Are your wheels still the stock diameter?
EPAS Terrible Shudder
- Thread starter jsnyng
- Start date
Are your wheels still the stock diameter?
Stock brembo wheels with the same size tire
Full_Tilt
forum member
- Joined
- Jan 20, 2011
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I too feel a noticeable difference in steering feel when I go into "sport mode" or w/e.
I wish I had a way of measuring it.
No shimmying or shuddering or anything in my car, but my wheels and sus[ension are still 100% stock (sadly).
I wish I had a way of measuring it.
No shimmying or shuddering or anything in my car, but my wheels and sus[ension are still 100% stock (sadly).
Xorak
forum member
captdistraction
Corner Carver
Mine is a Koni yellow, eibach swaybar, eibach sportline and J&M CC plate car. Brake ducts as well (since they do add to the input feel of the steering). Though the shudder on mine has been consistent before any of the modifications.
Front wheel width slightly narrower than stock (8.5 vs 9), slightly more aggressive offset, though shudder felt on many wheels including stock ones.
Car is a brembo pack.
Though after my first few days back with the car, the shudder doesn't bother me as much as it once did. I'll likely get a rack down the road from FRPP, but for now I'll just live with it.
Front wheel width slightly narrower than stock (8.5 vs 9), slightly more aggressive offset, though shudder felt on many wheels including stock ones.
Car is a brembo pack.
Though after my first few days back with the car, the shudder doesn't bother me as much as it once did. I'll likely get a rack down the road from FRPP, but for now I'll just live with it.
Interesting...
My 2011 is sitting on Koni Yellow, Steeda Sport spring/HD mounts/adjustable panhard bar, and Strano F/R sway bars. Neg 1.5 degree camber.
The ONLY time I felt the steering shudder is going clockwise at Hallett under hard braking into "The Bitch". The suspension was modified as listed above, and I was using stock Brembo wheels and stock PZero at the time. TCS turned off completely.
No shuddering at all at TWS with much shorter than stock (275/35-18) R888/GT500 18x9.5 wheels.
Just spent a couple of days commuting to work in Sport Mode with 275/40-19 tires (27.7" vs OEM 27" tall) and no shuddering at any speed including 65+.
Francis
My 2011 is sitting on Koni Yellow, Steeda Sport spring/HD mounts/adjustable panhard bar, and Strano F/R sway bars. Neg 1.5 degree camber.
The ONLY time I felt the steering shudder is going clockwise at Hallett under hard braking into "The Bitch". The suspension was modified as listed above, and I was using stock Brembo wheels and stock PZero at the time. TCS turned off completely.
No shuddering at all at TWS with much shorter than stock (275/35-18) R888/GT500 18x9.5 wheels.
Just spent a couple of days commuting to work in Sport Mode with 275/40-19 tires (27.7" vs OEM 27" tall) and no shuddering at any speed including 65+.
Francis
Last edited:
JpMotorSport
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Have Koni yellows, Eibach Pro kit, GT500 Strut mounts + BMR panhard. Also have 19 x 9.5 RTR wheels + 275/40 tires.
I found that if I turned up the front Konis + Sport mode, shudder would be more likely to happen.
I have since kept them on full soft (NYC roads suck) and a few times in sport mode the shudder is only very slight and sometimes not at all.
eventually I would plan on upgrading to this if it got worse.
I found that if I turned up the front Konis + Sport mode, shudder would be more likely to happen.
I have since kept them on full soft (NYC roads suck) and a few times in sport mode the shudder is only very slight and sometimes not at all.
eventually I would plan on upgrading to this if it got worse.
Last edited:
db4z
Junior Member
I can confirm my shudder definitely depends on road surface and therefore it is a not a rotating out of balance issue as it will completely go away on a smooth road. I've also tried playing with steering boost and traction controls as some have mentioned but they don't seem to have any affect.
I think ford probably pushed the limits of trying to balance good tire feedback with damping wheel angle vibrations due to road imperfections. I don't know if software is directly to blame but it does appear the steering system as a whole is very sensitive to any modifications. If the epas does in fact actively try to dampen road vibrations, as opposed to a passive system like a rag joint, mods could easily put it in a state of constantly overcorrecting. Having different damping parameters could be the reason for the different steering rack part numbers, or it could be as simple as each rack just has its boost (assist) matched to the weight and width of each stock size of wheels and tires (larger diameter stock wheels being heavier, with wider tires, should be harder to turn).
