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Watts Link

Do you recommend a watts link setup?


  • Total voters
    20
  • Poll closed .

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9
4
Exp. Type
Time Attack
Exp. Level
Under 3 Years
Philadelphia
Ive always thought a watts link was a great idea but am seeing mixed emotions on a question I posted. So let's see, watts link yes or no?
 

racer47

Still winning after 30+ years
392
497
Exp. Type
W2W Racing
Exp. Level
20+ Years
SE WI
Ive always thought a watts link was a great idea but.....
It is a great idea ..... for cars designed for it. All the new tube frame SCCA TA2 cars have a watts. Plus all the Trans Am cars and GT-1 cars have had watts since the 80's. They don't have to. They could use a panhard or triangulated links or whatever. But they have all converged on the watts.

The issue is that Mustangs are not designed for watts. So you end up with this heavy mess of brackets to make it work. Plus the stock panhard is light and well designed. It is as long as is practical and is level (give or take a little, depending on ride height).

But, there are several fast, stock chassis, race cars on this site that are using the watts. And as a long time racer, I believe in real, proven, track results. I'm still on a panhard. But I don't have a "racecar". I have a fast street car. In my opinion, there is no clear winner. You can be fast either way.
 
179
67
ny
Actual watts links started back in 69 trans am cars.pan hard bars go even earlier. With pan hard bar you have a fixed length bar on angle sort jacks the rear /chassis to opposite sides in a turn. Watts has 2 bars parallel to rear 1 pulling rear and 1 pulling ( or pushing) chassis.
I agree some watts are bulky .

Cortex I have in my fr500c. Boss ls has a Hayes
I love the way they handle.
 
I voted no cause I don't know watt the heck that is........old school has its downfalls now and then.............sue me..........................You won't get the Boss...that's in GOD's name...............;)
 
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8,184
The angles of the panhard bar, really aren't all that binding, watts answers a question that wasn't asked. This is one reason you will find panhard bars on cars with leaf springs, you would think that would create a massive bind in the chassis, in reality it doesn't. I agree, if the car was designed from the ground up, like a TA2 car, or was re engineered like @Fabman 's car it might make sense, but look at the link I shared, they are not faster than a PHB in our chassis, and a whole lot more to go wrong.
 

Fabman

Dances with Racecars
6,518
8,154
Exp. Type
W2W Racing
Exp. Level
20+ Years
Pleasanton: 1/2 way between Sonoma and Laguna Seca
This again. (sigh) Let me get my soapbox out....

The question isn't' as much about the method of attachment as it is about where the roll center IS.
Both methods have been proven to work well when properly set up. Again, its about where the roll center is located that has the most profound effect on handling, and much less about the bar that locates it.
I could absolutely guarantee that I could provide 2 identical cars, one with a panhard bar and one with a watts link with the roll center set in the same location (this is the whole point here) and no one but the very most discerning professional drivers would be able to tell you which was which.
Then why do we change from one to the other? Besides the obvious monkey see monkey do and placebo affects so common on the internet, the stock panhard bar is in a semi fixed position. The roll center is where Ford put it with the exception of very small changes made when ride height is changed. The watts link typically has a wider and more easily adjustable range so if you like the roll center very high you just use the top hole. If you like it very low like I do, you use the bottom hole or somewhere in between. You have choices. If you don't know where you want the roll center and are too afraid to make changes and experiment with different setups then you are probably not going to benefit from changing the method of attachment. If you LIKE where the stock roll center is and have actively tested other roll centers and linkages like the Phonix crew has done then a simple light weight stock height bar is perfectly fine. But wait....can't you adjust the RC Height with a panhard bar? yes and no. The stock arrangement has no adjustment for RC height. However, there are ways to make it adjustable for RC height but those usually include the use of heavy fabrication or the purchase of a kit, most of which will alter the roll center but have very limited adjustment. So stop asking is a watts better or a panhard bar better....that is not the question. The question is: "Do I want to change my RC height and how easy do I want it to be adjustable". But then you say: "My buddy put a watts link on his car and he loves it". That is almost certainly because when the linkage was installed the roll center was changed at the same time. Almost always lower. Lower roll centers make the car hook up while higher roll centers help the car rotate. Chassis setup is a soup that we season to taste and if you are like me, I never stop adding a little of this or that to sweeten the pot until I find the perfect recipe so gimme all the variables in the kitchen and I'll decide what belongs and what doesn't. But not everybody wants that. How about an easy button for enthusiasts that don't have the skill or will to fool with chassis setup? Find yourself a reputable after market provider and buy what they sell, do what they say and you will have a car with parts that are engineered to work together. If you cherry pick parts based on price or folklore you have embarked upon your own research and development program. I hope you are ready for that. It can be very rewarding and educational....and it can also be a total nightmare. Choose wisely.
 
