kirt8548

I'm planning some Winter work on my lady. My tires are 235/60R15 tires and in really bad need of some suspension attention. The front bushings (control arms and sway bar) are shot. The rear needs new wheel bearings, and t/a bushings.

My questions are:

When I push down on the rear quarter I have absolutely no give. The rear suspension is hard as a rock. I don't run a spare tire and the correct shocks. Why is the rear so stiff?

What can I do to lower the rear ride height?

Thanks..

Bob Heine

It looks like you have a replacement 7-leaf rear spring. The steel band is used to keep the spring lined up for shipping and should really be removed. Not much you can do to soften that spring except to replace it with a softer one.

Lowering the rear ride height is pretty easy. All you need is a longer pair of mounting bolts between the TA and spring.
http://www.vbandp.com/C2-C3-Corvette...2-1997-05.html

If the cushions (rubber donuts) are cracked and crumbling, you can replace those at the same time.
http://www.vbandp.com/C2-C3-Corvette...2-1997-05.html

72LS1Vette

Your front ride height looks way too high also. Did you rebuild the suspension yourself or buy it that way?



Rick B.

kirt8548

Bob.

Thanks for the information. I bought this car in April and my day job (network engineer) simply funds my passions (wife and Vette). It also means that in just about every way I'm a a novice.

I was afraid that the band removal will cause the springs to fan out like playing cards. Are you saying that I'm needlessly worrying about that? If so, do you have a correct tool for cutting the band?

Both sides of the leaf spring/trailing arm connection have bushing that are pretty bad. I bought the Energy (poly) replacements and plan on changing them out this winter.

kirt8548

72LS1Vette.

Thanks for the reply. I bought it this way. So far I've done the following myself. Replaced the mechanical fuel pump, front crank seal, radiator and hoses, and replaced the original shroud and fan with a pair of electric fans, and valve cover gaskets.

The front control arm bushings and sway bar bushings are bad. So are the ball joints. The steering looks like it's been rebuilt/replaced which is strange to me. Makes me wonder why someone would go to the trouble of rebuilding the steering without going to the additional length of resolving the suspension issues.

Anyway, the front is that high even with the issues.

Thanks for any advice.

Kirk

Bob Heine

You're welcome. Funded mine with technical writing job in the computer hardware and software world from the 60s through the 90s. Everyone here is or was a novice so don't be afraid to ask questions.

When a supplier bolts the stack of leaves together at the center of the spring with a single bolt, the leaves can fan out just as you fear. Once the spring is installed it's locked in place by the steel plate and four bolts that attach it to the differential. There's no way for the leaves to move radially. Once the spring is installed, the shipping strap is no longer needed. I don't think it's doing a lot of harm but it's possible it is causing a slight bind, restricting the movement of the leaves.

My car has the original 9-leaf spring so I've never taken one of those clips off. It looks like a big screwdriver or prybar and a pair of pliers would do the job.

If you already have the poly replacement spring cushions, all you need are bolts. The stock bolts are 6.5-inches so you'll be able to lower the rear 1.5-inches with the 8-inch bolts. If you want to lower it more than that, VB&P sells custom lenths as well.

kirt8548

Removed the clips. That was a tough hour job. I should have cut them off, would have been easier.

I know that this sounds strange, but I think that it may be worse. I'm sure that it is at least as high. I'm scratching my head over this one.

The upside is that the rear end doesn't squeak. There is a little more give in the rear end when I push down. Before there was no give with the rear end.

I need to drop the rear end 3 inches and the front 2.

HEEELLLPPP!!!

Kirk

Bob Heine

Kirk,
You have several options, some more expensive than others. I think you have to determine if the car rides the way you like. If it's too stiff, changing the ride height will not make it softer. Just a thought but you live about 60 miles from Vette Brakes so that might be a place to visit and get some professional advice. Here's their contact info:
http://www.vbandp.com/Contact-Us/VBP...t-Support.html

Least expensive fix for the rear end is to replace the spring bolts. If you have the stock bolts that connect the end of the leaf spring to the trailing arm, they are 6.5 inches long. Vette Brakes and Products sells an 8-inch bolt but offers any length bolts you want -- the longer the bolt, the lower the rear sits. Before I ordered a 9.5 or 10 inch bolt, I'd drive the car a few miles to see if it settles.

