1973 Leaf Spring fitment with isolators.

[TreborsRR]

Hello, I am new to the forums and am excited to find so many knowledgeable Mopar heads.
I have a 1973 Plymouth Road Runner that I purchased when I was 16, I saved my money for years before buying my first car and I was excited to own a muscle car. After driving it for half a year, my cousin and I decided to put in some time rebuilding it since the previous owner had sort of cobbled things together.
We got a new motor up front and started to work back to the rear end and the suspension parts when we started having trouble getting the rear end to sit straight. My cousin and I started to lose the free time we had working on it and the car found itself being stored in a barn for over ten years.

We have got it back into said cousin's garage, and we are going to attempt to get it back on the road this summer. I have a new rear end and leaf springs to install. The rear end is a 71-74 8 3/4" Musclepak 391 purchased from Moser Engineering. The leaf springs are a set I have purchased from Yearone the pair parts number is FDP19823.
I'm currently trying to track down a missing clamp for the top of the isolators that runs along the rear end. With the full set I do have though, the nub on the leaf springs fits through the isolator, but doesn't extend far enough to index onto the rear end. I have seen on these forums that some people get rid of their isolators all together, but I would like to keep them if I am able especially with how the rear sway bar mounts up.

I'm confused, and am hoping on clarification with how others manage to fit up their rear end with the "stock" suspension set-up. Do I have the wrong set of leaf springs? The service manuals don't give me the best exploded diagrams, but I am trying to track down the last clamp and get everything refitted so I can begin finishing the rest of the car.
I'll try to take some more pictures next weekend when I get some time to go to the garage to maybe better explain my dilemma.

Thank you for any help.

 

[pnora]

Hello, I am new to the forums and am excited to find so many knowledgeable Mopar heads.
I have a 1973 Plymouth Road Runner that I purchased when I was 16, I saved my money for years before buying my first car and I was excited to own a muscle car. After driving it for half a year, my cousin and I decided to put in some time rebuilding it since the previous owner had sort of cobbled things together.
We got a new motor up front and started to work back to the rear end and the suspension parts when we started having trouble getting the rear end to sit straight. My cousin and I started to lose the free time we had working on it and the car found itself being stored in a barn for over ten years.

We have got it back into said cousin's garage, and we are going to attempt to get it back on the road this summer. I have a new rear end and leaf springs to install. The rear end is a 71-74 8 3/4" Musclepak 391 purchased from Moser Engineering. The leaf springs are a set I have purchased from Yearone the pair parts number is FDP19823.
I'm currently trying to track down a missing clamp for the top of the isolators that runs along the rear end. With the full set I do have though, the nub on the leaf springs fits through the isolator, but doesn't extend far enough to index onto the rear end. I have seen on these forums that some people get rid of their isolators all together, but I would like to keep them if I am able especially with how the rear sway bar mounts up.

I'm confused, and am hoping on clarification with how others manage to fit up their rear end with the "stock" suspension set-up. Do I have the wrong set of leaf springs? The service manuals don't give me the best exploded diagrams, but I am trying to track down the last clamp and get everything refitted so I can begin finishing the rest of the car.
I'll try to take some more pictures next weekend when I get some time to go to the garage to maybe better explain my dilemma.

Thank you for any help.

As I remember the axle mount/perch is different between an isolated and non-isolated mount. What perch is on the axle? I assume non-isolater.

 

[71Beeper]

I had the same issue on my 76 Volare Road runner.
When I bought it - it had an 8 3/4 from a 66 Charger.
All I did was have a bushing machined to fit inside the isolator hole and a small hole in the center of the bushing to locate the leaf spring pin.

 

[TreborsRR]

I had the same issue on my 76 Volare Road runner.
When I bought it - it had an 8 3/4 from a 66 Charger.
All I did was have a bushing machined to fit inside the isolator hole and a small hole in the center of the bushing to locate the leaf spring pin.

After being installed over the leaf spring pin, then that bushing narrowed back down to fit through the perch on the axle?
I've seen a machine shop outside of town and I may look at how much they'd charge to get something manufactured for that.

Thank you for the input.

 

[TreborsRR]

I'm planning to put up another post tonight and hoping I can hear alternatives in the sense of removing the isolators all together. I have seen some posts referencing that it's been done. But I could use a little more specifics on what has worked for others.

 

[71Beeper]

I removed it all from my F-body.

As the rubber gets old it deteriorates, not to mention the soft mushy ride.
That might be nice on a big Cordoba or New Yorker but if you want a nice firm suspension, remove it.

On the front, I replaced the iso bushings with the solid ones that Firm Feel makes (not the poly ones).
Back in the day you could get cast ones thru Direct Connection but not any more.

Night and day different with the front end being tighter feeling and I didn't have a front sway bar in it.

 

[TreborsRR]

I removed it all from my F-body.
View attachment 1655594
As the rubber gets old it deteriorates, not to mention the soft mushy ride.
That might be nice on a big Cordoba or New Yorker but if you want a nice firm suspension, remove it.

On the front, I replaced the iso bushings with the solid ones that Firm Feel makes (not the poly ones).
Back in the day you could get cast ones thru Direct Connection but not any more.

Night and day different with the front end being tighter feeling and I didn't have a front sway bar in it.

Did you have to do any sort of additional modifications? Different shocks or anything?
I believe I read on another thread that someone used a previous year's leaf spring, or another had their leafs custom bent. I imagine removing the isolators in the back will raise the back end up a solid inch, which I'm not opposed to.
I think if I were to get rid of the isolators I will have to forget about reinstalling the rear sway bar because the plates look like they need to be fitted against the isolator clamp.

Thanks for the replies, and I may not be a huge fan of that body style, but green is my favorite color, and it's easy to say that is a sweet ride!

 

[71Beeper]

No additional modifications were done.
The height of the bushings I had made were to sit flush with the top of the ISO perches.
Shocks did not need to be changed.
As far as a height difference in the rear, I did not notice any - but the reason for that was my leaf springs were tired - so I had them re-arched which did bring the height up slightly.

As far as retaining a rear sway bar - a rear bar from an earlier B-body, like a Charger may work well.

I plan on installing a rear bar on my nearly finished 71 Runner - the bar came from a 1971 Charger which did not have the ISO setup in those early years.