Comprehensive Steering Information Thread

[BBRTuning]

I don't have any desire for a faster than stock ratio (as in, I thought going to the ZHP rack was a downgrade in speed, just did it for the feel), but I am curious-- does DSC have any issues with the faster racks? I ask because steering ratio is an option in NCS (between stock and ZCP/ZHP), which implies it's somehow using that in it's calculation for something.

Yeah, this has been covered a lot. Changing steering ratio significantly from stock will cause the DSC to go nuts. Steering angle is one of the core inputs into the stability system determining if the vehicle is following the intended trajectory and calculating understeer or oversteer, and it needs to know the relationship between steering shaft angle and steered wheel angle to calculate expected lateral accel/yaw vs measured accel/yaw.

Mk20 seems much more sensitive, and seems to be hard-coded to the E46M3 rack, vs the Mk60 which can be programmed for at least the ZCP/ZHP ratio, if not custom ratios (haven't seen anyone definitively figure this out yet). With Mk20, even with the Z3 rack, if I left DSC on it would start intervening dangerously even at freeway transitions with moderate steering angle. However my ZHP with its Mk60 and the SLR angle kit (super fast steering ratio), the DSC will freak out at low speeds such as doing a U-turn, but even at high speeds driving 7/8-10ths it doesn't seem to care as much. Still does cause it to kick in earlier than it should, as it thinks the car is oversteering and will start to grab the outside tire if left on.

[Obioban]

LPSR Black Label quick-ratio rack update.

Wow, yeah it's fast. I can say confidently it's a bigger jump in ratio going from Z3 -> LPSR Black Label, compared to E46M3 -> Z3 rack. The change to the Z3 rack from OEM that I did many years ago was noticeable but not huge. If I hadn't driven the car in a while I may not have even noticed. However this change from Z3 to LPSR BL is noticeable instantly from when you first turn the wheel, and actually took a bit to get used to in the canyons, but in a good way.

For a pure track car, especially if you're running a smaller diameter steering wheel, I'd say it's possibly too fast, or at least faster than you need it to be, and a ZHP/Z3 rack speed may be a better choice. However, for mixed street/track use or street/canyons, it's amazing. It's still a slower steering ratio than what you get on say a 992 GT3, but it's getting damn close. It's also a bit slower than the Z3 + SLR angle kit in my 330i, which is a good thing.

Steering feel and weighting is back too, loads up very nicely immediately off center, and steering feels tight as ever. I'm happy.

I don't have any desire for a faster than stock ratio (as in, I thought going to the ZHP rack was a downgrade in speed, just did it for the feel), but I am curious-- does DSC have any issues with the faster racks? I ask because steering ratio is an option in NCS (between stock and ZCP/ZHP), which implies it's somehow using that in it's calculation for something.

[maksezzy]

Just measured the zhp rack i pulled out of my car and it has 3.2 turns, but is linear with a 50mm per rotation. I also had 2 purple tag racks (678) and one was 3.0 turns and the other was 3.2 turns, but both were linear with 50mm per rotation. My purple tag racks are built one month apart based on their label dates.

I heard that the zhp rack feels heavier than all the others, but my stock m3 rack, zhp rack, and purple rack all felt the same. I also have under drive pulleys, which shouldn't effect my judgement since I'm just comparing how the steering feels compared to the different racks. Stock M3 rack was just very slow in comparison.

[BBRTuning]

LPSR Black Label quick-ratio rack update.

Wow, yeah it's fast. I can say confidently it's a bigger jump in ratio going from Z3 -> LPSR Black Label, compared to E46M3 -> Z3 rack. The change to the Z3 rack from OEM that I did many years ago was noticeable but not huge. If I hadn't driven the car in a while I may not have even noticed. However this change from Z3 to LPSR BL is noticeable instantly from when you first turn the wheel, and actually took a bit to get used to in the canyons, but in a good way.

