Dr Diff Offest Kit With Oval Track Springs

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I`m no expert, but reverse arch springs aint right on a mopar, or much anything else ! -----------jmo
 

I don’t have any pics, but the wheel was centered when I first put them on. Now the front of the spring is curves up. It wasn’t like that before, it was more flat. The torque obviously deformed them. Perhaps these springs are designed for 2000lb cars, not 3400lbs
 
I don’t have any pics, but the wheel was centered when I first put them on. Now the front of the spring is curves up. It wasn’t like that before, it was more flat. The torque obviously deformed them. Perhaps these springs are designed for 2000lb cars, not 3400lbs


Did the ride height change after the springs deformed into reverse arch ?
 
I don’t have any pics, but the wheel was centered when I first put them on. Now the front of the spring is curves up. It wasn’t like that before, it was more flat. The torque obviously deformed them. Perhaps these springs are designed for 2000lb cars, not 3400lbs

It’s not a design problem. The old oval track springs were fine. The new springs are just crap, they’ve got some kind of production issue.
 
Flattened out circle track spring vs Hotchkis.
E8E8D42E-2B62-4FCA-8E8B-540FCE671B96.jpeg
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Bergman Autocraft sells a custom set of Eaton springs with a 130 lb/in rate that Peter Bergman spec’d out. They’d be my first choice, they’re high quality springs. But again, expensive.

I don’t think they are specially spec’d out. They are right out of the Eaton catolog and are are drop shipped to ya. He does recommend getting the -1” ones for like $40 more though. I went stock height because I was worried about sitting too low. I should have gone with the -1” springs.
 
@72bluNblu

Do you have Afco leaf springs on your Duster ?

Yes. The ones I run are AFCO 20231m’s, they’re a 120 lb/in spring. They’re no longer available from AFCO, they were discontinued immediately following the re-release of the MP oval tracks. The specs are identical to the MP springs, I have wondered since it happened if there wasn’t a licensing deal there.

The AFCO Chrysler style springs are still available in other spring rates, but 105 lb/in is too light and 142 lb/in is too heavy for most A-bodies in my opinion, at least for streetable tire compounds. The 142 lb/in springs might work if you have a heavier car and skip the rear sway bar.

I don’t think they are specially spec’d out. They are right out of the Eaton catolog and are are drop shipped to ya. He does recommend getting the -1” ones for like $40 more though. I went stock height because I was worried about sitting too low. I should have gone with the -1” springs.

I’m just going off of what Peter has said here. He’s said before that the Eaton springs on his car are custom built.
 
I’m just going off of what Peter has said here. He’s said before that the Eaton springs on his car are custom built.

I don’t think so. He has the same spring he sold me only with a 1/2” lowering block. I found them on the Eaton site pretty fast before ordering them from Pete. They are just a 383 dart spring.
 
I don’t think so. He has the same spring he sold me only with a 1/2” lowering block. I found them on the Eaton site pretty fast before ordering them from Pete. They are just a 383 dart spring.

Like I said...
Custom Eaton springs, moved in .5". Bilstein RCD shocks.

And
After playing with several types of springs for my Dart, I have a formula that works...However, I wanted to share a profile shot of the Dart with the springs installed. These are 130 lb springs that have a heavily reinforced front section and sit at the proper height. If you use a 26" tall tire, the height will be 22" vertically from the ground, through the centerline of the wheel up to the wheel lip. The picture is at 21.5" because I use a 1/2" lowering block as well.

Doesn’t sound stock to me. What say you @GMachineDartGT ?
 
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. At the time he described them in a thread (maybe he deleted this part) but he had posted what you highlighted plus said they were Eaton springs made for a 383 dart. Just had to plug in the info and they popped right up.

He did his homework and found
/researched them, then tried them on his personal car and spread the word which is why I bought them from him. I could have bought straight from Eaton but figured I’d give Pete the sale and credit for a sale to eaton.

Product Inquiry by vehicle look up 69 dart gts with 383 engine.


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Flattened out circle track spring vs Hotchkis.
View attachment 1715321648 View attachment 1715321649

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.

Haven't compared them to other springs, just a thought.

I am going to replace mine, and I only have 50 miles on them (drove it to Dad's and parked it all winter while I upgraded the front). I expect to have the same issue as racerjoe with a pinion angle being way off. Not sure what direction to go for another spring yet, but have to do something. Frustrating.
 
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.

Haven't compared them to other springs, just a thought.

I am going to replace mine, and I only have 50 miles on them (drove it to Dad's and parked it all winter while I upgraded the front). I expect to have the same issue as racerjoe with a pinion angle being way off. Not sure what direction to go for another spring yet, but have to do something. Frustrating.

