I am asking this question and would like some informed replies.

Tuff Country and Rancho sell extended Radius arms that differ from Superlift and some other manufacturers.

The question I have is related to the mounting points that attach to the chassis.

The Ford/Superlift setup uses a similar setup to a Rangie, which allows Left and Right movement as well as up and down movement.
I believe this is required due to the way the TTB front works, as you all know the wheels/diff under full articulation actually move either in / \ or out \ / .

I was wondering if the Rancho/Tuff Country links are designed with an offset to allow for this?

The reason I ask is that we only have superlift gear here, and I am keen to replace the Drop down brackets with extended radius arms. I can see that the Rancho/Tuff Country ones will allow more up and down movement but am concerned about chewing out bushes with the amount of sideways movement that the TTB setup has.

Your informed opinions would be greatly appreciated.

Dazza.

 

The radius arms don't move with the tires, so that's unrelated. You're thinking about a double A-arm suspension.

The bushings in the back of extended radius arms are stressed LESS than in short arms, so don't worry.

 

I'm a bit confused, check out my pics at superford, of the bronc comming up the track, the wheels look like this \ /, due to the way the axle pivots.
The Axle is held onto the front cross member by the 2 axle pivot brackets, then also supported by the radius arms which in turn are bolted to the chassis.

That is how the ttb works, jack up the front of the bronco's or f- series and the wheels will pivot in at the bottom. They sort of "hang"
so my question still stands.

Perhaps the distance that the extended brackets are from the axle means that the amount of l-r movement is only mimimal?

Daz.

 

Dazza, I don't believe it is possible for the TTB suspension to move side to side due to the pivot points that secure to the frame. The tires do move up and down in an arched type motion, but don't move left to right (not possible with the center pivot points). Therefore, the only concern about bushings should be if they can handle the twisting of articulation. My superlift (6" with extended radius arms) kit bushings have not given me any problems. I can't speak for the other kits, but I would imagine there bushings should be able to handle the twisting as well.

If this doesn't answer your question, maybe I am not understanding it. Hope this helps.

 

Dazza,

I understand exactly what you are talking about with the radius arm setup. I was concerned about this myself but went ahead and put the Tuff Country arms under my 92. I have had no problems with the radial movement of the axle halves and side torque wear on the radius arm bushings. The additional wheel travel is really nice too.

Guys, the concern is that the raduis arm is rigidly attached to the axle half and in the course of the suspension travel, the arc of the axle half causes the radius arm to rotate just a bit as it moves through the arc. With the way Tuff Country mounts the radius arm, there is a regular bolt and split bushing at the end of the radius arm, creating a positive up/down movement with a lot less room for slop from side to side. As the axle half drops, the radius arm swings down with it, the concern is that the new mounting style won't allow for the slight rotary twist that the raduis arm MUST make to move with the axle half. As Dazza showed already, at full extension the wheels look something like this if you look at the truck from the front...\ /... cambered way in at the bottom. The axle halves remain perpendicular to the wheels (or should unless you have broken something). Since the radius arms are rigidly attached to the top and bottom of the axle halves, this forces the raduis arms to rotate just slightly as the suspension travels. In my experience, the movement is not great enough to cause any sort of bind or bushing damage.

 

Here's how to understand the motion of the TIB/TTB suspension:

A moving part attached at 2 points rotates around the line thru those 2 points. So the axle pivot & the radius arm bracket are the 2 points, and if you imagine the line passing thru both of them (for ONE axle half), you can then imagine the actual arc the hub cuts as that suspension travels. It not only moves inward, but also rearward. The furthest out it ever gets is when the hub is straight to the side of the axle pivot, and the furthest forward is when it's straight on level with the radius arm bushing.

To reduce the twisting in the bushings, you could redesign them so their bolts pointed along the line from the axle pivot to the radius arm bushing, like the door hinge pins line up. You'd still get the arc motion, but the bushings wouldn't get twisted & crushed. I'm not sure why Ford didn't design it that way to begin with, but it could be as a droop-limiter, like limit straps on lifted solid axle suspensions.




I'm not sure why I said, "The radius arm doesn't move with the tires". For some reason, I had steering in my head - not articulation.

 

See I knew you guys would figure out what I wanted to know
thanks heaps for the explanations and feedback.
Steve, you had me worried, but have redeemed yourself

I like the Idea of the Tuff country arms you are running greystreak, so I will attempt to import a set of 2nd hand ones. (good ones).

Thanks again for your feedback, It has helped a lot.

Dazza the Aussie