Leaf Spring Education Needed

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gerahead

gerahead

Glutton for Punishment
Joined
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Maple Grove, MN
My project is a 71 Dart Swinger, originally with 318 and automatic transmission. Dug the rear springs out today because I'm going to Have a guy look at them tomorrow to assess their suitability for re-arching. That is where the fun began. The two springs are no where near the same. One side has 5 leaves, the other side 4. The leaf clamps are in entirely different points along the length of the spring because the length of the leaves are dramatically different from side to side. I found the original part number on one of the springs, but nothing on the other. The unmarked spring seems to be about a 1/2" longer than the original. I suspect that the unmarked spring is an aftermarket replacement. The Mopar spring has the part number 3722242 stamped into it near where the mounting pad would be located. The Mopar spring is the one shown at the top in the photos. Are the two springs supposed to be the same? I know that there are some racing applications where a leaf is added to one side, but this was by no means ever a race car. Any help will be appreciated! TIA!

Jim

Original springs 1.jpg


Original springs 2.jpg


Original springs 4.jpg
 
I’m not sure I can help with numbers but I had a 318 duster when I was 20, almost 20 years ago and I put super stock springs on it just because they were half the price of factory ones back then. They would be different sizes. Just a thought.
 
Just from the picture of the PN. That spring is rusted beyond saving. The extra long shackles were on the springs for a reason. Time to look for another set.
 
I've agree with the above posts, I haven't heard anything bad about the ESPO springs, but another option would be the Mancini Extra Heavy Duty springs, I've had them on my Dart for years and they are a great spring too.
 
As others have said, there no point extending the life of those springs by re-arching them. Toss them in the recycle pile and buy a new pair. New steel that hasn’t already spent 45+yrs holding up over 1,200lbs and flexing/bending while covering well over 100,000 miles.
 
gerahead said:
My project is a 71 Dart Swinger, originally with 318 and automatic transmission. Dug the rear springs out today because I'm going to Have a guy look at them tomorrow to assess their suitability for re-arching. That is where the fun began. The two springs are no where near the same. One side has 5 leaves, the other side 4. The leaf clamps are in entirely different points along the length of the spring because the length of the leaves are dramatically different from side to side. I found the original part number on one of the springs, but nothing on the other. The unmarked spring seems to be about a 1/2" longer than the original. I suspect that the unmarked spring is an aftermarket replacement. The Mopar spring has the part number 3722242 stamped into it near where the mounting pad would be located. The Mopar spring is the one shown at the top in the photos. Are the two springs supposed to be the same? I know that there are some racing applications where a leaf is added to one side, but this was by no means ever a race car. Any help will be appreciated! TIA!

Jim

View attachment 1716076778

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Those springs are not rusted beyond use but the fact they had extended shackles in the rear suggests the metal is worn out. All metal have a life expectancy.

It is often found that the passenger side has an extra leaf to balance the rear end & car under hard acceleration to keep the car going straight. This is often a normal occurrence with this set up but not every car received 4/5 spring split.

The old MoPar Super Stock springs are biased in this fashion with the number of leafs increasing for heavier cars. Currently, I do not recommend the S/S springs for daily drivers though they can be used as such.

S/S springs have a large arc to them for big/tall tire clearance. They move the rear end of the car up a lot for this. There a bit stiff for what I’d call a comfortable daily driver ride.

One spring is always longer than the other in springs designed to do their job properly and even more so under more power than a stock engine. This should be ignored as when the car rests on the springs, there lengths are changed and set properly.

Leaf spring clamps are so set at there points in order to stiffen the front segment as well as help keeping the spring leafs together. The clamp placement was factory engineered.


IMO, abodyjoe gave the best advice for anything from a daily driver & long term usage to a pretty darn hot driver. I myself have used springs from espo.com a couple of times. They’re an excellent quality spring that will hold a OEM engines power and ride very well for years. I have a set in use for over 18 years now.

Again, I do not recommend re-arcing the spring due to metal fatigue and the properly operating spring performance that has gone through its cycles.

I do very much recommend a new set of springs and hardware to replace what you have now. Espo springs are IMO an excellent choice in which I highly recommend.

Contact espo and have a chat with them and tell them exactly what you have and what you’re looking for from the spring. If it’s just a replacement or a high performance spring, stock height or an inch lower or higher, they end it for you, no problem.

New springs and shipping is a bit expensive but ever so worth every penny in the end and down the road after years of use, you’ll forget the price you paid by the time you need new springs.

By which time you’ll probably need a hard bag on the spring price.
 
rumblefish360 said:
Those springs are not rusted beyond use but the fact they had extended shackles in the rear suggests the metal is worn out. All metal have a life expectancy.

It is often found that the passenger side has an extra leaf to balance the rear end & car under hard acceleration to keep the car going straight. This is often a normal occurrence with this set up but not every car received 4/5 spring split.

The old MoPar Super Stock springs are biased in this fashion with the number of leafs increasing for heavier cars. Currently, I do not recommend the S/S springs for daily drivers though they can be used as such.

S/S springs have a large arc to them for big/tall tire clearance. They move the rear end of the car up a lot for this. There a bit stiff for what I’d call a comfortable daily driver ride.

