Fay's watts linkage or panhard bar?

[1967marti]

I'm wondering does the Fay's watts linkage replace a panhard bar? AKA does the same thing?
Also what about when the rear axle tries to rotate upwards under hard acceleration?
And as a side question, do you need to have a truss welded to your rear axle? I'm thinking of having new big bearing caps welded onto my 9inch and was thinking now would be a good time to have that welded on?

 

[Mach1ne]

Plenty of Internet babble about this. Suspension experts like Watts Links but you will get different answers regarding all of the brands out there, Griggs, Fays, Cortex, etc..

I have a Saleen Watts Link on my Mustang but they have been known for their failures. I need to replace it if I continue to track the car. I will be going with a Cortex.

Here is a good explaination of the differences between Watts and Panhard.

Question: Do I need a Watts Link or is the Panhard bar enough?
Bruce Griggs / Griggs Racing

Answer: That selection is based on either one of two things; performance demand on your chassis or aesthetics.

Basically, both a Panhard Bar and a Watts Link serve the same function, laterally locating the rear axle in the car, and linking the lateral loads generated when the vehicle is turning. As these loads increase the strength of this linkage must be adequate to the task. 2005 and up Mustangs are originally equipped with a Panhard bar that bends under raised lateral loads, as evidenced by multiple failures in the Miller Cup Series FR500 s which have to retain the OEM unit by the rules. So all our kits include a bar adequate to the loads, along with adjustability and reduced compliance.

The improvement a proper Watts Link makes is the roll center is fixed, it does not move up and down with ride height changes due to braking, acceleration, and road undulation. This creates more consistent tire loading, which yields more predictable behavior. The shorter couple and consistent roll center height definitely improve transitional response and build confidence in the driver. So you definitely need a Watts Link if you are in competition of any sort involving lateral loads, Road Racing, Autocross, Canyon racing etc., anywhere that a performance edge is required, especially if the car needs to make rapid left right transitions. The more esses, the more a Watts link is favored. Also, unlike other Watts Links on the market the GR40 unit has roll center height adjustment in four positive positions which allows the user to tune the chassis balance to conditions and record the settings, which if you are competing will prove most valuable.

If you are building a street cruiser, it is not required, unless you need it for the bling factor. Also, as a priority of design, the cost of a Watts Link option should never prevent the installation of a GR40 system. If you install even the least expensive of our GR40 systems on your car, which all use Panhard Bars as standard features, you are far better off than not doing anything or adding a competitors parts to a mix just to have the watts link.