All over the road... suspension improvement possible?

[Vortech347]

Just don't try to take any fast turns.  You'll understeer and plow like a farmer with that tire combo.

TQ steer is gonna happen, our car's front wheels are directly driven.  The rear's only get power occasionally and it's not even a big transfer, it's only about 150-200ft-lbs if I remember right.

Now if we had AWD systems like a Focus RS...oh boy, things would be very different.

This isn't understeer.

I know.  What you've got is a characteristic of the drive train/power of this car.  I just mentioned the understeer comment because I do auto-x and open track. Anytime you take a car dialed in with equal tires and run staggered you get to enjoy frustration inducing under steer.

And I'm not really even talking about turns. Here's an example, when I pass somebody under heavy throttle, the car almost dives as the crown in the road changes, creating an sway-like motion. This only happens under heavy acceleration. Straight line or curve doesn't make a difference, it's only under power and when the road dips or changes. (I.E right side crown to left side crown.)

 

[Izzybird]

I almost put the wife’s car in the ditch taking down a Audi one afternoon, I’ve never had a vehicle come out of control like that. I had one front tire slightly lower on air than the other and chalked it up to that. Wife kept saying it drove scary sometimes. Drove it again one day and it would give a little yank to the right EVERY time it shifted to third driving normal, couldn’t hardly punch it anymore without one hell of a firm grip. Heard a slight rattle on bumps from the front right so started investigating. Inner tie rod had ever the slightest amount of play was all I could find, to the stealer she went. After ALL day and half a tank of tire burning fun, they figured it out. Found a bolt on the front end that had slightly backed out, a little Loctite and ran it back home. Drives like new again. I asked what bolt but the guys were packing up for the day and I was tired and hungry, he told me they said you couldn’t even see the bolt had backed off some and they’d found it by just going around and tightening on everything. I bought the two mechanics and the service writer lunch the next day, most dealerships would have never found something like that...if the even tried at all.

 

[SHOdded]

Back to basics ... like it :thumb:

 

[avidmotion]

I think the OP has a two or three fold problem, the giant oversized tires, the mismatch of sizes, low psi and tires themself and wait more-car is lowered. With all that it could be a real problem. That being said I had some tramlining etc on WOT on crappy bumpy roads with the cheap chineese tires that came on my used SHO. It was not too bad. Then I changed tires to new GMAX RS summer tires in stock size. I run 40 psi. Bingo like a new car no tram;lining or crappy behavior at all!

 

[ZSHO]

Im a bit surprised the speed sensors have not emitted a code in conjunction with Traction control issues.  Z

 

[geophb]

Im a bit surprised the speed sensors have not emitted a code in conjunction with Traction control issues.  Z

His side wall is shorter with the wider tires so overall dia is only off like 2%

 

[ToMang07]

There's less than a 1% difference in diameter between the front/back tires. 

Sent from my SM-G960U using Tapatalk

 

[ZSHO]

Im a bit surprised the speed sensors have not emitted a code in conjunction with Traction control issues.  Z

His side wall is shorter with the wider tires so overall dia is only off like 2%

The AWD system continuously monitors vehicle speed, throttle position, steering wheel angle and wheel slip to seamlessly deliver torque to the appropriate wheel!  Z
Here's a good article on the AWD System. 

http://www.hendonpub.com/resources/article_archive/results/details?id=5091

 

[ZSHO]

There's less than a 1% difference in diameter between the front/back tires. 

Sent from my SM-G960U using Tapatalk

I have had my own issues with Traction control and the very reason I mentioned this ^^^
I hope this helps any!  Z

If DTC C1B00 is setting it is suspected there is likely an intermittent ABS/ADV TRAC/steering fault occurring. If you refer to section 206-09 of the online workshop manual DTC C1B00 sets as a result of a steering wheel angle, accelerometer and WSS input correlation issue. This DTC can be caused by a wheel/tire issue, chassis modifications, a faulted EPAS steering gear, a faulty SCCM, a faulty RCM or a WSS/tone ring/wheel bearing issue. In order to accurately diagnose this concern it will need to be present at the time of testing, otherwise your test results will be inconclusive with no problem found.

Before any further diagnostics inspect for any chassis modifications on this vehicle (i.e. lowering kits) and ensure that the tires on this vehicle are the factory original size, sufficient tread remains, that they are inflated to specification and that their circumferences are all within ½” of one another and replace any affected tire(s) as needed.

https://www.ecoboostperformanceforum.com/index.php/topic,6676.0.html

 

[Vortech347]

Our system cannot send 100% of torque to the rear axle let alone one rear wheel.  It can only send around 150-200ish through the rear clutch pack.  Even when it's sending it's best torque to the rear it's still slipping.    That's why we still get wheel spin from the front wheels that are directly driven.  Mechanically the only variable in actual power transfer is the rear clutch.  The brakes are used to stop a spinning wheel to send more force to the other.  If wheel spin is too great it pulls power via ignition/fuel/Throttle body.  Drive by wire makes that process less nasty feeling than TC systems on cable actuated throttle bodies.  (Anyone ever get thrown into the dash of a terminator on the 1-2 shift if you kick the TC on? haha)

If our cars were flipped around and it was a RWD full time and the front wheels came in to assist, it would be a COMPLETELY different handling car, more fun too.  Ford is going back to a RWD bias with the new explorers.  I'm thrilled about it.

 

[SHOdded]

IDK ... maybe it changed in later iterations of Gen V SHOs.  FoMoCo had at one point said he saw 100% or nearly 100% of power being sent to the rear wheels on launch (momentarily of course) via the AWD gauge display in his 2015.  Do you have the display turned on?  The story might be completely different when driving around compared to launch, of course.

 

[geophb]

There's less than a 1% difference in diameter between the front/back tires. 

Sent from my SM-G960U using Tapatalk

I have had my own issues with Traction control and the very reason I mentioned this ^^^
I hope this helps any!  Z

If DTC C1B00 is setting it is suspected there is likely an intermittent ABS/ADV TRAC/steering fault occurring. If you refer to section 206-09 of the online workshop manual DTC C1B00 sets as a result of a steering wheel angle, accelerometer and WSS input correlation issue. This DTC can be caused by a wheel/tire issue, chassis modifications, a faulted EPAS steering gear, a faulty SCCM, a faulty RCM or a WSS/tone ring/wheel bearing issue. In order to accurately diagnose this concern it will need to be present at the time of testing, otherwise your test results will be inconclusive with no problem found.

Before any further diagnostics inspect for any chassis modifications on this vehicle (i.e. lowering kits) and ensure that the tires on this vehicle are the factory original size, sufficient tread remains, that they are inflated to specification and that their circumferences are all within ½” of one another and replace any affected tire(s) as needed.

https://www.ecoboostperformanceforum.com/index.php/topic,6676.0.html

Punched in his tire size into online calculator just for kicks and they are .3 inch off........

 

[ToMang07]

I would like to report that increasing air pressure did improve it. Didn't cure it, however I'd say it's 1/2-2/3s better than it was (As in dives/pulls less; less aggressively.)