Kenny Brown PHB relocation help

[Fabman]

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?

Torque arm. In this vid I had the BMR lower relo brackets but this lead me to change to the MM brackets that had more adjustment holes and finer adjustment. This video is a few years old....a lot has changed.

 

[Fabman]

One thing about Oval trackers, we do a lot of testing. I built Hundreds of stock cars and personally ran every single weekend at tracks all over the western states. Every car I built had a minimum 6 to 8 holes in every link, including on the brake floaters.
Every one of them has been tested and proven. When you put a link-whatever that link is, in the center position, and then the extreme lower hole followed buy the very top hole you know EXACTLY what happens....something that others can only dream about. Here is one of them....note all the adjustment. More than you can ever get into a mustang.
There is no substitute for experience.

 

[Fabman]

And yes, they were all panhard bar cars.
(Panhard bar is in front of the diff on this one-others were mounted behind the diff in the usual way)

 

[302 Hi Pro]

Excellent Post Fabman and the rear suspension ‘action’ vid really brings home the importance of proper RLCA slope.

Experience is King.

What are your thoughts on why the OP has left turn only understeer and/or push?

Thanks so much.

 

[Fabman]

Excellent Post Fabman and the rear suspension ‘action’ vid really brings home the importance of proper RLCA slope.

Experience is King.

What are your thoughts on why the OP has left turn only understeer and/or push?

Thanks so much.

I don't really have enough information, a lot was changed with the car-K member etc.
IIRC the OP has a push everywhere but seems to be worse in one direction.
Kenny Brown alters the front geometry on his K members/Control arms but doesn't say how, I can pretty well guess how but I don't know for sure.

What I do know is what happens when you move piviot points around and how that affects handling and the interplay with bars and springs. When you move the rear roll center down that moves the car towards understeer. That's just a damn fact supported by oodles of data I posted earlier in a similar thread. Clips from chassis books, quotes form Famous Crew chiefs and engineers etc. Not to mention actually doing it myself. There's an old racers saying; "Never get your setup advise from the bleachers, go straight to the winners and talk to them".

Now I'm not saying a low roll center is bad, in the right combination its awesome. My stock cars always had very low roll centers, much lower than the competition. But its one part of a package, there are other setup items that compliment or exacerbate that. So saying either high or low is good or bad doesn't really tell the whole story. What you need to know is what happens when you go higher or lower and whats needed to compliment that particular setup. Driving style also has a major affect on this....major affect.

 

[Grant 302]

and am getting more push in left bank turns.

Maybe you just need more negative camber in the front right. Is there a specific track you have the issue?

@blacksheep-1 might have more suggestions.

 

[blacksheep-1]

I've never run a torque arm in a Ford product, with the Foxbody cars it was either the factory crappy 4 link (due to the rules) or the redneck 3 link, or an IRS. With the S197s I have never run a torque arm either. The only thing I ran a TA on was an 83 Z28 Camaro, it did wheel hop under baking, but was fixed by aftermarket lower trailing arms and a solid front Torque Arm bushing. So, I'm out of my depth on torque arm mustangs.
this is what happens when you go off the reservation on suspension mods, there's just not a lot of experience to assist you.

 

[Grant 302]

I've never run a torque arm in a Ford product, with the Foxbody cars it was either the factory crappy 4 link (due to the rules) or the redneck 3 link, or an IRS. With the S197s I have never run a torque arm either. The only thing I ran a TA on was an 83 Z28 Camaro, it did wheel hop under baking, but was fixed by aftermarket lower trailing arms and a solid front Torque Arm bushing. So, I'm out of my depth on torque arm mustangs.
this is what happens when you go off the reservation on suspension mods, there's just not a lot of experience to assist you.

OP doesn’t have a torque arm.

He has issues with push on left turn banking. I thought you’d have an opinion on that and the camber needed on the front right.

 

[blacksheep-1]

Oh, sorry, maybe that was some other thread, they all run together after awhile.
Have you ever scaled it?
Have you ever taken to a real good alignment shop to see exactly how it all works?
Depending on the "new" KB geometry, try adding at least 4degrees of caster, normally, with that much caster the tire will add camber into the corner. Now, what the KB deal does, I have no idea, some of that may be pre dialed into the geometry. you've also removed considerable weight off the nose which is generally a good thing, but again, if it doesn't stick, you need to remove or go to a smaller bar on the front, or lighter spring..or softer initial shock setting for turn in., But you've removed the bar from the REAR, which should stick the rear more, causing part of your problem.

