RADIUS ARMS

Motorider

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Ok. after I post this everyone is going to think that I am stupid, but I don't understand why changing the radius arms matters so much. The only reasons that I can see are that it will give you extra stregnth, but it just doesn't seem like you are gaining that much stregnth. HELP! I'm confused.

thanks
 

jeff

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Picture your motorcycle with a 4" long swingarm, yes, 4 inches... now imagine the angle that would be created during the suspension cycle... meaning the suspension fully extended to fully compressed. You'd have almost no travel due to its short length, in addition, the angles required to achieve full suspension travel would around 45 degrees, way beyond an ideal figure. By the time you reached the bumpstop (compression) your swingarm would be pointing almost at the sky. Now picture your current swingarm... as the tire goes up and down through the travel cycle the angle of the swingarm stays in a reasonable relation to the ground... this is nowhere near as severe as you'd have if your swingarm was shorter. Radius arms are very similar. The longer the radius arm, the less severe the working angle of the suspension, this means more travel and less bind. Building a longer radius arm in most cases is not for strength, it's to allow for additional wheeltravel without the increased working angle of the suspension. Now picture this... as the tires of a radius arm equipped truck extend into the droop region of the suspension cycle, the radius arm is following a natural arc, since the radius arm length remains constant, the tires and beams must follow whatever arc the radius arm happens to be traveling in. A supershort radius arm would cause the tire and beam to travel backwards as well as down. Longer arms help prevent this to some degree.

0-------------------| |

0-----------------------------------------------------------| |

Think about the arc that the two lines above would create if they could move from a fixed point at the left, now think about how much more the longer line can travel up and down in relation to the shorter line if you kept the lines parallel. The tire is represented by the | |

If you still don't understand it just say so.

Aloha
 

sirhk100

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Jeff,
I already understood the function of the Radius Arms, I just wanted to let you know that that was an EXCELLENT explination!!

'99YZ400,
'92 Ford Exploder lifted work in progress,
lifted golf cart
 

Waldo

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Good use of analogy. You get an A+ from this teacher!

P.S. Don't forget about the linkage on the swingarms of most MotoX bikes.

BRAAAAAAAAP!
 

Ryno

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Damn Professor-

If you would have taught me physics, I would have done much better. Great analogy though. Maybe send that over to the Chevy design team so they get a clue sometime over the next 10 years why Ford kicks their ass offroad in stock classes. All about KISS.

Ryno

Build it like a Rhino, and Leave it be.
 

sirhk100

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Speaking of linkage, I'm waiting for someone to show up with some stupid 60" travel rearend that can drop verticle using linkage. I know it's not practicle but how many trucks are running around out there with owners that can't think of ways to get rid of there money!!!

'99YZ400,
'92 Ford Exploder lifted work in progress,
lifted golf cart
 

Motorider

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OK. that was great. I think that some of my confusion was the thought that the radius arms that camburg and other companies sell, kept the same mounting points as the stock radius arms. But now that I know that it is not the case, what is a typical extension legnth for the radius arms? Can you bolt a f-150 radius arms to the I beam, and remount the rear pivot points? Thanks again for the help with the radius arms

Patrick
 

sirhk100

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I've got an Explorer, peak your head under a stock one and notice where the stock ones mount to. Then look at the transmission crossmember. Mine are going to bolt to the cross member when I get them. (Hopefully end of next week, I've already paid for them, now I'm just waiting!!) That's a huge difference. I'm sure Jerry, from Camburg, can tell you exactly how much longer then stock theirs are.

'99YZ400,
'92 Ford Exploder lifted work in progress,
lifted golf cart
 

Motorider

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I have a 93 Ranger, and I can see where mine mount up, and i get the point. Where did you have your radius arms made? sirhk

thanks
Patrick
 

sirhk100

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Donahoe makes them. They are $750 for the heim jointed extended radius arms with the replacment cross member. Camburg has a set that are like $450 for the normal bushing setup or $850 (I think) for the heim jointed setup. The difference is Camburgs are a little bigger but also a little shorter cause their arms mount to brackets that you bolt on right in front of your transmission cross member.



'99YZ400,
'92 Ford Exploder lifted work in progress,
lifted golf cart
 
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