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Kenny Brown PHB relocation help

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I have a complete Kenny Brown set up with PHB relocation kit and front K member set up and control arm relocation brackets. Car previously had the complete Ford suspension package. I do not have Coilovers, and am not looking to upgrade to Coilovers. After instillation of the Kenny Brown kit, I get quite a bit more push compared to the Ford kit. I am not running a rear sway bar as the Ford Performance blue bar, interferes with the PHB relocation bracket. To me there seems to be more body roll compared to the Ford kit. I have been unable to find information on anyone running a smaller rear sway bar with the KB kit. From my understanding, without the rear sway bar my effective spring rates in turns is now reduced without the rear bar.

I am trying to find anyone that has run a rear sway bar with the KB relocation kit, and what size they used. To me I feel too much roll compared to the Ford kit, and am getting more push in left bank turns. The Ford kit with Ford blue rear sway bar did not have this push, and felt more control in left turns, which in turn I felt more confident in curves. The KB kit leaves me less confident in curves, and makes the car less fun to drive.

I am trying to find if I could use a 20mm or 18mm rear sway bar with the KB relocation brackets, or I am looking to just revert back to the Ford blue sway bar and remove just the KB PHB relocation kit, and replace it with and adjustable Panhard Bar. I read in some post that Yopauly added a rear bar to the KB relocation kit, but no information was given on size or anything. KB on videos says he has used a smaller rear sway bar, but no information was given on the size, and I could not get an answer on size from calling KB.

Any assistance would be greatly appreciated. Thank you all.
 
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Norm Peterson

Corner Barstool Sitter
939
712
Exp. Type
HPDE
Exp. Level
5-10 Years
a few miles east of Philly
As an individual effect, relocating the PHB downward increases the understeer (probably corner entry and midcorner in particular) and results in a bit more roll. Lowering either geometric roll center reduces the amount of lateral load resisted that does not cause any roll, which now makes the springs and bars have to resist a greater proportion of LLT (the total LLT is fixed by track, CG height, and cornering g's). Since the springs and bars are not "infinitely" rigid, more roll results. Has to. Separately, the balance of LLT through the geo roll centers has shifted forward, which is an understeer effect.

Removing the rear bar serves to add more push and more roll. This time it's the balance of LLT through the elastic suspension elements - springs/bars/shocks/struts - that shifts forward. And obviously when you throw away some of your roll resistance you're going to get a little more roll.


Some years ago an engineer I knew on a number of message boards got into lowering the PHB on his 4th gen F-body. Ended up DIY-modifying that car's rear sta-bar to be both stiffer and slotted-adjustable circle track style rather than with two or three separate holes like everybody's aftermarket adjustables are these days. Car was tracked.


Norm
 

Grant 302

basic and well known psychic
Where is the front bar set? And what springs?

And if I understand correctly, the PHB bracket has two adjustment points. Which one are you using? And what is the approximate static angle of the bar?
 
Front bar is in middle hole. Springs are Pedders 200 front/186 rear linear. Have tried with two staggered set ups. 18x9.5 all around with 255/24/18 front and 175/40/18 rear. The other set up is 18x9.5 with 275/40/18 front and 18x10 with 285/40/18 rear. The 9.5/10 stagger seems to push just a little less. And this is the set up I will be using daily.
 

302 Hi Pro

Boss 302 - Racing Legend to Modern Muscle Car
2,009
441
Southeast
What is the current set-up on your lowered PHB?

I have mine set-up to the lowest position that levels it, (to ground).

I've not experienced understeer. You can actually feel the rear come around for an instant as it begins to rotate at turn in. Corner exit is excellent with throttle up as soon as I can see around to the straight ahead.

I ran Ford Boss 302 springs but needed another 1/2” of clearance above the axle then changed the rear to Steeda Boss 302 springs. (I know, I know, but I run 3.0” exhaust pipes & a 4.0” 1 piece aluminum DS.)