I'm running wider tires with much more aggressive offset, effectively increasing the track width, which probably is screwing with all fords optimized geometry and programming. My suspension however is bone stock.
Does anyone think adding slightly more toe angle or any other alignment tweaks would help?
I think ford probably pushed the limits of trying to balance good tire feedback with damping wheel angle vibrations due to road imperfections. I don't know if software is directly to blame but it does appear the steering system as a whole is very sensitive to any modifications. If the epas does in fact actively try to dampen road vibrations, as opposed to a passive system like a rag joint, mods could easily put it in a state of constantly overcorrecting. Having different damping parameters could be the reason for the different steering rack part numbers, or it could be as simple as each rack just has its boost (assist) matched to the weight and width of each stock size of wheels and tires (larger diameter stock wheels being heavier, with wider tires, should be harder to turn).
I'm running wider tires with much more aggressive offset, effectively increasing the track width, which probably is screwing with all fords optimized geometry and programming. My suspension however is bone stock.
Does anyone think adding slightly more toe angle or any other alignment tweaks would help?
07gtcs
forum member
Kicking up an old thread. I saw somebody suggested it earlier but did anybody actually disconnect the PCM's signal? From the diagram I saw its just
Power
Ignition
Ground
CAN +
CAN -
I couldnt care about what lights it might throw just how the steering itself responds to losing the Canbus signal.
Power
Ignition
Ground
CAN +
CAN -
I couldnt care about what lights it might throw just how the steering itself responds to losing the Canbus signal.
07gtcs
forum member
It mentions the systems method of activation when you start the car and the fail safe if it loses the signal. Question is what will it do if you start it without the signal.
DESCRIPTION AND OPERATION
Steering System
Electronic Power Assist Steering (EPAS) System
The Electronic Power Assist Steering (EPAS) system consists of the following components:
• Power Steering Control Module (PSCM) — The PSCM controls the functions of the EPAS system and communicates with other modules that are on
the High Speed Controller Area Network (HS-CAN) bus. The PSCM is attached to the EPAS gear assembly and is not available separately for service.
• Motor — The EPAS gear uses a 12-volt reversible motor to control the steering effort. The motor is connected to the steering rack by a toothed belt
and a pulley/bearing assembly. The motor is used by the PSCM to move the rack inside the gear housing. Motor position is used to determine steering
wheel angle/position instead of using a separate sensor. The motor is attached to the RH side of the EPAS gear assembly and is not available separately
for service.
• EPAS gear assembly — The vehicle has three EPAS steering gear options available: 75mm travel, 68mm travel and a 63mm travel option. The steering
gear installed to the vehicle is dependant on the wheel and tire configuration the vehicle was built with.
• Steering shaft torque sensor — The steering shaft torque sensor is used by the PSCM to determine how much force is being used to turn the steering
wheel. The sensor sends out 2 signals, one for left and one for right. When the steering wheel is turned to the left, the left signal increases while the
right signal decreases, likewise when the steering wheel is turned to the right, the right signal increases while the left signal decreases. This allows the
PSCM to determine if the driver intends to go left or right in order to spin the motor in the appropriate direction. The sensor is mounted inside the
EPAS gear assembly and is not available separately for service.
• Inner tie rod — One inner tie rod is located at each end of the EPAS gear assembly and is available separately for service. There are three different
inner tie rods available, each matched to one of the steering gear options available for the vehicle. Care must be taken to make sure the correct tie rod
for the steering gear installed to the vehicle, is used when replacing an inner tie rod. For additional information, refer to Section 211-02.
• Outer tie rod — One outer tie rod is located at each end of the EPAS gear assembly and is available separately for service. For additional information,
refer to Section 211-02.
• EPAS gear bellows boot — One bellows boot is located on each side of the EPAS gear assembly. Each boot is held in place with 2 boot clamps. The
boots and clamps are available for service, refer to Section 211-02.
• EPAS gear isolator — One rubber isolator is located on the right rear attaching point of the EPAS gear assembly. The isolator aids in the reduction of
NVH concerns and is not available separately for service.
The EPAS system utilizes a rack-and-pinion type steering gear. Power assist is provided by a motor that is connected to the steering rack by a belt and a
pulley and bearing assembly. The steering gear and motor/module are serviced as an assembly. A new steering gear includes inner tie rods, however, the
inner and outer tie rods can also be serviced separately. For additional information on tie rod end service, refer to Section 211-02.
