Steering rack

[romkasponka]

I am curious how you would make a variable ratio rack. It's basically two gears.

With different tooth prifile along axis.

[sheepdog]

I am curious how you would make a variable ratio rack. It's basically two gears.

Variable hydraulic pressure.
You can increase or decrease sensitivity and feel that way.

[91318isguy]

Hey I have something for everyones opinion. I called BMW the other day because my mothers husband (worked for Pep Boys for 20 years) said that even though it's just power assisted steering, not having the power steering pump hooked up (taking the belt off the pump to get more power) could damage stuff.

BMW says that it is a hazard. Has anyone else taken their power steering belt off and had either any issues or no issues at all? I ran mine for a year before I wrecked it and had no problems.

[D. Clay]

Variable hydraulic pressure.
You can increase or decrease sensitivity and feel that way.

I was thinking that if you took the rack and bent it into circle it would basically be a ring and pinion.
The variable isn't the steering gear ratio, it is the power assist.  I had a Honda once that was setup this way. It had a little distributor type thing driven by the transmission. The centrifugal weights opened a valve that bypassed more fluid as the speed increased. Over 20 MPH there was no power assist at all.

[romkasponka]

I was thinking that if you took the rack and bent it into circle it would basically be a ring and pinion.
The variable isn't the steering gear ratio, it is the power assist.  I had a Honda once that was setup this way. It had a little distributor type thing driven by the transmission. The centrifugal weights opened a valve that bypassed more fluid as the speed increased. Over 20 MPH there was no power assist at all.

http://www.canadiandriver.com/articles/jk/031112.htm

Some cars have variable-ratio steering, which uses a rack-and-pinion gearset that has a different tooth pitch (number of teeth per inch) in the center than it has on the outside. This makes the car respond quickly when starting a turn (the rack is near the center), and also reduces effort near the wheel's turning limits.
http://auto.howstuffworks.com/steering2.htm

http://www.zakgear.com/Rack.html

http://www.dhub.org/articles/56

[sheepdog]

Hey I have something for everyones opinion. I called BMW the other day because my mothers husband (worked for Pep Boys for 20 years) said that even though it's just power assisted steering, not having the power steering pump hooked up (taking the belt off the pump to get more power) could damage stuff.

BMW says that it is a hazard. Has anyone else taken their power steering belt off and had either any issues or no issues at all? I ran mine for a year before I wrecked it and had no problems.

I did it for a year and half or so. Pretty much had no fluid in it, as it had a serious leak. I just added a small amount every now and then, worked fine.

You could make a pipe going from one port to the other, or make both go straight up to the reservoir. Either way it would not matter.

I can and could see no reason it would be unsafe to disconnect it at all as long as nothing can get inside.

[Vladi]

I drove 600km of highway without power steering. Except the fact that i felt the car pull better in low rpm there was no problem.

[D. Clay]

Some cars have variable-ratio steering, which uses a rack-and-pinion gearset that has a different tooth pitch (number of teeth per inch) in the center than it has on the outside. This makes the car respond quickly when starting a turn (the rack is near the center), and also reduces effort near the wheel's turning limits.

Interesting! Do you know which, if any, of the E30 and E36 racks are variable ratio and /or variable assist? I 'm curious how much this effect can increase or decrease the ratio.

[gearheadE30]

All E30 racks are variable assist iirc. I'm fairly positive at least the late model ones are. The e90/91/92 is the first 3 series to have a variable ratio system, which is why all of the tech magazines made such a big deal out of it when it came out. I think it would be a bit of a chore to install, with minimal benefits in our cars.

[sheepdog]

After driving mine with no assist, it is unnecessary in our cars.

Honestly, the assist does very little above 5mph as it is.
On a lower ratio rack like the Z3, it will make a larger difference, but still not much once moving.

[91318isguy]

Sheepdog,

Have you ever bled the system. Now that I have everything hooked back up I'm going to put fluid in there (anyone see anything wrong with just putting Prestone power steering fluid with stops leak ( I have 2 quarts of it) in there, since I am just going to have it not hooked up to the P/S pump?

Also, what forum would I put pics of my car in, as far as the swaps and mods.

[oldtimer]

My two cents.  Just about a Month ago i replaced the Rack and Pinion on my car.  One bending the tab, gently will make the removal and re_install easier and second not having the belt installed can and will cost steering seized unexpectedly.  I tried it, because since I had a 1982 Ford Fiesta the UK version it had a rack and pinion steering without assist from a pump.  So I thought I would remove the belt on the 318is free up some HP and to see just how hard it is to steer in a stop and go traffic.   Not bad but as I said the steering will siezed at time to time.  did not try to drive it on highway after it siezed on me.

[sheepdog]

Sheepdog,

Have you ever bled the system. Now that I have everything hooked back up I'm going to put fluid in there (anyone see anything wrong with just putting Prestone power steering fluid with stops leak ( I have 2 quarts of it) in there, since I am just going to have it not hooked up to the P/S pump?

Also, what forum would I put pics of my car in, as far as the swaps and mods.

Rule #1 on e30 steering.
Do not put power steering fluid in there, it will destroy the seals.
As will power steering fluid stop leak. Did that, I went from a small leak, to a drain.

There are some minor differences between ATF and power steering fluid. They are somewhat interchangeable, but not entirely. On our cars it is not.

As for bleeding, I filled up the reservoir, cranked the wheel around a bit (lock to lock), fired it up, repeat. It should bleed itself. Not really a lot of places for air to hide.

[Vladi]

Installed the e36 rack today. Woohoooo!! Worth every cent!