Rear upright clevis

[Pete]

After looking at these two pictures and noticing that they have been made 90 degrees from each other where the heim joint connects, I'm wondering if there is a preferred position. Can somebody comment? I'm getting ready to machine a set and happen to run across these two styles.

Pete

 

[Jac Mac]

Top pic is 'correct', but you could play around with settings similar to bottom photo in order to tune in traction/braking issues if your that way inclined, always bearing in mind the limits of the rod ends and tyre clearance etc.

Jac Mac.

 

[Pete]

Thanks Jac Mac.

 

[Howard Jones]

Jac, Why? What I mean is I would think that the bottom rod end alinement/orientation would be correct. Now I have learned that you are to be believed but in this case I don't understsnd why. Can you help me with this?

I did once see a TRANSAM car's front a-arms (inboard upper rodend to chassis pickup point) designed with a similar setup (yourway) and I thought at the time, that doesn't LOOK right. However I remember thinking people at this level of the sport wouldn't make that kind of design error, so it must be OK. I have wondered about that one ever since.

Howard

 

[Jac Mac]

Jac, Why? What I mean is I would think that the bottom rod end alinement/orientation would be correct. Now I have learned that you are to be believed but in this case I don't understsnd why. Can you help me with this?

I did once see a TRANSAM car's front a-arms (inboard upper rodend to chassis pickup point) designed with a similar setup (yourway) and I thought at the time, that doesn't LOOK right. However I remember thinking people at this level of the sport wouldn't make that kind of design error, so it must be OK. I have wondered about that one ever since.

Howard

Howard,
The top photo is correct in that it is an original GT40, not a replica thats all. It could be said that the lower pic would allow more suspension travel, but given the long length of the forward links this should not be an issue.

Now the T/A car that you observed with the inner rod ends orientated so the bolt is vertical has this done so that the w/bone can be raised/lowered at either end to tune in the anti-dive under braking & create more castor on turn in, along with a few other changes that you get for free & dont necessarily need.

With regard to the lower pic the 'cranked' top/bottom upright attachments could be rotated in the upright to raise /lower the effective attachment points to dial in traction /braking.

Jac Mac

 

[Ted Reese]

On a radius rod I am not sure that it matters, as long as the clevis is angled to align with the rod.

Mounting it so the bolt is vertical is the safe way to do it. In this orientation the bolt should be inserted from the top so the head of the bolt is on top and the nut is on the bottom. If the nut were to loosen and fall off, gravity is still holding the bolt in place, hopefully long enough for you to do an inspection and notice the lack of a nut.

Mounting the bolt horizontally, if the nut were to loosen and fall off, vibration and movement could result in losing the bolt as well.

Seeing how inboard A-arm mounts were brought up, the correct way is with the bolt vertical. The forces of braking and acceleration on an A-arm create tension and compression in the tubes of the arms. With the bolt vertical and the body of the rod-end horizontal, all the forces go straight through the shank of the rod-end, to the ball, and into the bolt. This is radial loading, the strong direction for rod-ends.

If the bolt is horizontal and the body of the rod-end is vertical, the forces go through the shank of the rod-end, to the ball, but now the ball is trying to slide down the bolt. The ball will be restrained by the clevis, but we now have a force acting axially along the bolt, the weak direction for a rod end. If overloaded, the ball will pop out of the body. Suspension is often designed like this because it allows more suspension travel, but that does not make it right.