Okay, why won't this work?

Okay, I've got another "Why won't this work?" type idea, but I'm writing it up at 2am, after a couple beers, so bear with me...


The problem: Spring wrap and axle hop.

The cause, as I understand it: Leaf springs, which do a good job with jounce and rebound, don't do a good job controlling the rotational forces of a driven axle. The front half of the spring flexes, takes on a negative arch, and lets the axle twist pinion-up.

My quandary before the mass: Does the front half of a leaf spring assembly have to be flexible? Could it be replaced with a solid swingarm, leaving the "suspension" to the back half and shackle?
Wouldn't that swingarm eliminate the axle wrap?

Basically, I guess I'm proposing a quarter-elliptical two-link. Or maybe not. The "links" would be solidly mounted to the axle, so maybe that makes 'em "swingarms," I don't know the terminology.


I think I'd have to add on to the springpack, rather than replace it and try to engineer something strong enough to attach the swingarm to the axle, without creating any lateral slop.

It might be as simple as a 24" piece of box tube, with one end in the stock spring hanger, then securely mounted to the topside of the main leaf (with the springeye cut off.)

A very rough sketch:



I'd like to bolt the swingarm right through the springpack, but I understand that springsteel is a b!tch to drill. I may have to clamp it on with square ubolts.

The only drawback I see is that you might lose some flex, since the box won't twist like the leaf. Maybe it would need some sort of heim joint at the frame mount, I dunno.

So would it work? If not, why not? And if so, why isn't anybody already doing it?

Feedback, constructive criticism, mockery and name-calling are all welcome...

Robert

try googling "traction bars"

ive got no idea if it would work or not. but an idea that came to mind while reading this was:

could you eliminate the box tubing you suggested by; NOT cutting the spring eye off but by welding the leaf springs together half way through the arc?



(black = the half of the leaf pack welded together)


it might not be a good idea for the average person to do seeing as how the welds would be under a crazy amount of stress. but if you really know what your doing when you weld it and you know how to weld things that will be under alot of stress then it might work and have the same effect as the box tubing. just an idea that came to mind

I've also seen alot of people use like the top half of a 4 link system attached to a braket over the pumpkin and then to the frame rails to stop the axle rotating but still allow the axle to flex. If you're really worried about the axle wrap in the back and want to upgrade then switch to a coil spring setup with 4 link and that would get rid of it all together.

Neither idea will work because each individual leaf has to slip and move on the leaf above it as it goes through its regular up/down movement. So you cant do anything that will tie the leafs together.

Ladder bar. Traction bar. They both do the same thing you want to do.

Way back when Cheysler had a way of controlling axle wrap on their passenger cars. They mounted the axle on the front 1/3 of the packs and if that car also had an exeptionally powerful engine ( as in HEMI or SIXPAK), they'd add an extra half leaf on the front of the right side pack to reduce wrap further. Probably wouldn't work on a vehicle that actually need suspension flex off road, but it was effective!

FoMoCo said:

try googling "traction bars"

Click to expand...

dave92cherokee said:

I've also seen alot of people use like the top half of a 4 link system attached to a braket over the pumpkin and then to the frame rails... or a coil spring setup with 4 link would get rid of it all together.

Click to expand...

I understand I'm not the first guy to conceive of a traction bar. But the ones I've seen here (like dave is talking about) are horribly complex, requiring a mount that has to be welded to the diff housing, the bar with three ends and a swivel in it, and a shackle to mount it to a whole new crossmember. And of course, a full four link would be even more involved.

My idea uses what is already there, to try to keep it very simple.

FoMoCo may be talking about the old Lakewood style traction bars, that kids used to run under their Camaro's (usually backwards!) Those are a lot more like what I'm talking about. But they hung down below the spring, and I keep mine up out of the way. But the ground clearance may not be that big a loss, and a $39 bolt-on from Summit would be a whole lot easier than even my "easy" idea...

XCastleXJ said:

could you eliminate the box tubing you suggested by welding the leaf springs together?

Click to expand...

I bet you could. I'm such a mediocre welder that I always think in terms of what I can bolt together. And I think spring steel is as hard to weld as it is to drill, but I bet that would have the same effect, if you could get the welds to hold...

