dgheinen

I just installed longer leaf spring bolts from a C4 on the back end of my 78 to be able to lower the back end to a custom ride height. I also installed a new set of 18 inch wheels, and they sit about 3/4" too close to the rear suspension. In order to avoid making contact with the rear leaf spring, I had to tighten the nuts on either side of the leaf spring, raising the back end of the car again (to about stock height). Besides longer studs & a spacer, what options do I have to bring the car back down and avoid the rear leaf spring? I was looking at offset trailing arms, but I'm hoping to avoid pushing the wheels outboard any more, because they are almost perfectly flush with the body right now, and I would like to keep it from protruding. Are the composite leaf springs any narrower than the steel ones? Right now everything is doable, but I would really like to be able to lower the back end again. Thanks so much for the help!

Damon

stingraymax

You can buy a shorter spring, read this post...

https://www.corvetteforum.com/forums...e-vbp-one.html

Metalhead140

You can also shorten your spring if you're a masochist like me. Dismantle the spring, cut one end off the main leaf and make a new hole in it, then redrill the centre hole and reassemble. Drilling spring steel is fun, but it's certainly doable. Fair bit of work, but basically free...

Metalhead140

Thought I'd post my pm to the OP for the benefit of anyone reading this in future:

Hey mate,

Take the spring apart. Then cut one side of the main leaf (longest leaf), make a new hole, and install the cup that holds the bushing on the bolt. Then drill a new centre hole (again in main leaf only) centred between the 2 spring bolt holes, and reassemble the spring. For the spring bolt hole, I drilled it to ~1/2" from memory, then opened it up to the right size with a carbide burr on my die grinder. There's a bunch of threads on here about doing this, a quick search found this one, but I remember when I was planning to do it that there were others: https://www.corvetteforum.com/forums...ring-pics.html

I haven't got pics of the whole process, but I do have these:

New hole cut next to old hole, spring bolt cup sitting in place:



Modified spring end complete:



Reassembled, clearance to my 17"x9.5" 5.05" backspace wheels:



Hope that helps!

brent319

I don't think that offset trailing arms will change where the wheel is in relationship to the spring anyway.

resdoggie

I'm thinking that will increase the spring rate a bit. Was there any difference in the ride quality? I was considering doing the same thing.

Metalhead140

Correct.
Yes, theory says that it should have stiffened the spring slightly, but I think the change would be minor given it's only a very slight stiffening of a single leaf with the rest of the spring pack unchanged. Impossible to say in my case if that particular change affected ride quality, as I also rebuilt the rear suspension with new poly bushes, new Bilstein shocks and lowered the inner strut rod pivot points, and of course the new wheels and tyres at the same time... But I doubt it would make much difference. My car both rode and handled much better after the combined set of changes.

I believe you can buy a shortened main leaf also to save the effort in modifying the leaf. I should have mentioned - I wouldn't recommend attempting to drill the leaf without a drill press.

resdoggie

Did you need to do any trimming with the next leaf above the one you drilled?

Metalhead140

Nope, i didn't. Though obviously if you get carried away with shortening it then it's possible I guess.

resdoggie

Thanks, mate!

lvrpool32

I see a major safety issue with bolts this long , what if your rear tire goes flat??? the bolt will hit the ground first and lead to who knows what damage. I would investigate why your car needs to be lowered so much in the rear. Are the rear tires shorter than stock? rear leaf spring with incorrect arch?