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Wristing a Radius Arm on a
live axle coil sprung
Ford
Let me first explain the coil sprung solid axle suspension system,
If you tear down off all the parts but the radius arms and diff you
have what in effect looks like an anti-sway bar,
This in fact functions like a sway bar as well, when the drivers side
tire drops downward it puts a bind at the C bushing on the driver
side witch then transfer to the Passenger side C bushing witch is
not trying to push the Passenger tire up, it instead wants it to twist
backwards, these two forces end up fighting each other and end up
with marginal flex because about 30-40% of the binding transfers to
radius arm end bushing, witch then allow in both up and down flex
of the bushing resulting in wheel travel
I will discuss Radius arm Drop down brackets because I do not like
them; they hang down and get caught on every rock on the trail
You add can heims to the end of the radius arm instead of the bushing,
but your still no better off then you were before, because now all
of the binding is in the C bushing because the heim’s will not bind
up, the only go up and down not in and out like the radius arm would
like. The heims want the tires to either both drops down or both go
up, at the same time, not in differing directions like what you would
need in Rock crawling. The heims also will send a lot more road vibration
through your truck as well.
You can also extend the Radius arm’s about 12-14 inches. This is most
popular with Desert runners, Pre runners, Stadium trucks and so on,
but it is catching on in the rockcrawling world. This does help, doing
this transfers that 30-40% bind at the radius arm end bushing and
reduces it to about 20-30% because of the decrease angles of the extended
arm places on the end bushings
There is a draw back of this how ever, now that you decreased the
“sway bar” factor by adding the longer arms, you have made it handle
worse on the highway, (witch might not be a deal for you) add in some
soft springs a tall lift and your in a really scary ride. The long
radius arms also lower your break over point and tend to get caught
up on rocks easily.
Wristing the arm, Either a Donavan (forgot his last name) or a Boyd D. Johnson
(web page)came
up with the idea of wristing an arm about 5 years ago, what this does
is put a pivot on one radius arm near the C bushing to eliminate all
of the bind on the radius arm and gain you the most front end travel
your shocks will allow. The wristed arm is normally located on the
passenger side of the rig because on a ford the diff is on the driver
side. With the wristed arm on the passenger side it helps reduce Driveline
binding. This pivot is normally lockable with either a pin or a bolt,
this way, you will have your handling back to normal on the road,
but once you get to the trail you can unbolt or UN pin the arm and
see the added flex!
There is also the Twister Arm made by Coby, These are
sold through BCbroncos.
These are very highly engineered piece of work, these use a custom
like hinge on the back end instead of the bushing and a sliding arm
up front for flex, check out his pics here.
Start Building it, Click here
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