I just bought a 70 L46 coupe. It's a mild resto job and one of the issues is the rear suspension. The spring bushings are shot as well as the bottom shock bushings. They are actually GONE. The bottom shock mounts are just rolling around in the eyelet.

After reading about the composites, I'm going to get the VBP 330# spring. And the Bilstein HD shocks all around. This will be more of a cruiser than a canyon carver. My question is, should I go ahead and get new front springs now? The front suspension still looks pretty good, but will the stock front spring rate be OK with the composite and Bilsteins? Or do I need to go ahead and get the 460 GT VBP coils?

 

I just replaced my spring with a new stock spring with new bushings and Bilsts. in the rear. Very surprised at how well it rides and the height of the car, which had a serious sagging problem. Also stayed with the originality factor. Just a thought regards R

 

If you want to use the 330# rear spring (which is nearly twice the stock rear spring rate), and keep the stock front springs, you will have to compensate with at least a 1" (or even 1 1/8") front stabilizer bar, otherwise I think the car's balance will be towards oversteer.
The 460# front springs will balance the 330# rear spring a bit better, with increased ride harshness. What you can do to try to get the best of both worlds is to install the 460s with an upper spring seat cushion. I used the Moog K160066, which almost fit. I taped one to the top of each front spring with fiberglass reinforced strapping tape.
But if you just want a comfortable cruiser, you might be happier with a softer rear spring. The Hyperco EZ Ride composite rear spring has a rate of 180 or 200 lb/in, probably within 15% of stock. You will most likely not need to change anything else if you use that. Eckler's, and I think, Van Steel both sell them.
Have fun.

 

Thanks for the input guys. At first, I thought this was going to be an easy decision. I had seen a number of posts that said the VBP 460/330 combo actually rode better than stock, which I took to be a less harsh ride while providing better handling. After reading your responses, I searched again and read a lot of posts that really just served to confuse me, like this one:

http://forums.corvetteforum.com/c3-t...af-spring.html

I guess a car's ride is as subjective as music or food preferences. No way to know for sure what you like till you try it.

gcusmano74, I had read a couple posts on the Hyperco springs raising the rear too much so I'd discounted them for the VBPs. Unfortunately, VPB doesn't sell a near-stock rate composite, which is what prompted this post. After your post, I did some more searching on the Hypercos and it seems some, like you, like them and some don't. But I guess that's the same with any product.

I think what I may do for now is just get a new set of spring bolts/cushions and complete set of stock style shocks. I can drive it awhile like that and then when I decide to change (if I do) to a sportier suspension. At least then I'll be able to make my own comparisons.

 

I've been doing more reading about Corvette suspensions. My car has a 7-leaf rear spring. I've read this is a big block only spring so I guess someone swapped it out at some point. It does have the curled leafs though so I guess they swapped it for an original?

I'm thinking this spring is not a good match for the rest of the suspension, given gcusmano74's comments above. I read that the 7 leaf spring is 305#. This would put it back in the same territory as the VBP spring. The front sway bar is 3/4" and there is no rear. The front spring diameter measures at .600, which I've read is stock small block.

It looks to me like someone just swapped a big block/F-41 rear spring on. Maybe they were drag racing and were trying to reduce squat? Not sure. It's looking like I'm going to make some changes though to make the car handle properly.

 

FWIW, the 305# is all the rear spring rate most road going C2/C3's will ever need. And, you can also properly balance a shark without a rear bar.

TSW

 

Thanks TSW, if I stay with that spring for a while, should I go to a 7/8" or 1" sway bar (not sure what the options are) to offset the stiffer rear spring?

 

Your best option is to get a 1 1/8 sway bar from an 81-82 vette. There is a man just south of us that parts out vettes. I'm sure he has several.
Mike

 

Yes, with stock or 460# front coils and 305# or higher rear spring I'd step on up to the 1-1/8" bar, and then see where that puts you.

 

I took a look at :

gmheritagecenter.com for your front/rear spring specs and they are:

Front coils: base 250 lbs, 284 lbs-Sport? or BB

Rear-9 leaf listed only-base- 140lbs

Based on these numbers the spring rates were VERY soft. Going to a 300/330 rear spring and a good shock like the Bilstein HD's will really stiffen the car out back BUT not as much as the numbers indicate since monoleaf composites have VERY different ride and handling characteristics versus a steel spring even one of MUCH less of rating.

Going to a 460 front spring (from a 250/284 Stock spring) and a 1 1/8 inch sway bar (and no rear bar) will almost guarantee the car will understeer severely IF you pushed it hard but it should ride pretty nice with much less float and lean.

As a comparison my 78 with the gymkhana suspension and stock front coils of approximately the same ratings as yours and a Steel 7 leaf 292 rear spring with a 1 1/8 inch front bar AND a 7/16 th rear OEM type bar was setup up from the factory to understeer which it did. I now have a 360 rear mono spring with Bilstein sports and 550 front springs with Bilstein HD shocks with the stock 1 1/8 inch front bar and a 3/4 inch rear OEM TYPE BAR and the car is very neutral, no oversteer, and handles and rides great.

Hope that helps!