I installed the new Hotchkis springs over the weekend. I have the Mopar offset hangers, not the Dr. Diff ones, so I'm not familiar with the hole location on those. Years ago, I had drilled a second hole for the spring higher than the original hole to lower the car. The "geometry corrected" Hotchkis bracket has the hole just about in between the two holes I had in my bracket. Instead of drilling another hole I tried the top hole first- way too low. Took it back apart and put them in the lower hole, which I believe may be close to same location as a stock hanger. This resulted in a good ride height.
 
I installed the new Hotchkis springs over the weekend. I have the Mopar offset hangers, not the Dr. Diff ones, so I'm not familiar with the hole location on those. Years ago, I had drilled a second hole for the spring higher than the original hole to lower the car. The "geometry corrected" Hotchkis bracket has the hole just about in between the two holes I had in my bracket. Instead of drilling another hole I tried the top hole first- way too low. Took it back apart and put them in the lower hole, which I believe may be close to same location as a stock hanger. This resulted in a good ride height.

On the offset MP hangers I have on my Duster the spring eye hole was a little higher than the stock ones on my car. Not much though, maybe like a 1/4” drop? They’re probably supposed to be stock height.
 
Well, swapped my 45+ year old springs back into the car.

Just to refresh, I bought the Circle Track springs last year about this time, installed them last September or October, drove the car to my Dad's about 40-50 miles and it has sat ever since. I haven't even dropped the clutch on the car yet.

The new leaf springs are documented to have a front segment 1/2" longer than stock, but based on the first picture with the the "new" leaf springs and the last with the old ones back in, the difference in axle location is about an 1". I did measure the front segment and agree with the published data, so I am guessing that the extra 1/2" is due to the rear axle rolling backwards due to the S curve in the front segment.

MP springs:

P5040617.JPG


MP Spring Axle Location.JPG


OEM spring:

OEM Spring Axle Location.JPG


I am convinced that the springs deformed as soon as I loaded them. I am basing this on the trouble I had getting the bottom eye of the shock installed on the pin. I thought this was due to the axle moving back in the chassis, but the more I think back on it, I am sure that it was because the spring had deformed putting a significant misalignment between on top and bottom pins. In addition, I don't believe the axle has changed location in the wheel well since I installed the springs as I noticed how far back the axle was immediately after setting the car on the ground.

Here's some comparison pictures of the 45+ year old springs that were under the car and the "new" MP springs. I did clean the OEM springs up and put some paint on them just because I didn't want to put rusty springs back under the car. But they are just OEM 6 leaf springs that held the car up fine.

Even unloaded you can you see the S curve in the front segment. In fact, it really doesn't look like the springs have any "spring" to them based on a comparison of the installed and loose pictures.

P5040619.JPG

PA050616.JPG

P5040621.JPG

P5040622.JPG

P5040629.JPG


@72bluNblu, I would be curious to hear how the front segment of your AFCO springs are built. Do they have a leaf that extends all the way to the front eye like my OEM springs? Or do they leave the main leaf unsupported for 4" or so like these MP springs?

Either way, I see a real issue with materials based on the fact that they spring didn't even try to return to it's previous shape when unloaded.

Pure junk.
 
Well, swapped my 45+ year old springs back into the car.

Just to refresh, I bought the Circle Track springs last year about this time, installed them last September or October, drove the car to my Dad's about 40-50 miles and it has sat ever since. I haven't even dropped the clutch on the car yet.

The new leaf springs are documented to have a front segment 1/2" longer than stock, but based on the first picture with the the "new" leaf springs and the last with the old ones back in, the difference in axle location is about an 1". I did measure the front segment and agree with the published data, so I am guessing that the extra 1/2" is due to the rear axle rolling backwards due to the S curve in the front segment.

MP springs:

View attachment 1715331355

View attachment 1715331349

OEM spring:

View attachment 1715331350

I am convinced that the springs deformed as soon as I loaded them. I am basing this on the trouble I had getting the bottom eye of the shock installed on the pin. I thought this was due to the axle moving back in the chassis, but the more I think back on it, I am sure that it was because the spring had deformed putting a significant misalignment between on top and bottom pins. In addition, I don't believe the axle has changed location in the wheel well since I installed the springs as I noticed how far back the axle was immediately after setting the car on the ground.

Here's some comparison pictures of the 45+ year old springs that were under the car and the "new" MP springs. I did clean the OEM springs up and put some paint on them just because I didn't want to put rusty springs back under the car. But they are just OEM 6 leaf springs that held the car up fine.

