[tetsuo111]

E9x steering ratios:

xDrive - 18:1
non-M RWD - 16:1
M3 ratio - 12.5:1

I find myself at the limits of crossing my arms on the steering wheel on slow, tight turns (Pacific Raceway 3A and 3B and the Ridge corkscrew and thumb). Short of redesigning the front suspension Ackerman point (don't want to go that deep), I believe my options are:

1) M3 rack, or
2) steering quickener as used on some track and rally cars

Sadly the M3 and non-M racks are not PNP jobs. The racks attach to different parts of the front subframe. I suppose anything is possible by welding new tabs on both the subframe and M3 rack to fit, but this borderlines on heroic effort.

Steering quickeners have been around for awhile, and come in standard 2:1 and 1.5:1 gear ratios. A 1.5:1 quickener ought to result in 12:1 steering ratio. This would be a fine compromise for dual use street and track. Proper install seems somewhat invasive, but again anything is possible with $$ and commitment, right?.

Anyone reading with direct, first-hand experience? Any safety or reliability issues? Will the column still collapse as designed? Does the quickener introduce slop into the system?

Thanks.

[justpete]

Originally Posted by tetsuo111

2) steering quickener as used on some track and rally cars

Steering quickeners have been around for awhile, and come in standard 2:1 and 1.5:1 gear ratios. A 1.5:1 quickener ought to result in 12:1 steering ratio. This would be a fine compromise for dual use street and track. Proper install seems somewhat invasive, but again anything is possible with $$ and commitment, right?.

Anyone reading with direct, first-hand experience? Any safety or reliability issues? Will the column still collapse as designed? Does the quickener introduce slop into the system?

Steering quickeners. No shit. Never heard of these things. Gonna be following to see if it's easier and/or cheaper than swapping in an M3 rack. Cool.

[shirtpants_]

If this works, it'd be great for the x-drive guys. I think I'd consider this over the M3 rack if it works out. Although that 2nd picture makes me think you'd have to do a lot of disassembly to get one of these in.

[tetsuo111]

The installation requires cutting and welding the steering column as part of splicing the steering quickener into the system.

I believe that locating the unit low on the column, under the crumple zone would retain the collapsable design. This is a very high priority for me. I will not proceed if this safety feature is compromised.

I assume the unit would introduce some slop. The question is whether or not this is enough to be an issue, or just slicing hairs over theory.

There are also higher requirements for the PS pump, but again the relevant question is if it matters here. The OE pump may very well have adequate headroom for the job

[tetsuo111]

Originally Posted by justpete

Steering quickeners. No shit. Never heard of these things. Gonna be following to see if it's easier and/or cheaper than swapping in an M3 rack. Cool.

Pete, if not too much hassle, I'm curious what the guys at your shop have to say about these.

It gets old fast doing advanced yoga shoulder exercises to navigate the tight turns.

[justpete]

Originally Posted by tetsuo111

Pete, if not too much hassle, I'm curious what the guys at your shop have to say about these.

It gets old fast doing advanced yoga shoulder exercises to navigate the tight turns.

Two things - 1) the steering angle sensor won't work which would confuse the hell out of the stability system but I'm totally eliminating it so that's not an issue. 2) will ask the guys when they get back from racing in Canada in a couple of weeks.

[tetsuo111]

Originally Posted by justpete

Two things - 1) the steering angle sensor won't work which would confuse the hell out of the stability system but I'm totally eliminating it so that's not an issue. 2) will ask the guys when they get back from racing in Canada in a couple of weeks.

The steering angle sensor is a problem, agreed. Thanks for bringing it up with your team.

Is anything simple on a BMW? Sheesh.....

[rothwem]

I've noticed the same issue. My truck had a faster steering ratio than my BMW does.

Rather than mess with cutting the steering column, what about taking apart an xDrive steering rack and replacing the pinion gear and the rack with parts that have a different ratio? Perhaps if you were able to match the E90 m3's ratio, you could use the m3's steering angle sensor/settings too?

[tetsuo111]

Originally Posted by justpete

Two things - 1) the steering angle sensor won't work which would confuse the hell out of the stability system but I'm totally eliminating it so that's not an issue. 2) will ask the guys when they get back from racing in Canada in a couple of weeks.

It looks like the DSC SAS can be coded with new values. I need to do further diligence to confirm. If correct, I believe this would remedy the problem.

[justpete]

Originally Posted by tetsuo111

It looks like the DSC SAS can be coded with new values. I need to do further diligence to confirm. If correct, I believe this would remedy the problem.

[NiNeTyOne]

Tetsuo, if you ever figure out a way to get the other rack in I'd be very interested.

Since you're in Seattle, I'd love to see the car some time. Not many of us 91's around.

[rothwem]

I wonder if a mini-cooper rack would work. They're both BMW-based front drivers...whatchya think?

[tetsuo111]

I'll check the Mini rack.

