Watts Link for improved street manners

Norm Peterson

corner barstool sitter
Joined
Feb 5, 2011
Posts
3,615
Reaction score
316
Location
RIP - You will be missed
Fly around a left hand corner..and simultaneously hit a bump (s) with the RR, the axle will shift towards the driver's side if a phb used.
Hitting a 1" one wheel bump with a stick axle is about the same as combining half an inch of two wheel bump with about 1° of roll.

Half an inch of two wheel bump (like only half an inch of lowering) isn't going to geometrically move the axle very far at all. If anything, it'll be the 1° of axle roll relative to the chassis from the bump added to the maybe 2 degrees of [suspension] roll from the cornering that you'll be seeing visually with a fender-mounted GoPro.

I'm intentionally ignoring the component of roll due to tire vertical stiffness and lateral load transfer . . . for now.


Norm
 

2008 V6

forum member
Joined
Mar 18, 2012
Posts
335
Reaction score
1
This debate seams to come up every year or so. DO a search.

Panhard bar is lighter than a Watts Link = Less sprung weight.
Rear roll center for a Panhard bar is determined by where it is situated to the ground.
It should be as low as possible and parallel to the ground at ride height.

I have driven the same car on track with a properly set up Panhard bar and then a Watts link. I could not notice any discernable difference in lap times or predictability between the two – Not on a S197 - Everything Heim Jointed.
They might act different on rough Auto Cross Course with quick and forced transitions. I don’t know some say yah some say nay. I chose to go with the weight savings on our S197. I didn’t relocate the Panhard bar as low as I would have liked because the development stopped.
Gentlemen – We have a heavy straight chunk of steel that both our rear tires are connected to.
When one tire come in contact with a bump it affects the other tire regardless of what we want.
Purchasing decent springs with dampers that can control that straight lump of steel would be my first suggestion. After that – How much money and time do you want to spend to make out boats predictable? Nothing wrong with a straight axle on a smooth surface but most places are not smooth.
OHH - This should stir the pot LOL.
 

Pentalab

forum member
Joined
Mar 5, 2013
Posts
5,211
Reaction score
1,093
Hitting a 1" one wheel bump with a stick axle is about the same as combining half an inch of two wheel bump with about 1° of roll.

Half an inch of two wheel bump (like only half an inch of lowering) isn't going to geometrically move the axle very far at all. If anything, it'll be the 1° of axle roll relative to the chassis from the bump added to the maybe 2 degrees of [suspension] roll from the cornering that you'll be seeing visually with a fender-mounted GoPro.

I'm intentionally ignoring the component of roll due to tire vertical stiffness and lateral load transfer . . . for now.


Norm

Points well taken. But if a 1" drop moves the axle 3/8"... then a 1/2" drop will move the axle 3/16". Even if it shifted only 1/8"... it might not seem like much, but if you hit a series of bumps on the RR, the axle will shift 1/8"- 3/16"..... in a pulsating / hammering action. Take XXX amount of weight (weight of back end of car + axle assy)..and slam it 1/8" - 3/16" over towards the drivers side several times, in an oscillating fashion.... the back end could partially break semi loose, resulting in the skittering effect folks are feeling. That's just conjecture + speculation on my part.
 
Last edited:

Pentalab

forum member
Joined
Mar 5, 2013
Posts
5,211
Reaction score
1,093
This debate seams to come up every year or so. DO a search.

Panhard bar is lighter than a Watts Link = Less sprung weight.
Rear roll center for a Panhard bar is determined by where it is situated to the ground.
It should be as low as possible and parallel to the ground at ride height.

I have driven the same car on track with a properly set up Panhard bar and then a Watts link. I could not notice any discernable difference in lap times or predictability between the two – Not on a S197 - Everything Heim Jointed.
They might act different on rough Auto Cross Course with quick and forced transitions. I don’t know some say yah some say nay. I chose to go with the weight savings on our S197. I didn’t relocate the Panhard bar as low as I would have liked because the development stopped.
Gentlemen – We have a heavy straight chunk of steel that both our rear tires are connected to.
When one tire come in contact with a bump it affects the other tire regardless of what we want.
Purchasing decent springs with dampers that can control that straight lump of steel would be my first suggestion. After that – How much money and time do you want to spend to make out boats predictable? Nothing wrong with a straight axle on a smooth surface but most places are not smooth.
OHH - This should stir the pot LOL.


