Re-arching leaf spring

[David B.]

I am replacing the spring on my 71 with a used original. It is in good condition with only a little surface rust. I was considering having the spring re-arched. I checked the archives and could find nothing on the process that eaton springs uses to re-arch springs. They actually re-heat treat the leafs and then anneal them. My main concern with this is the loss of carbon in the metal and the affect it would have on the spring. Has anyone had this done to their springs or know of someone that has? I have checked eaton springs web site and have their info but would rather hear from people I trust, NCRS people.

Thanks Dave

[Craig S.]

Re: Re-arching leaf spring

Hi Dave - another option is to replace the lower main leaf only, and just use the original upper leaves versus rearching. Gary Beaupre wrote several articles on this in the restorer in the past year or two. I personally would use this approach versus rearching. Also, make sure new cushions are installed in the end links as this can also result in loss of height....Craig

[Dave Suesz]

As the late Dale P explained to me...

Heat treating is essential. If the arch is changed cold, the spring is merely weakened. The spring must be annealed to take the arch, and heat treated to restore proper hardness. I doubt the amount of heating involved would have any measureable effect on the carbon content, we're not taliking about re-forging at yellow or white heat. Dale did hundreds of these, maybe someone will tell you how they held up on their car.

[Louis F.]

Re: Re-arching leaf spring

Dave, i had my spring re arched at a well known corvette restoration shop.While i was having a lot of other work done.There was mutual agreement that my car was sitting low in the rear and that re arching was an alternative.They told me re arching a spring has a 50% success rate.I agreed to having it done to preserve the original spring. I don't know what process was used, or if it was even done right. I can only tell you after a few months if that the car was sitting low again.I still have the original spring in my garage. So if anyone knows of a place i can send it to have it properly re arched please let me know.

[Richard E.]

Re: Re-arching leaf spring

Dave - John Hinkley did a great article for the Corvette Enthusaist last month. It covers in detail the process that Eaton does, at least for C-1 springs. They cover heat trating, annealing, shot peening, etc. A lot of guys, will "cold arch" springs, but I don't think they will hold up. The procedure Eaton uses can also be found on their website: http://www.eatonsprings.com/rearching.htm

Regards, Dick Eaton (no relation, darn it)

[Jim T.]

Re: As the late Dale P explained to me...

Dave did Dale P. tell you where and who did the actual annealing?

[Gary S.]

Re: Re-arching leaf spring

There is an article in a very old Restorer, by Tim Gilmartin, about re-arching an original 64 spring. If you have the CD you might do a search on it. I believe he did a cold re-arch.

IIRC, Gary Beaupre's article mentioned an unsprung resting height of 10.5" +/- (don't remember the fraction). There have been a lot of comments about resting height being restored merely by adding new liners and spring end cushions. Does your spring have a negative arch - the ends are higher than the middle? With a standard load, the springs I have seen are almost, but not quite, flat. Very little positive arch in them.

I had my 72 spring re-arched 3 1/2 years ago. The car sat just a wee bit low and the arch was 9.?" Don't remember that fraction either. Duke's advice not withstanding, all he did was use a 100 ton press and add some more arch to the spring. This spring shop, in the Pittsburgh area, does a lot of custom and classic car spring work, according to the owner.
Gary

[Chuck S.]

Re: Re-arching leaf spring

I haven't seen John's article, but that's at least two really nice tech articles he's done for them...I may have to subscribe (or join..."Just the magazine would be worth the dues!").

Let's see if I can remember something I learned during my matriculation at Hard Knocks U. (formerly known as Whatsamatta U.). There is a temperature ("transition" temperature?) above which the elemental molecules in steel will be begin to "migrate in solution", but the steel remains in a solid (but VERY HOT) form.

If steel is heated above the transition temperature and allowed to slowly air cool, THERE IS NO LOSS OF CARBON, but the carbon molecules tend to migrate to the grain boundries during cooling. This maldistribution of carbon molecules creates weakness at the grain boundries and a tendency to cracking. The trick, and not too difficult considering the heat it takes to get steel to that stage, is to remain below the transition temperature.

Maybe a real metallurgist will chime in here.

Bullwinkle

[Dave Suesz]

As far as I know...

He was doing it himself, but he may have been taking the bare leaves to a shop somewhere. A good industrial spring shop should be able to do that part for you.

[John H.]

Re: As far as I know...

Dale had his springs done by a fellow named Gary Smith in Memphis, Tennessee, whose shop had the proper heat-treat, annealing, and shot-peening facilities to do it correctly. Don't have any more contact info than that.

[John H.]

Re: Re-arching leaf spring

I described the Eaton spring manufacturing and re-arching process in the March issue of "Corvette Enthusiast" magazine; in short, the leaves are heated to 1800*F, formed, oil-quenched to room temperature, then annealed in a draw furnace at 1000*F for 30 minutes, allowed to cool in ambient air, and are then shot-peened. The shot-peening process reduces residual stresses on and adjacent to the surface, and doubles or triples the service life and durability of the spring.

Cold mechanical re-arching doesn't restore a spring's load capacity or service life, and doesn't erase a spring's "memory"; cold re-arched springs will soon deflect back to their previously "sagged" state, as that process doesn't deal with spring metallurgy.

[Gary A.]

Re: Re-arching leaf spring

I have a bent spring on my 59. I have talked to Mike at Eaton and have had the great input of the guys on the forum. I am pulling the springs this week and sending them to Eaton for the whole process. I'll keep you posted on how they turn out. gary

[David B.]

Re: Re-arching leaf spring

Hello Gary and everyone else that responded to my question.

I have my spring crated up to ship out tomorrow to eaton spring also. After hearing what everyone else had to say and talking to Mickey at eaton I think it is the best way to go. A little expensive, but what on a corvette is cheap.

Thanks again everyone , Dave