WHICH LEAF SPRINGS? 68 Barracuda

[SGlez10]

Hi guys. I have a 1968 Plymouth Barracuda Notchback. Originally it was a 6cyl car, automatic, it’s now a 340 4 speed.

The leaf springs on there now are the 5 leaf.

I need a new set.

My questions are: What is the difference in a standard 5 leaf vs a 6 leaf? Are all 6 leaf heavy duty? Why is a 6 leaf recommended for a 340? How does either a 5 or 6 affect the stiffness? I’d prefer it to be a smoother ride, as I’m not going to be using my car to race or not really looking for “performance”

I’m looking for the car to have a level stance, I’d prefer it raised a tiny bit in the back as opposed to it lowering.

I ordered a pair from Classic Industries (MR3108) manufactured by Eaton Springs (ML289) they’re a 6 leaf but CI has them listed as a 5 leaf (go figure).

I was recommended ML229 by Eaton Springs.

 

[Ottmundr]

@72bluNblu

 

[72bluNblu]

So Eaton lists a bunch of A-body springs, this is what I was able to get using their website and just picking different A-body years/models EATON Detroit Spring

ML117- 4 leaf, 85 lb/in (73+ slant 6)
ML4955- 4 leaf, 85 lb/in (73+ slant 6)
ML693- 5 leaf, 85 lb/in (74 V8)
ML323- 5 leaf, 85 lb/in (67 slant 6)
ML107 - 5 leaf, 85 lb/in (68-72 slant 6)
ML3575- 5 leaf, 85 lb/in (75 360 SD)

ML665- 6 leaf, 110 lb/in (67 V8)
ML289- 6 leaf, 110 lb/in (68-69 V8)
ML463- 6 leaf, 110 lb/in (70-72 V8
ML079- 6 leaf, 110 lb/in (74 V8)
ML3677- 6 leaf, 110 lb/in (73 V8)
ML3619- 6 leaf, 110 lb/in (75 360 HD)

ML229 - 6 leaf, 130 lb/in (68-69 340/383)

EPS229- 6 leaf, 180 lb/in (383 HD)

Now, I have NO idea why they list this many springs. Seriously, there weren't this many different factory part numbers. And I don't know how any of them are actually different beyond leaf count and spring rating. All the factory A-body springs that I'm aware of were the same length and had the same eye size, and even the same eye bolt diameter for all of the factory stuff. So what makes one 6 leaf, 110 lb/in spring different from the next you'd have to ask Eaton, because again they list more part numbers than the factory did. And I'm not even sure what some of the different factory numbers were about, because near as I can tell (and I could be wrong) the factory springs didn't really change much as far as arch/ride height so I don't know why the part numbers changed.

For the purposes of this, the 5 leaf vs 6 leaf thing is pretty much just a spring rate difference, but you can see that you can have a 6 leaf spring with different spring rates, or a 4 leaf spring with the same rate as a 5 etc, because it depends not just on the number of leafs but also their thickness. As far as why they're recommending a 6 leaf for your 340, that's just what their parts book says. But the higher output engines got stiffer springs, or at least had that option.

For ride height, if you use the "standard height" spring you should end up with a pretty close to factory ride height, which should be pretty level if you're using the factory ride height in the front. Some of that will depend on your tire height too of course.

Best of luck with Classic, I'll never order anything from them. They're overpriced, slow, and have lousy customer service. For Eaton springs I'd either use @BergmanAutoCraft or buy direct from Eaton themselves.

 

[SGlez10]

So Eaton lists a bunch of A-body springs, this is what I was able to get using their website and just picking different A-body years/models EATON Detroit Spring

ML117- 4 leaf, 85 lb/in (73+ slant 6)
ML4955- 4 leaf, 85 lb/in (73+ slant 6)
ML693- 5 leaf, 85 lb/in (74 V8)
ML323- 5 leaf, 85 lb/in (67 slant 6)
ML107 - 5 leaf, 85 lb/in (68-72 slant 6)
ML3575- 5 leaf, 85 lb/in (75 360 SD)

ML665- 6 leaf, 110 lb/in (67 V8)
ML289- 6 leaf, 110 lb/in (68-69 V8)
ML463- 6 leaf, 110 lb/in (70-72 V8
ML079- 6 leaf, 110 lb/in (74 V8)
ML3677- 6 leaf, 110 lb/in (73 V8)
ML3619- 6 leaf, 110 lb/in (75 360 HD)

ML229 - 6 leaf, 130 lb/in (68-69 340/383)

EPS229- 6 leaf, 180 lb/in (383 HD)

Now, I have NO idea why they list this many springs. Seriously, there weren't this many different factory part numbers. And I don't know how any of them are actually different beyond leaf count and spring rating. All the factory A-body springs that I'm aware of were the same length and had the same eye size, and even the same eye bolt diameter for all of the factory stuff. So what makes one 6 leaf, 110 lb/in spring different from the next you'd have to ask Eaton, because again they list more part numbers than the factory did. And I'm not even sure what some of the different factory numbers were about, because near as I can tell (and I could be wrong) the factory springs didn't really change much as far as arch/ride height so I don't know why the part numbers changed.

