Dr Diff Offest Kit With Oval Track Springs

[72bluNblu]

the point is, if the thickness of the main leaf is different then the spring rate is different.

First, that isn't true. The spring rate isn't determined just by the thickness of the main leaf. It depends on the entire spring pack, even the length of the other leafs in the pack makes a difference. It also depends on the spring constant of the steel being used, which depends on the composition of the steel and the heat treat. The main leaf being a different thickness, by itself, doesn't prove the spring rate is different. If the spring constant of the steel is different the thickness of all the leafs could be different and the spring rate could be exactly the same.

And, even if the spring rate is different, what does it prove? All it proves is that the springs aren't meeting the advertised specs, which we already know because they don't work.

even better, if you have some old MP oval track springs, you can measure the main leaf and then the OP that mangled his newer MP springs can measure his main leaf and figure out if that has changed.
I put some MP SS springs on my car a few years ago, i read all the posts about the hecho mexico springs sagging and I was actually hoping mine would level out some. no luck there..

I can measure the AFCO's and the new oval tracks, but again that doesn't really tell us anything important. We already know there's a manufacturing problem.

I don't have a set of the old oval tracks. I wanted a set, but they were out of production when I started buying springs, which is why I got the AFCO 20231M's. You can still buy the chrysler style AFCO's, just not in a 120 lb/in spring rate (next available is 142 lb/in, 20230). The AFCO's went out of production at exactly the same time the Oval Tracks came back. I suspect that's because of a copyright deal, AFCO could make them when MP wasn't. But I don't know that for sure, maybe AFCO just didn't want to compete, or they weren't selling enough for it to matter much. All I know is that whenever the MP oval track springs have been available the AFCO 120 lb/in springs haven't been. And it was literally at the same exact time, I wanted another set of AFCO's. Summit only had one spring left and no one else had any at all. And the MP oval tracks were available again with an estimated ship date dependent on the arrival of the first shipment.

 

[72bluNblu]

I had a minute so I measured the thickness of the main leaf on the AFCO 20231M’s on my Duster and the yet to be installed MP oval track springs that already look goofy (flat spot in the arch).

AFCO 20231M main leaf = .300”

MP oval track main leaf = .325”

Now what was I saying about there being more to it than the thickness of the main leaf?

 

[AJ/FormS]

IDK if this will help but here's what I did
Back in the late 70s I had a 73 Swinger 318 with saggy springs. I removed the Springs and took them to a local Spring Shop. I told them to re-arch them 1 inch and add a second mainleaf, eye to eye. Those springs have gone from car to car ever since and over 40 years later are on my current 68 Barracuda still in use today. Yes they have sagged a lil over the years but I have dropped the front to match, and the car handles pretty good.
I have no clue what the spring rate might be;Is there room on the spec table for "pretty doggone stiff"?

 

[cookietruck]

I had a minute so I measured the thickness of the main leaf on the AFCO 20231M’s on my Duster and the yet to be installed MP oval track springs that already look goofy (flat spot in the arch).

AFCO 20231M main leaf = .300”

MP oval track main leaf = .325”

Now what was I saying about there being more to it than the thickness of the main leaf?

that's interesting. you said these two sets of springs are the exact same specs.
so all the supporting springs are the same lengths on each and the arches are the same, the main leaf is thicker on the MP spring by almost 10% but it is actually weaker. crazy.

 

[72bluNblu]

that's interesting. you said these two sets of springs are the exact same specs.
so all the supporting springs are the same lengths on each and the arches are the same, the main leaf is thicker on the MP spring by almost 10% but it is actually weaker. crazy.

As far as I know they’re the same specs. The list the same spring rate and the same overall length with a 1/2” longer front section than original (22.5”). They have same number of leafs (4), and are supposed to have the same arch.

Now, I hadn’t measure the leaf thickness until yesterday, and I’ve never had the spring rate confirmed through testing. Like I said though, the same spring rate doesn’t necessarily mean the same thickness leafs. That depends on the metallurgy of the steel.

