Comprehensive Steering Information Thread

[Radekxpl]

I'm considering to buy a yellow tag rack from rackdoctor. As far as I can see, the inner rods are included in the price and the outer rods could be additionally purchased. Is there any difference between the inner/outer rods of the ZHP and the M3 ones?

Yes there is a difference can’t use Zhp putter tie rods on M3 only the inner are the same.


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[injekciona]

I'm considering to buy a yellow tag rack from rackdoctor. As far as I can see, the inner rods are included in the price and the outer rods could be additionally purchased. Is there any difference between the inner/outer rods of the ZHP and the M3 ones?

[Volke]

Thanks for putting together it is good to have all this info in one place again! I have an 01 which has an MK20 ABS module (which is the abs in the earlier modules). I have seen on the M3 cutters that there have been some work arounds with changing parameters but the reviews have been mixed some people say you should stay away (if you have MK20 specifically) and some say you should do it. I know build journal has an update for the MK20 module which converts it to something similar to an "MK 60 M Track Mode". I was going to rebuild/replace or change out the steering rack anyways because there is play right now in mine.

1. I wanted to bring this up for anyone that needs to factor this in since it is comprehensive steering thread and I had not factored the difference between MK20 and MK60 ABS Modules.
2. I didn't know if there was anyone that has a work around for this if it becomes a problem during normal driving (other than turning DSC off)?

The DSC unit uses the output of the steering column rotation sensor to calculate which direction the wheels are pointed. Changing to a quicker rack will cause the DSC unit to assume less steering angle than is actually applied, and will not match the lateral G measured by the yaw sensor, so the car may think something is wrong and cut power / apply brakes as it thinks necessary.

The MK60 can be toggled to the ZCP steering settings when 50 mm/rev rack is installed and everything will work perfectly. I'm not aware of any such setting on the MK20.

There was someone on the old M3 Forum working on a dualCAN gateway that could be plugged in between the steering column sensor and DSC unit, to intercept the column sensor signal and scale it as necessary to maintain proper DSC function. Unfortunately, I don't remember his username. If anyone else has the skills to do it, the trick is to scale the column sensor output as follows:

[column sensor output] * [new rack mm/rev] / [stock rack mm/rev] * [stock knuckle steering arm length] / [new knuckle steering arm length]

[Volke]

Measurements on a Z4MC green tag rack.

Rack Rate = 50 mm/turn

Turns Lock to Lock = 2.8

Total Rack Travel = 140 mm

Linear

Also, the pinion shaft is taller than the gold tag E46 rack. Approximately 70 mm. The gold tag rack is 40 mm.

I also noted that the rack has built in limiters, so while the rack shaft length is the same (575 mm) the Z4MC has 10 mm less travel. Which also makes the lock to lock look better than it is.



Rack Rate = 50 mm/turn

Turns Lock to Lock = 3.0

Total Rack Travel = 150 mm

Linear


Steering knuckle on Z4MC:

Tie Rod Distance from Steering Axis = 130 mm

Post #3 updated. Thank you so much for helping out!

[Michael9218]

Measurements on a Z4MC green tag rack.

Rack Rate = 50 mm/turn

Turns Lock to Lock = 2.8

Total Rack Travel = 140 mm

Linear

Also, the pinion shaft is taller than the gold tag E46 rack. Approximately 70 mm. The gold tag rack is 40 mm.

I also noted that the rack has built in limiters, so while the rack shaft length is the same (575 mm) the Z4MC has 10 mm less travel. Which also makes the lock to lock look better than it is.



Rack Rate = 50 mm/turn

Turns Lock to Lock = 3.0

Total Rack Travel = 150 mm

Linear


Steering knuckle on Z4MC:

Tie Rod Distance from Steering Axis = 130 mm

[01LSBM3]

Thanks for putting together it is good to have all this info in one place again! I have an 01 which has an MK20 ABS module (which is the abs in the earlier modules). I have seen on the M3 cutters that there have been some work arounds with changing parameters but the reviews have been mixed some people say you should stay away (if you have MK20 specifically) and some say you should do it. I know build journal has an update for the MK20 module which converts it to something similar to an "MK 60 M Track Mode". I was going to rebuild/replace or change out the steering rack anyways because there is play right now in mine.

1. I wanted to bring this up for anyone that needs to factor this in since it is comprehensive steering thread and I had not factored the difference between MK20 and MK60 ABS Modules.
2. I didn't know if there was anyone that has a work around for this if it becomes a problem during normal driving (other than turning DSC off)?

[Johnvu]

I forgot to post an update but I used 4 shims for 50% reduction and I love it! I do notice that at stop or in a parking lot, more force is required to turn the wheel but nothing crazy. I drove my friend's NSX with no PS and that was a nightmare compared to mine lol.

This is the perfect solution to the overly light steering from the factory. Thanks Volke for making this DIY and selling those shims!

[Volke]

Guys do you know if that alignment plastic cover can be removed from our racks?

Yes, the black plastic on the spline can be removed, but years of dirt may make it hard to do so. Just go slow and use some WD40 to avoid breaking it.

Sorry, for the slow response, I only check here when I get a PM.

[nervous24]

Thanks for all this, Volke! I will be needing some shims from you when I switch steering racks.

[rbg]

Guys do you know if that alignment plastic cover can be removed from our racks?

[rbg]

Do you know if e90 m3 steering rack would fit e46?

[Volke]

Has anyone used shims along with a smaller diameter power steering pulley?

There's no reason you can't do both. The pulley doesn't affect the steering weight. The smaller pulley just makes it more likely you will momentarily have zero assist if you try to turn the wheel too fast at too low engine RPM due to voiding in the steering rack from the pump not being able to output enough flow.

I perhaps should have inquired before I had mine installed, but is there any *disadvantage* to this?

Nothing you need to worry about. It changes the scrub radius a tiny bit, and less SAI also reduces the centering force that makes the wheels seek the straight ahead position. You can always add a little caster with plates to make up for this if you notice the reduction and don't like it.

[terra]

The CSL king pins either add 1 degree static negative camber without increasing SAI by 1 degree like you get using camber plates to make the same adjustment, or they decrease SAI while keeping static camber the same. Just depends how you align your car. Either way, the result is your car loses slightly less caster when you turn the wheels off center compared to a regular M3 with the same camber specs, and that means you gain a little less positive camber when the wheels are turned. I've heard it makes turn in feel a little better, but I cannot confirm.

I perhaps should have inquired before I had mine installed, but is there any *disadvantage* to this?

[terra]

Might have more to do with the cars they're installed in stock-- e.g. the Z3 has a short wheelbase, so it likely does feel twitchier on the highway with the same rack.

I meant those were the sort of statements in the context of retrofits into e36 M3s and such.

[Pace]

Has anyone used shims along with a smaller diameter power steering pulley?