Leaf Spring Sag

AMC Diplomat

Well-Known Member
Joined
Feb 14, 2023
Messages
1,019
Reaction score
480
Location
NY
I'm no Mopar expert, but I don't think this looks right. The passenger side looks like it bent. Or if this M body trash is supposed to look this way ill just ignore it. 20230524_164459.jpg20230524_164547.jpg
 

Camtron

Well-Known Member
Joined
Apr 25, 2019
Messages
1,814
Reaction score
1,376
Location
US
Toast.
I ordered 5 leaf, leaf springs from, GeneralSpring KC, 4 years ago and they’ve held up really well with aggressive daily driving on shit roads. Like, $130 each.
1976 - 1990 Chrslyer, Dodge, Plymouth rear leaf spring, 5 leaf
Edit: this was done when I deleted the rear ISO set up. I don’t believe the 5 leafs work with the 4 leaf ISO set up but, I’ve been wrong so many times.
 
Last edited:

Camtron

Well-Known Member
Joined
Apr 25, 2019
Messages
1,814
Reaction score
1,376
Location
US
Yeah I figured this was done for. Any recommendations on an easy ISO replacement?
Assuming you have the 7.25” with 3” tubes, I’d try to grab a set (can find used for cheap sometimes) of the A,B,C,E-body shock plates and grab some new shocks and ditch the ISO all together. The shocks available on the market for the A,B,C,E-body style plates offer a lot better ride and handling to the limited options for the stock style plates and would be an easy replacement. Less parts all together technically. Deleting the rear ISO also lifts the rear end a little bit on its own.
I couldn’t tell you, if or who offers ISO bushings and plates, I never looked into it myself but, I think I’ve seen people say they’ve rebuilt theirs so, there maybe a factory type option available, idk about it though.
 

AMC Diplomat

Well-Known Member
Joined
Feb 14, 2023
Messages
1,019
Reaction score
480
Location
NY
Assuming you have the 7.25” with 3” tubes, I’d try to grab a set (can find used for cheap sometimes) of the A,B,C,E-body shock plates and grab some new shocks and ditch the ISO all together. The shocks available on the market for the A,B,C,E-body style plates offer a lot better ride and handling to the limited options for the stock style plates and would be an easy replacement. Less parts all together technically. Deleting the rear ISO also lifts the rear end a little bit on its own.
I couldn’t tell you, if or who offers ISO bushings and plates, I never looked into it myself but, I think I’ve seen people say they’ve rebuilt theirs so, there maybe a factory type option available, idk about it though.
Yeah it's the crappy 7 1/4. Now I'm beginning to wonder if it would be more cost and time effective to hunt down an 8 1/4, drive shaft, and springs out of a 5th ave. It's like the further I get into this thing, the more annoying it gets. My only concern is my goal for an 8 hr road trip this summer with it. Otherwise it's a goof off car I drive for fun.
 

Mikes5thAve

Well-Known Member
Joined
Mar 3, 2020
Messages
1,375
Reaction score
538
Location
Canada
5 leaf works with what's there but you need to use a spacer on the clamp that wraps around the springs. You can get replacement pads in poly.

Some 5th avenues had HD suspension with 5 leaf springs, my 84 has it, but 8 1/4 in them was rare.
 

Camtron

Well-Known Member
Joined
Apr 25, 2019
Messages
1,814
Reaction score
1,376
Location
US
Maybe more cost time effective to grab an 8.8 out of a mustang or even look for a 68-70 B-body rear 8.25” or 9.25”. The M-body 8.25” are hard to come by; particularly with all the hardware and springs, ect…for how much I spent on a 8.25”, shipping, rebuilding it, ect…I could have built a super stout 9” or 9.25” that could live behind about anything.
 

Aspen500

Well-Known Member
Joined
Feb 14, 2015
Messages
7,030
Reaction score
2,759
Location
Rib Mountain, WI
Assuming you have the 7.25” with 3” tubes, I’d try to grab a set (can find used for cheap sometimes) of the A,B,C,E-body shock plates and grab some new shocks and ditch the ISO all together. The shocks available on the market for the A,B,C,E-body style plates offer a lot better ride and handling to the limited options for the stock style plates and would be an easy replacement. Less parts all together technically. Deleting the rear ISO also lifts the rear end a little bit on its own.
I couldn’t tell you, if or who offers ISO bushings and plates, I never looked into it myself but, I think I’ve seen people say they’ve rebuilt theirs so, there maybe a factory type option available, idk about it though.
Poly ISO spring pads are readily available. Not as solid as ISO delete but it's darn close. New springs also get rid of the stupid oval front hanger bushing in favor of standard round ones.
 

AMC Diplomat

Well-Known Member
Joined
Feb 14, 2023
Messages
1,019
Reaction score
480
Location
NY
Maybe more cost time effective to grab an 8.8 out of a mustang or even look for a 68-70 B-body rear 8.25” or 9.25”. The M-body 8.25” are hard to come by; particularly with all the hardware and springs, ect…for how much I spent on a 8.25”, shipping, rebuilding it, ect…I could have built a super stout 9” or 9.25” that could live behind about anything.
Christ. Well there goes that idea for the short term.

