Is 1/2" leaf spring relocation worth the trouble?

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Mojoe9955

Mojoe9955

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I'm looking at doing a leaf spring relocation and wonder if it's worth the gain against the work involved.
Also right now the relocation kits seem to be unavailable. I've read that using a 3/4" kit while relocating the front mount actually only gains more like 1/2" while the back shackles gain a full 3/4". Which according the the discussion I read here, seemed to be somewhat heated BTW. Part of it of it was, there was some noticeable binding which may cause premature wearing of the components involved. My point is since I'm trying to put a 68/70 B rear under a 74 Duster or 72 Demon should I might as well just do it? I'm told the Doctor Diff 1/2" kit which I'd like to use is maybe a month or more out. I'm pretty decent at fabrication so could make up the front hangers and have seen a few other homemade solutions like these shackles I might try to keep the ball rolling.

offset shackles.jpg
 
If you are putting the B rear under the car WITHOUT relocating the perches then I would say it would be best to relocate the spring mounts to match the rear perch width.

If you are worried about the extra width of the B axel, wheels with a different Backspace can solve that.

If you have specific wheels and they need an additional inward spacing of the spring to fit, then you have to move the spring or space the wheel out if you can
 
For what ever reason im leaning towards 18X10's
I have 17s with spacers on my 70 Duster with an A 8.25 and am comfortable with that. 255X15 on my 74 Duster with a 65/67 B. I have a 72 Demon with a 7.25 that I might swap one or the into it. The 72 needs some serious metal work in the rear so I might even just go for a 3" relocation, then the possibilities are endless :p

20230118_163151.jpg


20240407_131401.jpg
 
Dana67Dart said:
If you are putting the B rear under the car WITHOUT relocating the perches then I would say it would be best to relocate the spring mounts to match the rear perch width.

If you are worried about the extra width of the B axel, wheels with a different Backspace can solve that.

If you have specific wheels and they need an additional inward spacing of the spring to fit, then you have to move the spring or space the wheel out if you can
Click to expand...
I definitely am moving the perches, and probably know the way I'm going, but just wanted some validation on my ideas. I'll probably never get this far, but my 70 with the 8.75s is close as the front suspension is already sorted with all BAC type upgrades. The cars pictured below both have 18×10 outback

20240712_124422.jpg


sidedriv.jpg
 
I also have a spare A body 8.75 as well
I'm liking this yellow car too
It's hard to tell what wheel it has though

FB_IMG_1716121077211.jpg
 
I think the 1/2” relocation is worth it, on a Duster/Demon/Dart Sport it will let you run 295’s and actually have them tucked into the quarters. Without the 1/2” relocation you’re only going to be able to do that with 275’s. Not gonna count the guys with SS springs and 4x4 ride height that have the tires outside of the quarters.

The “3/4” location is not a 3/4” relocation. It is physically impossible to move the hangers inboard 3/4” on these cars. I literally use the MP hangers on my Duster, they’re a 1/2” offset. The shackles are a 3/4” offset, but all that does is put a bind on the springs. If you move the perches 3/4” it will bind in the front half of the spring, if you move them a 1/2” it puts the rear half of the spring in a bind.

I use the MP offset hangers with the spring perches moved a 1/2” with rear leaf spring sliders that I located a 1/2” inboard from the OE shackle location, the MP kit only screws things up if you use both the hangers and shackles together. Although the DoctorDiff kit is nicer, the hangers are better quality and don’t require dimpling and drilling a hole in the frame rail like the MP kit does. I’d wait on the DoctorDiff parts myself.

The B rear is useful but it depends on what you want to do for wheels. In the 18x10” size there are a lot of wheels in the +12 to +20 which actually work well with the A-body width 8 3/4. I run a 68-70 B rear in my Duster with 18x10’s, +38 offset and 295/35/18’s
 
MidnightSwinger said:
I like my 1/2” relocation. I’ve got tons of room for more tire if the 255/60’s ever seen too skinny.

View attachment 1716281902
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But even that, just having a little extra space makes things easier especially if you haven’t picked wheels yet.

