mudgudgeon
Resident galah
It'll come around again
another radius arm flip
- Thread starter bigdfzj80
- Start date
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It'll come around again
I am a mere layman with no suspension engineering experience.
I am imagining hitting a speed bump at 25 mph.
If my arms are angled down, the force of that bump is going to be transmitted up the arm and into the chassis.
If my arms are more level, more of the force is going to compress my suspension.
If I imagine a line that starts at the chassis mounts for the radius arms and travels through the middle of the axle mounts, that lines relationship with the ground is going to have a big effect on how my suspension reacts to bumps, right?
I am imagining hitting a speed bump at 25 mph.
If my arms are angled down, the force of that bump is going to be transmitted up the arm and into the chassis.
If my arms are more level, more of the force is going to compress my suspension.
If I imagine a line that starts at the chassis mounts for the radius arms and travels through the middle of the axle mounts, that lines relationship with the ground is going to have a big effect on how my suspension reacts to bumps, right?
@bigdfzj80 - any update? I know the original brackets have been reused by others but I’m sure that making a set would not be overly difficult.
Keep this thread going, I’m sure I’m not the only one following.
Keep this thread going, I’m sure I’m not the only one following.
Almost. The line you need to imagine goes between the 'chassis' (frame) mount and the center of the axle shaft. It doesn't change when you move the arms to the top. The force is centered at the axle shaft, everything else is rigid (with the slight exception of the radius arm bushings, but that is negligible for the purposes of this discussion).
Sounds like a flip is pointless other than better ground clearance.
I'm not sure about that. There may be some benefit to the orientation of the bushings, also more clearance for the relay rod. However, you do sacrifice the protection the arms give you as 'sliders', keeping some rocks or whatever away from your drive shaft, rocker panels, etc. That's one reason I haven't done this, and also applies to three and four link suspensions when the arms are moved up. There are almost always trade offs to mods, this one doesn't have enough benefits to outweigh the drawbacks and fab work for me. Some of that could be attributed to laziness.
nukegoat
Should have bought a Jeep
Not true. Youre saying radius arm length doesnt matter?
Edit: So this one sort of does actually matter, but only inasmuch as the bushing compliance goes. You could change the bushing compliances and make it effectively the same
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y'all r talkin over my head.Will observe an learn.
First sensible statement made, all these enijawneers trying to accomplish, something that can be done simple, but nooooo the wheel needs to be reinvented. But hey it is you vehicle @landtank is like every couple of years
Is that your hangup? I never even mentioned changing the length of the radius arm, the OP didn't say anything about it, don't believe the usual method of flipping the arms changes the length, or if it does ever so slightly it's not significant enough to make any appreciable difference. Of course if you change the length, the geometry and driving characteristics change, but that is true no matter where the arm is mounted to the axle. Mounting the arm on top (changing the vertical plane of the axle mount points) doesn't make it longer or shorter, unless you move the mounting points in the horizontal plane as well. Unless you're arguing that fractions of an inch matter, flipping the arms has no effect on the arc of travel.
Also, technically it doesn't matter how long the arm is, the distance from the axle shaft to the frame pivot is the relevant spec. Make an S shaped arm that's 4 yards long, as long as the axle and frame mount are in the same place, the geometry doesn't change.
nukegoat
Should have bought a Jeep
Uhhhhhhhh..... so I dont even know your position now. The axle mounts changing would change the geometry?
Edit: Nope
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Either I didn't explain myself well or you are just being difficult. Both are very possible.
I am misusing the term 'axle', referring to both the housing and the axle shaft. I should have clarified 'axle shaft' in the above quoted statement.
Putting the axle mounts on top of the axle doesn't (significantly) lengthen (or shorten) the distance between the axle shaft and the frame mount. Therefore, no change in geometry. The axle travels through the same arc either way.
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Actually now I think about my statement, if the arm is flipped to the top of the axle, the wheelbase doesn't change right? The arm is in a different point in its arc, but the axle hasn't moved. Am I right?
LINUS
Waiting for the Great Pumpkin
I get this is going full tangent, but through the arc of travel because the arms are static mounted on the axle shell this flip using anything close to the stock rear pivot point means that it's going to be different.
The arm bolts to the axle don't hit the centerline of the axle, so flipping them 180* is going to put them in a different spacial plane, in as plain speak as I can say it to let whoever shoot down my 'crayon drawing' reasoning.
--I'm fine being wrong if you can state it in plain speak.
I'm betting the panhard rod bushings wear & where the springs may start catching & clipping / bind on the inner coil to the bumpstop cups/that flare at the base will prove that out too.
Again, full 'gut & crayon sketches', I'm not a KOH buggy builder
Right.
Correct.
I think one thing that would change is stress on the bushings though correct? Because having the bushings/arm on the bottom gives the bushings better leverage to limit rotational forces because of being closer to the contact patch vs on top of the housing and further from the tire contact patch.
And possibly why toyota always runs leaf packs under the axle too. We always lose something to gain another. I’m happy with how my junk rambles on down the trail.
this will all be rendered moot once you start welding on a stock axle tube anyway.......im predicting a bent axle in the very near future. 
geometry and engineering needs to take a back seat to some basic metallurgy of 25year old already noodly Toyota housing and housing deflection as it relates to your soon to be twisting splines and exploding diff. 
geometry and engineering needs to take a back seat to some basic metallurgy of 25year old already noodly Toyota housing and housing deflection as it relates to your soon to be twisting splines and exploding diff. 