211-00-2 Steering System — Electronic Power Assist Steering (EPAS) 211-00-2
2011 Mustang,
Electronic Power Assist Steering (EPAS) System
The Electronic Power Assist Steering (EPAS) system provides power steering assist to the driver by replacing the conventional hydraulic valve system with
an electric motor coupled to the steering rack by a toothed belt. The motor is controlled by the Power Steering Control Module (PSCM) that senses steering
effort/use through an internally mounted steering shaft torque sensor. Steering assist is provided in proportion to the steering input effort and vehicle speed.
The EPAS system requires a 12-volt, hot at all times feed for system operation. The PSCM is activated when power is applied to the hard-wired ignition/run
input. After activation, the PSCM monitors the High Speed Controller Area Network (HS-CAN) bus to determine if the vehicle is operating in a manner
capable of supporting the EPAS system.
Once this is determined, vehicle speed sent by the PCM over the HS-CAN bus, steering shaft speed and direction sent by the steering shaft torque sensor and
steering wheel angle/position determined by the motor position all provide the necessary information for the PSCM to determine the amount or level of
assist provided by the EPAS system.
Assist is primarily based off of vehicle speed. As vehicle speed increases, the amount of assist provided by the system is decreased to improve and enhance
road feel at the steering wheel. As vehicle speed decreases, the amount of assist provided by the system is increased to ease vehicle maneuvering. If the
vehicle speed is missing or out of range, the PSCM defaults to a safe level of assist for all driving conditions. If the vehicle speed returns to the correct inrange
values, the PSCM adjusts the level of assist accordingly. Steering wheel/shaft speed, torque and direction information allows the PSCM to determine
how much assist is needed to turn the wheels right and left.
The PSCM continually monitors and adjusts steering efforts based on the torque sensor inputs to enhance the feel of the steering. Compensation is made to
reduce the effect of pull or drift that may be experienced when driving on roads with a high degree of camber. Active nibble control is also employed by the
PSCM to reduce the vibrating movement felt at the steering wheel that can be caused by driving on rough surfaces or out of balance wheels.
The PSCM is self-monitoring and has the capability of setting and storing DTCs. Depending on the DTC set, the control module enters into a "safe mode" of
manual steering. In addition, the PSCM may send a request to the Instrument Panel Cluster (IPC) module over the HS-CAN bus to display a message in the
message center to alert the driver of a potential EPAS concern.
DESCRIPTION AND OPERATION
Steering System
Electronic Power Assist Steering (EPAS) System
The Electronic Power Assist Steering (EPAS) system consists of the following components:
• Power Steering Control Module (PSCM) — The PSCM controls the functions of the EPAS system and communicates with other modules that are on
the High Speed Controller Area Network (HS-CAN) bus. The PSCM is attached to the EPAS gear assembly and is not available separately for service.
• Motor — The EPAS gear uses a 12-volt reversible motor to control the steering effort. The motor is connected to the steering rack by a toothed belt
and a pulley/bearing assembly. The motor is used by the PSCM to move the rack inside the gear housing. Motor position is used to determine steering
wheel angle/position instead of using a separate sensor. The motor is attached to the RH side of the EPAS gear assembly and is not available separately
for service.
• EPAS gear assembly — The vehicle has three EPAS steering gear options available: 75mm travel, 68mm travel and a 63mm travel option. The steering
gear installed to the vehicle is dependant on the wheel and tire configuration the vehicle was built with.
• Steering shaft torque sensor — The steering shaft torque sensor is used by the PSCM to determine how much force is being used to turn the steering
wheel. The sensor sends out 2 signals, one for left and one for right. When the steering wheel is turned to the left, the left signal increases while the
right signal decreases, likewise when the steering wheel is turned to the right, the right signal increases while the left signal decreases. This allows the
PSCM to determine if the driver intends to go left or right in order to spin the motor in the appropriate direction. The sensor is mounted inside the
EPAS gear assembly and is not available separately for service.
• Inner tie rod — One inner tie rod is located at each end of the EPAS gear assembly and is available separately for service. There are three different
inner tie rods available, each matched to one of the steering gear options available for the vehicle. Care must be taken to make sure the correct tie rod
for the steering gear installed to the vehicle, is used when replacing an inner tie rod. For additional information, refer to Section 211-02.
• Outer tie rod — One outer tie rod is located at each end of the EPAS gear assembly and is available separately for service. For additional information,
refer to Section 211-02.
• EPAS gear bellows boot — One bellows boot is located on each side of the EPAS gear assembly. Each boot is held in place with 2 boot clamps. The
boots and clamps are available for service, refer to Section 211-02.