For a pure track car, especially if you're running a smaller diameter steering wheel, I'd say it's possibly too fast, or at least faster than you need it to be, and a ZHP/Z3 rack speed may be a better choice. However, for mixed street/track use or street/canyons, it's amazing. It's still a slower steering ratio than what you get on say a 992 GT3, but it's getting damn close. It's also a bit slower than the Z3 + SLR angle kit in my 330i, which is a good thing.

Steering feel and weighting is back too, loads up very nicely immediately off center, and steering feels tight as ever. I'm happy.

[SQ13]

Anyone have a shim on hand that they can measure for me? Trying to see if I can source some for myself.

OD 12.88 mm
ID 10.07 mm
Thickness 0.47 mm

[jayjaya29]

Another +1 here for shims if anyone wants to take the initiative to make more.

[BBRTuning]

LPSR Black Label rack update and various rack adventures over the years -

Just got the new LPSR rack in yesterday. This will now be the 4th and hopefully final rack in this car..

Back in 2016 I swapped to a used Z3 rack rebuilt by Rack Doctor. The steering ratio and overall steering feel was a big improvement. Over the years from all the track abuse and miles it slowly developed a bit of play, still miles better than a stock M3 with spherical bearing everything but felt a bit more dead on-center. With how hard it is to find a good used rack nowadays, I decided to purchase a brand new Z3 rack that Strom Motorsports had produced for them in quantity. They use these on their B46 racecar programs. That rack was incredibly tight, the car has absolutely zero play in the steering now, even with 275 fronts, you could move the wheel a couple mm and you're moving in your lane. Felt like a modern M car or Porsche and was quite shocking. However, I lost almost a ton of feel. The rack felt over-boosted and had very little on-center, even with a ton of the Volke shims (I think I have 6 in there?). So, once again, started looking into racks and came across the LPSR with its extra quick ratio.

I'll be installing it shortly, just wanted to share ratio measurements for the database. 58.5mm!! Measured three times different ways and all within 0.5mm of 58.5. Sounds like at least a big of a jump as E46M3 > Z3, but again. Pretty cool.

Doubt it will feel too fast - I have a full SLR drift angle kit + Z3 rack combo on my ZHP which is still significantly quicker ratio than this LPSR will be. While the ratio with the SLR kit is certainly much faster than it needs to be for track use, it definitely doesn't feel close to being too twitchy at speed. Hoping this is the golden steering ratio and that nice steering feel comes back. Updates soon.

BLACK LABEL | BLACK TAG BMW E46 LHD STEERING RACK | lpsr (steeringlpsr.com)

[repoman89]

Anyone have a shim on hand that they can measure for me? Trying to see if I can source some for myself.

Bump, wondering as well. Looks like 0.5mm thick from the OP but he didn’t post ID/OD. Come back Volke, you have buyers

[Taz]

Anyone know if a rack from a UK Z4M Coupe would fit our US E46 M3? Are the racks the same on the U.S. and UK Z4M Coupes?

UK drive on the wrong side of the street. Wait... right side.
No, racks are not the same as the steering wheel is in the wrong place.

Sent from my SM-S918B using Tapatalk

[bigjae46]

Anyone know if a rack from a UK Z4M Coupe would fit our US E46 M3? Are the racks the same on the U.S. and UK Z4M Coupes?

It’s probably going to be RHD…so my guess is no.

[Advorsor]

Anyone know if a rack from a UK Z4M Coupe would fit our US E46 M3? Are the racks the same on the U.S. and UK Z4M Coupes?

[Ubaderb]

Anyone have a shim on hand that they can measure for me? Trying to see if I can source some for myself.

[digger]

If some is good more is better?

[YoitsTmac]

I hadn't. Instant buy. Thanks for linking

[stephen]

Wondering if anyone here has heard of the new steering rack LPSR in Australia plans on releasing for the E46. Promises 2.5 turns LTL.

https://www.steeringlpsr.com/product-page/black-label-black-tag-lhd