I kinda doubt the design specs were changed, I would wager that was a change at the production level. And apparently not a good one. Could have been deliberate, trying to make up for lesser quality steel. Or it could have just been what that factory was set up for, so, easier and cheaper and to hell with the specs as long as it’s close.

Lots of changes happen between design and manufacturing, usually not for the better. Obviously Mopar Performance isn’t doing much quality control on this stuff anymore.

 

[famous bob]

that's interesting. you said these two sets of springs are the exact same specs.
so all the supporting springs are the same lengths on each and the arches are the same, the main leaf is thicker on the MP spring by almost 10% but it is actually weaker. crazy.

Not really, depends on the quality of the metal, and heat treatment .

 

[kursplat]

It’s a stock 383 spring. Go look on the Eaton site. They are listed there. took me 5 minutes at the time to find them at the time. No where does he say they were specially spec’d for him...
Product Inquiry by vehicle look up 69 dart gts with 383 engine.
View attachment 1715322342

i'm guessing we're talking about the 130lb ?

 

[abodyjoe]

yes

 

[kursplat]

since Bergman was brought up earlier, i emailed to see what they have:

"Hi Chuck,
I do. 6 leaf, 130lb. 595 pr. Ride height would be similar to the attached."

 

[1975abody]

Is it possible they are putting the spring pack together backwards? The bottom leaf looks like it might be much more effective if at least it was reversed.

I installed the MP oval track springs on the Scamp last weekend and had the same thought. As soon as I set the car down, the springs did the typical reverse arch, so I took the bottom leaf off and spun it around so that the longer end of the spring was supporting the forward section of the pack.

That took most of the reverse arch out of the forward section of the pack.

My take was screw it, they're junk anyway, have nothing to lose.

I've put about 500 miles on it since then without any problems.

@72bluNblu - do your Afco oval tracks springs have a bottom leaf that is longer towards the front, or is the long end towards the back ?

 

[DionR]

I installed the MP oval track springs on the Scamp last weekend and had the same thought. As soon as I set the car down, the springs did the typical reverse arch, so I took the bottom leaf off and spun it around so that the longer end of the spring was supporting the forward section of the pack.

That took most of the reverse arch out of the forward section of the pack.

My take was screw it, they're junk anyway, have nothing to lose.

I've put about 500 miles on it since then without any problems.

I am working on doing a defective part return with Jeg's. Got the ok and the paperwork, just need to put it all together and ship them back.

I know I am throwing away some on shipping, but at least I get some of my money back (assuming I have to pay for the shipping back).

@72bluNblu - do your Afco oval tracks springs have a bottom leaf that is longer towards the front, or is the long end towards the back ?

See this post: Dr Diff Offest Kit With Oval Track Springs

 

[72bluNblu]

I installed the MP oval track springs on the Scamp last weekend and had the same thought. As soon as I set the car down, the springs did the typical reverse arch, so I took the bottom leaf off and spun it around so that the longer end of the spring was supporting the forward section of the pack.

That took most of the reverse arch out of the forward section of the pack.

My take was screw it, they're junk anyway, have nothing to lose.

I've put about 500 miles on it since then without any problems.

@72bluNblu - do your Afco oval tracks springs have a bottom leaf that is longer towards the front, or is the long end towards the back ?

I'll take a look in the morning and compare them to my Oval Tracks. It's occurred to me before the spring pack could be assembled wrong, but I haven't mounted the oval tracks yet so it hasn't been a priority for me. Too many projects.

 

[famous bob]

I'll take a look in the morning and compare them to my Oval Tracks. It's occurred to me before the spring pack could be assembled wrong, but I haven't mounted the oval tracks yet so it hasn't been a priority for me. Too many projects.

I bought a pair of s/s 002/003 springs some yrs back that the pass side was assembled wrong .
Guess where it was made !!

 

[1975abody]

I flipped the lower leaf on the Scamp last week, and drove it back and forth to work all week, and then on a 400 mile work trip today and have not seen any issues.

So I flipped the lower leaf on the Duster today.

Before and after pics below.

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