• EPAS gear isolator — One rubber isolator is located on the right rear attaching point of the EPAS gear assembly. The isolator aids in the reduction of
NVH concerns and is not available separately for service.
The EPAS system utilizes a rack-and-pinion type steering gear. Power assist is provided by a motor that is connected to the steering rack by a belt and a
pulley and bearing assembly. The steering gear and motor/module are serviced as an assembly. A new steering gear includes inner tie rods, however, the
inner and outer tie rods can also be serviced separately. For additional information on tie rod end service, refer to Section 211-02.
211-00-2 Steering System — Electronic Power Assist Steering (EPAS) 211-00-2
2011 Mustang,
Electronic Power Assist Steering (EPAS) System
The Electronic Power Assist Steering (EPAS) system provides power steering assist to the driver by replacing the conventional hydraulic valve system with
an electric motor coupled to the steering rack by a toothed belt. The motor is controlled by the Power Steering Control Module (PSCM) that senses steering
effort/use through an internally mounted steering shaft torque sensor. Steering assist is provided in proportion to the steering input effort and vehicle speed.
The EPAS system requires a 12-volt, hot at all times feed for system operation. The PSCM is activated when power is applied to the hard-wired ignition/run
input. After activation, the PSCM monitors the High Speed Controller Area Network (HS-CAN) bus to determine if the vehicle is operating in a manner
capable of supporting the EPAS system.
Once this is determined, vehicle speed sent by the PCM over the HS-CAN bus, steering shaft speed and direction sent by the steering shaft torque sensor and
steering wheel angle/position determined by the motor position all provide the necessary information for the PSCM to determine the amount or level of
assist provided by the EPAS system.
Assist is primarily based off of vehicle speed. As vehicle speed increases, the amount of assist provided by the system is decreased to improve and enhance
road feel at the steering wheel. As vehicle speed decreases, the amount of assist provided by the system is increased to ease vehicle maneuvering. If the
vehicle speed is missing or out of range, the PSCM defaults to a safe level of assist for all driving conditions. If the vehicle speed returns to the correct inrange
values, the PSCM adjusts the level of assist accordingly. Steering wheel/shaft speed, torque and direction information allows the PSCM to determine
how much assist is needed to turn the wheels right and left.
The PSCM continually monitors and adjusts steering efforts based on the torque sensor inputs to enhance the feel of the steering. Compensation is made to
reduce the effect of pull or drift that may be experienced when driving on roads with a high degree of camber. Active nibble control is also employed by the
PSCM to reduce the vibrating movement felt at the steering wheel that can be caused by driving on rough surfaces or out of balance wheels.
The PSCM is self-monitoring and has the capability of setting and storing DTCs. Depending on the DTC set, the control module enters into a "safe mode" of
manual steering. In addition, the PSCM may send a request to the Instrument Panel Cluster (IPC) module over the HS-CAN bus to display a message in the
message center to alert the driver of a potential EPAS concern.
Napoleon85
forum member
I would be interested to see these results as well. I haven't personally had any issues (yet) but it would be nice to know how it reacts.
firefighterhill
forum member
Maybe someone can come up with something similar to a "mil eliminator" to plug into the steering rack. Throw some dip switchs on it and you could "TUNE" it.
What would be better is FORD realizing this is an problem and issuing a TSB for it. They have already done so for the gt500's that had the same exact issue.
firefighterhill
forum member
Ford will just say its only a problem with modified cars and wash there hands of the matter.
What TSB are you referring to? This is the first time I've heard of it.
Napoleon85
forum member
Ditto ... if the same parts are used, one would think the TSB would apply.
I tried to get the TSB for the GT500 EPAS software uploaded on my 2011 GT's steering rack. The software was totally wrong and caused this epic fail...
Needless to say it was FUBAR and I immediately asked the brilliant mechanics at my local Ford dealer to remove that software and reflash the EPAS with the old OEM software. At least it wasn't lit up like a Christmas tree, but still had "the shudder of death".
I've talked to many movers and shakers in the aftermarket about this issue. If you have changed the front LCA bushings in your 2011+ GT or Boss or GT500 it will bork up the EPAS software. I am about to do the front bushings again on my 2013 GT (the stock bushing is a big hydraulic marshmallow and screws up geometry under braking and cornering), and once again will probably have to buy the $999 racing steering rack (which is a stock rack without the goofy software issue).
If/when Ford will step up and offer this revised "Race" software for normal street cars is anyone's guess. Likely never.
Good luck,
Napoleon85
forum member
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