Watts link or panhard bar?

[philofab]

What is the advantage of mounting the center crank to the chassis rather than the rear axle on a watts link?

[Silver69Camaro]

Originally Posted by Maximum Bob

it is from Canada though.

Then all bets are off!

[Maximum Bob]

Originally Posted by Silver69Camaro

Then all bets are off!

LOL...I go round and round with my Canadian hockey mates all the time....they do know how to drink though.

[Silver69Camaro]

Originally Posted by philofab

What is the advantage of mounting the center crank to the chassis rather than the rear axle on a watts link?

Less unsprung weight and zero roll center migration.

[mazspeed]

Originally Posted by Steve1968LS2

That's a shame, he makes some nice stuff and he's a great guy.. and a racer.

Did he say if he was gonna try to work around it?

Jim is a great guy and was great to deal with, but he didn't really say if he was going to fix it or not, but he was well aware of my problem. I would buy one again as would others if he could make it a little more compact.

[mazspeed]

Originally Posted by Maximum Bob

Alert....

just spoke with Jim about Mazspeed's situation and he agreed, but did say it should fit with an aluminum cover.

He is going to send some pics over and I wll post them up.

As far as a re-design....Im thinking he would have to get three or four guys with the same problem or interest....tank/cover...

You would have to call him though.

The guys over at Campbell Auto called me when it was there and showed me that it would not fit with the aluminum cover and Rick's gas tank that we have. I assume that the tank is the exact same size as the stock unit. If you have a fuel cell, you can set it back a bit too clear the al cover, but it just did not work with our setup. It was close but we needed some space to make sure it would clear, and it did not. Maybe Kevin here can also solidify what I'm saying as he knows of the problem as well. If Jim makes it a bit slimmer, I will buy it again no problem. I think if this could be fixed, this could be a very cheap soloution to a 4 link as this will keep the rear end in line and make the car handle much better.

[EvolutionMotorsport]

Originally Posted by jdwill13

I see a lot more cars with a panhard bar than a Watts link setup. I keep reading great things about Watts link but have yet to see it on any cars. Does anyone have Watts on their car?

Here is some general info you might find useful.

Watts Link/Panhard Bar:

WL: Constant Roll Center Height While Cornering
PHB: Roll Center Rises in One Direction and Falls in the Opposite Direction

WL: True Vertical Motion of Axle Thru Jounce/Rebound
PHB: Axle Travels in an Arc defined by the Length of the Panhard Bar

WL: Lateral Loads Reacted @ Both Frame Rails
PHB: Lateral Load Reacted @ One Frame Rail

Note: The constant rear roll center height, of a Watts Link System, will give the vehicle consistent and equal handling on both left and right turns. The overall benefits to the performance enthusiast include improved steering response, linearity, turn-in and overall cornering response, making the vehicle more predictable and easier to drive on all road at track surfaces.

A Watts Linkage is a lateral control device which consists of (2) horizontal links, (1) vertical link and a structural cradle. The cradle is mounted to the vehicles rear sub-frame (sprung weight) and used as a mounting location for the Watts Linkage. The vertical link or “Crank” is mounted to the center of the cradle which is designed to be at the centerline of the vehicle cross-car. The horizontal links are both mounted to the crank; one at the top and the other at the bottom. The opposite end of each link is mounted to a tower that extends from the rear axle housing. When the vehicle is at ride height, the optimum (rear view) orientation for the links is parallel to ground, with the crank positioned vertically. The optimum (plan view) orientation for the links is parallel to the rear axle tube.

The Watts Link System positively locates the rear axle, preventing it from moving side to side while cornering. With the rear axle essentially fixed in the lateral direction, there is now more real estate for larger rear tires without the worry of tire interference with the inner wheel well while cornering. The rear roll center is also lowered to be approximately equal in height to the center of the crank pivot. The rear roll center is the point where the lateral force is being transferred from the sprung weight to the unsprung weight. Lowering the rear roll center will reduce the portion of lateral weight transfer due to roll center height (a parameter which is not easy to tune) and allow the customer more freedom to tune front and rear roll couple distribution. The geometry of a Watts Link System also produces a constant rear roll center height while cornering unlike a panhard bar which has varying roll center height depending on whether you turn right or left. The constant rear roll center height, of a Watts Link System, will give the vehicle consistent and equal handling on both left and right turns. The overall benefits to the performance enthusiast include improved steering response, linearity, turn-in and overall cornering response, making the vehicle more predictable and easier to drive on all road at track surfaces.

More Notes:
While a vehicle is cornering and producing lateral force, the axles natural tendency is to move in the cross-car/lateral direction. With a Watts Link installed, as the vehicle builds lateral force, the lateral force is transmitted through the links into the crank, then into both frame rails through the cradle. Since one link is in tension and the other link is in compression, the load in each link is equal and the crank will not rotate. Since there are two links and one crank the lateral load is distributed between each of the two links and both frame rails, unlike a panhard bar which relies on one link and one frame rail to react all the lateral force. When the vehicle is not cornering, as the suspension goes into jounce and rebound, the crank travels with the body and will rotate to compensate for the vertical rotation of each link. This geometry will produce true vertical motion without any lateral component, unlike a panhard bar that will travel on an arc defined by the length of the panhard bar link.

Thanks....Mike

[louie@g-machine]

mount the bar low, make it level, and make it as long as possible. most of our designs utilize a panhard bar that is approximately 40" long. Over the usable travel of the car we are getting about .05" of lateral movement. it is so miniscule for 99.99 percent of cars that the weight savings and reduced costs all of a sudden make the panhard bar look like a superior option.