Because that could mean a bunch of different offsets fit, as opposed to say my set up where I probably only have a 5-7 mm offset window for wheels that fit with my tire combination. So picking wheels is less about what I like visually and more about what’s offered in the right specs.

Plus now you can go up a size if you want next time. Nothing wrong with that, certainly less expensive than trying to absolutely max out and missing and having to buy another set of tires.
 
72bluNblu said:
I think the 1/2” relocation is worth it, on a Duster/Demon/Dart Sport it will let you run 295’s and actually have them tucked into the quarters. Without the 1/2” relocation you’re only going to be able to do that with 275’s. Not gonna count the guys with SS springs and 4x4 ride height that have the tires outside of the quarters.

The “3/4” location is not a 3/4” relocation. It is physically impossible to move the hangers inboard 3/4” on these cars. I literally use the MP hangers on my Duster, they’re a 1/2” offset. The shackles are a 3/4” offset, but all that does is put a bind on the springs. If you move the perches 3/4” it will bind in the front half of the spring, if you move them a 1/2” it puts the rear half of the spring in a bind.

I use the MP offset hangers with the spring perches moved a 1/2” with rear leaf spring sliders that I located a 1/2” inboard from the OE shackle location, the MP kit only screws things up if you use both the hangers and shackles together. Although the DoctorDiff kit is nicer, the hangers are better quality and don’t require dimpling and drilling a hole in the frame rail like the MP kit does. I’d wait on the DoctorDiff parts myself.

The B rear is useful but it depends on what you want to do for wheels. In the 18x10” size there are a lot of wheels in the +12 to +20 which actually work well with the A-body width 8 3/4. I run a 68-70 B rear in my Duster with 18x10’s, +38
Click to expand...
 
Using the A-body 8.75 and 10" wheels, the springs need to be offset as well?
 
Mojoe9955 said:
Using the A-body 8.75 and 10" wheels, the springs need to be offset as well?
Click to expand...

If you want to run tires bigger than 275’s, yes.

Whether you run an A or B body 8 3/4 doesn’t really change what width wheel you can run, it just changes the backspace/offset you need on the wheel.
 
When I get it all done, I want to hear you say...Damn, "will you look at the backyard on her" :p
 
Mojoe9955 said:
When I get it all done, I want to hear you say...Damn, "will you look at the backyard on her" :p
Click to expand...
Sounds like you want at least a 1/2” offset to me. These are the 295/40/18’s on my Duster

IMG_0163.jpeg
 
Is an extra 1/2" worth the trouble? Depends on the tire you're wanting to run. For larger tires, it absolutely is worth the "trouble," if you can even call it that. A tiny amount of work, yeah. But I wouldn't call it trouble.
 
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mopowers said:
Is an extra 1/2" worth the trouble? Depends on the tire you're wanting to run. For larger tires, it absolutely is worth the "trouble," if you can even call it that. A tiny amount of work, yeah. But I wouldn't call it trouble.
Click to expand...

Yeah it really isn’t that bad, moving the perch is the hardest part but if you’re using a B-body rear or 8.8 you’re doing that regardless. The rest can be a bolt in operation

And the 1/2” offset is the difference between a 275 and a 295, which is more than a 1/2” of tire gain
 
That is a nice set of tires you have there and I see you have some sliders as well. I think if I'm going to the trouble of moving the perches I might as well go all the way, which I want to do ASAP, but waiting a month or more for parts, while I have the time now is hard for me.
 
Speaking on the sliders, I read a post here about them in conjunction with switching from the 74 plus to an earlier bumper which was a little confusing, but I've since figured it out.
You made the sliders or purchased them. I see some info about Calvert but the don't seem to have anything specific to Mopar A bodies. Car Tool seems to have them though. I'm not adverse to trying anything, so all
this is about ingenuity as well as having something to do. I haven't heard any comments about the half pipe offset shackleI pictured. It was made by a Chevy guy, but I don't see why it wouldn't work. That and a homemade front bracket would put me in business.
 