My WL watts link is just 2 x short bars vs the long BMR adj PHB. The BMR PHB brace gets replaced with the WL equivalent. Oem diff cover gets replaced with a thicker aluminum cover. Difference in weight between the 2 x setups is minimal. Pass end of a PHB is bolted to the body, driver's side of PHB is bolted to the axle. Outer ends of my wl watts are bolted to the body, inboard ends bolt to the diff cover. How much is sprung weight and how much is unsprung ? I'd take the weight of the phb, and divide it in half.... since half is bolted to body and the other half bolted to axle.... and ditto with wl watts. So it comes out a wash.

On a lowered car, the phb is at a shallower angle vs oem phb..which is good. The steeda adj length phb is also adjustable in height..at both ends, so in theory, you should be able to get their phb almost parallel to the ground.

The BMR phb has a poly bushing at each end. My wl watts has a elastomer bushing at each end of each rod, so 4 in all...... vs just 2 for a phb. So you also have to factor in the compliance of 4 bushings vs 2.

How many bumps are you hitting on corners on your track ? Most tracks are pretty smooth for the most part. Even if they are not, you at least know where the bumps are, since it's a closed loop. Even on a rough autoX course, you know where the bumps are. Out on the street, it's a whole different ballgame. Around town here, bumps can change by the week. Some roads deteriorate over a few months, some are fixed, some get good repairs, some get lousy repairs. I never know what condition the roads will be on the other side of town, since I'm seldom over there. Even when I think I have it figured out, it will either change or I'll have a tough time trying to remember specific road condx, for hundreds of miles of road surfaces. At night, it's worse.

Bottom line is... the watts is planted on bumpy corners...and the poly phb isn't. From a safety point of view/inspires more confidence, I feel its worth it.
 
Last edited:

Norm Peterson

corner barstool sitter
Joined
Feb 5, 2011
Posts
3,615
Reaction score
316
Location
RIP - You will be missed
Points well taken. But if a 1" drop moves the axle 3/8"... then a 1/2" drop will move the axle 3/16".
That much movement from a PHB that started out only slightly inclined is geometrically impossible. I measured about 1.5" difference when the car was bone-stock, which ends up being pretty close to level with the car in its "fully loaded" condition.

FWIW, it's not a linear relationship between lowering and axle movement. Even if the geometry was such that you did get 3/8" lateral movement toward the driver side at 1" drop, a half inch drop would only move the axle about 0.075". But that PHB geometry isn't possible on the S197 (mounting the chassis side of the PHB the necessary amount higher than it is would have the PHB running through its own brace). Not that any sane chassis designer would intentionally set a PHB for a road car at over 9° inclination.


Something else has to be going on, including the possibility that the 'before lowering' and 'after lowering' measurements were not made under conditions that were identical except for the lowering.


A Watts link does a better job of isolating the chassis from lateral forces caused by vertical bumps, most likely because the "football" is free to rotate about its main pivot. It's not perfect, though, as a little net lateral movement still sneaks through the main pivot. A PHB has no such isolating mechanism. Fun fact that may be relevant here . . . circle track guys intentionally use track bar inclination as an "on the fly" tuning tool to either add or subtract vertical loading from the tire nearest the axle-side pivot, and they deal in small vertical pivot height adjustments.


Norm
 

Sky Render

Stig's Retarded Cousin
S197 Team Member
Joined
Feb 24, 2011
Posts
9,463
Reaction score
357
Location
NW of Baltimore, MD
This debate seams to come up every year or so. DO a search.

Panhard bar is lighter than a Watts Link = Less sprung weight.
Rear roll center for a Panhard bar is determined by where it is situated to the ground.
It should be as low as possible and parallel to the ground at ride height.

