Watts Linkage Tech

S197 Quiet Watts Linkage

Watt's linkage (also known as "parallel linkage") is a type of mechanical linkage invented by James Watt (19 January 1736 – 25 August 1819) in which the central moving point of the linkage is constrained to travel to a straight line within a certain travel length. Its applications in automobile suspensions are that of allowing the axle of a vehicle to travel vertically while preventing sideways motion. This type of locating device, however, does so much more than that for a race or track prepared vehicle. 

SN 97 Watts Linkage installed

Watt's linkage is used in the rear axle of some car suspensions as an improvement over the Panhard bar or rod, which was designed in the early twentieth century by a French car company of the same name. Both methods intend to prevent relative sideways motion between the axle and body of the car. Watt’s linkage approximates axle movement in a vertical straight line motion more closely, and does so while locating at the center of the axle rather than toward one side of the vehicle, as more commonly used when fitting a long Panhard rod. By locating the center of the axle the roll center of the vehicle can be clearly defined and thus be predictable and, in the case with Griggs Racing Watts links, completely tuneable. In fact we have found that our tuneable watts linkage lends itself to consistently Quicker lap times than a Panhard Bar. The reason for this is because, unlike a Panhard Bar, both right and left cornering characteristics are identical. This is due to the fixed roll center relative to ground of the GR40 Watts link, which is not so with Watts links from other companies.  

Not only are the linkages fully adjustable laterally for accurate real axle alignment, but also the Pivot which locates the roll center is vertically adjustable allowing quick easy and tuning of chassis balance with accurate and predictable results simply by unbolting it and moving it up for reducing understeer, and down for reducing oversteer. This Increases controllability and driver confidence under power and in cornering because the driver can predict easily what the vehicle will do. By having this adjustable rear roll center drivers have found maximum corner exit traction achievable while optimizing corner balance for faster lat times, and therefore optimizing their driving experience.  

SN 95 Watts Linkage/ TorqueArm  assembly  

 When used with a TorqueArm lateral tire loads are made independent of changes in engine & brake torque loads, vastly improving handling and power, applied performance, and braking making this rear suspension geometry THE best choice for competition vehicles, drag, autocross, road racing, and serious open tracking. However if a TorqueArm cannot be used due to race class rules or various other reasons the Griggs racing watts link can be installed independently of  our TorqueArm on any 9 " rear axle in any vehicle.  On Cars equipped with 8.8 rear ends, the addition of a TorqueArm Delete Bracket is required.

Watts Linkage for Ford 8.8" with TorqueArm Delete 

You can also trust that the Griggs Racing Watts link kit is going to be light adding minimal sprung and unsprung weight when compared to all other lateral linkages on the market. Not just light but also very strong; No bends in the main brackets affords zero flex and zero chance for failure of a well set up system. large tire guys need not fear either since the Griggs racing Watts linkage kit positively locates the rear axle laterally  use of maximum tire sizes is allowed with the least chance of rub.  

A further feature is the progressive failure design.  This feature has been proven real world testing. Lateral impact, such as impacting a curbing, can result in serious damage in competitors systems, but can be contained to the severity of the impact, as each part is designed to fail in progression. If the standard Watts link with Aluminum Arms is installed, in an impact, the arms bend first, then the bell crank fails, then the main plate.  This saves the Aluminum rear end cover, so a quick repair can often be made so the car can continue to race.  This is not possible with copy cat designs that delete the Main plate. 

Therefore the very best choice in a lateral axle locator available regardless of ride height movement is The GR40 Watts Link.

Want one for your ride? Contact us at Sales@Griggsracing.com to get yours.

Tech Question:  Why does your Watts Link attach to the axle instead of the chassis like other manufacturers do?  Wouldn't it be simpler and less expensive to make it the other way? 

Answer:  Very good question.  The difference in performance between the two mounting methods has to do with roll center migration.  Variations in roll centers as the ride height varies up and down with acceleration braking, turning and road surface irregularities causes variations in the vehicles attitude as this occurs which. This translates into what is at a minimum a confidence killing “unsettled feel” in a corner; and at worst, difficulty in maintaining control while driving at the limit. Spring and damping rates that compromise ride quality and tire are usually employed when roll centers are variable.  We went to great lengths in the design of the front SLA system to            reduce vertical roll center migration to an absolute minimum.  So, at the back end of the car we do the same. 

The greatest advantage of a Watts link over a Panhard bar is the ability to fix the roll center at the center of the Watts link bell crank. With a Panhard bar, as the vehicle rises or squats, the roll center rises and falls as well.   With a Watts link, if attached to the rear axle housing the roll center does not move at all relative to ground, (except for minor amounts due to compression of the tires).  When attached to the chassis the roll center rises and falls like the Panhard bar, negating most of the advantage of using a Watts link in the first place

Like many Griggs Racing products, there are emulators in the market.  Griggs Racing does not compromise performance for expedience of production, or cost.  So, as in all things, you get what you pay for.

Tech Question:  Do I need a Watts Link or is the Panhard bar enough?

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.  2005up 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.  To quantify as a example, on an ‘05 GT, our base GR40SS system is retails for $3600 with P/Bar.  Installing the SS kit will reduce lap times at Infineon Raceway by about 6 seconds over stock.  A Watts Link adds nearly $1000 to the price.  And only lowers the time by another second.    At Buttonwillow where there are more rapid esses and other rapid transitional factors present, the Watts is worth a little over 2 seconds lap time difference , so waiting to install a system based on cost is foolish if performance is the requirement.  All our systems are engineered to be easily to upgraded, so a Watts Link can be added later if the need arises.  We believe that you should not install any more devices on your car than you need.  If you need to win, or impress at the car show, install the Watts.  If not, don’t.