One spring is always longer than the other in springs designed to do their job properly and even more so under more power than a stock engine. This should be ignored as when the car rests on the springs, there lengths are changed and set properly.

Leaf spring clamps are so set at there points in order to stiffen the front segment as well as help keeping the spring leafs together. The clamp placement was factory engineered.


IMO, abodyjoe gave the best advice for anything from a daily driver & long term usage to a pretty darn hot driver. I myself have used springs from espo.com a couple of times. They’re an excellent quality spring that will hold a OEM engines power and ride very well for years. I have a set in use for over 18 years now.

Again, I do not recommend re-arcing the spring due to metal fatigue and the properly operating spring performance that has gone through its cycles.

I do very much recommend a new set of springs and hardware to replace what you have now. Espo springs are IMO an excellent choice in which I highly recommend.

Contact espo and have a chat with them and tell them exactly what you have and what you’re looking for from the spring. If it’s just a replacement or a high performance spring, stock height or an inch lower or higher, they end it for you, no problem.

New springs and shipping is a bit expensive but ever so worth every penny in the end and down the road after years of use, you’ll forget the price you paid by the time you need new springs.

By which time you’ll probably need a hard bag on the spring price.
Click to expand...

I believe mine shipped were just under $300.... which isn't cheap.. but for piece of mind and knowing it's all gonna last a long time it's worth it
 
rumblefish360 said:
Those springs are not rusted beyond use but the fact they had extended shackles in the rear suggests the metal is worn out. All metal have a life expectancy.

It is often found that the passenger side has an extra leaf to balance the rear end & car under hard acceleration to keep the car going straight. This is often a normal occurrence with this set up but not every car received 4/5 spring split.

The old MoPar Super Stock springs are biased in this fashion with the number of leafs increasing for heavier cars. Currently, I do not recommend the S/S springs for daily drivers though they can be used as such.

S/S springs have a large arc to them for big/tall tire clearance. They move the rear end of the car up a lot for this. There a bit stiff for what I’d call a comfortable daily driver ride.

One spring is always longer than the other in springs designed to do their job properly and even more so under more power than a stock engine. This should be ignored as when the car rests on the springs, there lengths are changed and set properly.

Leaf spring clamps are so set at there points in order to stiffen the front segment as well as help keeping the spring leafs together. The clamp placement was factory engineered.


IMO, abodyjoe gave the best advice for anything from a daily driver & long term usage to a pretty darn hot driver. I myself have used springs from espo.com a couple of times. They’re an excellent quality spring that will hold a OEM engines power and ride very well for years. I have a set in use for over 18 years now.

Again, I do not recommend re-arcing the spring due to metal fatigue and the properly operating spring performance that has gone through its cycles.

I do very much recommend a new set of springs and hardware to replace what you have now. Espo springs are IMO an excellent choice in which I highly recommend.

Contact espo and have a chat with them and tell them exactly what you have and what you’re looking for from the spring. If it’s just a replacement or a high performance spring, stock height or an inch lower or higher, they end it for you, no problem.

New springs and shipping is a bit expensive but ever so worth every penny in the end and down the road after years of use, you’ll forget the price you paid by the time you need new springs.

By which time you’ll probably need a hard bag on the spring price.
Click to expand...
With that rust on the exterior just think what they look like between the leafs.

original-springs-2-jpg.jpg
 
Thanks guys for all the responses. I am especially grateful for the tip on the link to ESPO. I have requested a quote for new replacements. The "shackles" were added, I'm sure, to create enough lift for the tires on wheels that too much positive offset. Plus they are dead flat with the normal weight of the car on them. Sorry for sure.
 
Update . . . I had already dropped the springs off to be evaluated for repair/re-arch when I made the original post. As it turns out, even if I wanted to go that route, the shop said it probably wouldn't last long and they didn't recommend it (good, honest shop!). If, after all that, I still wanted to go through with it, it would have cost about 2X the cost of a new set of springs. Gonna be placing an order with ESPO today! Thanks to all who replied!
 
H22A4 said:
As others have said, there no point extending the life of those springs by re-arching them. Toss them in the recycle pile and buy a new pair. New steel that hasn’t already spent 45+yrs holding up over 1,200lbs and flexing/bending while covering well over 100,000 miles.
Click to expand...
I did read it thanks for the info it all helps ME
 
harrisonm said:
Wow. I would not have expected that. Then why offer the service?
Click to expand...
Because some people HAVE to have the correct part number on their springs and are willing to pay for it. Some times replacement springs aren't available. Some times you have to use your local guy because you don't trust some stranger over the phone. Lots of reasons why people rebuild their original springs. I used ESPO myself and Laura is very helpful and made sure that I got the right spring for my car.
 
BrianT said:
Because some people HAVE to have the correct part number on their springs and are willing to pay for it. Some times replacement springs aren't available. Some times you have to use your local guy because you don't trust some stranger over the phone. Lots of reasons why people rebuild their original springs. I used ESPO myself and Laura is very helpful and made sure that I got the right spring for my car.
Click to expand...
Thanks. I guess I knew that, but I was just surprised it was so expensive. I have never had springs rebuilt/re-arched, and I had no idea how expensive it was. I assumed it would be cheaper than buying new.
 
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