Rear spring re-arcing

[Dave C.]

One of my projects this winter is to fix my rear spring, it is the original 7 leaf F41 unit, but it has collapsed so much that someone has installed 3"" spacers on bolts that go to the trailing arms, just to keep it at the right height, I do have a local spring shop here that could probably re-arc them , but how would they know the right amount to make it sit properly, am I better off to just buy an I an aftermarket spring?

[Larry M.]

Re: Rear spring re-arcing

America's Finest Corvettes advertises an exact replacement/reproduction for the 7 leaf HD rear spring.

I would also check with Gary Beaupre on this forum. He may have some measurements and specs on this spring. He did a couple of articles for the Restorer awhile back.

Larry

[Dave C.]

Re: Rear spring re-arcing

Thanks , Larry, just looked that up, at $380.00 for an exact reproduction, it might not be worth screwing around with my old one, I will check with Larry though

[Bob R.]

Re: Rear spring re-arcing

Many of the smaller local spring shops use a cold method to re arch the spring and this typically will not last long. Eaton Spring Company uses to process to properly get the spring back to the original shape and strength. However when I sent them my spring they told me there was too much pitting to re arch. I suggest you call and speak to them. I think the cost is around $150.00 plus shipping if my memory is correct.

[Gary B.]

Re: Rear spring re-arcing

America's Finest Corvettes advertises an exact replacement/reproduction for the 7 leaf HD rear spring.

I would also check with Gary Beaupre on this forum. He may have some measurements and specs on this spring. He did a couple of articles for the Restorer awhile back.

Larry

Larry,

I think the article that Joe Lucia and I wrote for the Restorer around 2003 or 2004 has the specs for the HD spring, but other than that I really don't have any other data to add to the discussion. Years ago I purchased a repro 9-leaf spring from Eaton Detroit and measured its load-displacement properties up to around 1400 lbs using a heavy duty, servo-hydraulic materials testing system. The results of that test are in the first of three articles i wrote for the Restorer on the standard, 9-leaf spring. I've never had the inclination to purchase one of the "exact" repro 7-leaf springs from AFC, so I can't speak with any authority about the AFC spring. For several years AFC claimed they were working on making an exact 9-leaf standard spring, but it's been long enough now that I think they must have scrapped those plans. It seems to me it was a strange choice to make a 7-leaf repro when there should be much more demand for an "exact" 9-leaf repro, which to this day does not exist.

I would advise anyone thinking of purchasing a 7-leaf spring from AFC to look at the article that Joe and I wrote and make sure the AFC spring matches the style for the year of car that it will be used on. The 7-leaf spring changed in various ways over the years, as is described in a table in our article, including things like the presence or absence of a flat spacer plate.

Gary

[Mike M.]

Re: Rear spring re-arcing

One of my projects this winter is to fix my rear spring, it is the original 7 leaf F41 unit, but it has collapsed so much that someone has installed 3"" spacers on bolts that go to the trailing arms, just to keep it at the right height, I do have a local spring shop here that could probably re-arc them , but how would they know the right amount to make it sit properly, am I better off to just buy an I an aftermarket spring?

over the years, i've had c-1 and c-2 original springs re-arched locally, cold style process. as long as the cars are essentially trailer queens, the arch holds up. i think even a thousand miles a year won't de-arch the puppies all that much. i did have one bad experience with re-arching a pair of 57 springs(on the 283/283 that has been to the drag strips multiple times after it got its Duntov and before i installed a set ofLakewood traction bars.) i ended up installing a pair of after market springs to level the old 57 out. mike

[Joe L.]

Re: Rear spring re-arcing

One of my projects this winter is to fix my rear spring, it is the original 7 leaf F41 unit, but it has collapsed so much that someone has installed 3"" spacers on bolts that go to the trailing arms, just to keep it at the right height, I do have a local spring shop here that could probably re-arc them , but how would they know the right amount to make it sit properly, am I better off to just buy an I an aftermarket spring?

Dave------


I don't recommend "re-arching". First, you need to disassemble and inspect the spring leaves. If there is serious corrosion-induced pitting on any of the leaves, the spring (or, at least, those leaves so-pitted) is unfit for any further use.

If the leaves all check out as OK, then all you need to do is to clean up the spring, paint the leaves, and install new liners. Then, install the spring with new cushions and you should be fine.

[Dave C.]

Re: Rear spring re-arcing

Thanks guys , good info here, Joe the spring in the car is really nice other than the fact that it is sagging so bad, I think I am probably better off to replace it , although the car is probably only going to see 1000 miles a year or less, I guess I'll give the spring shop a call and see what they will charge, then make a decision .

[Paul O.]

Re: Rear spring re-arcing

Dave

I would do what Joe has stated first. The change in your ride height with new liners and cushions most likely will return your car very close to original. Have seen several re-arched springs by Eaton on cars the ride height was to high. Just my 2 cents.

[Duke W.]

Re: Rear spring re-arcing

Dave------


I don't recommend "re-arching". First, you need to disassemble and inspect the spring leaves. If there is serious corrosion-induced pitting on any of the leaves, the spring (or, at least, those leaves so-pitted) is unfit for any further use.

If the leaves all check out as OK, then all you need to do is to clean up the spring, paint the leaves, and install new liners. Then, install the spring with new cushions and you should be fine.

Exactly! Contrary to popular belief, springs do not "sag" unless seriously overloaded during their life. What typically kills them is corrosion, which can eventually break a leaf. If it took a three inch spacer in the trailing arm link bolt to establish normal ride height, I would suspect a broken leaf, but before any conclusions can be drawn, a thorough inspection is required.

Minor surface pitting is okay, but large corrosion craters or notches would indicate the spring is no longer serviceable.

For reference it might be a good idea to weigh the spring on a bathroom scale before disassembly and after all the leaves are cleaned up. I think a new original 9-leaf weighs somethilng on the order of 43 pounds. If you can get a weight spec for a 7-leaf, comparing it to your measured weighs will give a good idea of how much material has been lost to corrosion, and I would be concerned if it's more than about 5 percent and definitely if more than ten percent.

The most common cause of low rear ride height is simply compressed/hardened spring link cushions. They can be replaced in less than an hour by jacking up the spring ends until tension is removed from the link bolt, then removing the link bolt and hardware and replacing with new cushions.

Duke

[John H.]

Re: Rear spring re-arcing

Link below will take you to the feature article I wrote in "Corvette Enthusiast" magazine on the Eaton-Detroit Spring manufacturing process, which is the same process they use to "re-arch" existing springs.

http://www.lbfun.com/warehouse/tech_...ton_Spring.pdf