Ray H said:

Neither idea will work because each individual leaf has to slip and move on the leaf above it as it goes through its regular up/down movement.

Click to expand...

Well, you're right that the springs won't flex if the leaves can't "slip."

But that's the point: to keep the front half from flexing at all, while the back half does all the work. The leaves are already fixed to one another at the center pin. I don't think tying the front halves together will affect the back.

The rate might change, using half as much spring, but I'm sure it would still flex.

Robert

welding to spring steel is bad mojo.It will make the steel brittle and the last thing you want to happen at 65mph is your leaf cracking......

As RayH said the leaves have to be able to slide.When your suspension compresses the leaves flatten out and become longer.if they were fixed at the front you would have hardtail.lol

If I were you I would make a small scale model of a leaf and adapt you design to the front of the spring and see if it flexes.I bet it won't(all due respect)
Or here is another idea get 3-4 big ass c-clamps and clamp them on the front of the spring pack and jack the axle up so the suspension compresses.....just throwing ideas out there..

So you're saying that clamping the front of the spring will keep the back of the spring from flexing? I just don't see how that can be.

Not saying it can't be, just that I can't see it...

Robert

New or stiffer leafs seems like a better alternative. Or traction bars. Or coils with a 3 or 4 link

I'm sure it'd be a flex monster by immobilizing the front half of the leaf packs.

Will it work,Yes.Will it work cost effective and usefull,most likely not! It would take some time to work out the rear 1/2 leaves!Build a traction bar,a whole lot easier!

When you are ready to purchase new leaf packs get them from a company who will make them to your specs. After a set of Rusty's 3", and a pro-comp set; both of which wrapped bad, i called on Alcan. They ask you all sorts of questions like how much lift you want, are you running a lift shackle, bumpers, where is the spare, fully loaded weight, passengers in back or not, amount of flex etc. Then if you have any 'special' requests you tell them you don't want axle wrap. These springs are unreal! Best purchase i've made, and they only cost me $400 for the pair. I really recommend this approach to axle wrap elimination.
As someone posted, the Mopar muscle cars had anti-wrap leaf springs from the factory, same deal. You can make your own, i remember Lou from Muscle Car made a set. Try the 'Power Block' archives for a write-up @ www.powerblocktv.com
.

yup, I was refering to the old school traction bars, I found these that are pretty close to your idea and you don't lose ground clearance etc.



kinda spendy tho, $70 at GayC Whitney

RCP Phx said:

It would take some time to work out the rear 1/2 leaves!

Click to expand...

Okay, there's the rub. I was thinking about adding this to my existing springs. If it will affect my spring rate so badly as to render them useless (and I do see how it could double it), then it ruins the whole "easy bolt-on" point...

RCP Phx said:

Build a traction bar,a whole lot easier!

Click to expand...

Well, I guess "easier" is in fact a relative term.

Remove the rear axle,
Fabricate and weld on a mounting bracket,
Reinstall axle,
Design, fabricate and mount a new crossmember,
(Working around the driveshaft and exhaust)
Design, fabricate and install a three-ended, swiveling traction bar.

Yeah, sure. Easy!

Robert

FoMoCo said:

yup, I was refering to the old school traction bars, I found these that are pretty close to your idea and you don't lose ground clearance etc.

kinda spendy tho, $70 at GayC Whitney

Click to expand...

Cool. I was thinking of these:



...but I don't know how well they'd work with the spring-over.

The ones you've found should work the same either way.

Robert

bjoehandley said:

Way back when Cheysler had a way of controlling axle wrap on their passenger cars. They mounted the axle on the front 1/3 of the packs and if that car also had an exeptionally powerful engine ( as in HEMI or SIXPAK), they'd add an extra half leaf on the front of the right side pack to reduce wrap further. Probably wouldn't work on a vehicle that actually need suspension flex off road, but it was effective!

Click to expand...

Um, XJ leaves use a forward offset spring pin, too......

Robert 771 said:

Cool. I was thinking of these:

...but I don't know how well they'd work with the spring-over.

The ones you've found should work the same either way.

Robert

Click to expand...

yeah thats exactly what I was thinking when I saw your sketch