I have driven the same car on track with a properly set up Panhard bar and then a Watts link. I could not notice any discernable difference in lap times or predictability between the two – Not on a S197 - Everything Heim Jointed.
They might act different on rough Auto Cross Course with quick and forced transitions. I don’t know some say yah some say nay. I chose to go with the weight savings on our S197. I didn’t relocate the Panhard bar as low as I would have liked because the development stopped.
Gentlemen – We have a heavy straight chunk of steel that both our rear tires are connected to.
When one tire come in contact with a bump it affects the other tire regardless of what we want.
Purchasing decent springs with dampers that can control that straight lump of steel would be my first suggestion. After that – How much money and time do you want to spend to make out boats predictable? Nothing wrong with a straight axle on a smooth surface but most places are not smooth.
OHH - This should stir the pot LOL.

Hey, look, someone who grasps suspension geometry. :highfive:
 

2008 V6

forum member
Joined
Mar 18, 2012
Posts
335
Reaction score
1
Hey, look, someone who grasps suspension geometry. :highfive:

Thank you - But - Every time I think I know something, I find out just how little I know. Some of the people, I am privileged to know, always leave me scratching my head after I ask what I think is a basic question. It usually takes me a day or two to figure out what they said even though they think they are explaining it in laymen's terms. Very, very humbling.
 

2008 V6

forum member
Joined
Mar 18, 2012
Posts
335
Reaction score
1
Bottom line is... the watts is planted on bumpy corners...and the poly phb isn't. From a safety point of view/inspires more confidence, I feel its worth it.

85% - 90% of going quicker is confidence in your platform. If you feel comfortable and the feed back from your chassis works - Screw what everyone else is doing.
Confidence and a set up in your platform - That works for you - is everything.
 
Last edited:

Saleen304

forum member
Joined
Aug 11, 2011
Posts
451
Reaction score
2
I don't know why this has to be so complicated. The OP asked if the watts link improves the skittish feeling on bumpy roads. He is interested in street driving, not road racing or autocrossing. He is not comparing lap times pre and post watts link. He is also not asking what is the most bang for the buck. The obvious answer is yes. Yes the watts link gets rid of the skittish feeling on bumpy roads. Whatever the suspension geometry is doing with the panhard bar or tire carcass to cause the sensation is gone with the watts link.
 

Norm Peterson

corner barstool sitter
Joined
Feb 5, 2011
Posts
3,615
Reaction score
316
Location
RIP - You will be missed
OP also mentioned opening up a conversation, which implies a somewhat wider thread scope than just a simple "yes it will/no it won't" answer.

And sometimes there's more than one person who benefits from a widened scope. Frequently, that group includes me, like it did here.


Norm
 

Sky Render

Stig's Retarded Cousin
S197 Team Member
Joined
Feb 24, 2011
Posts
9,463
Reaction score
357
Location
NW of Baltimore, MD
I don't know why this has to be so complicated. The OP asked if the watts link improves the skittish feeling on bumpy roads. He is interested in street driving, not road racing or autocrossing. He is not comparing lap times pre and post watts link. He is also not asking what is the most bang for the buck. The obvious answer is yes. Yes the watts link gets rid of the skittish feeling on bumpy roads. Whatever the suspension geometry is doing with the panhard bar or tire carcass to cause the sensation is gone with the watts link.

It will not improve a "skittish" feeling if that feeling is caused by improperly setup suspension, which is what the OP appears to have.

I have a panhard bar on my car, and it does not feel skittish on bumpy roads.
 

Pentalab

forum member
Joined
Mar 5, 2013
Posts
5,211
Reaction score
1,093
It will not improve a "skittish" feeling if that feeling is caused by improperly setup suspension, which is what the OP appears to have.

I have a panhard bar on my car, and it does not feel skittish on bumpy roads.

So what's your magic suspension setup then ? Oem rear springs + oem rear shocks doesn't work, nor does stiffer /lower rear springs + soft to hard shocks. ( and this all assumes poly PHB, like a BMR adj unit). They all skitter, never seen one that doesn't. That doesn't leave anything left to try. Maybe 220 lb rear BMR springs + Vorshlag Bilsteins.... but I wouldn't hold my breath. We are talking about flying around bumpy corners here, not going straight on a bumpy rd.
 