Poly ISO spring pads are readily available. Not as solid as ISO delete but it's darn close. New springs also get rid of the stupid oval front hanger bushing in favor of standard round ones.
Stupid question, can I get these 78-755 Leaf Spring Assembly
"Rebuild" the iso pads
And slap it all together in the car? Or is there some kind of mopar mystery alignment angle issue that I should be worried about?
 

Duke5A

Well-Known Member
Joined
Apr 6, 2018
Messages
1,640
Reaction score
856
Location
Michigan
All you need to run 5 leaf springs on the 4 leaf ISO setup are some spacers made out of flat stock. It's not difficult at all. I did this on my car for a couple years before I ditched the ISO setup altogether.
 

Camtron

Well-Known Member
Joined
Apr 25, 2019
Messages
1,814
Reaction score
1,376
Location
US
All you need to run 5 leaf springs on the 4 leaf ISO setup are some spacers made out of flat stock. It's not difficult at all. I did this on my car for a couple years before I ditched the ISO setup altogether.
Well there you go. Some 1/4” flat stock and send it.
My ISO boxes rotted away and split on the insides of the leafs. Rebuilding/reusing them was never a thought, lol
 

AMC Diplomat

Well-Known Member
Joined
Feb 14, 2023
Messages
1,019
Reaction score
480
Location
NY
Anyone have anything good bad or indifferent to say about dealing with Stengel Bros?
 

AMC Diplomat

Well-Known Member
Joined
Feb 14, 2023
Messages
1,019
Reaction score
480
Location
NY
5 leaf works with what's there but you need to use a spacer on the clamp that wraps around the springs.
All you need to run 5 leaf springs on the 4 leaf ISO setup are some spacers made out of flat stock. It's not difficult at all. I did this on my car for a couple years before I ditched the ISO setup altogether.
My brain isn't catching on by what you guys mean by spacers. My brain is looking at the set up and thinking I would need longer U bolts to run with an extra leaf. Is there some kind of differece in the widths of the springs between 4 and 5 spring leaf set ups?

I've been hunting through the forum trying to find information on the rear suspension. Some really good posts that could be consolidated into a sticky post. I should have hunted around more before asking questions. This seems like common subject matter.

Right now I'm just above $600 with the springs and all new hardware/bushings/pads and shipping. I'm gonna poke around the spring shops on Tuesday and see if they'll ballpark me an idea on the price. Because if they can do it for $800 or less I'd gladly pay someone. At a grand I'd say screw it I'll do it myself.

Hope you all are having a good weekend
 

Camtron

Well-Known Member
Joined
Apr 25, 2019
Messages
1,814
Reaction score
1,376
Location
US
To run a 5 leaf in the factory 4 leaf ISO, you’d want to add a 1/4 spacer between the lower ISO box and the upper shock plate to make up the difference for the extra leaf spring.
 

Mikes5thAve

Well-Known Member
Joined
Mar 3, 2020
Messages
1,375
Reaction score
538
Location
Canada
Look at your first pic. The squared off bracket that wraps around the springs that clamp it all together will no longer be tight to the axle if you add another spring. So you need to add a spacer there to make up the difference. A chunk of old spring is good for that.
I usually replace u-bolys when it's apart and because they're cheap but there's still lots of u bolt left to take the difference.
 

Aspen500

Well-Known Member
Joined
Feb 14, 2015
Messages
7,030
Reaction score
2,759
Location
Rib Mountain, WI
About your spring width question, Mopar leaf springs are all the same width from at least the late '50's to 1989 and probably beyond '89 on trucks and vans.
 

Sub03

Well-Known Member
Joined
Apr 5, 2020
Messages
137
Reaction score
89
Location
Norway
I'm borrowing your thread AMC Diplomat, hope that's OK.

I started working on the rear end on the Aspen yesterday and some questions popped up.
The plan is to replace the bushings, poly pads, brake lines and wheel bearings. Gathered all the parts needed this winter.
Laura at Springs'n'things could only offer 5 leaf springs, so I decided to keep the old ones.

I've always thought i had the 4 leaf setup, my car being an 318 - 4door sedan. Somebody once told me the bottom leaf doesn't count.

So the stupid question first; is this a 4 or 5 leaf spring?

20230601_221122.jpg


If that is a 5 leaf setup, is it possible that a previous owner replaced the 4 leaf with a 5 leaf spring?
The reason I'm asking is the way the ISO box is deformed like it's missing the spacer Duke mentioned above. Also the U-bolt is bent and not sitting straight agains the axle. Something is just not looking right.

20230601_221116.jpg


After reading this thread I'm thinking I should order some 5-leafs after all. The sad part is the Aspen have to stand in my garage with the rear end in the air, wating for shipping over the Atlantic.
 

Mikes5thAve

Well-Known Member
Joined
Mar 3, 2020
Messages
1,375
Reaction score
538
Location
Canada
Yes that is 5 leaf. More then likely rather then the springs being replaced an additional spring was added before. That used to be a very common thing to do as springs wore put or people needed stiffer springs.
 
Back
Top