Re-arching is a term which applies to steel leaf springs only. Once fiberglass or composite springs loses their ability to support weight, nothing can be done to salvage them.
Also nothing can be done to salvage tired coil springs.
The re-arching process results in the spring being brought back to it's original free arch. There are 2 ways of re-arching a spring. But only one correct way.
The most popular method is to use either a hammer or a press to change the arch. This is known as "cold setting". This is the method used by most shops.
Using the "cold setting" method will result in a short term fix. Spring steel has a memory and unless this memory is erased the spring will return to the height it was prior to it being raised and will happen even without weight on the spring.
Cold setting is not an acceptable way to re-arch a spring.
The only acceptable method of re-arching starts by erasing the spring's memory. This is done by annealing, then reshaping and finally re-heat treating each leaf in the spring.
In order to anneal a spring it must first be taken apart. Then each leaf is visually inspected for signs of fatigue.(see below)
Then each leaf is blasted to remove all paint, rust or whatever and re-inspected.
If the leaves are OK then each leaf is heated to at least 1,650 degrees Fahrenheit.
Once heated the leaf is placed on a pattern which has the correct shape and arch.
Once re-shaped the leaf is quenched in special oil to quickly cool it. The heating and quick cooling process results in a leaf which is too hard or brittle to be a spring.
So the leaf is then re-heated to at least 950 degrees for a set amount of time drawing out some of the hardness.
Once cooled the leaves are then shot peened to relieve stress.
The final product is a properly tempered re-arched, re-heat treated spring.
We are one of the few companies with the ability and equipment required to perform this operation.
First is cost. Re-arching is at a premium above the price of new springs. Minimum charge for re-arching is $225.00 per spring assembly. Add to this the price of new bushings, liners, clips, labor to re-assemble them and shipping costs. No, the old parts cannot be reused.
However, if you have a straight axle Corvette or any other car with original style grooved steel, the cost is well worth it to maintain originality because this type steel is no longer made.
Second consideration is the condition of the springs.
If your springs show any of these conditions, they would not be candidates for re-arching.