Mojoe9955 said:
Speaking on the sliders, I read a post here about them in conjunction with switching from the 74 plus to an earlier bumper which was a little confusing, but I've since figured it out.
You made the sliders or purchased them. I see some info about Calvert but the don't seem to have anything specific to Mopar A bodies. Car Tool seems to have them though. I'm not adverse to trying anything, so all
this is about ingenuity as well as having something to do. I haven't heard any comments about the half pipe offset shackleI pictured. It was made by a Chevy guy, but I don't see why it wouldn't work. That and a homemade front bracket would put me in business.
Click to expand...

I made the 1/2" offset slider brackets myself, there's some info here and then more on the next page of my build thread

My "new" '74 Duster- or why I need a project like a hole in the head
The sliders I have on my Duster came from AFCO-
AFCO Racing 20236S AFCO Racing Leaf Spring Sliders | Summit Racing

They don't have a built in angle though, which ideally they should have or the brackets should have to put the slider track more inline with the motion of the spring. The Calvert spring sliders have this angle built in. In a perfect world you'd match the angle to the angle on the exact springs you have on your car, but really the generic angle on the Calverts would be better than nothing IMO. There's nothing "A-body" about the sliders, they work with any 2.5" wide leaf spring but you have to fabricate a way to mount them. Or just weld them direct to the chassis, but that might make things difficult to change things later. These are the Calvert sliders

SPRING SLIDERS for Calvert Springs (SL-300CR ) – Calvert Racing, Inc.

I don't really see a reason to fabricate the 1/2" rear shackles. If I was going to fabricate something I'd fabricate the bracket to mount the spring sliders, then you don't need shackles. The front spring hanger can also be fabricated, but personally with my time/money ratio if they'll be available in a month or less I would buy them, simply because I'd have them before I had the time to fabricate them myself. Plus the DoctorDiff front hangers are very nice, they'd definitely be prettier than anything I would do even if the functionality was the same.

US Cartool seems to have 1/2" offset shackles as well, but not the hangers. And they probably make the nicest 3" relocation if you want to do that. But for the 1/2" offset I think DoctorDiff has the nicest one.
 
I'm retired and unencumbered, so my free time, usually lots of it, is essentially free. I'll make up my rear for the 1/2" offset and have a few other things I can do to bide my time until the DD stuff becomes available.
Thanks for the input Bryan
 
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Quick question. Using the 1/2" relocation, will 18×10 with +24 and 295/40/18 work on the back?
I found a good deal a used set. They are like the wheels on the yellow car

FB_IMG_1716121068002.jpg
 
Mojoe9955 said:
Quick question. Using the 1/2" relocation, will 18×10 with +24 and 295/40/18 work on the back?
I found a good deal a used set. They are like the wheels on the yellow car

View attachment 1716282934
Click to expand...

The offset is the problem, so it’ll depend on the rear axle. That’s about 10mm less than what you need for a 68-70 B rear, and probably about 12mm too much for an A body 8 3/4.

I’d have to refresh my memory on the uncut 8.8 width, I think it would be close because I recall that one being a bit narrower than the 68-70 B rear.

The 18x10 and 285/40/18 would work with the 1/2” offset. You’d just have to make the +24 part work.
 
72bluNblu said:
I’d have to refresh my memory on the uncut 8.8 width, I think it would be close because I recall that one being a bit narrower than the 68-70 B rear.
Click to expand...

The '65-67 B-Body 8.75 is about 5/8" narrower than the '68-70 at 59.5" drum to drum. Should be about right for those wheels, I think?

An uncut explorer 8.8 is pretty close to that same width. I calculate 59.375" axle flange to axle flange, so it would depend on drum or disk for the overall width.
 
The package comes with newer 295/40 Nitto G2's tires
The fronts a 18×9 +30 and 274/40
I have a stock 8.25 A, 65/67 B 8.75 to fit an A, a stock 8.75 A and a 68/70 B 8.75 the I'm getting ready to move the perches to the A body + 1/2" relocation.
 
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