Suspension design..........

[Milan]

Originally posted by Darrell C
I've been doing some research about double triangulated setup also, since I'm considering it. And putting a slight arch in my lower arms.

In addition to factors Blaine mentioned about bending the lower arms, I read a post on POR about someone who put a "decent" bend in the arms and ran into clearance issues with the lowers hitting the uppers. He ended up manufacturing new lowers without a bend to resolve the clearance issue. I would think a slight bend (whatever that is) would improve approach angle to the rear axle without causing too many untoward effects.

A local guy put bends in both uppers and lowers. But this is where I'm afraid they might "fold" on me when backing down off of an obstacle and landing with most of the weight going through the arms. But maybe I'm worrying about stuff needlessly.

[Darrell C]

Originally posted by Milan
A local guy put bends in both uppers and lowers. But this is where I'm afraid they might "fold" on me when backing down off of an obstacle and landing with most of the weight going through the arms. But maybe I'm worrying about stuff needlessly.

If the axle end of the lower arms are relocated upward and mounted to the center point of the axle tube, they should be entirely responsible for locating the axle under the vehicle from front to back, and hence carrying most (if not all) of the rig's weight when it starts to go nose up. If they are triangulated, they should also assist with locating the axle side to side.

The upper links should be responsible for assisting with side to side location, and controling axle tilt (pinion height). Consequently, I would think putting a slight bend in the uppers shouldn't contribute much to failure (assuming it happens) in that situation. But I would manufacture the lowers out of some pretty stout material; say 2" OD .5 wall tube, and use a gradual radius in the bend.

After studying this a bit under my rig, I can't see where a mild bend (say 15-20 deg) in the lowers would result in contact with straight uppers. Bend them any more than that, and rear axle pinion will be the low point (assuming a low pinion axle to start with). The rear swaybar links are a given problem, and will be removed/replaced by a rear AR.

I think Currie's J-arms are less than 1/2" wall (7/16" IIRC), they seem to hold up well with their mounting location.

[Milan]

Thanks for all the replies. Less than 20 deg of bend is what I had in mind. Just to help with clerance issues. But I was thinking either just bent lower or both lowers and uppers depending on clearences between them.