Leaf spring shackle inversion

[Asher Bird-Meyer]

Hello all. I have a 1974 Plymouth Duster in which I have replaced the leaf springs. And now the rear shackles are both totally inverted and pushing hard into the trunk floor. I'm using a slightly taller and wider wheel and tire setup (15x8 wheels and a 255/65 tire) and because of this I guessed I would need as much clearance as possible, so I ordered a 6 leaf spring that provides a 2.5" lift from General Spring (part # 33-909). In hindsight - probably overkill. But I really did not want these wheels to not fit. I installed the front mount first and when I went to install the rear shackle mount I noticed it was a bit of a reach. Almost like the spring was short. Not sure if anyone has experienced this before but I'm not sure what to do. Did I mess up ordering such a beefed spring? Do I need longer shackles? Really not sure...
The car has a 7 1/4 rear with the larger 4.5" bolt pattern. Any tips would be much appreciated. Thank you.

 

[Professor Fate]

Not an uncommon situation.
Jack it up so the suspension is hanging. Then get a pry bar in the shackle and twist it around to it's proper position, and set it back on the ground.
It will look a bit iffy, but new springs will settle a bit and you'll usually be okay.
If you really feel that the 6 leaves are overkill, you could always try removing the small leaf from each pack and see how that rides and how the height suits you.

 

[Kendog 170]

I had the same thing. I was afraid if I went upward on a bump they might flip and damage my trunk. I took them out and added a leaf to my current springs with a leaf from an old set I had. Maybe I'll try again this year.

 

[72bluNblu]

Not uncommon when installing new springs, have had it happen a couple times. Just do as professor fate said and flip them back, shouldn’t be an issue.

 

[Murray]

Make sure you have the correct shocks on it with the correct travel/droop.

 

[Dana67Dart]

You should be fine as long as when the shocks are attached and the rear is at full droop the bottom of the shackle is still pointing rearward. If its still an issue you can add a plate 1/2" thick maybe 1/4" thick ( longer bolts too) behind the shackle perch to move the perch forward


Obviously the shackle would be put into the correct orientation before bolting it all back together

 

[dano]

The spring gets longer when weight is placed on it. Flip it around as others have stated, as the springs settle with weight, it will bias the shackle towards the back of the car.

That said, a 2.5" lift is not a good way to get tires to fit. That is accomplished with the proper wheel offset (or back spacing if you swing that way) and a 255 should fit a Duster easily without any lift at all. The 2.5" lift is likely compounding your current issue too.

 

[Locomotion]

 

[RustyRatRod]

I normally do not jack the car up and let the suspension hang completely off the ground. I take most of the weight off "almost" getting the tire off the ground but not quite. I've found there's not as much of a "shock" when the shackle flips down, because there's still "a little" weight on it.

 

[toolmanmike]

Hello all. I have a 1974 Plymouth Duster in which I have replaced the leaf springs. And now the rear shackles are both totally inverted and pushing hard into the trunk floor. I'm using a slightly taller and wider wheel and tire setup (15x8 wheels and a 255/65 tire) and because of this I guessed I would need as much clearance as possible, so I ordered a 6 leaf spring that provides a 2.5" lift from General Spring (part # 33-909). In hindsight - probably overkill. But I really did not want these wheels to not fit. I installed the front mount first and when I went to install the rear shackle mount I noticed it was a bit of a reach. Almost like the spring was short. Not sure if anyone has experienced this before but I'm not sure what to do. Did I mess up ordering such a beefed spring? Do I need longer shackles? Really not sure...
The car has a 7 1/4 rear with the larger 4.5" bolt pattern. Any tips would be much appreciated. Thank you.

View attachment 1716527508

I got in there with a long pry bar and popped them back where they belong.

 

[RustyRatRod]

Oh and WEAR SAFETY GLASSES! It will likely pop hard enough to knock dirt rust and debris off the car right in your face.

 

[RAT ROD AL]

And a hard hat.

 

[Dana67Dart]

Always know where your fingers are...

And what they will hit or hit them...

Before it happens.

I don't remember but it looks like a portrait of Abe Lincoln

I was holding a screw and pressing really hard with a drill gun with a Phillips bit. Needless to say, It slipped


Red lines are the direction the bit was when it entered my finger

Left hand wrapped around a large pipe wrench, pipe wrench was attempting to rotate a KH piston. I thought where are my fingers....bam. Finger smashed between the wrench handle and edge of the flat anvil on the vice. I had gloves on so I finished before taking my glove off, I did not want to see my severed finger tip just yet.

To my pleasant surprise just a bad smashed finger nail.

11/2025

4-31-2026

 

[RustyRatRod]

Always know where your fingers are...

And what they will hit or hit them...

Before it happens.

I don't remember but it looks like a portrait of Abe Lincoln

View attachment 1716527675

I was holding a screw and pressing really hard with a drill gun with a Phillips bit. Needless to say, It slipped


Red lines are the direction the bit was when it entered my finger
View attachment 1716527678

Left hand wrapped around a large pipe wrench, pipe wrench was attempting to rotate a KH piston. I thought where are my fingers....bam. Finger smashed between the wrench handle and edge of the flat anvil on the vice. I had gloves on so I finished before taking my glove off, I did not want to see my severed finger tip just yet.

To my pleasant surprise just a bad smashed finger nail.

11/2025
View attachment 1716527679

4-31-2026
View attachment 1716527680

View attachment 1716527673

View attachment 1716527674

Nice carnage! ...and exactly WHAT finger is that you're givin us? lol

 

[Dana67Dart]

.and exactly WHAT finger is that you're givin us? lol

Ab's giving you the bird, screwdriver bit pointer left hand, missing nail ring right hand

 

[Oldmanmopar]

The springs are to short with the arc in them. Move the front hanger back with a 1/4 inch shim and the rear hanger forward with a 1/4 inch shim. This should stop them from flopping . If not add more to the rear with longer bolts.

How close are the tires to the front of the quarter panels? There were times when we added shims and needed to use longer studs up front. That is why it is easier to shim the rear forward .

 

[Dart Frog]

You've been given some good advice on how to address your problem. I think once you make the adjustments you will be happy with your setup. I run the same spring on my Dart so I could accommodate 275 drag radials without cutting into it. I needed that much tire so when I sprayed 150 shot on a 425 horse 340 it would actually stick.

 

[Asher Bird-Meyer]

Thanks everyone for the tips. I was able to get them flipped down to where they need to be. Jacked it up, and used a pry bar to push them backwards, then let it down. The right side settled right in but the left side didn't, so I jacked it back up just before the tire came off the ground, held it back with the bar and at the same time I eased the car down and it went home. Seems to be fine now. Stays in place when jounced. It's not sitting drastically high now that everything is settled how it should. Sits just the way I like. A little rake in the back. Again, thanks for the advice! First time doing leaf springs. Oh and I can fit about 3 fingers in between the front of the tire and the quarter panel. Something like 1 3/4 to 2 inches there.

 

[Dana67Dart]

How close are the tires to the front of the quarter panels? There were times when we added shims and needed to use longer studs up front. That is why it is easier to shim the rear forward

Plus no issue with drive shaft length