S197 with S550 EPS Steering Rack Slop / Play

[Datsun40146]

Good day everyone,
I’ve been fighting steering play on my 05’ Mustang for a while. It’s not a S550, but the parts used were.
Throughout the steering range, not just on center the car has about an inch of total free play in the steering.

In an attempt to correct and replace worn components the follow measures were taken

The entire front and rear suspension is new GT500 or Ford Performance parts. Shocks, sways, FCA, etc etc,

Inner and outer tie rods are new as are the ball joints.

The steering column shaft was replaced in its entirety with a solid Borgenson unit from LMR. So it’s right and there is no bushing any longer. The bolts are in the correct direction.

I’ve had my partner move the steering wheel and the movement is 100% going into the rack. It’s just not moving the tie rods. I have no idea what’s left? I assume at this point it has the be the rack.

The OEM hydraulic rack and pump were removed and replaced with a used S550 EPS rack with a Wireeverything harness. Sport mode is selected all the time. The problem persists in all modes regardless.

To that end, there is a epoxy covered preload adjustment on the Mustang EPS rack. I checked it, adjusted it tighter and adjusted it back. (See the image if you want to know where that’s at) The wheel wouldn’t recenter on its own when it’s too tight. So, the preload I don’t thinks the issue. Even with it cranked down the play was still there.

I can’t believe this amount of slop is normal. Can anyone suggest anything else to try?

Steering slop video example

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[WolfMxbee]

Check the belt inside the rack, there is a serviceable belt and see, i heard it can cause a whine when turning or be missing some ribs

 

[Cobra Jet]

This thread has a ton of EPAS PSCM tech that may be helpful;
https://www.mustang6g.com/forums/threads/s550-epas-pscm-tech-accumulation.160616/

 

[WolfMxbee]

I just want to verify, its not like there is a dead spot as in steering feel having no feedback but its where you turn the steering wheel and lets say like theoretically, the steering wheel is turned 10 degrees left or right and road wheels wont react, but past that they actually turn almost like mechanical hence why your checking physical parts and connections like tie rods, my bet is the belt is missing ribs or the worm gear having issues but highly unlikely unless the rack was from a front end collision vehicle

 

[Datsun40146]

Correct. this is different from steering feel.
This is the issue
say you turn the wheel 90 degrees and held it there you could wiggle the steering wheel plus or -5°. Inside of those that +-5° range there is no effect on the wheels or steering input.
You can repeat this trial when the steering wheel is centered or turn the other direction you still get the + or -5° of play where the tire rods do not react to the input of the steering wheel

I just want to verify, its not like there is a dead spot as in steering feel having no feedback but its where you turn the steering wheel and lets say like theoretically, the steering wheel is turned 10 degrees left or right and road wheels wont react, but past that they actually turn almost like mechanical hence why your checking physical parts and connections like tie rods, my bet is the belt is missing ribs or the worm gear having issues but highly unlikely unless the rack was from a front end collision vehicle

 

[Datsun40146]

The rack did come out of wrecked car best I recall. It’s been about 9 months.
it’s a quiet rack tho, no damage I can see on it.
The guy I bought it from was parting out a 2011/2012 v8 car.

 

[WolfMxbee]

Heres what i want ya to do, since ya verified there is movement going to the rack but not to the wheels, i have pictures of how it looks

Your gonna have to remove (ill verify which side) but x1 outer tie rod and the bellow boot then remove the bolts holding the access panel that covers the rack, then once you can see the belt, obviously inspect the belt but have 1 person turn the wheel while that cover is off so you can visually see the worm gear moving, then have the person slowly ever so slightly turn the wheel in one consistent direction to see if the worm gear and belt are consistently rotating, if there is a hicup or dead play for a second, inspect that section of the belt, i do have a video of where a guy did the opposite of you and put a s197 rack into a s550 and tore apart the old rack so you can see what else moves in the rack to help narrow it down if theres no issues at the worm gear or belt

 

[Datsun40146]

I’ll see if I can pull it apart over the thanksgiving holiday.
One point, the play is there whether the car and therefore rack is powered on or off. It’s same in both conditions.
wouldn’t this eliminate the motor / belt as a likely root cause?

 

[WolfMxbee]

Ahhhh gotcha, I would still remove the cover to verify how the worm gear itself is moving then cause it connects to the intermediate shaft that mounts to the steering column, is the intermediate shaft bolt tight on the coupler

Heres the link

 

[Datsun40146]

The bolts are tight, there is no coupler on my shaft.
it’s a solid Borgenson unit from LMR. It’s all U joints but yes they are tight.
The final clamp onto the rack input is tight, I can watch the shaft turn the input into the rack as we wiggle the steering wheel. That’s how I know movement is getting to the rack and the issue probably isn’t upstream

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