Project Budget 400WHP S197 Mustang Track Car: Part 6 – Going Through the Suspension with Steeda

This is where we defy the misconceptions and show how to make an S197 Mustang into a corner-carving track car.  We are going to cover the pros and cons of Panhard Bars vs Watts Links, and go through the entire suspension with Steeda, picking the least expensive way to make our car fun to drive and competent on track.

In Part 4, we upgraded to the Roush Performance 3rd Link; arguably the best 3rd link ever made for the S197 Mustang.  Now we tackle the rest of the suspension with Steeda.

Steeda MustangOver the past 30 years, Steeda’s production-based equipped vehicles have won more championships, set more track records, and won more races than all of their competitors combined (including Shelby, Roush, and Saleen).  Racing and performance is at the core of Steeda’s DNA and they are committed to providing the best customer service and highest quality parts on the market.

Billy Johnson Roush Performance Jack Roush Jr Daytona Victory DriftTaking my experience winning more professional races in the S197 Mustang chassis than any other driver (apparently the FIA does not recognize the SCCA), and competing in everything from the FR500C, FR500S, BOSS 302R, and BOSS 302S; I worked with Steeda to put together what I feel is one of the least expensive ways to make the Mustang extremely reliable, fast, and fun to drive for the beginner on up to what I would enjoy lapping for an entire day.  It was also important to make sure the car was still comfortable as a daily driver and not turned into a compromised “racecar for the street”.

PANHARD BAR VS WATTS-LINK

The first thing to address is the age-old debate between the Panhard Bar (PHB) vs Watts Link (WL).  While they both locate the solid axle laterally when cornering, each layout has their own inherent strengths and weaknesses.  I am going to limit discussing “theory” and focus on how S197-specific products effect the S197 platform.

S197 Mustang Panhard Bar vs Watts LinkThe S197 Mustang’s 3-link rear suspension comes from the factory with a PHB (left).  Aftermarket WL’s (right) are far more complex, heavier, and use two arms that are roughly half the length of the factory PHB, which are then bolted to a bell-crank that is either mounted to a beefy aftermarket rear diff cover, or to a tubular sub-structure that is bolted to the rear of the car.

Feel free to read though all of the ensuing technical analysis of PHB vs WL, or skip ahead to PAGE 4 to see the install.

PANHARD BAR (Positives):

-Less expensive.  $160-260 vs $810-1,300

-Light weight.  Lowest weight and unsprung weight option.

-Roll center moves ½ the distance of the Center of Gravity with suspension travel.

-Roll centers can be easily lowered ½-1” by drilling a new hole.

PANHARD BAR (Negatives):

-Rear axle moves less than 0.1” laterally in the normal suspension travel range – (not significant).

-Rear axle moves less than 0.2” laterally from full droop to full compression travel – (not significant).

-Asymmetric roll center migration in roll left to right.  Left turns lowers RC, right turns raises RC.

WATTS LINK (Positives):

  • Zero lateral movement of the axle with suspension travel.
  • Symmetric roll center migration in roll left to right.
  • Roll centers may be fairly easy to adjust depending on design.

WATTS LINK (Negatives)

  • More expensive.
  • Heavy.  Increased sprung & unsprung weight.
  • Often raises the rear roll center even at its lowest setting – reducing rear grip. (Depending on design).
  • Often reduces suspension travel due to links binding. (Depending on design).
  • Often requires stiffer rear springs – reducing rear grip. (Depending on design).
  • WL is Axle-Mounted  = Roll Center is fixed to the ground, causing rear roll moment & roll resistance (distance from Roll Center to Center of Gravity) to change with ride height.  = Roll stiffness variation 2X that of a PHB. OR:
  • WL is Chassis-Mounted = Roll Center stays at a constant distance (constant roll moment) to the Center of Gravity, but these are significantly heavier both from a sprung and unsprung standpoint.

Quick Reference:

Page 1 – Panhard Bar vs Watts Link Pros & Cons
Page 2 – Analysis: Panhard Bar Geometry vs Watts Link
Page 3 – Overview & Front S197 Geometry vs Extended Ball Joint LCA
Page 4 –
Front LCA Removal
Page 5 –
Front LCA Install
Page 6 –
Rear Axle Weight Removal
Page 7 –
Rear Lower Control Arm & Panhard Bar Install

13 comments

  1. I’ve always felt polyurethane or delrin bushings in live axle control arms to be a counterintuitive choice. With the non-compliant bushing the control arms turn into torsion springs when one side articulates. Or on the other hand – great way to save weight on an anti-roll bar.

    Secondly, won’t the front tie rod end also need relocating when moving the outer ball joint? On an E36, moving the ball joint 10mm introduces basically an equal amount of bumpsteer.

    1. It depends on the durometer of the polyurethane and the articulation of the arms. Poly bushings in the 4-link 79-04 chassis is quite terrible in terms of ride quality, roll resistance and grip; but for the S197 a softer durometer polyurethane isn’t that bad due to the S197’s rear geometry and lack of articulation. Now using Delrin isn’t the best idea.