If it was me, I'd be burning the phone lines up with KB, they built it, they should've experienced this before.

 

[Norm Peterson]

I don't really have enough information, a lot was changed with the car-K member etc.
IIRC the OP has a push everywhere but seems to be worse in one direction.

Seems that the left turn is apparently banked significantly and the right turns aren't has to figure in to it somehow. Some trig function times the apparent cornering g's would be effectively pushing the car directly toward the track and having a compressing effect on both the inside and outside suspensions. Resulting in geo roll center and roll steer effects, probably both understeerish, that aren't happening in the (presumed flat) right turns.

Kenny Brown alters the front geometry on his K members/Control arms but doesn't say how, I can pretty well guess how but I don't know for sure.

He gives some pretty clear hints about what, without giving away the "how much" part.

Kenny’s exclusive AGS 4.0 Geometry raises front Roll Center
Improved Caster, Camber Gain

I'm thinking that the required K-member is how he's addressing bumpsteer (in his video it looks like there are spacers under the R&P unit at its frame mount locations).


Norm

 

[Grant 302]

Seems that the left turn is apparently banked significantly and the right turns aren't has to figure in to it somehow. Some trig function times the apparent cornering g's would be effectively pushing the car directly toward the track and having a compressing effect on both the inside and outside suspensions. Resulting in geo roll center and roll steer effects, probably both understeerish, that aren't happening in the (presumed flat) right turns.

Panhard Bar geometry...both angle and effective RC change very, very, differently in left vs. right conditions.

There’s also driver weight.

 

[Fabman]

Seems that the left turn is apparently banked significantly and the right turns aren't has to figure in to it somehow. Some trig function times the apparent cornering g's would be effectively pushing the car directly toward the track and having a compressing effect on both the inside and outside suspensions. Resulting in geo roll center and roll steer effects, probably both understeerish, that aren't happening in the (presumed flat) right turns.



He gives some pretty clear hints about what, without giving away the "how much" part.



I'm thinking that the required K-member is how he's addressing bumpsteer (in his video it looks like there are spacers under the R&P unit at its frame mount locations).


Norm

I suspect that the lower control arm pivots are raised for roll center correction instead of the more common "tall ball joints" which would explain the spacers under the rack, But again, I don't know that. I suspect.

 

[67GTA]

Torque arm. In this vid I had the BMR lower relo brackets but this lead me to change to the MM brackets that had more adjustment holes and finer adjustment. This video is a few years old....a lot has changed.

I asked about the UCA and torque arm, as each plays it’s own role in anti-squat % at each different angle of the lower trailing arms. You touched on this in your posts about considering the entire system as a whole, and not just one adjustment. @APharaoh06 - what year S197, and has the upper trailing arm length been modified?

As I struggled with my own handling issues related to roll steer and anti-squat % (unbeknownst to me until you and others with experience and knowledge explained it!), I stumbled across a really helpful chart in the instruction manual for the Maximum Motorsports LCA relocation brackets. I won’t post the chart here out of respect for their copyright, but it’s available on their website here for anyone that would like to look at it (page 4). This REALLY helped me visualize the impact on roll oversteer and understeer, and also the difference from the shorter 05-09 UCA and the longer 11-14 UCA. Your torque arm setup would have its own set of varied anti-squat % at each adjustment of the lower trailing arm and ride height. In my particular case, the 3-5* of trailing arm angle that worked for you pushed my car past the anti-squat sweet spot and introduced nasty axle-hop under hard braking.

The only reason I bring this all up is to agree with your advice of first understanding the basic concepts of suspension tuning, and then using that knowledge to make educated adjustments until the right setup is found for the specific car/driver/track/etc. And luckily for us - there’s a lot of really great people on TMO to help us with the understanding and educated guesses part! Without that, I would still be wasting money on track time trying to chase a problem with no clue on what to do.

 

[blacksheep-1]

money well spent

Carroll Smith Books . The Official Carroll Smith Site

 

[Fabman]

money well spent

Carroll Smith Books . The Official Carroll Smith Site

Carrol Smith, Steve Smith and Fred Puhn among others adorned my bookshelves for many years.
I wish I still had them; all dog eared and covered in notes but they went with my stock car shop when I sold it years ago.

 

[Fabman]

money well spent

Carroll Smith Books . The Official Carroll Smith Site

I just bought "The works" package. Every. single. book.
I'm going to pour back over these and re live my formative years as a young aspiring racer and car builder so many decades ago. A refresher will be nice and maybe I can learn some new things I may have missed and remember some that I forgot.
Thank you @blacksheep-1 for the link!

