DOM radius arms/coil spring location

[Gunnibronco]

When I swap axles, I'm planning on replacing my Bloody Knuckle extended radius arms with fabricated DOM arms. My goal is a straight arm with no bends.

Right now I'm running 79 Bronco D44 (I think it's a 65.5" WMS) and adjustable upper coil buckets with extra width to match the wider 79 axles. I plan to build my new axles at the same width.

I'm thinking of going back to a narrower stock coil bucket location. This would allow me to run a straight radius arm without compromising turning radius/tire rubbing on the radius arms. I'm also a bit concerned the larger D60 knuckles won't allow for the same WMS width with the wider coil mount locations. So going back to the stock Bronco coil location would solve both problems.

Would this possibly cause any negative ride/articulation issues? I don't think having a couple extra inches of axle outboard of the coil springs would be terribly detrimental, but wanted input before I put things in motion.

Also, is there any advantage/disadvantage to running shorter or longer upper links? I'm basically going to duplicate the Ruffstuff kit, but they call out longer upper DOM lengths than I expected. My arms should be about 40" (or a little less) long with 7" link separation at the axle.

I'm going to build a set up like the image below and use axle brackets from Ballistic Fab.

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[ZOSO]

dont see why it would be an issue.

[Gunnibronco]

I took measurements off the 72 and the 74 today. The stock spring location is about 5" narrower than the full width/79 axles.

A friend sent me this, regarding moving the springs in:

"inboarding the springs and keeping the same spring rate will reduce roll stiffness, depending on suspension geometry can also add more roll oversteer"

So I'm going to expect some change to the ride, but hopefully it won't be significantly worse. I think Cody's rig had full width axles with narrow stock upper coil bucket.

[Justin]

He's right, but with a correctly set up radius arm/panhard bar setup I'm not sure I'd be that worried about roll oversteer. If you're keeping the springs in the stock EB location, I can't imagine you'd pick up meaningful body roll, either, given the same spring rates, etc.

If you separated the coil mounts from the radius arm location and moved the radius arm inboard from stock you'd pick up some roll. You could tune some of that out with stiffer bushings or add a sway bar.

[Gunnibronco]

He's right, but with a correctly set up radius arm/panhard bar setup I'm not sure I'd be that worried about roll oversteer. If you're keeping the springs in the stock EB location, I can't imagine you'd pick up meaningful body roll, either, given the same spring rates, etc.

If you separated the coil mounts from the radius arm location and moved the radius arm inboard from stock you'd pick up some roll. You could tune some of that out with stiffer bushings or add a sway bar.

Thanks, it all makes sense. I don't expect to see a big difference in how it drives.

[Digger]

I took measurements off the 72 and the 74 today. The stock spring location is about 5" narrower than the full width/79 axles.

A friend sent me this, regarding moving the springs in:

"inboarding the springs and keeping the same spring rate will reduce roll stiffness, depending on suspension geometry can also add more roll oversteer"

So I'm going to expect some change to the ride, but hopefully it won't be significantly worse. I think Cody's rig had full width axles with narrow stock upper coil bucket.

Even with the springs pushed out on my full width, I still needed a sway bar to keep the front end under control. If you need to move the springs inboard, just do it and compensate with a sway bar if needed.

[Jesus_man]

Even with the springs pushed out on my full width, I still needed a sway bar to keep the front end under control. If you need to move the springs inboard, just do it and compensate with a sway bar if needed.

That would be my advice as well. But are you saying they are 5" narrower total or 5" per side?

One other thing to consider is mounting your frame brackets to the inside of the frame. That would allow them to not be an anchor over the rocks. But there are other things vying for that space. This is what I did. Ignore the novice welding.

[Gunnibronco]

Even with the springs pushed out on my full width, I still needed a sway bar to keep the front end under control. If you need to move the springs inboard, just do it and compensate with a sway bar if needed.

That would be my advice as well. But are you saying they are 5" narrower total or 5" per side?

One other thing to consider is mounting your frame brackets to the inside of the frame. That would allow them to not be an anchor over the rocks. But there are other things vying for that space. This is what I did. Ignore the novice welding.

Total added width is 5”, so 2.5" per side. Not a huge difference.

I've looked at some brackets that hang on the side of the frame. It's interesting. Even mounted outside the frame it might reduce the turning radius/rub at lock. I'm also thinking that the larger D60 knuckle packaging might not allow the same WMS with the springs where they are. It's going to take some measuring/mocking up to see how everything fits together. Straight arms, keeping WMS width and full lock steering will be the primary goals. I'll move the springs in before going wider or losing turning radius.

Edit: I noticed your link brackets are inside the frame. I was thinking outside the frame to reduce the angle from the frame to the spring/axle mount. Inboarding the frame bracket with the wide axle mount would make the angles more severe.


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[Gunnibronco]

Part of my response to your questions ended up on your 4 link thread. Weird.

I removed and replaced the stock frame brackets when I went to long arms (12”ish longer and thru bolted heims). The brackets that came with the arms were parallel with the frame. The heim misalignment and the bend in the arm allowed everything to work even with the wider axle mounts.

I removed and replaced those brackets when I moved the axle forward 2". Mine are now angled slightly out towards the axle mounts. I think I'll probably be able to leave them as-is and they will be pointing very close to the stock mounting width with straight arms.

[Jesus_man]

I saw it. There is something said to now have to rework those brackets. And the front isn't too bad since it's a steering axle and you can maneuver around something if you are getting hung up on that bracket. The rear is a different story, at least it has been for me.

Since I was already cutting off factory stuff, it made sense to try and tuck every up as high as possible, and I went thru all the effort to clock my Atlas flat so anything I can do to improve breakover is worth it.

[Gunnibronco]

I saw it. There is something said to now have to rework those brackets. And the front isn't too bad since it's a steering axle and you can maneuver around something if you are getting hung up on that bracket. The rear is a different story, at least it has been for me.

Since I was already cutting off factory stuff, it made sense to try and tuck every up as high as possible, and I went thru all the effort to clock my Atlas flat so anything I can do to improve breakover is worth it.

I looked at my bracket angle last night in relation to the potential new location of the springs. They are "aimed" about 2.5” inboard of the stock spring location, and 5" inboard of the current full width springs. So to have a truely straight arms and little stress on the bushings they will need cut off and repositioned. I'll probably go that route.

The Metalcloak joints on the back of my arms are not supposed to be mounted with misalignment strain, nor are the poly bushings that will be on the front of the arms. So I need to get things pretty well aligned.

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