334
352
OP, along the lines of what @Fabman is saying about roll centers, on a WL the rear RC stays in the same spot left versus right turns while with a PHB the RC is higher on right turns and lower on left. I don't know how much of this is a theoretical engineering difference versus an actual one. Personally I use a PHB and I don't think I can feel the difference (does the car rotate more on right handers? Is it placebo?? I don't really know). Anecdotally both of my spins on track have been trail braking into right hand turns but there user error unquestionably was a primary cause in both instances. I feel like the car MIGHT have a bit more tendency to rotate in slower right handers compared to left on trail braking. I have coilovers and have raised the left front and right rear a touch to counter this.

To be clear overall the car feels very balanced and handles terrific with a PHB. I don't want to make more of this than what is really there - but it potentially is a difference between PHB and WL.
 
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From the article written by some guy named Billy Johnson

" most arguments against PHBs use irrelevant diagrams with short bars at steep angles to justify the ‘extreme’ lateral axle movement claims. In reality, there is less than 0.1” of lateral travel in most cases and less than 0.2” over the entire 4” of vertical suspension travel. This is insignificant when compared to the amount of flex that wheels and especially tires see when cornering.

In regards to the PHB’s asymmetric handling argument, this problem is easily overcome by adjusting the car’s static cross-weight. If the car has suspension with adjustable ride height (like coilovers), placing a few tenths of a percent more static weight on the left front & right rear tires will easily offset and balance out the PHB’s inherent asymmetry of understeer in left-handers and oversteer in right-handers."
 
Last edited:
6,361
8,184
This again. (sigh) Let me get my soapbox out....

The question isn't' as much about the method of attachment as it is about where the roll center IS.
Both methods have been proven to work well when properly set up. Again, its about where the roll center is located that has the most profound effect on handling, and much less about the bar that locates it.
I could absolutely guarantee that I could provide 2 identical cars, one with a panhard bar and one with a watts link with the roll center set in the same location (this is the whole point here) and no one but the very most discerning professional drivers would be able to tell you which was which.
Then why do we change from one to the other? Besides the obvious monkey see monkey do and placebo affects so common on the internet, the stock panhard bar is in a semi fixed position. The roll center is where Ford put it with the exception of very small changes made when ride height is changed. The watts link typically has a wider and more easily adjustable range so if you like the roll center very high you just use the top hole. If you like it very low like I do, you use the bottom hole or somewhere in between. You have choices. If you don't know where you want the roll center and are too afraid to make changes and experiment with different setups then you are probably not going to benefit from changing the method of attachment. If you LIKE where the stock roll center is and have actively tested other roll centers and linkages like the Phonix crew has done then a simple light weight stock height bar is perfectly fine. But wait....can't you adjust the RC Height with a panhard bar? yes and no. The stock arrangement has no adjustment for RC height. However, there are ways to make it adjustable for RC height but those usually include the use of heavy fabrication or the purchase of a kit, most of which will alter the roll center but have very limited adjustment. So stop asking is a watts better or a panhard bar better....that is not the question. The question is: "Do I want to change my RC height and how easy do I want it to be adjustable". But then you say: "My buddy put a watts link on his car and he loves it". That is almost certainly because when the linkage was installed the roll center was changed at the same time. Almost always lower. Lower roll centers make the car hook up while higher roll centers help the car rotate. Chassis setup is a soup that we season to taste and if you are like me, I never stop adding a little of this or that to sweeten the pot until I find the perfect recipe so gimme all the variables in the kitchen and I'll decide what belongs and what doesn't. But not everybody wants that. How about an easy button for enthusiasts that don't have the skill or will to fool with chassis setup? Find yourself a reputable after market provider and buy what they sell, do what they say and you will have a car with parts that are engineered to work together. If you cherry pick parts based on price or folklore you have embarked upon your own research and development program. I hope you are ready for that. It can be very rewarding and educational....and it can also be a total nightmare. Choose wisely.
Your car doesn't count..
 