Least expensive fix for the front end is to cut the coil springs. You mentioned you have to rebuild the front suspension anyway so this could be done when you have it disassembled. For a little bit more money you could buy new springs and put them in instead.

kirt8548

Bob.

Thanks. I did experience improved ride and feel, even though it is stiffer than I like. I wish I had a point of reference in the form of a ride in another C3. I think when I drove home yesterday I saw a '80-'81 at a local car dealer. I might fake some interest and take a test drive.

I'm going to the Turkey Run Swap Meet at the Daytona Speedway tomorrow with a friend looking for parts for his '65 'Cuda. I'm hoping to be able to see some C3s and network a little bit.

What do you see as the negative of going with a 9-10" bolt?

I've seen a rear suspension replacement called "Shark Bite" and Van Steel has some great replacement suspension alternatives, including a rear coil over conversion as well as a front coil over as well. All it takes is money...right?...LOL!

Alan 71

Hi Kirt,
Since your rear spring is an aftermarket spring of some sort you really don't know what it's specs are. It COULD be causing your high rear ride height; but it certainly could be something else or a combination of things.
Putting in longer bolts will help lower the rear of the car but is just covering up the problem.
I think you need to decide if you want a stock suspension or an aftermarket suspension with different specs than stock. Then buy parts accordingly.
If you don't have the Assembly Instruction Manual for your car you may want to consider buying one. It has the factory set ride height dimensions that will give you an idea of where it was originally compared to now. It also has info you'll find useful as work on your car. Think about buying the GM Chassis Service Manual for your car too. Both are money well spent.
The 235/60 tires are smaller in diameter (and thus in height) than the original tires. This is contributing to the distance you're seeing from the top of the tire to the wheel arch. It could be as much as 1" of what you're looking for.
Good Luck!
Regards,
Alan

billsfan

The negative to having a 9 or 10" spring bolt is that it might hang below the lower part of the rim. Flat tire means you'll stick the spring end into the road.

kirt8548

Thanks Alan.

Tire size. Again, I'm disappointed by the advice I got from Firestone. When I bought the car it had a terrible rear vibration. I drove it from the sale straight to Firestone. Another expensive novice mistake. What is the right tire size?

I have the assembly manual. You are so right about the manual's value. I have forgotten to start there for my points of reference.

Thanks to everyone for your insight/advice. Every word you give is appreciated.

kirt8548

I have the correct number of leafs (7). Under the subject of "you don't know if you don't ask", what is the harm in removing 1-2 leafs?

Thanks Billsfan. You are right. A quick measurement leads me to one conclusion. Anything but me discovering the tire flat in the garage, such as a blow out would mean that the bolt would drag the ground, which I can only imagine would do trailing arm damage.

noonie

One of the biggest problems with using the long bolts is that the leaf end can easily hit the tire wall under certain conditions.
You really are better off to change the spring or rework it.
Here is a pic with a shorter Guldstrand bottom leaf and 6-1/2" bolts with a couple leafs removed from the oem spring. It sits lower than stock with oem size dia tires (approx 27" high). There is approx 1" from the top of the tire to the fender lip.
Definitely got rid of the 4x4 look.

Alan 71

Hi K,
I believe the 215/70/15 is today's replacement for the original tire. It's a diameter of ABOUT 27". A 225/70/15 is a size that many people choose for a STOCK look... a tiny bit taller and a bit wider.
The 235/60 tire you have has a diameter of about 26" So to my eye it doesn't fill the wheel-well like the original tires.
Many people use a 255/60 because it's a good diameter but also a LOT wider; so it changes the look of the car. This tire gives some people trouble with the tire rubbing on sharp turns. If you go to a site like TireRack you can find tires of various sizes and check their specs to see their diameter and width.
All this only considers 15" wheels and average performance tires. There's a WHOLE WORLD of performance wheels and tires out there.
From your pictures I think you have various things contributing to your ride height. Both suspension and tires.
The longer bolts only trick the suspension into letting the car sit lower.
Hope this helps a bit.
Regards,
Alan

Bob Heine

Noonie,
See picture below with stock 9-leaf spring, 8-inch bolt and 17" rim with stock 4" backspacing and 255-50/17 tires (27-inch tall)... I've got the problem you describe.

