3 link Tech for dummies

[Fluxion]

BillyShope, I was playing around with your 3 link calculator on page 18. I was wondering why the offset of the odd link can't be zero. I am just wondering what changes when you place the odd link centered on the rear end like in a Lateral Dynamics or Art Morrison 3 link rear suspension.

[BillyShope]

BillyShope, I was playing around with your 3 link calculator on page 18. I was wondering why the offset of the odd link can't be zero. I am just wondering what changes when you place the odd link centered on the rear end like in a Lateral Dynamics or Art Morrison 3 link rear suspension.

When you center the odd link, you give up the advantage inherent to a 3link: The ability to dynamically cancel the unloading of the right rear during forward acceleration. With a beam rear axle, the driveshaft torque tends to unload the right rear (and, of course, load the left rear). The link loads are proportional to the driveshaft torque, so, if the odd link is offset correctly, it is possible to cancel the driveshaft torque effect for any and all values of driveshaft torque. Jaguar used the offset link in the early C-Type Jaguar.

So, why didn't Ford use an offset link on the Mustang? All you've got to do is take a peek at the Mustang underside and you'll see that there's a serious packaging problem with an offset link.

Some raise questions with regard to unequal wheel loading during braking, but this only comes into play as the rear wheels go into lockup, which, as I think I've stated earlier in this thread, is something to be greatly avoided in any case. Still, an outfit like Ford has to worry about legal claims after accidents, which, unfortunately, also affects design decisions.

http://home.earthlink.net/~whshope

[Norm Peterson]

With an offset odd link, what happens to the rear tire loading due to roll caused by engine torque reaction and the rear suspension's proportion of roll stiffness? I know that's a big reason for the huge rear sta-bars sometimes seen on dragstrip cars and I don't see it going away entirely. Is rear roll stiffness something that can be used in conjunction with some other amount of odd link offset to advantage?


Norm

[BillyShope]

With an offset odd link, what happens to the rear tire loading due to roll caused by engine torque reaction and the rear suspension's proportion of roll stiffness? I know that's a big reason for the huge rear sta-bars sometimes seen on dragstrip cars and I don't see it going away entirely. Is rear roll stiffness something that can be used in conjunction with some other amount of odd link offset to advantage?Norm

Norm, if an asymmetric suspension is used to cancel the driveshaft torque's effect on rear wheel loading, the car's roll stiffness distribution doesn't enter into the picture. In other words, the reaction to the driveshaft torque is taken entirely through the links and no roll deflection occurs.

http://home.earthlink.net/~whshope