Last edited:

2008 V6

forum member
Joined
Mar 18, 2012
Posts
335
Reaction score
1
So what's your magic suspension setup then ? Oem rear springs + oem rear shocks doesn't work, nor does stiffer /lower rear springs + soft to hard shocks. ( and this all assumes poly PHB, like a BMR adj unit). They all skitter, never seen one that doesn't. That doesn't leave anything left to try. Maybe 220 lb rear BMR springs + Vorshlag Bilsteins.... but I wouldn't hold my breath. We are talking about flying around bumpy corners here, not going straight on a bumpy rd.

It’s a straight axle – It’s going to feel skittish over bumpy surfaces because both rear tires are tied together by a heavy chunk of steel. It can be improved upon but it aint gona go completely away. One persons skittish is another persons joy.
To make this simple because this can go on for pages and I am not gona deal with that - Even independent suspensions have their advantages and disadvantages.
A De-Dion is a vast improvement over the weight of a self contained straights axle but it still will feel skittish on bumpy surfaces.
The advantage of a straight axle (This type of basic design) is that both tires remain flat and parallel to the surface provided it is flat – No funky camber curves of the in-depended suspension. If you get away from the camber curve on a independent suspension, you will scrub your tires to death on a street car. Everything has it’s pros & cons. I think that Ford chose to stay with a straight axle for so long is because of cost and an independent suspension usually does not last under Drag Racing launches – Good old boy Mustang Haven - Proven by the loss to Ford with the S195 Cobras - Huge financial loss because of parts breakage. Maybe with the new generation of Mustangs with better and more cost friendly materials, it will change and I am happy about that.
 

Sky Render

Stig's Retarded Cousin
S197 Team Member
Joined
Feb 24, 2011
Posts
9,463
Reaction score
357
Location
NW of Baltimore, MD
So what's your magic suspension setup then ? Oem rear springs + oem rear shocks doesn't work, nor does stiffer /lower rear springs + soft to hard shocks. ( and this all assumes poly PHB, like a BMR adj unit). They all skitter, never seen one that doesn't. That doesn't leave anything left to try. Maybe 220 lb rear BMR springs + Vorshlag Bilsteins.... but I wouldn't hold my breath. We are talking about flying around bumpy corners here, not going straight on a bumpy rd.

Koni yellows, some steeda springs, and rod-end BMR panhard and control arms. Go look at my build thread.

I find it funny that the people who scream the loudest about how necessary a watts linkage is are often not the same people who actively race or compete with their car in autocross or road racing. Just sayin'.
 

El_Tortuga

forum member
Joined
Oct 29, 2014
Posts
92
Reaction score
2
Koni yellows, some steeda springs, and rod-end BMR panhard and control arms. Go look at my build thread.

I find it funny that the people who scream the loudest about how necessary a watts linkage is are often not the same people who actively race or compete with their car in autocross or road racing. Just sayin'.

:clap::clap::clap:

This. Lowering my car eliminated a snootful of the L-R variation of the PHB. Its damn near horizontal now. Whiteline PHB under, Eibachs, Koni Yellows.
Very little L-R movement with vertical travel. Good thing or the 315s would rub (they don't). I've only driven 1 watts link car but he was on spherical bushings. Felt better? Sure, but by a very small margin and the clunk would drive me nuts on my city's heaves and bumps. I'm more than satisfied with the PHB.

For the OP, I'd do shocks first and see where you are from there.
 

Norm Peterson

corner barstool sitter
Joined
Feb 5, 2011
Posts
3,615
Reaction score
316
Location
RIP - You will be missed
Crude approximation for the amount the car settles when you get in - take your weight and divide that by the total of (2 x front spring rate + 2x rear spring rate). The PHB's chassis-side pivot will drop roughly the same amount.


Norm
 

Mark Aubele

forum member
Joined
Feb 11, 2015
Posts
247
Reaction score
0
Another example of pretty massive tire deflection. 315 R6 on a 10.5. Still had the panhard at the time.

 

CobraRed

Creator of Tools
Joined
Oct 8, 2014
Posts
281
Reaction score
0
Location
LA
I heard my Watts linkage makes my car basically an S550 with IRS

images


It also does cool things which look cool too

http://gfycat.com/ExcellentOddCrocodile#?speed=2
 
Last edited:

Latest posts

Support us!

Support Us - Become A Supporting Member Today!

Click Here For Details

Sponsor Links

Banner image
Back
Top