I am the original owner of a 1972 Corvette Stingray, 454 c.i., 4-spd, PB, PS, A/C, Air Injection Reactor (A.I.R.). The car is original and I want to keep it that way as much possible. 89K miles. The rear leaf spring has flattened out some.

I am trying to decide whether or not to replace the rear leaf spring (9 leaves - curled ends). I read about some of the aftermarket springs have a ride heighth that is too high. I have been talking with Mike at Eaton Detroit Springs. Here is his response:

"2 different 9 leaf springs were used. The 1st is a 2 stage spring with the 6 longest leaves curved and the shortest 3 leaves straight. This rate for this spring is variable starting at 140 lbs for the 1st stage and 196 for all 9 leaves.
The second 9 leaf spring has all 9 leaves curved. The rate for this spring is 196 lbs.

We have them both. The ends are as close to OE as possible but the indivual leaf thickness is slightly thicker because the steel mills are no longer making the GM size. The functionality of the spring is the same.

We dip the springs in black EPA friendly paint to keep rust from forming. we do not attempt to paint them like GM did.

The spring you need is our part number ML357P"

Has anyone had any experience with Eaton Detroit Springs?

Any advise would be appreciated.
You can see a pricture of it at my Web Site.

 

Hi Lady -

Nice Vette!

A few thoughts:
1) If your cars frame is in pretty darn good shape, you might look into having your leaf spring re-curved. Perhaps someone locally could do it. The reason I suggest this is because you said the spring has flattened "some," meaning it's not too bad. If re-curving it works, you'll be able to hang on to the original spring, which might help with NCRS judging.
There might be others who can discuss the success of re-curving your spring.
2) If you decide on a new spring - From what Mike is saying, I'd have a tendency to go with the spring with 3 flat leaves. I've seen photos of Vettes with new springs and some of them are really high in the rear! Not good! Even though the spring rates are both 196 max, you might ask Mike if the height of the spring is the same on both (the highest point of the arch).
3) Pay with a credit card. That way if there is a problem, you have recourse. I think you'll be OK with Eaton, although I've never used them.

 

I'm also interesting on the rear 9 leaf spring for my 72 SB, I know Duntov sale like original with the Curled Leafs for $204 Free Freight, but I know there is also a company that have a boot at Carlisle sale also the rear spring with Curled Leafs, I don't remember there name.
What the cost at Eton?
Thanks, Avner

 

There are spring shops that can re-arch the springs. If you order springs you could also get the longer end bolts so you would have them if needed.

 

The 1st spring being offered to you by Eaton is the best steel spring available at present. It's not a 100% perfect repro from a cosmetic point of view, but is spot on from the functional side.

You have my word of honour that I will never lie on the ground and crawl underneath to tell you that it's 'wrong'. Word around here is that's what all of us evil NCRS types do all day.

 

72 Corvettes with the 454 used a 7 leaf rear spring, not a 9 leaf. The original GM part number for the all rear springs used with 454's was 3977578. There was only one spring rate for rear springs on 454's, this spring did not change based on optional equipment. Front springs varied based on whether or not the car had air condintioning. Actually, all 65-74 Corvettes with big blocks (396, 427 or 454) came with a 7 leaf rear spring, and a rear sway bar. 9 leaf rear springs only came with small blocks, and did not include the sway bar.

Neither of the springs mentioned would be correct for your car and a 2 stage spring would not be correct for any Corvette, as all original Corvette rear springs utilized curved springs for all 7 or 9 leafs.

None of the aftermarket springs currently available are exactly correct in appearence to original. The thickness, as mentioned above, and also the cut of the spring ends is different on all of the aftermarket springs I'm aware of. I would consider having spring shop look at them.

 

Thank You Z-Man.

My car has never been abused. I drove this car to work (18 miles round trip) everyday for 18 years. After that I decided (because it was still original in mint condition) to show this car in Local Shows; drove it less to keep the mileage down. In 1992 it was NCRS judged and won Top Flight. Best I remember the score was 97.1. In 1993 it won the Bloomington Gold “Survivor” Award. At the Corvette Homecoming it won “Best Coupe.” I belong to NCRS and the National and Regional Antique Auto Club of America.

I know every inch and parts of this car. It has never had to have anything major done – just good maintenance. Always did the work myself.


So, the frame is in Excellent Condition.

I had a trusted Corvette mechanic look the car. He said although the spring had flattened “some”, that he would not recommend replacing it. He said it was still within good limits. He said that I needed to replace the leaf spring bushings and link ends. The rubber has dried out, cracked and some of the rubber is gone. The mechanic said he has not seen a replacement spring with the correct ride height, yet. The replacement he has seen have had too high of a ride height.