For the purposes of this, the 5 leaf vs 6 leaf thing is pretty much just a spring rate difference, but you can see that you can have a 6 leaf spring with different spring rates, or a 4 leaf spring with the same rate as a 5 etc, because it depends not just on the number of leafs but also their thickness. As far as why they're recommending a 6 leaf for your 340, that's just what their parts book says. But the higher output engines got stiffer springs, or at least had that option.

For ride height, if you use the "standard height" spring you should end up with a pretty close to factory ride height, which should be pretty level if you're using the factory ride height in the front. Some of that will depend on your tire height too of course.

Best of luck with Classic, I'll never order anything from them. They're overpriced, slow, and have lousy customer service. For Eaton springs I'd either use @BergmanAutoCraft or buy direct from Eaton themselves.

100% agree about Classic. They’re about a 30 minute drive for me, so I use them out of convenience but their customer service is really bad.

Thanks for breaking down all this information too, for someone like me that isn’t well versed and is doing their best to continue this restoration, your help isn’t overlooked. So again, I appreciate you taking the time. I’ll call Eaton and ask a few more questions but I think I’m leaning towards the ML229’s. I’ll also check out Bergman.

 

[BergmanAutoCraft]

Eaton Springs are now $800+ a pr. I don’t use them any longer. I’m having springs made quickly for much less cost. Also, here are some pics of my offset spring kit to be available with the month most likely.

 

[MichiDart]

Another query to those who know more than myself (most of you). Purchased a set of leafs from Mancini originally intended for my 71 Dart after upgrades-Mopar P412 0863. Now looking to put them on my 68 Formula S Barracuda restoration. Springs that came off the 68 were 6 leaf, but looked pretty tired. New springs are 5 leaf but appear to have much more arc (obviously new). It appears to me the front mount for both is 5/8 so no issue there. But the rear bushing (hole) on the old seems to be about 7/8" while the new is 1". My guess is I need a new mount and shackles for the rear. Or is there just a larger bushing that works with the existing hdwr? Would be interested in any feedback about the springs I purchased as they are not on the car yet.

 

[72bluNblu]

Another query to those who know more than myself (most of you). Purchased a set of leafs from Mancini originally intended for my 71 Dart after upgrades-Mopar P412 0863. Now looking to put them on my 68 Formula S Barracuda restoration. Springs that came off the 68 were 6 leaf, but looked pretty tired. New springs are 5 leaf but appear to have much more arc (obviously new). It appears to me the front mount for both is 5/8 so no issue there. But the rear bushing (hole) on the old seems to be about 7/8" while the new is 1". My guess is I need a new mount and shackles for the rear. Or is there just a larger bushing that works with the existing hdwr? Would be interested in any feedback about the springs I purchased as they are not on the car yet.

There’s a larger bushing. The part # I’ve got handy is for the poly bushings from Energy Suspension, 2-2117G. It’s listed as a Jeep application, there’s rubber bushings available as well if you work backward from the application list.

Energy Suspension 2.2117G Energy Suspension Frame Shackle Bushings | Summit Racing

 

[lemondana]

ESPO, don't know how much they are these days.

 

[RustyRatRod]

ESPO, don't know how much they are these days.

Under 400 bucks. I'd just get the 340 XHD springs or maybe some +1s and be done with it.

 

[lemondana]

I bought some same as above damn near 20 years ago. I was thinking they were around 350-400 then. So that's good to know. I need some for my 69 R/T.

 

[MichiDart]

Thanks blu. I paid about $350 for my pair including tax last year. Was kinda surprised to see what others were spending but I understand others have specific needs, applications

 

[cosgig]

I had a pair of SS springs that I got in a deal, put em on the 67 Barracuda. I think the stance is too high. I would like to change to the XHD springs, which I put on my buddies 66 Valiant, I think they are about perfect. Slightly higher in the rear than stock springs, and a level stance. My advise would be the XHD and steer clear of the SS springs.