Thoughts on rearching front spring

[Gold Digger]

My 30 Tudor is about 3 1/2 inches low in front. Just wondering how long a rearch job will last on the front spring. I've rearched springs on jeeps years ago and the arch stayed for 4 years with out loosening it in one of them when I sold it and lost track of it. Others I've done seemed to hold up OK.

[updraught]

A bit of an explanation here

https://www.youtube.com/watch?v=leOdN0mO9DI

Seems to depend on how much torture you give it afterwards.

[J Franklin]

Originally Posted by updraught

Seems to depend on how much torture you give it afterwards.

Springs done properly will last many years.

[BRENT in 10-uh-C]

Not sure what I gained by listening to that video.

Now here is my opinion based on actual experience doing this on a Model-A. Each leaf was forged into shapes starting with a high carbon steel. Over time through constant pressure, the spring leaf takes on a new shape. So by pressure onto the spring over time can cause the spring leaf to be re-shaped, then contrary to what some may say, with an opposite higher force of pressure that same spring leaf can be shaped again. In this instance, the leaf has opposite pressure thus returning it to near a former shape. We have been doing this on quite a few cars for the past several years, and we have not seen any failures. Something to note however, just because a spring leaf has been re-shaped does not guarantee it will retain that shape forever. Having that mindset of a permanent repair is like suggesting a engine that has been rebuilt should last forever, -or replacing body wood should be permanent too. Everything has a life cycle, and re-arched spring leaves is no different.

More to this here.... https://www.fordbarn.com/forum/showp...38&postcount=6

[Will N]

From posts I've seen here, looks like re-arcing the spring might be your only option, as it seems new authentic springs are not being reproduced at this time.

[Phil Brown]

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Even if you could get an authentic looking new spring now who's to say how long that it might last the way quality is on so many things today.
I'll take the known good quality steel that was made 90 years ago and give it a "tune up" I'm sure that it'll out last most of us

[alexiskai]

Brent, how much force are you using when re-arcing? Having the sweeps is important but are you doing it in a press or just through leverage of some sort?

[BRENT in 10-uh-C]

Colin, I use a press. While it has a gauge, I don't think we are even applying enough pressure to measure it. On the top side is a 1" round bar, and underneath we fabbed 2 pieces of 2" to maybe 2½" round bar that is spaced a few inches apart. The spring just clears the upper and lower bars when slid in, and one pump on the rapid side is what we use to save time. It is basically one stroke, then release, then move the leaf an inch and make another stroke. Sometimes we have an area that needs more so we may press with two strokes to over-bend it. Layout from the center hole where the tiebolt goes, and make chalk measurements about every inch until the end going both directions. Use the chalk marks to align the upper die in the press to. Again, the sweeps and out setup fixture is what helps us save time, but it is easy enough to do with whatever tools someone has.

[JayJay]

I re-arched my front spring using a much less precise method than Brent, but in the end it was effective. First, determine that your spring needs to be re-arched. The eye center-to-eye center measurement should be 30-5/8" to 30-13/16", and the arch should be 4-7/8" to 5-1/8" from the bottom of the spring leaf to the table when the spring is resting on its eyes. These numbers are published in a number of places, but I used this document that appears to be pretty well accepted (I don't know who wrote it or when it was written, but it's pretty comprehensive).

I followed the directions in the document for hand arching the springs. I used a Sharpie to put tick marks on the underside of the spring, and then clamped the leaf in a big bench vise with the tick mark at the top of the jaws. I used a couple of pieces of 1/4" steel to avoid getting vise jaw marks on the leaves. I then put a big crescent wrench on the end of the leaf and leaned on the wrench until the back of my workbench lifted up (I told you this was crude!). Rinse and repeat. I did not bother to re-arch the top (short, with the square hole) leaf. I measured the arch of each leaf before and after, I got anywhere from about 1/8" to 3/8" on each leaf I worked on.

When I put the spring back together it was actually a bit over-arched, but I think that will even out in use.

I tried the same on the rear spring but the leaf material is so much thicker that it only was effective on the longest of the leaves.

All the spring leaves needed to have their lower surfaces relieved at the tips to get rid of the sharp sheared edge. In addition, quite a few had trenches dug into their top surfaces from the aforementioned sharp edges, and I ground those lips down. I did this all before I re-arched.

I painted the bottom of the bottom leaf and the top of the top leaf with enamel, and then all the rest of the leaves with graphite paint.

In hindsight, it would have been nice to have the sweeps to be able to verify that each leaf was where it should be. I found a local company that would have hot-arched to original sweeps, but since I didn't have that data I decided to do it the way I described above.

[alexiskai]

Originally Posted by JayJay

I re-arched my front spring using a much less precise method than Brent, but in the end it was effective. First, determine that your spring needs to be re-arched. The eye center-to-eye center measurement should be 30-5/8" to 30-13/16", and the arch should be 4-7/8" to 5-1/8" from the bottom of the spring leaf to the table when the spring is resting on its eyes. These numbers are published in a number of places, but I used this document that appears to be pretty well accepted (I don't know who wrote it or when it was written, but it's pretty comprehensive).

I recently watched a video by a fellow who followed this procedure. It's a two-part video – in part 1 you see him arc the leaves and in part 2 he re-assembles. Long story short, it's ineffective. He gets a higher arc on paper but the car sits the same as it did before he started.

I think it's hard to use this method, in part because the force is applied crudely and it's easy to underestimate how hard to pull, and in part because most guys won't have a known-good reference arc to aim at.

https://www.youtube.com/watch?v=VpGXCdKo05w

[Phil Brown]

Here is what I made to do mine, very similar to what Brent described
Also one added note DO NOT press at the very center of the spring where the bolt hole is, you will break the spring through the bolt hole. Start an inch away each direction.

[alexiskai]

Originally Posted by Phil Brown

Here is what I made to do mine, very similar to what Brent described
Also one added note DO NOT press at the very center of the spring where the bolt hole is, you will break the spring through the bolt hole. Start an inch away each direction.

I feel inspired, I kinda want to make my own. I'd need the sweeps though.

[JayJay]

Originally Posted by alexiskai

I feel inspired, I kinda want to make my own. I'd need the sweeps though.

Same here, if I ever do another one (which at this point in my life I think is unlikely).

[mcgarrett]

An interesting read on this topic from Hagerty:
https://www.hagerty.com/media/mainte...gs-a-lost-art/

[Fullraceflathead]

Excellent spring rearching fixture!!!

[JRrev]

Years ago a guy in our city had a business that he called a blacksmith shop. He made springs as well as rearching/rearcing springs. So, my first Model A's spring was fatigued and I took it to him. It didn't last a driving season. I had him make a new one and it lasted several years. Don't know his method and don't think he did it so I'd buy a new one.

Relative to new ones by Eaton Detroit, they told me they had the original print but didn't make them to print because the sales volume wouldn't support the minimum order for those various thicknesses of steel. Likely, someone needing a new spring wouldn't notice the difference in load and rate of their not-to-print spring. A friend who was a Ford suspension engineering supervisor used Eaton Detroit to make prototype springs. Because of his pull he was able to get Eaton Detroit to make each of us a spring to print by having thicker steel milled to spec. It cost us roughly 3 to 4 times their normal repro Model A front spring.