 

Thanks for the info guys. I decided to put major changes to the suspension off for a bit. I bought this car from out of state and here in Texas it has to pass a state inspection before I can title and license it. I have 30 days from the date of sale to get that done or I pay a penalty and it's already been a couple weeks. I've got to replace the wiper motor, windshield and fix the headlight wiring and vacuum before I can get it inspected.

So for a temporary fix, I put on a new set of inexpensive Monroe shocks yesterday. The old ones were completely shot and it was bottoming out over big bumps. I replaced the sway bar links and am going to replace the strut rods and spring bushings in the rear as they're pretty shot too. Once I get it legal, I'll drive it around a bit like that just to get a feel of what a pretty close to stock Vette feels like. I'll do some more readin' and thinkin' in the meantime and figure out what I want this car to be and what I need to do to get there.

 

When you get back to it, do bear in mind you needn't have written off a 6-figure tub to accept that it's prudent to take conservative steps in solving from the understeer end of the equation, rather than to risk overstepping things in one swell foop. Besides, one can't accurately gauge a car's true balance (IMCO, "neutral" handling can be somewhat an ambiguous/confusing term) by anything indicated at less than its actual limits anyway. ...whether you intend on finding the edge or not. So, assuming it is adequately calibrated or can become sufficiently educated, I'd recommend you listen to what your backside tells you more than any specific advice (including mine) of what particular collection of kit should do the trick.

 

Looks like you're in a very similar situation to mine. I got a 1970 L46 and knew the entire suspension will have to be looked at. I left the front springs stock, rebuilt the control arms, new ball joints, tie rods. In the rear had to get new trailing arms, got a VBP 330 spring and Bilsteins HD all around. Also got the competition heim strut rods. I went with the 330 as I did not want it to be too harsh. Car will be getting aligned and back on the road in 1-2 weeks. Interested to see how it feels.....

Oh... and 330 + HDs was also recommended to me by the VBP guys for the "perfect" NJ roads....

 

Very interested to hear your feedback. Your car should ride great (versus a steel spring) and handle significantly sharper. My car has a 360 composite, poly everywhere (including front control arm bushings), 550 front springs, and competition heim joints struts and Bilstein Sports in the rear and HD's in front, and the ride is NOT harsh at all-Its very comfortable BUT i don't have the POS balloon 255/60/15 tires any longer (255/45/17 ZR Modern rubber)-they are BIG contributors to the fair handling of stock C3's the poor bouncy ride quality of these cars.Karol and I were just speaking last night at a car show about how bouncy/harsh his 78 L-82 all stock base suspension (not a gymkhana) and stock tires (255's) is versus my L-82 original gymkhana (all upgraded now). He has ridden in my car and commented that the car rides MUCH better than his base suspension and is just planted on the road. My car rides and steers like a modern sports car. Offering 30 years of experience working/repairing and upgrading my 78 L-82.

Hope that helps!

 

I will be very interested in your impressions too, rafalc. Let us know what you think.

So far, I've rebuilt the brake calipers, put new Cooper Cobras on (225/70's), replaced the shocks with the Monroes and replaced the sway bar links. Still waiting for the strut rods and rear spring mounts, but I took it for a short drive yesterday. Just doing that much was a BIG improvement. It was all over the road before, and now it drives decently. The tires were probably from the 70's (F70 Polyglas), wore out, and as jb mentioned, I suspect they made the most difference with a significant help from the shocks. I was hitting the bump stops on the back over rough bumps and it's not doing that anymore. Not sure how long the Monroes will last with the stiffer spring though.

I'll probably still replace the front sway bar soon to try to balance the stiffer rear spring. I'm also going to have to address a pretty serious off-idle stumble. It has a Holley that may need to be rebuilt as I suspect this car has been sitting for quite a few years.

jb78L-82, you mentioned you used poly bushings all around. Do they squeak at all? I have a 2004 Grand Prix GTP as a daily driver. A couple of years ago I completely rebuilt the suspension with performance stuff all around. It was the first time I'd ever used poly and I'd always heard that a lot of people have squeaking issues. But I figured I'd take a shot. The poly is definitely good stuff for performance. That thing will go around a corner at 300 MPH, but it squeaks and groans like grandpa's old farm truck. I swore from now on that unless I'm building a track car I'll never use poly again, or at least not without installing grease fittings if possible.

 

If you're interested.... you can see here what Ive done so far. Lots of suspension work. Should be back on the road in 2 weeks.

http://forums.corvetteforum.com/c3-g...r-project.html

 

Wow! Nice work. I'm in the middle of a full resto on a classic Mustang. I've stripped it down to the shell (unibody) and done all of the rust repair and body work, and it's now ready for painting in my homemade garage booth. One thing I really like about Corvettes is no sheet metal to repair. It's my first complete restoration and I'm finding out just how much work it really is, so kudos for what you're doing.

I particularly like your garage. Mine is full with the Mustang so I'm working on the Vette in the driveway under a Coleman camping canopy to keep the Texas summer sun off me. It's only 12' X 12' so I gotta keep moving it around to the part of the car I'm working on at the moment. It's been 100 degrees or more pretty much every day since I got the Vette. Can't wait for fall.

 

No nothing squeaks on the car. I heavily greased the control arm bushings before I put them in-Not a daily driver though.