Power steering: how much power drain?

[cmac2012]

I was going to adjust my power steering pump belt on my 325i yesterday. It was squeaking whenever I'd tax it hard, such as fast cranking at a standstill.

It was real loose and I had very little room left to tighten it. I took it off to take it in to check it against the next smallest size to see if that might be the way to go, and to try to tell if it had just stretched.

I didn't want to drive my low mpg truck to the auto parts store (my 300SD is down for a while ) so I just tightened the pump pivot bolt back up and drove the beemer.

I don't know if I'm imagining it but I could swear I notice a nice little bit of extra punch and zip. Wishful thinking on my part perhaps?

The extra steering effort is not too bad except at a stop and it's not excessively bad then. Maybe it'll save me some trips to the gym. However, I'm a bit worried that the whole linkage might not do well with the extra stress put on it over time, as normally most of the work is done in the steering gear box with pressurized oil.

Of course it's set up to work in case of emergency loss of power assist but I'm not sure about the long run.

There's an after-market manual steering gear that weighs 20 lbs less than the power unit and I understand it's quite a bit easier to crank than a depowered power unit. Costs around $500 though -- who knows, maybe I'll do it someday.

Right after I find and install an E-30 M3 engine, 2.3 or 2.5 liter 4 cylinder with more punch than my 6 and less weight. That shouldn't cost me more than $4 or $5 grand.

I know a manual gearbox exists for the W123, I've been keeping an eye out for it. Not for power drain/economy, but to clear up room in the engine bay.

[cmac2012]

If you feel like it, I'd be interested to hear how an experimental removing of the belt worked out in the power dept.

The pump doesn't cause in problems in my Beemer, engine compartment space wise, but then I don't have any intercooler amibitions or the like. No turbo.

Originally Posted by cmac2012

If you feel like it, I'd be interested to hear how an experimental removing of the belt worked out in the power dept.

I did try running without a powersteering belt and it was not fun at all! It works "okay" if the car is moving at a good rate but otherwise takes too much effort to use under normal driving conditions. The manual gearbox most likely has a different ratio to reduce the torque needed to turn at low speed.

[cmac2012]

It is a bit of work all right. I have a hunch that the reduced effort with a gear that is manual from inception has other factors involved than just gear ratio but I could be wrong. It's happened.

I thought that the only time a power steering unit drew any significant power was when it was being used -- IOW, at straight ahead driving, no work is being done so very little resistance in the pump -- just spinning pretty much freely.

Again, this is not soundly based suspicion, I regret to confess

[t walgamuth]

i had manual steering in my 72 220d. no problemo. much easier than steering a ps car with the belt off.

i willl guess that the ps may use from 3 to 6 hp.

i am thinking of putting one on my 280e euro autocrosser to save weight. i think a 115 box will interchange and i have a ms buddy who is taking one off and will sell it to me.

tom w

Originally Posted by t walgamuth

i am thinking of putting one on my 280e euro autocrosser to save weight.

If you use it for autocross, you definitely need power steering.

[Jim H]

I expect the effect to be similar to turning the a/c to OFF.

[t walgamuth]

Originally Posted by ForcedInduction

If you use it for autocross, you definitely need power steering.

you havent seen my arms and shoulders.

tom w

[Matt L]

Originally Posted by ForcedInduction

The manual gearbox most likely has a different ratio to reduce the torque needed to turn at low speed.

The manual box isn't trying to push fluid through a nonfunctional pump.

[t walgamuth]

Originally Posted by Jim H

I expect the effect to be similar to turning the a/c to OFF.

i would bet the ac takes a lot more power than the ps.

tom w

[t walgamuth]

Originally Posted by Matt L

The manual box isn't trying to push fluid through a nonfunctional pump.

exactly.

on my ms 220d the only real time you felt the lack of ps was when parking. once rolling you didnt miss it at all. and there is just nothing like the wonderful communicative feel of manual steering.

one of the big reasons a porsche 911 had such a reputation for excellent road feel and handling. perhaps the newer ones have power but for a long long time they had manual steering and unboosted brakes. it probably also saved close to 100# of weight.

tom w

[Matt L]

The new Jetta has electric power steering. I've never driven a car with this before, but I approve.

[t walgamuth]

have you driven one? how does it feel?

tom w

[Matt L]

We have one. The steering feels like there is absolutely no assist at speed, and plenty when stopped or moving slowly. Really, the best of all worlds.