Had discussions with some people who build race cars. I'm getting conflicting input - one recommends the quickener, the other recommends a new rack. The reason given for both recommendations is ease of implementation.

Both options are invasive. A quickener has to be installed somewhere on the column, by cutting and welding the column. The rack needs to be modified by welding tabs on to either or both the rack itself and the subframe.

A third option is using a non-BMW rack.

So the project is shaping up to be non-trivial. I'm not close to giving up yet. The payback is too good to ignore.

[whosdady]

Originally Posted by tetsuo111

I'll check the Mini rack.

Had discussions with some people who build race cars. I'm getting conflicting input - one recommends the quickener, the other recommends a new rack. The reason given for both recommendations is ease of implementation.

Both options are invasive. A quickener has to be installed somewhere on the column, by cutting and welding the column. The rack needs to be modified by welding tabs on to either or both the rack itself and the subframe.

A third option is using a non-BMW rack.

So the project is shaping up to be non-trivial. I'm not close to giving up yet. The payback is too good to ignore.

I would look at getting an m3 rack. They are available for as low as $500 and are plug and play. Of course you lose the light power steering feel at low speeds. But at high speeds it's less obvious... There are guys that have the m3 rack and have figured out how to improve the low speed issue.

[rothwem]

Originally Posted by whosdady

I would look at getting an m3 rack. They are available for as low as $500 and are plug and play. Of course you lose the light power steering feel at low speeds. But at high speeds it's less obvious... There are guys that have the m3 rack and have figured out how to improve the low speed issue.

The M3 is not plug and play for the xdrive cars, the xdrive rack attaches at the front, the RWD racks attach at the rear of the rack.

[tetsuo111]

Originally Posted by rothwem

The M3 is not plug and play for the xdrive cars, the xdrive rack attaches at the front, the RWD racks attach at the rear of the rack.

This.

The xDrive front subframe is "reversed" compared with the RWD chassis. So the steering rack attaches to the aft side of the fwd front subframe beam. RWD racks attach to the fwd part of the aft front subframe beam. Point being the xDrive architecture makes a rack swap more invasive. At the minimum it would be necessary to fabricate a way to attach a standard rack designed to connect on one side, to the other side. Hard to explain without a pic, but RealOEM makes it clear.

I spoke with Zionsville BMW about this yesterday. They do a lot of steering upgrades for the E46 / E36 people. We're taking measurements to see if an E46 M3 rack could be re-purposed to this application. The E46 isn't as quick as the E90 M3 rack at 15.4:1

[rothwem]

Originally Posted by tetsuo111

This.

The xDrive front subframe is "reversed" compared with the RWD chassis. So the steering rack attaches to the aft side of the fwd front subframe beam. RWD racks attach to the fwd part of the aft front subframe beam. Point being the xDrive architecture makes a rack swap more invasive. At the minimum it would be necessary to fabricate a way to attach a standard rack designed to connect on one side, to the other side. Hard to explain without a pic, but RealOEM makes it clear.

I spoke with Zionsville BMW about this yesterday. They do a lot of steering upgrades for the E46 / E36 people. We're taking measurements to see if an E46 M3 rack could be re-purposed to this application. The E46 isn't as quick as the E90 M3 rack at 15.4:1

If you're going to use an e46 rack, why not the ZHP? I think its faster than the e46 M3 rack.

[tetsuo111]

Originally Posted by rothwem

If you're going to use an e46 rack, why not the ZHP? I think its faster than the e46 M3 rack.

Valid point - no reason not to. I think the discussion was more about fitting a faster rack versus the fastest fitting rack.

[JustinGTP]

you could do active steering - but 3k usd for the rack alone reman. i have active steering in my e90 335 and its amazing at low speeds, hardly any work.

This thread talks about it - people like it at autocross - http://www.e90post.com/forums/showth...1#post19991461

Full lock to lock at lower speeds in 1.5 turns ish

[tlow98]

Originally Posted by rothwem

If you're going to use an e46 rack, why not the ZHP? I think its faster than the e46 M3 rack.

Touche.

Originally Posted by tetsuo111

Valid point - no reason not to. I think the discussion was more about fitting a faster rack versus the fastest fitting rack.

FWIW, I auto crossed my E46 M3 (a lot) and didn't find the ratio to be too much work. I would think this would be substantially tighter than the courses you are on.

However, if they're both equal work then ZHP all the way.

[rothwem]

Originally Posted by JustinGTP

you could do active steering - but 3k usd for the rack alone reman. i have active steering in my e90 335 and its amazing at low speeds, hardly any work.

This thread talks about it - people like it at autocross - http://www.e90post.com/forums/showth...1#post19991461

Full lock to lock at lower speeds in 1.5 turns ish

The active steering is only for RWD cars. I had it on my 2006 and it was fucking awesome, but the rack won't fit for the same reason the M3 rack won't fit.

[Cloud9blue]

I have a feeling that the steering angle sensor and the DSC isn't gonna like this.