Even unloaded you can you see the S curve in the front segment. In fact, it really doesn't look like the springs have any "spring" to them based on a comparison of the installed and loose pictures.

View attachment 1715331351
View attachment 1715331356
View attachment 1715331352
View attachment 1715331353
View attachment 1715331354

@72bluNblu, I would be curious to hear how the front segment of your AFCO springs are built. Do they have a leaf that extends all the way to the front eye like my OEM springs? Or do they leave the main leaf unsupported for 4" or so like these MP springs?

Either way, I see a real issue with materials based on the fact that they spring didn't even try to return to it's previous shape when unloaded.

Pure junk.



Funny you mention you had problems with the shocks. I also had problems with that. What I hadn't noticed prior to taking everything apart was the shocks were also contacting the gas tank. They are a big fail all around. I hope this prevents someone from spending money on them.
 
Well, swapped my 45+ year old springs back into the car.

Just to refresh, I bought the Circle Track springs last year about this time, installed them last September or October, drove the car to my Dad's about 40-50 miles and it has sat ever since. I haven't even dropped the clutch on the car yet.

The new leaf springs are documented to have a front segment 1/2" longer than stock, but based on the first picture with the the "new" leaf springs and the last with the old ones back in, the difference in axle location is about an 1". I did measure the front segment and agree with the published data, so I am guessing that the extra 1/2" is due to the rear axle rolling backwards due to the S curve in the front segment.

MP springs:

View attachment 1715331355

View attachment 1715331349

OEM spring:

View attachment 1715331350

I am convinced that the springs deformed as soon as I loaded them. I am basing this on the trouble I had getting the bottom eye of the shock installed on the pin. I thought this was due to the axle moving back in the chassis, but the more I think back on it, I am sure that it was because the spring had deformed putting a significant misalignment between on top and bottom pins. In addition, I don't believe the axle has changed location in the wheel well since I installed the springs as I noticed how far back the axle was immediately after setting the car on the ground.

Here's some comparison pictures of the 45+ year old springs that were under the car and the "new" MP springs. I did clean the OEM springs up and put some paint on them just because I didn't want to put rusty springs back under the car. But they are just OEM 6 leaf springs that held the car up fine.

Even unloaded you can you see the S curve in the front segment. In fact, it really doesn't look like the springs have any "spring" to them based on a comparison of the installed and loose pictures.

View attachment 1715331351
View attachment 1715331356
View attachment 1715331352
View attachment 1715331353
View attachment 1715331354

@72bluNblu, I would be curious to hear how the front segment of your AFCO springs are built. Do they have a leaf that extends all the way to the front eye like my OEM springs? Or do they leave the main leaf unsupported for 4" or so like these MP springs?

Either way, I see a real issue with materials based on the fact that they spring didn't even try to return to it's previous shape when unloaded.

Pure junk.

The AFCO’s are similar to the MP’s with the last 4” or so unsupported by the second spring. I haven’t had any issues with the AFCO’s though. They’re pretty flat but they don’t reverse at all.

I think those MP’s are just made out of crap steel, or maybe not heat treated properly.

698B79D6-7A36-4D36-914B-A2A41EF0A80C.jpeg
 
if you guys have calipers, maybe measure the width and thickness of the main leaf of the MP oval track springs and the AFCO springs.
 
if you guys have calipers, maybe measure the width and thickness of the main leaf of the MP oval track springs and the AFCO springs.

To determine what? We already know something is wrong with the oval track’s production.

The AFCO 20231M’s are no longer in production. The MP oval tracks are not being made by AFCO. The AFCO’s are USA made, the MP’s are being produced in Mexico (all the MP springs have been for at least 10 years now).

The overall design of the AFCO’s is the same the the MP oval tracks. Same length, same axle location, same number of leafs, same designed spring rate. The difference is in the actual manufacturing. The old MP oval tracks didn’t have these issues either, it’s just the current production run of MP oval tracks that do.

I mean, sure, I can crawl under my Duster and measure the thickness of the leafs on the AFCO 20231m’s I have and compare that to the MP oval tracks I have for my Dart, but what is that supposed to tell me? If they’re the same, it just tells me the oval tracks have a manufacturing issue- heat treat, steel quality, whatever. If they’re different, it still just tells me they have a manufacturing issue. Either way, I can look at the oval tracks and tell something isn’t right.
 
The overall design of the AFCO’s is the same the the MP oval tracks. Same length, same axle location, same number of leafs, same designed spring rate. The difference is in the actual manufacturing. The old MP oval tracks didn’t have these issues either, it’s just the current production run of MP oval tracks that do.

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