Comprehensive Steering Information Thread

[Bry5on]

Figured I'd give my feedback after shimming the PS pump. Thanks to Volke and anyone who contributed, and thanks to bigjae for supplying the washers.

So I have an E90 m3 that has unbelieveably good steering feel and weight. After having an E36 325i with fantastic steering, I was always a bit disappointed when I moved up to the E46 M3. It has very good steering, but the feel was always "springy" and light to me.

After getting the E90, it just got exposed that much more, so I've been wanting to match them up as much as possible. I've already done things like wider wheels/tires up front for a"heavier" feel, but that didn't have a lot of impact. A Yellow tag rack didn't do anything either really.

I was hopefull shimming the pump would be the ticket. So the job isn't too bad, but you definitely need a good method for getting the valve out - I used magnets.

I started with 2 .5mm shims for reported 25% reduction in boost. I lost most of the fluid, so it got a good flush. Ok so how does it feel.? First, it did work, there is less boost, BUT it feels to me a bit progressive where the wheel is still very light and bouncy (snaps back to center quickly) but then starts to get stiffer as you turn.

The E90's wheel is super stiff 100% of the time. If you turn the wheel a little and let go, it doesn't snap back to center nearly as fast as the E46. It feels equally stiff no matter what amount of rotation you give it or at whatever speed. The E46's wheel now only really feels stiffer when you have more rotation.

So there must be something else involved. Both cars have 265 tires & 9.5" lightwieght 18" wheels. Similar high end suspension and spring rates. All factory parts when it comes to steering and front end bushings (except for plates in E46).

All in all, I'm happy to make the steering stiffer for such little money and time/effort, but it's bittersweet because it's not stiff right from the off. It still has its light and springy nature I was hoping to eliminate.

If you’re running offsets below et45 or so, this could partially explain it. The e9x has a virtual pivot to control keeping scrub radius smaller, which allows it to run low offset front wheels. A smaller scrub radius means that you’re pivoting the tire closer to its center, fighting it less as you turn more.

If you want to bring feedback closer to the e90 and a bit more linear, you’ll want the CSL rack (claimed stiffer torque bar internally) and/or less pump assist and an offset around stock e46 M3, not something like et35 like most folks seem to run. You may also want to eliminate the rubber steering guibo or go with a shorter ratio, as the e9x has an equivalent ratio of 13.3:1 when you adjust for wheelbase differences. The non-m e46 is 13.7:1, CSL/yellow is 14.5:1

Any and all of those should help. High offset wheels is the easiest.

edit: you will never be able to 100% recreate the e9x steering feel in an e46, because the e46 has a fixed kingpin axis, where the e90 has a kingpin axis that moves. When you turn the wheels in an e46, the wheel and tire move somewhat forward and backward in the wheel well. Because the e9x has a two-link lower and a virtual pivot point, the wheel doesn’t move forward/backward in the wheel well much at all. The force to push the outer tire forward when turning is generated from the steering wheel. I think this is the only thing you can’t recreate though, and just a portion of the total effort.

[bigjae46]

Figured I'd give my feedback after shimming the PS pump. Thanks to Volke and anyone who contributed, and thanks to bigjae for supplying the washers.

So I have an E90 m3 that has unbelieveably good steering feel and weight. After having an E36 325i with fantastic steering, I was always a bit disappointed when I moved up to the E46 M3. It has very good steering, but the feel was always "springy" and light to me.

After getting the E90, it just got exposed that much more, so I've been wanting to match them up as much as possible. I've already done things like wider wheels/tires up front for a"heavier" feel, but that didn't have a lot of impact. A Yellow tag rack didn't do anything either really.

I was hopefull shimming the pump would be the ticket. So the job isn't too bad, but you definitely need a good method for getting the valve out - I used magnets.

I started with 2 .5mm shims for reported 25% reduction in boost. I lost most of the fluid, so it got a good flush. Ok so how does it feel.? First, it did work, there is less boost, BUT it feels to me a bit progressive where the wheel is still very light and bouncy (snaps back to center quickly) but then starts to get stiffer as you turn.

The E90's wheel is super stiff 100% of the time. If you turn the wheel a little and let go, it doesn't snap back to center nearly as fast as the E46. It feels equally stiff no matter what amount of rotation you give it or at whatever speed. The E46's wheel now only really feels stiffer when you have more rotation.

So there must be something else involved. Both cars have 265 tires & 9.5" lightwieght 18" wheels. Similar high end suspension and spring rates. All factory parts when it comes to steering and front end bushings (except for plates in E46).

All in all, I'm happy to make the steering stiffer for such little money and time/effort, but it's bittersweet because it's not stiff right from the off. It still has its light and springy nature I was hoping to eliminate.

I'll have to pay more attention next time I drive my car. But that makes sense. The PS assist should be about the same until the RPMs get high enough to open the pressure valve which would be lower with the shims. Maybe if the pump was overdriven, then the pump could reach that point at lower RPMs but that would do the opposite of an underdrive pulley.

[Tbonem3]

Figured I'd give my feedback after shimming the PS pump. Thanks to Volke and anyone who contributed, and thanks to bigjae for supplying the washers.

So I have an E90 m3 that has unbelieveably good steering feel and weight. After having an E36 325i with fantastic steering, I was always a bit disappointed when I moved up to the E46 M3. It has very good steering, but the feel was always "springy" and light to me.

After getting the E90, it just got exposed that much more, so I've been wanting to match them up as much as possible. I've already done things like wider wheels/tires up front for a"heavier" feel, but that didn't have a lot of impact. A Yellow tag rack didn't do anything either really.

I was hopefull shimming the pump would be the ticket. So the job isn't too bad, but you definitely need a good method for getting the valve out - I used magnets.

