Comprehensive Steering Information Thread

[snaponbob]

Hi all. I was sent here from bimmerforums.

I have an 04 M3 that was an autocross car, but it's a slug against the newer M3 that run in the same class. So, after autocrossing since 1981, and loving the car over the past 4 seasons, I migrated to track days and SCCA Time Trials. The car is well setup and is an overdog in my TT class.

When I first started running solo, I climbed the learning curve after 5 seasons in E36s. One change I made mid first season was a ZHP rack. My first impression was how much heavier the steering felt, but couldn't definitively define the difference in response through slaloms and switchback sweepers. I didn't bother me enough to swap the M3 rack back in. Well, the entire front subframe is out so everything is laying on the floor. So, now that I am going into the 3rd season of track use ---

Is the heavier feel a function of a mismatch of steering pumps?
Given all I have read, I am not clear as to whether or not one rack is "quicker" than the other?
Is there a tangible benefit of one rack over the other?

[BBRTuning]

Hi all. I was sent here from bimmerforums.

I have an 04 M3 that was an autocross car, but it's a slug against the newer M3 that run in the same class. So, after autocrossing since 1981, and loving the car over the past 4 seasons, I migrated to track days and SCCA Time Trials. The car is well setup and is an overdog in my TT class.

When I first started running solo, I climbed the learning curve after 5 seasons in E36s. One change I made mid first season was a ZHP rack. My first impression was how much heavier the steering felt, but couldn't definitively define the difference in response through slaloms and switchback sweepers. I didn't bother me enough to swap the M3 rack back in. Well, the entire front subframe is out so everything is laying on the floor. So, now that I am going into the 3rd season of track use ---

Is the heavier feel a function of a mismatch of steering pumps?
Given all I have read, I am not clear as to whether or not one rack is "quicker" than the other?
Is there a tangible benefit of one rack over the other?

I much prefer heavier steering, to the point of swapping to a Z3 rack and I then shimmed the power steering pump to reduce assist.

Early 330i racks had the same quicker ZHP ratio but with a much lighter feel, enough so that some early owners complained and BMW replaced the racks. I have one of these sitting in my garage, PM me if you’re interested. They’re sometimes preferred by E46 endurance racers for obvious reasons.

[old///MFanatic]

Is the heavier feel a function of a mismatch of steering pumps?
Given all I have read, I am not clear as to whether or not one rack is "quicker" than the other?
Is there a tangible benefit of one rack over the other?

The ZF .712 “yellow tag” (sometimes called zhp) rack is a quicker ratio than the stock E46 M3 (non-CSL/ZCP). The internal torsion bar, and internal pressure valve are said to also give it a heavier feel compared to other same stock E46 ratios.

[snaponbob]

Interesting responses.

Before I even post the following question, it sounds STUPID !!! I've been autocrossing and now tracking since 1981. Knowing how light old American road barge power steering was/is (i.e. 60s Chryslers and GMs), I find most contemporary p/s systems firmer, and sometimes with very good feel. So, why is even heavier steering than stock E46 M3 beneficial? If firming the system results in ACTUAL improved feel, that's good. But, making a system require more muscle sounds like a fine way to get tired faster !!! ( I guess that goes to BBR Tunings' comment about endurance racing.) I can't imagine why people do p/s deletes on 36s and 46s other than for the minor weight savings.

I am recovering from rotator cuff surgery (10 days ago). I have the M3 on stands for the winter with a laundry list of changes before Mar/April track events start up again. All the trim in the front is off for a condenser delete and some ducting, oil pan is off to check things inside and thus the entire subframe is out. So, now is the time to gather info before stuff starts going back together once I can do that (mid/late Feb I hope).

[terra]

I didn't find the change in weight to be tremendous (though it is noticeable). The reduced steering ratio did make a nice difference even in daily driving though. Just feels more appropriate for a sports car.

The heavier feel compared to a non-M with the same rack is going to be mostly due to the suspension geometry. E46 M3 has more caster, more camber, both of which work against you in terms of steering weight. If you want something with the same ratio, but less weight - the 325i rack ("purple tag") might be worth considering, but I don't have first hand experience with that one. I'm also not quite sure where the actual ZCP rack lies in comparison with the ZHP rack when installed in an M3.

[snaponbob]

The current rack in my M3

[Taz]

Hey guys, amazing post with great detailed information.
I have a e39 520iA, I will ask something totally different. The car is used for long, cross Europe journeys, very docile driving( with 150HP can't be anything but docile) but handles the autobahn well. I want my steering as smooth as it can possibly get. I have retrofitted servotronic, but it still feels stiff. I have a brand new PS pump installed, the solenoid is good, everything else is new and fresh.
My friend has a e39 530IA also with servotronic, and his steering is ideal. So smooth and progressive.
If untighten the pre-load bolt on the steering rack, will that make the rack more smooth or will it introduce play in the rack.
Is there also a possibility of increasing the pumps assist, just like you added shims to decrease its assist?
Any insight is appreciated.

[Amoscake]

So all 2002-2005 330i/ci came with either a purple or yellow? No trw?

[Rich022]

Shim kit - Where do I purchase ? Rack is off the car, so figured this was the best time to tackle this! thanks

[sixthspeed]

Looks like volke hasn't been active since March and I got no response from PMing him. Does anyone have extra shims they can spare? I can buy, only looking for 3 or 4.

[Thoglan]

Looks like volke hasn't been active since March and I got no response from PMing him. Does anyone have extra shims they can spare? I can buy, only looking for 3 or 4.

From factory there is usually a shim in the regulator. I just went to a scrap yard and pulled the regulators out of a couple different e46's and measured/used the shims from those.

For what it's worth I ended up removing the additional shim from mine a few months after I put it in cause I hated the way it felt lol

[Richardracer]

Hi Volpe, I am a new subscriber (Richardracer) and can’t send messages yet. Could you message me with an email address. I would like to buy a set of yours shims please.

thanks

Richardracer

[bigjae46]

From factory there is usually a shim in the regulator. I just went to a scrap yard and pulled the regulators out of a couple different e46's and measured/used the shims from those.

For what it's worth I ended up removing the additional shim from mine a few months after I put it in cause I hated the way it felt lol

bro...you're committed! lol

[digger]

Has anyone measured the linearity of the rack travel just off centre?

All measurements seem to be based on 1 full rev when i would have thought you'd need to do various incremental measurements at 1/8, 1/4 turn etc to establish this

[lapoune]

Has anyone measured the linearity of the rack travel just off centre?

All measurements seem to be based on 1 full rev when i would have thought you'd need to do various incremental measurements at 1/8, 1/4 turn etc to establish this

The ones I measured I checked if linear, so e36 m3\z3m = progressive...z4mc\roadster, standard z3s, zcp = linear