AutoX: To power steer or not to power steer?

[Jparkr]

Josh, Personally I would keep power steering if you plan on running any autocross course.

I only go to lapping days now at road courses like Portland IR, Pacific IR, and Spokane IR. On tracks, like these, it is not needed and I prefer not having it.

[AlarmedBread]

You don't gain any feel by removing the PS, you simply increase the feel/effort. Not gaining anything that was not there before, it is simply more noticeable and requires extra effort. It felt that I was actually dampening the 'extra' feel that was supposed to be gained by removing the PS because I had to hold the wheel tighter and use more effort.

It's all personal preference in this area...

[gearheadE30]

^^yeah, that's what I was saying. The only "feel" that I think I gained on the street was on off-camber corners where it took more force to keep the car on the line.

[xLibelle]

steering responce is pretty important on autocross, but the handoff is detrimental to speed.
On fast +60sec courses i feel that i drove better with my manual rack. For anything else, its a slight annoyance.

I know ive mentioned this a few times before, but it makes a difference. Removing the PS rack ring alleviates any extra resistance from pneumatics making it a true manual rack.
Ring components removed and laid out above rack


Pack gearing with grease, oil the pressure rings in the pinion housing and rebuild rack.

You can plug the holes how ever you like (Or even leave the lines). I had a stick of ABS and drilled a hole in it and installed original bolts.

[Miatamania]

I've depowered it in my miata, its light enough to not really matter. However, if I do go back to seriously auto-xing the thing vs. track/street driving, I will definitely have the PS back on.


As for the E30, I've never driven one that I was happy with the PS gone. Then again, I bet a z3 rack with no PS would be pretty tolerable for the street on decent sized tires.

[JGood]

As for the E30, I've never driven one that I was happen with the PS gone. Then again, I bet a z3 rack with no PS would be pretty tolerable for the street on decent sized tires.

I daily drove my 2800lb e30 with 205's, 3.0 turn 95 M3 rack (same ratio as Z3), with no P/S. I thought I was going to rip the steering wheel off. It was absolutely impossible to park the car.

I tracked my other e30 (~2500lbs) with a stock rack, no power steering, and 205 v710's, and that was still too much effort IMO. Looking back, I don't think there is any additional "feel" to be gained. We're talking about a 20 year old flexible chassis with bushings and relatively soft springs... I don't think the P/S is the bottleneck regarding feedback.

[z31maniac]

3.0 turn 95 M3 rack (same ratio as Z3)

I thought the Z3 rack was 2.7 turns lock to lock? Same ratio, just less max steering angle?

[JGood]

I thought the Z3 rack was 2.7 turns lock to lock? Same ratio, just less max steering angle?

Correct.

[z31maniac]

Correct.

Ahhh that's good to know, from what I understood, all the E36 racks ended up with the same max steering angle.

Maybe now I want a '95 M3 instead of the Z3.

[xLibelle]

technically, the values are different, but so close, it doesnt matter, they result in the same. The ratios and amount of travel are different but they end up close to same resultant. I dont think you'd be able to tell which rack was in the car. Two tenths of a turn will not provide enough feedback. Its more about which can you find cheaply.

Quicker racks will be heavier, period. This is why true manual racks are even higher ratios than the PS counterparts. Its the same with Miatas. (typically half a turn more)

[z31maniac]

^True, I figure even a "normal" 3.2 E36 rack would be a huge improvement over the what's in the car now.

[JGood]

Maybe now I want a '95 M3 instead of the Z3.

Depends on your budget... For some reason, 95 M3 racks pull a nice price. Do you really need .15 turns more in each direction? That's, what, 20 degrees? It might make your turning circle 2" smaller.

^True, I figure even a "normal" 3.2 E36 rack would be a huge improvement over the what's in the car now.

Yeah, I would just go that route. $/gain is better.

[xLibelle]

the other thing is, with most interested in performing this mod, they cant even make the turn with the size wheels they have!!
The loss of rack travel in the z3 rack is a moot point. give it up and consider anything an upgrade. sheesh.

[guibo09]

quoted from an english forum, this info should be the same for both LHD and RHD?

There has been some mis-information for a while about the E36 rack ratios plus I remember someone on here running an E36 3.0 M3 rack in their E30. I have spent some time doing some measurements plus confirmed this data direct with ZF (I know someone who works there who can access drawings on their system).


The standard way ZF quote on-centre (straight ahead) ratio is in mm/rev, which is the travel in mm of the rack bar per revolution of the hand wheel. The higher the mm/rev the faster the rack.



M3 3.0 - 39 mm/rev - the slowest available rack. This is a variable ratio but it is slower than standard until 200 deg hand wheel angle



M3 3.2 and standard E36 - 45.5 mm/rev - the M3 3.2 rack has restricted lock.



Z3 rack - 53.5 mm/rev - by far the quickest rack you can fit.



E46 compact rack - 50 mm/rev - apparently this also fits the E36



Because the M3 3.0 has a variable rack it has the smallest lock to lock at 3.0 turns but don’t be fooled it is the slowest by a country mile. A worthwhile upgrade for any 3.0 M3 (or a track based E30 with one of these fitted) would be to fit a standard E36 rack (or even a Z3 rack) which is what I did a year ago with a noticeable improvement.

also mentioned that stock e30 is about 37-38 rev/mm. if these numbers are right, z3 rack nets ~42% quicker ratio!

[JGood]

quoted from an english forum, this info should be the same for both LHD and RHD?

I wouldn't bet that they are the same. Those are euro parts... the euro M3 got the variable ratio rack, while the U.S. did not. Who knows what else might be the same or different...