I started with 2 .5mm shims for reported 25% reduction in boost. I lost most of the fluid, so it got a good flush. Ok so how does it feel.? First, it did work, there is less boost, BUT it feels to me a bit progressive where the wheel is still very light and bouncy (snaps back to center quickly) but then starts to get stiffer as you turn.

The E90's wheel is super stiff 100% of the time. If you turn the wheel a little and let go, it doesn't snap back to center nearly as fast as the E46. It feels equally stiff no matter what amount of rotation you give it or at whatever speed. The E46's wheel now only really feels stiffer when you have more rotation.

So there must be something else involved. Both cars have 265 tires & 9.5" lightwieght 18" wheels. Similar high end suspension and spring rates. All factory parts when it comes to steering and front end bushings (except for plates in E46).

All in all, I'm happy to make the steering stiffer for such little money and time/effort, but it's bittersweet because it's not stiff right from the off. It still has its light and springy nature I was hoping to eliminate.

[bigjae46]

I’m very curious on this…I have a ZCP rack that is likely in need of a rebuild

I’ve considered purchasing a ZHP rack…I’ve driven a handful of E46s with ZHP racks however, and I’ve always preferred the ZCP rack. Curious if there’s anything quantifiable, or if it’s a placebo.

I think there would be too many other variables to make an accurate judgement unless it was on the same car. Does the non-M has different caster angles? But track width, tires, wheel offsets, suspension could also affect feel...I would think.

[cornerbalanced]

I’ll be opening up a CSL/ZCP 924 rack and comparing the guts to a ZHP 712 rack within the next week or so.

David

I’m very curious on this…I have a ZCP rack that is likely in need of a rebuild

I’ve considered purchasing a ZHP rack…I’ve driven a handful of E46s with ZHP racks however, and I’ve always preferred the ZCP rack. Curious if there’s anything quantifiable, or if it’s a placebo.

[SQ13]

I hadn’t (that day job thing got in the way the last few months) but I’ll open it up next week. I have a rack rebuild for a 712 pending so it will be a good time to lay the two out with measurements.

TBD!

Oh shit, I forgot to send you my old ZHP rack 😭

[davidinnyc]

Not to bother but did you get a chance to get to this one? Thanks!

I hadn’t (that day job thing got in the way the last few months) but I’ll open it up next week. I have a rack rebuild for a 712 pending so it will be a good time to lay the two out with measurements.

TBD!

[bigjae46]

If anyone wants some shims, let me know. $20 shipped for a set of 4.

[Bry5on]

I’ll be opening up a CSL/ZCP 924 rack and comparing the guts to a ZHP 712 rack within the next week or so.

David

Not to bother but did you get a chance to get to this one? Thanks!

[dewr]

Hi There David, new member so I can't PM, but very interested in the zhp rack refresh. How can I best reach you? Are you in Socal?

[Bry5on]

Hmm, I haven't had this exact issue with this rack, but I have had it in the past with Z3 racks. Can't really say what caused/fixed it. I run redline D4 ATF. I would recommend flushing the system after some time, which includes replacing the reservior since it has an internal filter.

However, with this LPSR rack, now in both my M3 and my ZHP, I occasionally get a sudden very brief dropout/pulsation in the assist when the front is heavily loaded in a corner and hitting a bump, especially when driving hard for a while (hot PS fluid?). On the ZHP I have an upgraded cooler too. Both cars have tons of tire, so lots of load on the PS system, but this didn't happen with the stock or Z3 racks. It's a bit unnerving and feels like extreme bump steer although I do generally know when to expect it. I do have a bunch of the Volke shims in my M3 pump, although interestingly I never really found those had much effect.

I also found the steering effort to still be too light for my liking with the LPSR black, and it the steering weight doesn't really build up as you turn in. I'm going to remove all the shims out of the pump and start over, as a test. I wonder if I've put too many in at this point or something.

If you are running a front wheel offset below 30-35, this could be an issue with scrub radius that was simply highlighted with the tighter rack.

[Bry5on]

I’ll be opening up a CSL/ZCP 924 rack and comparing the guts to a ZHP 712 rack within the next week or so.

David

Please take some good measurements of the torque shafts if you can!

[davidinnyc]

I’ll be opening up a CSL/ZCP 924 rack and comparing the guts to a ZHP 712 rack within the next week or so.

David

[BBRTuning]

BBRTuning, Did you have any issues with your system after installing the black label rack?

Hmm, I haven't had this exact issue with this rack, but I have had it in the past with Z3 racks. Can't really say what caused/fixed it. I run redline D4 ATF. I would recommend flushing the system after some time, which includes replacing the reservior since it has an internal filter.

However, with this LPSR rack, now in both my M3 and my ZHP, I occasionally get a sudden very brief dropout/pulsation in the assist when the front is heavily loaded in a corner and hitting a bump, especially when driving hard for a while (hot PS fluid?). On the ZHP I have an upgraded cooler too. Both cars have tons of tire, so lots of load on the PS system, but this didn't happen with the stock or Z3 racks. It's a bit unnerving and feels like extreme bump steer although I do generally know when to expect it. I do have a bunch of the Volke shims in my M3 pump, although interestingly I never really found those had much effect.

I also found the steering effort to still be too light for my liking with the LPSR black, and it the steering weight doesn't really build up as you turn in. I'm going to remove all the shims out of the pump and start over, as a test. I wonder if I've put too many in at this point or something.

[Ronan]

What have you tried to do? Did you try those shims in the pump?

When I cold start it doesn't do this pulsing. I also am thinking that the fluid viscosity may have something to do with it. Apparently the fluid spec calls for "pentosin chf-11s" and I've used Redline ATF.