 

[APharaoh06]

Spoke with Kenny and here is what I got. He only used a Panhard Bar on the SN95. So I guess for at least 8 years no one with his PHB relocation kit has inquired about sway bar usage. Very simple to me if his complete systems needs a minimum spring rate to run without swaybar, it should be noted in the advertisements. So the advertisements are very misleading. " you can throw away your swaybar". It should state swaybars will interfere with relocation brackets, or a small diameter swaybar can be used in some instances. Also, let people know the sizes used. I tried this system, with the intent if I needed to make an adjustment with a sway bar I could have that option. I ran just the Relocation kit with no Panhard Bar, hard push in left bank turns, 255/45/18 front and 275/40/18 rear. Also, ran it with the K-member set up and rear same thing. When I tried both set ups with 275/40/18 front and 285/40/18 rear with both set ups, the push improved just a little. But it is not a confident drive at all. The Ford Performance suspension kit without the adjustable Panhard Bar, felt better in the turns. And since it was lowered on K springs, the rear end was not even centered. But it still inspired more confidence in turns compared to the centered KB Panhard relocation kit. It was a bit harsher on bumpy roads due to the rear sway bar, but at least it was very controllable. The Kenny Brown rear is softer and more plush. Feel of vehicle is specific to each individual. As for me I do not like the feel, and of course there are some people who like the feel of his relocation kit. As for me, I will be pulling the rear parts off and selling them, going to go back to rear sway bar and adjustable Panhard Bar.

 

[Norm Peterson]

I suspect that the lower control arm pivots are raised for roll center correction instead of the more common "tall ball joints" which would explain the spacers under the rack, But again, I don't know that. I suspect.

Quite possibly, it's just too hard for me to tell from looking at his K-member video (and he never broaches the matter in his discussion). He may even be doing "some of each" - chassis-side pivot relocation and slightly taller balljoints instead of getting it all from just one or the other. At any rate, he's moving the geo-RC up and improving camber gain all in one shot.

But whether you move the chassis side pivots up on the inboard end, use tall ball joint on the outboard end, or some of each - you still have to do something with the tierod inclination. Absent the usual bumpsteer kits at the knuckle end - KB says absolutely nothing about those that I've seen - the only thing left is to space the rack upward.

In the S550 world, Steeda also offers a roll center correction kit (tall ball joints), and pairs it with a conventional bumpsteer kit.

The difference between the Steeda approach and KB's is that Steeda makes you correct the bumpsteer to suit your car, and KB basically says that he's corrected the bumpsteer in his K-member, control arms, and spacers for you. Whether or not KB's correction (including fabrication tolerancing) ends up being exactly right for your car as installed would be a separate question.


Norm

 

[Fabman]

Quite possibly, it's just too hard for me to tell from looking at his K-member video (and he never broaches the matter in his discussion). He may even be doing "some of each" - chassis-side pivot relocation and slightly taller balljoints instead of getting it all from just one or the other. At any rate, he's moving the geo-RC up and improving camber gain all in one shot.

But whether you move the chassis side pivots up on the inboard end, use tall ball joint on the outboard end, or some of each - you still have to do something with the tierod inclination. Absent the usual bumpsteer kits at the knuckle end - KB says absolutely nothing about those that I've seen - the only thing left is to space the rack upward.

In the S550 world, Steeda also offers a roll center correction kit (tall ball joints), and pairs it with a conventional bumpsteer kit.

The difference between the Steeda approach and KB's is that Steeda makes you correct the bumpsteer to suit your car, and KB basically says that he's corrected the bumpsteer in his K-member, control arms, and spacers for you. Whether or not KB's correction (including fabrication tolerancing) ends up being exactly right for your car as installed would be a separate question.


Norm

I suspect it would be a little of each, raising the pivots and rack accordingly to minimize bump. Hell, most folks that install bump kits don’t actually bump correct with a gauge anyway, they just stack spacers on until the tie rod angle matches the control arm angle and while that might be close, it’s not going to get you there. My old auto shop teacher used to call it “Mechanical masturbation” it feels good while you’re doing it, but some how it’s just not quite right.

 

[Grant 302]

In the S550 world, Steeda also offers a roll center correction kit (tall ball joints), and pairs it with a conventional bumpsteer kit.

How does Steeda do that? Isn’t one ball joint pointing ‘up’ and the other ‘down’?