top of inside fender arch to ground. all 4 corners. now measure frame to ground just behind front wheels and in front of rears. fender arch should be 27-1/2 for optimal. frame should be around 7 inches. but you are really looking for left to right diff. and also comparing to see if it is suspension-spring height or body sitting high on frame at one point. rear spring being low can make opposite corner front high. and rear can be done with trailing arm to spring bolts. you can play around by jacking the rear spring outer corners up and seeing how that effects front height. you can buy 8 inch spring bolts to get the rear lower and they can be adjusted side to side. generally these guys sit high. so if anything the front springs improve with age... post pics.
I will try to give you a few ideas to chase it down.
A low corner could be so many things, and it may not even be in the front. Bent frame, rusted/binding suspension bushing, broken rear leaf, busted shock, torched coils, etc.
Start with putting the car up on jack stands and level the frame. Check it for straightness. Disconnect the shocks and sway bars. Check suspension bushings for free movement, especially the outer strut rod joint in the rear. You can use a floor jack. With rear of frame on jack stands load the front and check D-heights. Ditto on the rear, front frame on jack stands and check rear D-heights. Or use a jack and a scale on one corner at a time. Rear leafs can crack much more often than coils, and usually sag on one side only.
Much easier would be a set of four corner scales from a race car. Check wheel weights and D-heights at the same time.
Next step is pulling front & rear springs.
Keep at it, sooner or later you'll find it.
My 1-1/2" low left rear was caused by a rusted solid right rear strut rod joint and a bent upward left front corner of the frame.
I will try to give you a few ideas to chase it down.
A low corner could be so many things, and it may not even be in the front. Bent frame, rusted/binding suspension bushing, broken rear leaf, busted shock, torched coils, etc.
Start with putting the car up on jack stands and level the frame. Check it for straightness. Disconnect the shocks and sway bars. Check suspension bushings for free movement, especially the outer strut rod joint in the rear. You can use a floor jack. With rear of frame on jack stands load the front and check D-heights. Ditto on the rear, front frame on jack stands and check rear D-heights. Or use a jack and a scale on one corner at a time. Rear leafs can crack much more often than coils, and usually sag on one side only.
Much easier would be a set of four corner scales from a race car. Check wheel weights and D-heights at the same time.
Next step is pulling front & rear springs.
Keep at it, sooner or later you'll find it.
My 1-1/2" low left rear was caused by a rusted solid right rear strut rod joint and a bent upward left front corner of the frame.
Here are a couple of documents you'll need.
Z & D heights tell you a lot about the condition of the springs due to the ride height. J & K help some too.
Check the Z height attachment, it is 3 pages from a service manual.
2020 Corvette of the Year Finalist (performance mods)
2019 C3 of Year Winner (performance mods)
2016 C3 of Year Finalist
short answer is yes they do. Especially after 50 years. WE saw it all the time when I was young with 15 to 20 year old cars. Remember these things are American made and the quality of the parts and the build were shoddy at best. No car was built to last very long back then, "planned obsolescence, make them wear out so we buy more". Having to re-curve leaf springs when the *** end sags was very common when I was a kid. Most muscle cars got really bad in the rear. Everyone sold shackle kits to get teh rear end height even again. If one side in the rear went out it caused issues in the front over time. Coil springs would wear out as well, especially when you have an extra 200 lbs on one side. If they are original replace them, but you may need to cut a coil to get it to look right
also the front springs have a clocking slot which Im sure was mentioned earlier. If they arent installed correctly you will notice.
YOur best bet its to upgrade to coil overs. If you upgrade you should look at an adjustable coil over. they are easily tuned and are much better than the stock set up. Prices have been coming done in affordability as well.
Here are a couple of documents you'll need.
Z & D heights tell you a lot about the condition of the springs due to the ride height. J & K help some too.
Check the Z height attachment, it is 3 pages from a service manual.
Do coil springs go bad?