captdistraction

GrumpyRacer
1,954
1,698
Phoenix, Az
To @blacksheep-1 's point, there's not a ton of meaningful lateral arc in the PHB - I think the real value is in the tuning the RC height to the driver's preference (which can somewhat be done with PHBs, but you add similar complexity). I don't think its really something anyone needs until they're racing or chasing hundredths and fighting driver habits and preferences. VS stock I think there's a huge benefit to removing those bushings and all the deflection from the stamped mass produced parts. At a given RC, there's no measurable lap delta between two similar cars with one having PHB and one having a watts.

That said, I'm on the watts kool aid :)
 

Frank.JD.Perez

FJD Performance
314
490
Exp. Level
5-10 Years
Pleasanton/Hayward, CA
i dont think i count either cause i have a sn95...

BUT

i have a phb currently, but will be switching to a watts for basically what Sal mentioned. We are doing some major changes to my car in the near future and having the adjustability to change things between sessions will be beneficial especially heading into higher competitive fields. Who knows, i may be using the lowest setting on the watts or one of the additional other 3 spots, but i tune my car and make adjustments when i can and have learned a lot from @Fabman whether it is in person at the shop, over the phone, or at the track
 
179
67
ny
I guess I don't count either I started with a car that had ride height changes from ford racing. There is no stock suspension in my car. It came with a phb and I hated it didn't like feel in turns. Cortex for me kept car more stable.
 
6,361
8,184
i dont think i count either cause i have a sn95...

BUT

i have a phb currently, but will be switching to a watts for basically what Sal mentioned. We are doing some major changes to my car in the near future and having the adjustability to change things between sessions will be beneficial especially heading into higher competitive fields. Who knows, i may be using the lowest setting on the watts or one of the additional other 3 spots, but i tune my car and make adjustments when i can and have learned a lot from @Fabman whether it is in person at the shop, over the phone, or at the track
Actually ANYTHING that improves that triangulated 3 link is going to be better than what you have.
 

Dave_W

Cones - not just for ice cream
984
1,277
Exp. Type
Autocross
Exp. Level
20+ Years
Connecticut
In addition to what @Fabman said, with a Watts link you also have to consider if the "propeller" pivot is attached to the axle or the body. The roll center for a Watts link is the propeller pivot. For a Panhard bar, it's where a line drawn between the two attachment points instersects the axle midpoint. At the very fine end of suspension tuning is dealing with Roll Center change in relation to the car's (sprung mass) Center of Gravity when the rear of the body moves up and down (brake dive & acceleration squat) in combination with lateral load (turning).

For the same conditions, moving the RC closer to the CG means more of the lateral weight transfer happens through the suspension links and less through the springs, dampers, and anti-roll bars, i.e., the spring mass develops less roll angle for the same lateral force. If you move the RC closer to the CG with the same springs & ARB, they're counteracting less roll angle force being developed by the sprung mass, so they're effectively "feeling" stiffer. Likewise, moving the RC away from the CG with the same springs & ARB will feel like less roll stiffness, as they're working against more roll angle force being developed.

Now, as the rear of the car moves up and down, the CG is moving up and down as well. With an axle-pivot Watts, the RC is not moving relative to the ground but is moving relative to the car's body, so the distance between the RC and CG is changing. For a body-pivot Watts, the RC moves with the body, so the RC-to-CG distance does not change. And for a PHB, the RC movement is half the CG movement, so midway between the two Watts designs.

With an axle-pivot Watts, under trail-braking the rear suspension can "feel softer" in roll due to the increased RC-to-CG distance under dive, and under corner exit throttle-on it can "feel stiffer" due to the smaller RC-to-CG distance under squat - which also changes the front-to-rear axle balance of total lateral load transfer, effectively making the car tend slightly more to understeer under trail-braking and ovesteer on exit when compared to a body-pivot Watts.

At least that's what I've come up with so far, but I'm not a suspension engineer. Someone like @Fabman or @TeeLew may correct me.
 

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