Of course it's going to drive better - his caster was way the heck out. There isn't a caster solution off the shelf readily available in the states for the amount of lift he has.
Radius Arm Flip
- Thread starter adventr
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Of course it's going to drive better - his caster was way the heck out. There isn't a caster solution off the shelf readily available in the states for the amount of lift he has.
Ah, back to the topic of YOUR thread. Obviously a few folks on Mud tend to hog others threads in an attempt to convince everybody that their theory is the right one; who has that kind of time? "You should have done this", "you should have done that". Good on you for diving in and doing what YOU wanted to do.
Am I wrong in thinking that slee radius arms or the ones from Iron Man do the same..... I may be way off though and if I am I may ditch my slee arms and go this route also.
Yes, the slee arms shoud do the same thing, but not for free. Also, they probably wouldn't be enough for his 8"+ lift.
So essentially it is better. I do know that my caster is out of whack even with the slee arms and was looking for something to return it to stock.
And they don't give you the ground cleance either. Not sure if they give enough tie rod clearance for cut and turn.
Interesting thread. Nice work Tim. Good explinantions W.E. but I think your missing one thing, don't forget he moved the mounts relative to the axle. The arm "changed shape" when flipped but like you pointed out that doesn't matter, what matters is the mounts moved when he cut and welded the brackets back.
Mounting the radius arm to the top of the axle does make the arm more flat. This is the only change other than MAF brackets I've seen that moved the mounts to really change the geometry.
That's where the improved ride came from. (less harshness from being on the vertical part of the travel arc instead of closer to the bottom) and of course the improved caster by rotating the axle back to stock helped steering too.
The radius arm flip is different than any bolt in arm. Bolt in would use the stock mounts so the arc is similar (but the axle is rotated for caster) this flip actually moves the mount locations.
If I ever go for a big lift this seems like a great way to go.
Another way to explain it, I'm thinking of a stock truck, 1. don't touch the arms 2. factory axle is mounted on top with 2 points 3. move it down to underneath the axle on 2 new points. = 4-6" of lift with stock arm geometry and caster. ...of course steering, driveline, etc. will need some attention.
axle
OO-------------O
OO-------------O
axle
Mounts down low...
Mounts up high...
Mounting the radius arm to the top of the axle does make the arm more flat. This is the only change other than MAF brackets I've seen that moved the mounts to really change the geometry.
That's where the improved ride came from. (less harshness from being on the vertical part of the travel arc instead of closer to the bottom) and of course the improved caster by rotating the axle back to stock helped steering too.
The radius arm flip is different than any bolt in arm. Bolt in would use the stock mounts so the arc is similar (but the axle is rotated for caster) this flip actually moves the mount locations.
If I ever go for a big lift this seems like a great way to go.
Another way to explain it, I'm thinking of a stock truck, 1. don't touch the arms 2. factory axle is mounted on top with 2 points 3. move it down to underneath the axle on 2 new points. = 4-6" of lift with stock arm geometry and caster. ...of course steering, driveline, etc. will need some attention.
axle
OO-------------O
OO-------------O
axle
Mounts down low...
Mounts up high...
That's cool.
Makes no difference. There is no pivot at the axle mounts, the forces still are driven through the center of the axle. For all intents and purposes, the arm and the axle are one and the same. The arm is an extension of the axle, as it's fixed in place in relation to the axle, with the very slight exception of the slight movement from the bushings.
Now that's a good point. I'll admit I missed something. I'm more used to one bushing on the frame and one on the axle. Long arms on a Jeep do what I was trying to describe.
Like you point out the two bushings do fix the axle to the arm. Same arc. I do still need to sketch this out some more to get it stuck in my head. That can wait till tomorrow at work with Pro-E.
I guess the improvements came from the springs not bending, the caster correction, and axle location (arm is effectively longer to center the axle).
I still think this is a great solution if your good with a welder.
Hold up now, I think Sean's on to something here.
After reading Sean's post, this was bugging me, so I went out (in the rain!) and took some actual measurements of my truck.
Between the frame mount and the rear axle mount, the arm is 28" long (assuming you followed a straight line). From the rear axle mount to the front axle mount is 7.5". There is a 3" drop between the frame mount and the axle mounts (on my truck, with a 3.5" lift).
Now the axle tube is centered between the two mounts, with the bottom of the tube even with the center of the two axle mounts. That puts the center of the axle just about 2" above the frame mounts.
For simplicity, I rounded all those off, but they should be accurate within 1/4" (close enough for rock and roll).
So I plugged all those into Google Sketchup, and here's what I came up with (using Google Sketchup's handy measuring tool).
Stock, the center of the axle is 1" below the frame mount. The distance from the frame mount to the center of the axle is 32". For those of you who remember their high school geometry (or cheat), that puts the total angle that the arm is at (relative between the frame mount and the center of the axle) at 1.79 degrees.
Okay, on to the flip. By doing the flip you're dropping the axle (in relation to the two axle mounts) by 4". Once again using Google's handy measuring tool, I found that the distance between the frame mount and the center of the axle is just a hair shy of 32.5".
Now if you are just moving the axle in relation to the arm (dropping it by 4", or 5" lower in relation to the frame mount) that would put the angle at......8.85 degrees. Granted this assumes that the axle physically moved 4" down (which it wouldn't due to the spring rate).
Assuming that the axle stays in the same location (1" below the frame mount) regardless of the flip (which it would, unless you changed the spring rate), the angle difference is much smaller at only 1.76 degrees (.03 degrees flatter if than stock if you've been keeping track).
So...is half an inch significant enough that it changes the way the vehicle handles? Probably not. But flipping the arms does actually both lengthen and flatten the angle of the arms. (Well the flip has nothing to do with it, but rather moving the axle side mounts to the top of the axle.)
It's cool! 
- Thread starter
- #114
Sounds like we need to get Mythbusters in on this one. Just don't let them loose with any cannons near my cruiser! 
Thanks for all of the support/comments! I'll be updating this thread on occasion, and anyone else that tackles the flip is welcome to post their progress/results in here as well.
Thanks for all of the support/comments! I'll be updating this thread on occasion, and anyone else that tackles the flip is welcome to post their progress/results in here as well.
Flex pics?
- Thread starter
- #116
After I extend brake lines. Also going to make some 2" shock spacers for the front so I can get more downtravel.
We've got a 20 degree ramp that I'll put it on.
I don't forsee gaining any extra flex from the flip though.
How are you planning to make the spacers?
- Thread starter
- #118
I'm going to steal Akarillo's design, and use some tubing to make the spacers. Pretty slick way to do it.
I'm going to steal Akarillo's design, and use some tubing to make the spacers. Pretty slick way to do it.
That's been on my list for a while too but I don't know if it can be done with just 2".
