65 progressive springs

[Daniel D.]

[Joe L.]

Re: 65 progressive springs


Daniel-------

Are there other Corvette front springs that are progressively wound and would appear the same as the 1965 small block springs? Well, there are other Corvette springs that were progressively wound but it would depend upon how closely you looked as to whether they would appear the same. Virtually all 1965 and later Corvette front coil springs were progressively wound and there were a whole slew of different part numbers. The 1965 and 1966 small block springs were the same except that 1966 small block springs for cars with C-60 were different.

The original spring for your application was GM #3851100. This spring should have a total of 12 coils, an outside diameter of 5-3/16", and a free length of 15-7/16". The wire diameter should be right at 39/64".

[Gary B.]

Re: 65 progressive springs

Daniel,

Do you know for certain that the two ends of your coil springs are properly seated in the recessed "tracks" in the lower A-arm and frame horn?

Gary

[Daniel D.]

Re: 65 progressive springs

Joe and Gary,
Thanks for your replies.

Gary, yes, I'm pretty confident that they are properly seated. I've been struggling with this issue for a few years, and at one point I was thinking that might be the problem. When I installed the springs, I recall seating them so they were adjacent (but not covering) the drain hole in the lower A-arm. Then I read conflicting opinions that they should be aligned relative to the recess in the frame horn, rather than the A-arm. So I then used a mirror to check the seating in the frame horn, and it seemed that they were naturally seated properly in the frame horn when they were properly seated in the A-arm.

Joe, I did not realize there were other Corvette springs that were progressively wound and similar appearing. As seen in the pictures, my springs do have 12 coils, but from what you are saying, maybe they are not # 3851100. I just measured the wire diameter with my cheezy Harbor Freight caliper and came up with .597". That is very close to 39/64 (.609"). Could my springs (shown in my attached pictures) possibly be C-60 ... or are they clearly visibly different? Now I'm really stumped.

Just another thought ... the A-arm bushings were installed by the previous owner when the car had aftermarket springs that were way too long. Is it possible that the bushings are somehow set, or seized, to the high ride height? As I mentioned, I did loosen the bushing bolts and pulled the car down with straps before tightening the bolts. I would think this would have gotten the bushings in the proper position, but maybe not? Here's a picture of how high the car was when I purchased it, and before I changed the springs.

Thanks again.

[Gary B.]

Re: 65 progressive springs

Daniel,

If the wire diameter of your springs is 0.597", then they should be less stiff than the 39/64" (0.609") springs that Joe mentions, and therefore your springs should result in a lower ride height, not higher.

Gary

[Bill M.]

Re: 65 progressive springs

I just measured the wire diameter with my cheezy Harbor Freight caliper and came up with .597".

The wire diameter from the Chevrolet Engineering drawing for 3851100 is 0.600. You're good on wire diameter.

[Timothy B.]

Re: 65 progressive springs

Daniel,

If it's only 3/4" high can you post a picture showing it as it is now.

[Daniel D.]

Re: 65 progressive springs

Here are some pictures as the car sits now. As another frame of reference, the measurements from the ground to the bottom of the fenders are very close to 26" at both sides of the rear, while the front left is 26.75" and the front right is 26.5". I don't think the .25" variation of the front left and front right is unacceptable. I do realized that these measurments bring in body variations. Based on these pictures, is the front to rear variation acceptable? Am I obsessing over a non-problem. In particular the view of the driver's side bothers me. Whenever I look at the car, I feel like the front end is up in the air, especially when parked next to other midyears. But maybe I'm being unreasonable? Again, since its not a fun job to change the springs, I'm hessitant to try another set without knowing for sure what the end result will be. Edit ... I also measured the wire diameter again ... my $10 micrometer now reads .603" ... based on the limitations of my micrometer I would think that is in line with the spec number of 39/64 (.609"). I apologize if some of the pictures came through upside down. I'm still getting used to the new phone.

[Timothy B.]

Re: 65 progressive springs

Daniel,

IMO, it's fine and has a nice rake front to back. Drive it for a season and enjoy your beautiful car.

[Daniel D.]

Re: 65 progressive springs

Thanks Timothy. Maybe I am getting hung up on nothing.

Dan

[Paul C.]

Re: 65 progressive springs

Daniel: What color paint did you use on the front springs or it that natural. I bought replacement springs for my 71 and they are painted black. Trying to figure out what color paint to use to get them close to original color. Thanks Paul

[Daniel D.]

Re: 65 progressive springs

Paul,
I used Seymour brand Stainless Steel paint. I'm pretty sure that's not the correct look for judging purposes, but I wanted to preserve them and I think it's a good look. From what I've seen on TDB, I believe they were left natural from the factory, and soon rusted. If you poke around TDB you'll find some recomendations for coatings that provide a natural look but prevent rust. It seems that there are a lot of preferred products, but not complete consensus.
Dan

[Joe L.]

Re: 65 progressive springs

The wire diameter from the Chevrolet Engineering drawing for 3851100 is 0.600. You're good on wire diameter.

Bill-------

There were actually quite a few Corvette springs that used this same wire diameter. However, I really believe that Daniel has the correct springs. The 3851100 was, by far, the most common C2 small block spring.

[Daniel D.]

[Joe L.]

Re: 65 progressive springs

Thanks to all who have responded. As Timothy suggested, maybe I just need to drive the car and have fun.

Joe, I’m pretty sure that I have the correct springs too. That’s why I’m so hung up on this. Regarding the Z dimension in the AIM of 2.45 +/- .25”, in your experience is it common to have cars that have correct front end parts, but that don’t fall in that range? I suppose anything is possible, but since I’m out of ideas, is there a chance that the control arm bushings are stuck, or seized, to the pivot shafts in the position they were in when the car had the long aftermarket springs? When I purchased the car, the front end was very high, and it clearly had aftermarket springs. As I mentioned, at one point, I loosened the bushing bolts, removed the shocks, bounced the car (w/o shocks), and finally pulled the car down with straps before retightening the bushing bolts. I would think that this would have loosened the bushings on the pivot shafts, but maybe the bushings are stuck in position on the pivot shafts, and are holding the car up? I guess the hard part is that I probably need to remove the springs to determine if the bushings are stuck? It is my understanding that the inner sleeve of the bushings should be able to rotate freely on the pivot shaft when the bolts and large washers are loose. Is that correct?

Daniel------


The bushings will not be stuck. If you loosened the retainer bolts and tightened them again only after the suspension was stabilized (i.e. after you actually moved the car on the wheels for some modest distance), the bushing situation should be normal.

Can you have all correct suspension parts and have incorrect suspension dimensions? Definitely yes. However, the amount that yours appears to be out of range does seem a little much.