I did talk with Mike at Eaton about rearching the spring. They provide that service. Following is his response:

“The rearch/retemper service we provide may be able to be done to your old spring. We cannot tell for sure until we have it in our hot little hands. No one knows for sure how long a spring will last, too many variables come into play. However, if everything is right, then the spring should last for a long time.”

Mike at Eaton had to the following to say about the ride height of their leaf spring:

“The free height of our spring has been adjusted so the car maintains stock ride height. Other technical things have been done so the spring provided factory ride qualities.”

Z-Man, you state you have never used Eaton’s springs. Whose have you used, if any? Who was the original manufacturer of the leaf spring for the 1972 Corvette?

Yes, I would be sure to pay via Credit Card.

 

Avner Thank You.

I talked with a gentleman at Duntov Motor Company about their nine-leaf spring that they have for $204. The gentleman, told me that he thought that the springs that they offer come from Eaton. They are dipped in black paint. I ask him to verify/confirm that because, if it is the same spring, Duntov is slightly cheaper. However, Duntov wants and extra $200 to paint their spring with the original gray primer to make it meet NCRS judging guidelines.

Eaton wants $224.95 plus shipping for their nine-leaf spring.

The gentleman at Duntov never returned my call to confirm or deny that their springs come from Eaton.

 

Mike Ward, Thank You.

That sounds encouraging.

 

Ganey, Thank You.

Yes, I would think it would be wise to have the longer bolts on hand.

 

abvette, Thank You.

I special ordered this car. I am the original owner of this car. Build Date: 11-71. It came with a nine-leaf spring. NCRS judging manual states that the 1972 454 with a standard suspension used a nine-leaf spring. Everything that I have read states they came with a nine-leaf spring. The heavy-duty (F-41) suspension used a seven-leaf spring.

What is your source that shows the seven-leaf spring for the 1972 454 with standard suspension and the part number specified? Or is the info you provided for the F-41 suspension?

I believe all 1972 Vettes with the standard suspension came with a nine-leaf spring.

I will take your advice and look into whether or not there is a local spring shop.

 

According to the Fourth Edition 1970-1972 Corvette Technical Information Manual and Judging Guide that is not correct.

"The standard rear spring was nine-leaf; heavy-duty (F-41) suspension used a seven-leaf spring. Factory production numbers indicate that in 1970 and 1972 F-41 heavy-duty suspension was only available with the ZR-1 option. In 1971 the F-41 suspension was available on any Corvette. Owners of 1970 and 1972 Corvettes with F-41 should be prepared to document the authenticity of that option when having their cars judged".

LadyStingray, you should stick with a nine-leaf unless F-41 is on your option list.

cc

I see you beat me to it.

 

If your are going NCRS, why not send your original spring to Mike. He can re-arch it and then you'll have the exact correct spring for the car!

Eaton Detroit can re-curve the spring and they will do this the correct way. Most spring shops do what is called cold arch and is not the correct way. Eaton will do this hot and re-temper the spring. (the only correct way to do it).

IMHO,

Willcox

 

F-41 is not on my list. I want to keep the car as much original as possible

 

Wilcox Corvette,

I appreciate the advice. I may leave the spring as is until I can get the car NCRS judged again. It been 15 years since they judged it. I don't want cold arching. The more info I get, the more I am leaning toward sending the spring to Eaton as you advise; if I do anything.

 

On a side note concerning your rear spring:
Have numbers matching '72 SB Coupe 108K miles. Did upgrades - Dart heads, Edelbrock intake, HEI dist, Holley carb, front steel springs & TRW fiberglass rear (longer link bolts are installed), suspension upgrade included (rubber) bushings, 5 speed Tremec, etc at 103K miles. Still sports original paint.
The TRW fiberglass spring sucks - can't find a shock to control rebound (on my 3rd set). Didn't know at the time of upgrading that I could have had the original spring recurved, so I trashed it - big mistake. Just bought a stock 9 leaf steel spring from MAM @ $129 (painted black). Will install as soon as weather gets warmer. I definitely remember after 30 years of driving this C3 how it rides and I thought it was very good with the original spring. Stay tuned for results. This is a driver (many great trips - East Coast/West Coast, Tijuana to Thunder Bay) and since we bought an '08 Z51 coupe is now a weekend car. Good luck with getting your spring recurved.
http://photos.stlcorvettes.com/2008P.../DSC_0159.html