      Good eye regarding the bumpsteer when using extended balljoint front lower control arms. We are going to discuss that and the importance of a bumpsteer kit when using extended ball joints in the next article.

    2. @twist, “With the non-compliant bushing the control arms turn into torsion springs when one side articulates.” That would be true for an unequal four-link suspension, such as the 79-04 Mustang. The four link binds a lot because the four links over-constrain the axle. The 2005-14 Mustang uses a three-link rear, with a Panhard, which is not over-constrained. There is no bind, even with spherical bearings in all the suspension joints. In fact, that’s what I have. One of the reasons the S197 is leaps and bounds ahead of the previous generation.

      Yes, Delrin wouldn’t make sense as it wouldn’t be able allow the links to “twist” during articulation.

  2. I know there’s probably a good reason Ford put those weights there, but something seems hilarious about it. “Hm, yes, let’s add unsprung weight to the live axle, this is an excellent idea.”

    The PHB vs Watts thing reminds me of stuff that comes up on discussions on how to fix the 1st gen RX-7, with a similar result, albeit it’s switching to the PHB instead of sticking with it. Unless you have a lot more design freedom in where stuff goes (ala Trans Am tube chassis stuff or so on) it just seems like weight trumps any benefit from more complex axle location.

    1. I have seen weights like that on other cars. I am pretty sure that they act as ‘tuned mass dampers’ to reduce resonance at certain speeds (most likely highway speed.)

      I really don’t understand why the owner opted out of stiffer bushings in the front and yet went ahead with PU on the rear.

      The front bushings see much higher loads and this has a huge effect on braking stability. From my experience the change in NVH is barely noticeable because the bushings only see high loads under acceleration and braking. The greatest change in NVH happens when you swap out vertical load carrying bushings.

      Also, not sure why the entire control arm needs to be replaced if all you are doing is swapping ball joints and bushings.

      And, yes, as the first commenter mentioned bumpsteer will be increased unless the front tie-rods are offset.

      The owner could simply have installed dampers with adjustable rebound if roll control was the primary goal. I am pretty sure that it would have been cheaper than dropping the entire front subframe, and swapping control arms, along with the necessary subsequent alignment.

      1. “…but since our car is a dual purpose street/track car, we didn’t want the increased Noise Vibration & Harshness (NVH) of a stiff bushing and decided to use a new large diameter OEM style bushing because they hold up quite well and don’t affect the geometry much when new.”

        The Steeda LCA with Extended Ball Joints cost $299 and include new bushings. The Extended Ball Joint costs $121 by itself and new bushings range from $145-184, and can cost up to $499 for the Ford Performance LCA Bushing Kit. The cheapest option to replace the bushings and ball joints on our existing arms would be $266; so we could have saved $33 if we wanted to spend more in the long run for time and labor to push out the bushings and ball joints and install the new ones. If you’re doing this at home and want to do all the work yourself, and value your time to do this job at less than $33, then it may make sense. For our project, saving money is a high priority and the Steeda LCA option is the least expensive and easiest solution.

        1. Well, I will say that this is a surprise. There are some reasons why modifying a domestic vehicle is better, and this is one of them.

          Just to excuse my concern, new control arms on a Mercedes run upward of $1000.

      2. Shock damping to counter geometry issues is kind of gross; strut suspensions do really awful things when the control arm orientation gets to certain ranges that are going to hurt predictability.

  3. I’m curious as to why you dropped the K-member/subframe to replace the front control arms. I replaced the control arms on my 08 GT without needing to do that, but I’m not sure if the later S197’s are a bit different in that regard (or if it was to make documenting the removal/install easier).

    I definitely think replacing the arms in lieu of just the ball joints are the way to go. I’ve done both and replacing the entire arm assembly was much easier as well as faster. Considering the price difference (depending on parts, etc), I wish I had done that the first time.

    I’ve been enjoying these articles. Hopefully more people can see how much fun these cars can be on track.

  4. I noticed that you didnt use relocation brackets for the lower control arms. Do you feel these are unnecessary?
    Also neither the UCA nor the LCAs are adjustable. Is the pinion angle not that important to get right?

    1. It’s just another adjustment tool to change the handling and effects of the car’s suspension. For a budget build, and based off of our level of lowering, it was not worth it or needed to raise the instant center with the lower control arm relocation brackets. They can be a useful adjustment tool, but not necessary for what we are trying to do. The money is better spent elsewhere.

  5. Is there a benefit in using a poly bushing on the rear to add traction, getting out the harsh response after bumps. With this you add a spring motion in the axle rotation.

    I mooved for the panhard on my project cos of the low RC, but its hard to calculate for the jacking effect when the bar is not paralele to the gound and you have a soft suspension with 8″ travel.
    Becouse of this im thinkin in making a dual suport so the linkage can be changed depending on the track is clockwise or counter clock.

    1. It depends on your application and what the problem is. In the application of an S197 Mustang, polyurethane can reduce traction when used in the 3rd link.

      NASCAR has adjustable mounts on both sides of the panhard bar so they have a lot of adjustability of the RC and jacking effect to make the car do what they need it to. With 8″ of travel, it sounds like you have an off-road application.

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