My RLCA’s canter on a 2-3 degree downward slope to the axle. I also run Koni Yellows.

Hope some of this helps you.
 
What is the current set-up on your lowered PHB?

I have mine set-up to the lowest position that levels it, (to ground).

I've not experienced understeer. You can actually feel the rear come around for an instant as it begins to rotate at turn in. Corner exit is excellent with throttle up as soon as I can see around to the straight ahead.

I ran Ford Boss 302 springs but needed another 1/2” of clearance above the axle then changed the rear to Steeda Boss 302 springs. (I know, I know, but I run 3.0” exhaust pipes & a 4.0” 1 piece aluminum DS.)

My RLCA’s canter on a 2-3 degree downward slope to the axle. I also run Koni Yellows.

Hope some of this helps you.
My PHB is level at the lowest setting. I get lots of push in left bank turns, its to a point I am nowhere confident to try to push the car in those types of turns. When I was running the Ford Performance package with rear sway bar, I was not exhibiting this kind of push. The car was more confident inspiring. I am wondering if the lack of sway bar with the softish springs causes this, as the rear sway bar would increase the spring rate in corners. I tried getting the information about what swaybar he used, but I cannot get an answer. If they used one on occasion, they would know the size. I am now under the impression you cannot run a rear swaybar with this kit. I tried my Ford Performance sway bar, but it would make contact with the PHB relocation bracket when the car is on the ground. Not sure of the design of the smaller 20mm and 18mm sway bars from Ford, to see if they would make contact.
 

Fabman

Dances with Racecars
6,519
8,154
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W2W Racing
Exp. Level
20+ Years
Pleasanton: 1/2 way between Sonoma and Laguna Seca
My PHB is level at the lowest setting. I get lots of push in left bank turns, its to a point I am nowhere confident to try to push the car in those types of turns. When I was running the Ford Performance package with rear sway bar, I was not exhibiting this kind of push. The car was more confident inspiring. I am wondering if the lack of sway bar with the softish springs causes this, as the rear sway bar would increase the spring rate in corners. I tried getting the information about what swaybar he used, but I cannot get an answer. If they used one on occasion, they would know the size. I am now under the impression you cannot run a rear swaybar with this kit. I tried my Ford Performance sway bar, but it would make contact with the PHB relocation bracket when the car is on the ground. Not sure of the design of the smaller 20mm and 18mm sway bars from Ford, to see if they would make contact.
Lowering the roll center increases body roll and promotes understeer. That’s a given. To pull this off it helps to have a lot of roll couple. Kenny brown runs extremely big springs Both front and rear to balance this out, as much as 1050# on the front of a strut car in racing conditions. That’s straight from his mouth. I would either run his recommended springs and giant Front sway bar (he does not recommend a rear bar) or dump the relo bracket because I don’t think it’s going to work for you with the springs you have. Mixing up components from multiple manufacturers often leads to headaches and handling ills. Personally I’d dump the relo bracket and put your FRPP rear bar back on and call it a day. That’s my opinion FWIW.
 
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Yes that's the plan to dump it. I had his set up yers ago, and it was nice. I just have a problem with his claims you can run a rear sway bar, and then does not give customers the size. IF a sway bar cannot fit due to clearance, he should state that. Also, the ads need to be changed, stating that very high rate springs are needed with this kit. I think I should have went with the Cortex Watts link, around same price, and still able to run a rear sway bar.
 

Fabman

Dances with Racecars
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Pleasanton: 1/2 way between Sonoma and Laguna Seca
Yes that's the plan to dump it. I had his set up yers ago, and it was nice. I just have a problem with his claims you can run a rear sway bar, and then does not give customers the size. IF a sway bar cannot fit due to clearance, he should state that. Also, the ads need to be changed, stating that very high rate springs are needed with this kit. I think I should have went with the Cortex Watts link, around same price, and still able to run a rear sway bar.
Race cars are a season to taste kind of deal. What works for one guy is crap to another. Seems everybody has a different idea on how to skin the cat. Web sites are notoriously bad about incomplete or misleading information. You can’t go wrong with anything cortex, most of us here are rocking those parts and the bonus is he answers his phone and will talk you through any problems. I’m not a commercial, for cortex, but experience has been good for an awful lot of us.
 

