Need help with a triangulated 4 link set up

[70chall440]

I am building a AAR clone/resto mod 73 Cuda and am putting a triangulated 4 link under it. I have fab'd up the arms and notice that I get about 6" of travel in the suspension from top to where the binding in the arms stop the axle. This will accomadate the rear wheels but I am wondering if this is acceptable or not. The biggest problem I have is room for the upper arms. It is symetrical and centered but this travel issue has me wondering.

[JRouche]

Can you tell if the binding is coming from the rubber or poly type bushings in the arms? If it is then I wouldnt worry too much. Im not sure how you are checking for bind.

Are you raising the body and letting gravity and the weight of the rear axle housing determine the bind point. If so put some extra weight on the rear end if you can. I have threaded sleeves sunk in my concrete floor so I can screw in eye bolts or whatever fastener to do some odd stuff. Ive used the threaded sleeves in the concrete for a few odd projects. Like strapping an axle housing down while jacking up the body of a car. And I can do one side at a time or both sides to show vertical travel.

But try to force (not a good picture, forcing the suspension) the suspension through its entire travel. And I say force meaning forcefully taking up any rubber bind that gravity cant give you a good idea on what exactly is binding.

And I like to be able to lock down the rear housing during a build to check for roll bind. That is pretty critical, specially if you are binding at 6" of vertical travel.

And I have to add. When I lock it down I dont really force anything. I creep up on the bind, constantly looking at the mechanical parts to make sure Im not running into a metal on metal bind issue. Im not looking to bend anything. Just trying to work the bushings like they would be worked on the road.

A vertical bind can be caused by a few things.

If the bushings are of a standard type. Where the inner metal sleeve is bonded to the rubber bushing, and the trailing arm is also bonded to the rubber bushing then thats a normal bind. You are twisting the rubber as it was designed.

But if your trailing arms are using floating poly bushings which dont grab the arms and inner sleeve then you should have alot more rotational movement.

Sounds like you have the side to side measurements down so you arent binding due to an offset of the arms.

So my question? What type of bushings are you using? JR

[70chall440]

I am using a poly bushing, the "kit" I am using is from Art Morrison. I think the binding is coming from the angle of the arms but overall I am not too concerned about it after talking to several others to include AM.

[JRouche]

Originally Posted by 70chall440

I am using a poly bushing, the "kit" I am using is from Art Morrison. I think the binding is coming from the angle of the arms but overall I am not too concerned about it after talking to several others to include AM.

Today, during my daily 4 mile walk I was thinking about it. Im not all the up on the triangulated 4-link suspension but was thinking the angle of the bars has to contribute to some of the bind. How does it work? A sharper angle means less travel?

Anyway. Sounds like you got some good info. With poly bushings you will reach a point of twisting till they load up. Then they may give some even after they have loaded up. Not as much as rubber bushings and not as much as bearing joints, like johnny joints. But they still have enough give so you wont be breaking arms.

Oh yeah. Six inches of travel is plenty I think for a road car. I dont think I have that much travel in my rear end.

Pictures!!!! I love to pics of the build... Everyone does... JR

[70chall440]

I appreciate your comments and the discussion. Not having ever built a 4 link before I am without an experience base to draw from which is why I came here. I will post some pictures as soon as I can down load them. Unfortunately my job and life gets in the way of working on the car but I am make some progress. The car is on a twirler and everything is incremental and interconnected so when I am doing one thing I have to stop and do something else.