Thread: re-arching your leaf spring tech

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The rear 1928A spring was tired from old age, had lost too much arch,so I need to add it back,this is my way,there are other ways but I did it this way on my race cars in the 60/70's; I'm rebuilding my old highschool hotrod from 1959 and took a few photos as igo.
Tech of Arching Leaf Springs Cold.
In photos you see drawing on floor so I can tell what I'm doing to each leaf, and my homemade jackbox that I use for more then just this,but a reguler press would work pritty much same way.
This done wrong can hurt you ,so it's a be super careful thing .
I've seen it done with a big F*#@%*^ hammer ,but I use a 8ton bottle jack,6ton would work OK I think.

I use my homemade jack/press box,that I also used to press other stuff like piston pins,axle bearing etc. with 8ton jack;
Before you take old spring apart,lay it down sideways on floor and draw a chauk line close around it,so you know the shape it was and can lay your re-arched spring down there a see the change. This also done with each leaf,but I like taking the size from the leaf from tip to tip,after you re-arch[ it has more arch and will get shorter from tip to tip size,this I think is a good way to be sure your getting a match to left and right leaf if doing parale leafs and also a good way to see how much it has gained in arch=some like to check height of arch/that's fine but length is most accurate.
Clamp the hole spring with two strong "C" clamps each side of center bolt before dissembling .
One leaf at a time is then laid across "C" and the jack press pushes it between the blocks with Angle welded on top of jack. Pressure is applied slow and care-full across each leaf at a 90-degree angle to places along the length to get bend into or out of spring=it can snap spring if you go to much and that is big danger.

This is done along the leaf mostly in the already bent area. Pressure is applied about every in. or so until the entire length of the leaf looks about as even a it did before but now a little more bend=it will be shorter/like if it was 36in. from tip to tip,it could be 35in, now. You get a feel of pressure on the leaf’s surface and try and use same amount each place. Applying too much pressure will break a leaf.
The 1 & 2 photos are of my "A" rear spring getting arch added.

Front spring was lost many years back,so had to make up a new one.
The last photo is my front spring all done,it's actuly made up from parts of two def front springs to get the rate/hight I needed. When I had the rod together,I was able to stack it a few times for testing how many and what size leaf it took to hold the right ride hight under the load.

Cold arching gives you a temporary "fix", but to get it more permanent each leaf is annealed to remove hardness and the "set" of the spring, re-arched as needed, then re-tempered to "set" the shape memory back in the metal. Gotta have an oven to do it hot, or you can mess up. How long does your cold arch process generally last before the spring starts working back?

Hi Roger,
I'm a bit low $,always have been, a do it your self type FOR THE PASSED 70 YEARS. Was thinking there is a few out here in hot rod land that may not of ever seen this done. We had a guy at the race track that would redo your springs with big fricking hammer on a peice of RR rail right there in the pits,but ya didn't wish to stand anywere near him as he did that. He's nick name was "Jimmy The Leaf" at Hialeah Speedway in the 1960's.
Going too far though can mess things up,like with most anything we do!
I've built hotrods and raced stock cars starting in the late 1950' and it was done this way then,under race condishtions cold rearch would last pretty well,but to put a time exactly is a bit hard. I never had a spring go back completly to were it started,but they do settle kind of just like a brand new spring dose for first 50 or so miles+ and kind of stops and holds that for some years.
Yes ,hot and retemper is engineering right way in the books,but costly high tech way that works only if some one knows how to retemper ,other then a pro spring place/shop.