Fabman

Dances with Racecars
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Pleasanton: 1/2 way between Sonoma and Laguna Seca
Additionally, there is nothing wrong with a pan hard bar in the stock location. The boss 302 race cars, FR500 race cars, the Phoenix race cars and more have all run and won with that setup.
 

302 Hi Pro

Boss 302 - Racing Legend to Modern Muscle Car
2,009
441
Southeast
I agree with Fabman’s above post. Stick with matched components as what works for one individual setup is crap for another. In fact, I too purchased a Cortex Watts Link but life got busy & I’ve yet to install it. And somewhere I have a 20mm Ford rear sway bar to go with it.

With that said, what I’m curious about is:

Why you only have push in Left turns & not all turn conditions? (If I read that right.). Any changes in your front suspension steering geometry?

Have you tried to call Kenny Brown or his Tech People? But if no help there and you do move to CorTex products, you can’t go wrong with that decision.

Let us know.
 

Norm Peterson

Corner Barstool Sitter
939
712
Exp. Type
HPDE
Exp. Level
5-10 Years
a few miles east of Philly
I have mine set-up to the lowest position that levels it, (to ground).

I've not experienced understeer. You can actually feel the rear come around for an instant as it begins to rotate at turn in. Corner exit is excellent with throttle up as soon as I can see around to the straight ahead.

My RLCA’s canter on a 2-3 degree downward slope to the axle.
I think I'm seeing slightly oversteerish roll steer being what's loosening up the car, rather than excess rear roll stiffness . . .


Norm
 

Fabman

Dances with Racecars
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Pleasanton: 1/2 way between Sonoma and Laguna Seca
I think I'm seeing slightly oversteerish roll steer being what's loosening up the car, rather than excess rear roll stiffness . . .


Norm
I used to keep my trailing arms about 1 to 2 degrees up to minimize roll steer until I made a suspension cam video of my car on some warm up laps. I was surprised to see that the trailing arms actually spent much of the time past center and in roll understeer. This prompted me to add angle and I'm now at the top of the Cortex Recommended 3 to 5 degrees up towards the front.

Two views:
 

Grant 302

basic and well known psychic
I think I'm seeing slightly oversteerish roll steer being what's loosening up the car, rather than excess rear roll stiffness . . .

This is one of the aspects I was considering in the context of previous discussions. But not addressing directly.

Anyway, this is one aspect showing how a lower rear RC can have more oversteer properties/tendency.

There’s also the way that this would affect ability to put power down...but not getting into that here. A lot of the tuning required wouldn’t apply to the OP and setups without ride height adjustment.
 

Fabman

Dances with Racecars
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Exp. Type
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Pleasanton: 1/2 way between Sonoma and Laguna Seca
Directly from the Cortex Website:

You are here: Home / Vehicle Balance
Vehicle Balance

Symptom: Front Understeer (car pushes)
Rear Changes:

  1. Raise rear watts pivot
 
1,161
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SoCal
I used to keep my trailing arms about 1 to 2 degrees up to minimize roll steer until I made a suspension cam video of my car on some warm up laps. I was surprised to see that the trailing arms actually spent much of the time past center and in roll understeer. This prompted me to add angle and I'm now at the top of the Cortex Recommended 3 to 5 degrees up towards the front.

Two views:
Are you still running the stock length early UCA (or upper trailing arm for you and blacksheep1!), or have you changed to the longer 11-14 length? Or perhaps neither and you’re running the Cortex torque arm?
 
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