I was planning to get the Guldstrand short leaf. I could also switch to a short composite but you can't remove a leaf to change the ride height then. Then there's Vansteel's coilover setup....

Back in the 60s I had a spring shop replace a broken leaf in my 47 Ford (transverse leaf just like the Vette). They re-arched the rest of the leaves to get me back to stock ride height (I assume they could have de-arched them if I wanted it lower). Is that still done today?

The Guldstrand site says you should use their 8" bolt with the shorter leaf. The leaf looks beefier than the main leaf on my stock 9-leaf spring so I would expect a stiffer ride along with the extra height. You solved the ride height problem by removing leaves. How many did you remove and which ones? Have you experienced more bottoming out with that setup?

noonie

All of the new springs I know of use 1/4" instead of 1/8". A real spring shop can build you whatever you want for ride height and spring rate, but without it being local, I didn't chance it.
The Guldstrand works well, it's firm, but a lot of that is the none gas Koni shocks I use. Really happy with the ride.
I know I took out the next to lowest leaf and another two closer to the top, but I tried a couple different ones until I got where I wanted. I wanted to keep the bolt length as short as possible. I also used poly spring cushions, no visible compression. Bolts are Grade 8 UNF from Ace Hardware and I drilled for a cotter pin.
If rebuilding the spring, you need a new center bolt (less than 2 bucks locally) that you have to shorten the head so as not to poke thru the diff cover.
I also made an additional bolt plate, since the original can bend and also as a spacer along with old leaf parts, so as to use the original mounting bolts, in case someone ever wanted to go back to a stock spring.

kirt8548

Wow. Thanks for all of the great information.

Another question......I'm certain there will be more.

Could I also have the wrong shocks or at the very least, do you have a suggestion of a set that will give me a softer feel in the rear?

I believe they are Gabriel.

Thanks...

kirt8548

The coil over I saw from Van Steel (I think) used a reinforced upper shock mount and a different trailing arm so that the coil over mounted in front of the bearing assembly. I think it kept the strut/camber rods.

The Shark Bite I saw was a radical design (if only radical looking).

My resto-mod project means to me that I want to replace the stock suspension with up-to-date replacement parts. A rack-and-pinion is coming as soon as possible.

I'd love to do a body-off resto, and an LS# replacement as well, but I'm not sure I can get that by my other lady. My plan, since she's only driven it one, is to get her to drive it more. Then when she falls in love with it as I have, the "stink eyes" will be less frequent.

Don't get me wrong, she's been wonderful so far, and understanding beyond my wildest dreams. However, I have not yet begun to spend. Besides the Vette, I'm planning on a 2-post installation in the late spring, and next year doubling the size of my 24'x24' detached garage. Yikes!!!

My wife's dream car........'69 Camaro..... Is that cool or what?

Bob Heine

Noonie,
Thanks, you answered my unasked question about adjusting for the removed leaves. Is there a reason you put the old leaf parts at the bottom of the stack?

Kirt,
I think the only shocks that could affect ride height are air shocks. If you don't have an air fitting on the shocks they aren't the problem. I have 30-year old Gabriels on mine so I'm not much help. Noonie has Konis on his car and I know they are a major upgrade over stock. I put adjustable Konis on my 71 Vega GT (in 1973) and it made a huge difference.

I haven't read any pro or con posts on either coilover setup. I can live with the $130 gamble on the Guldstrand leaf but ten times that makes me nervous.

If you want to do the frame-off and suspension upgrade, you can always replace the frame with one that has all C4 suspension mounts. That might raise a red flag with your other lady but tell her you don't want the stainless steel version -- you'd be doing it for half price!

Actually your wife's dream car is the real money pit. Decent looking (but potentially disaster zone) '69 Camaro goes for more than $20K. You can always buy a nearly new Foose '69 Camaro. They sold new for $127,000 (hmmm, Florida sales tax on that would pay for a C4 parts car and that new frame).