Late 63 Rear Spring

[Chuck G.]

I know it's been asked before. Searched the archives with no luck.

I have what I truly believe to be the original rear spring for my 63. I've owned this car since 67. It's a 2 stage spring, NOT a 1 stage. It's got 3 straight top leaves, and 6 curved lower leaves, NOT 9 curved leaves.

It's a late car, 194XX VIN, built in July of 63.

Back in 67, after I bought the car, I got "into" autocrossing. Took off the springs and replaced everything with F41 "stuff". Also put on some Hi Po cylinder heads. Stored the rear spring and heads in the basement of my parents house.

In the early 80's I retrieved these items from my parents home, and reinstalled them, SO, I know for a fact that this is/was the spring I removed in 68 or so.

The JG calls for a single stage spring for "ALL" 63's. What's your opinion? TIA. Chuck

[Gary B.]

Late 63 Rear Spring

Chuck,

Short of finding one or two Bowtie, late build-date '63 cars with two-stage rear springs, I think you'll have a next to impossible time convinving the judges.

Gary

[Tracy C.]

Re: Late 63 Rear Spring

Chuck,

15 years ago I bought some parts from a fella who totalled his 63 coupe back in 64. At the time he didn't have insurance so all he could do is strip it out before it went to the junk yard.

The rear spring I bought from him was the typical 63 9 leaf single stage spring. His car was late enough to have was the straight grain style machine marks on the steering wheel (I bought that too) The JG says that change occured after VIN 18400.

While 67 was early in your car's life, it would have been almost 4 years after the two stage spring arrived on the scene. That is long enough for the previous owner to know about the difference and "upgrade" the unit for what he believed to be an suspension improvement.

It would be interesting to hear from others on this. My car to 203XX and I plan to use the rear spring I got in that parts deal unless other evidence crops up.

tc

[Duke W.]

Re: Late 63 Rear Spring

I don't recall ever hearing any previous claims/discussion that late '63s have variable rate springs, either front or rear.

Duke

[Joe L.]

Re: Late 63 Rear Spring

Chuck-----

In my opinion, the spring is likely original to the car, whether or not it would be acceptable from a judging perspective. This is the sort of "running change" that could easily have occurred even though it might not be documented in the AIM or elsewhere. The "dual stage" spring is direct successor to the earlier "single rate". In other words, no other parts would have to be changed to use it in place of the earlier spring. If the "dual stage" springs had started to arrive in the plant before the beginning of the 1964 model year, I think that they would just have started using them in the cars (assuming that the supply of single rate springs was exhausted). While engineering approval would have been required, I don't think that it would have been difficult to get, whther or not any documentation of it exists. It's even possible that such a change is documented in a copy of the AIM with pages dated later than the copy from which all of the manuals we have were made. We tend to think of the AIM as "definitive". However, it was an "ever changing" document and there is no reason for us to really expect that the version that we have had the final, updated version of every single page for every single model year.

Personally, I highly doubt that anyone changed the spring during the first 4 years of the car's life, unless the car suffered some major rear damage during that time.

[Chuck G.]

Re: Late 63 Rear Spring

Thanks for the input. I've got the entire rear torn out of the car. I'm changing the ring and pinion, going from 4.11 to 3.55. If I'm going to change the spring, now is the time.

I could be wrong about this spring, but in "legalese", I would have to say that "to the best of my recollection" it is the spring I took off the car in 68. The car has never been hit, so damage isn't/wasn't an issue. The car had 30K miles on it when I bought it.

I understand that Eaton makes a "dead on" reproduction 63 spring. It goes for about $160.00 as I recall. Is anyone familiar with Eaton's repro spring? Chuck

[Ray C.]

Re: Late 63 Rear Spring

Hi! Chuck

I recently installed an Eaton 9 leaf single stage Eaton replacement spring in my 1963 SWC. The company was very easy to deal with and the spring was at my door step with in a couple days.

The spring came unfinished and with out spring liners. I used PPG DP-90 as a primer and Quanta Chevrolet spring gray as a top coat. I purchased my spring liners from Bair's. I am very happy with the results.

Ray
#36314

[Chuck G.]

Re: Late 63 Rear Spring

How does the spring look, compared to an original? End cuts/angles the same? Does it have the little "curl ups" on the end of each leaf? Chuck

[Gary B.]

Late 63 Rear Spring

Chuck,

The Eaton springs for 63-78 or so are NOT dead one. The taper rolled "curedl up" ends are clearly different from original. Any knowledgable chassis judge should be able to tell the difference. Having said that, no one makes a spring that is any closer cosmetically to the original than the Eaton spring. But if you want 100% correct cosmetics that will not get a judging deduct on looks, you'll have to restore an original spring. Used, original single stage '63 springs can be found.

Gary

[Michael H.]

Re: Late 63 Rear Spring

I agree with what the Duke said. In fact, I seem to vaguely remember that the 63 front AND rear spring package carried over to very early 64? Wonder if there's a part number change listed in the 64 AIM?

[Donald T.]

Re: Late 63 Rear Spring

The part number in the 64 AIM is 3850839. There is no part number change listed. There is an "NPC-18" handwritten after the part number - whatever that means. I don't have a 63 AIM for comparison.

[William C.]

Re: Late 63 Rear Spring

Spring in the '63 AIM (at least the on I have) calls for 3794095 spring exc Z-06 AIM page was updated 6-5-63 for Spindle change.

[Michael H.]

Re: Late 63 Rear Spring

Yep, the original master AIM shows the same Bill. No updates on the 3794095 spring number. The master was updated right to the end of 63 prod so if there was a change, it would have shown it.

The part number 3850839 for the new 64 spring is too high, numerically, to have been released for start of 64 production. Would probably have been somewhere around 3845xxx to 3847xxx.

I think the same is true for the new for 64 front coil springs. I believe that number, 3851100, is also too high, numerically, to have been used from SOP 64. I'm guessing some time within the first month of 64 production.

[Joe R.]

Re: Late 63 Rear Spring

The Eaton spring is similar, but not identical to the original. If the leaves of your original are in good shape, you may want to find a decent used 63 spring and get the top three leaves from that.

By the way, Eaton will also re-arch an original spring the "right" way, which consists of heating the leaves to remove the spring temper, bending them to achieve the correct arch, and then re-tempering them and shot blasting them.

It is possible that your top three leaves could be arched during this process to conform to the correct 63 design. To find out whether this is feasible, you can call Eaton Detroit Spring and ask Mike Eaton himself. He is quite accessible and easy to talk to.

[Gordon Peterson #4961]

Re: Late 63 Rear Spring

Joe -

How long did this two-stage spring remain in use? Did they ever go back to the single-stage 9-leaf design or is this 63-only?

THANKS

Pete