Electric Power Steering Malfunction

[rx7locost]

John,

I am considering installing an electronic PS unit in my MGB project. It sounds like you re highly recommending it?

I may have to look into the Toyota unit. Got any recommended links?

[ccrunner]

John,

I am considering installing an electronic PS unit in my MGB project. It sounds like you re highly recommending it?

I may have to look into the Toyota unit. Got any recommended links?

I know this wasn't directed at me, but here's my .02.... Chuck... I saw you posed this question the other day, so just for grins, today I dialed the assist out of my EPS as I drove to work.. Yuck

Not to put too fine a point on it, but if my classic didn't have EPS (or some other form of PS), I'm pretty certain that I wouldn't daily it- the EPS changes the driving experience that much..

Whether you end up with the GM or Toyota piece likely doesn't matter (it would be nice if the Toyota piece is as seamless as it sounds).. these bits take the work out of the drive.. it is so, so nice to drive the a classic with PS.. I don't think I'll go without it in future builds..

--ccrunner

[KB58]

To be fair, builders should keep in mind that steering effort is the sum of many factors. Granted, the context is for front engine Locosts, but if, for example, you're building a mid-engine car, the requirement for power steering goes away entirely. There's that, tire alignment, tire compound, width, drivetrain weight, etc, etc.

[C10CoryM]

Not sure if there is a specific Toyota EPS that people are using, but my Yaris has one with external EPS control module. Only signals it gets from elsewhere is vehicle speed (a pulse signal (43 Hz at 37 mph [60 km/h]) that alternates between 0V and 5V), and engine RPM (not sure why to be honest. Maybe just engine-on signal?). It will operate w/o, but will loose variable power assist and just be on steady at all speeds.

[KB58]

How do electric PS units act if the power is disconnected? I assume like a depowered hydraulic unit? Would hope that it doesn't freeze up.

[C10CoryM]

How do electric PS units act if the power is disconnected? I assume like a depowered hydraulic unit? Would hope that it doesn't freeze up.

Same failsafe mechanical link even w/o assist. Feels just like a manual rack with no power. There still is a torsion rod though which acts as your steering torque sensor so not ideal to run w/o power long term (same as a hydraulic rack).

Yaris EPS would probably be a good option for a Seven. Small, remote control unit so can package easier, very common, reliable.

[C10CoryM]

I'll add one thing about EPS: I was doing a rally on icy/gravel roads in the Yaris and there were a couple points where the roughness of the road + me driving hard upset the EPS and it stopped assisting for an instant. No big deal, easy to cope with, and hydraulic will do the same in more situations anyhow. Just something to note if you had a offroad build in mind for EPS.

[BBlue]

The reason for the malfunction is still a mystery, but that aside, I must say the EPS is a huge disappointment. In general, I find it hard to live with, but I bought my first power steering car when I was 50 years old. Why anyone that is driving a lightweight R&P steering car would want to add power steering is beyond me. Especially this unit. Maybe they like the "arcade" driving experience, I don't know. I find that while driving with EPS on, I have to have a hand on the wheel, either assisting or ready to assist, 100% of the time. This is especially true if any turning is involved.

Trying to live with an antique car on a daily basis is an entirely different matter. Even so, I'd recommend trying R&P instead of EPS, especially on a smaller car. We drove first generation Fiestas hundreds of thousand miles with no steering effort issues.

I've been messing around with my car's steering and wonder if some my issues are due to quirky "features" of the Alpine's recirculating ball steering. I have found that any wheel play leads to a terrible driving experience while driving with the unit "ON", mostly to disappear when turned "OFF". Have no idea what else I'm doing wrong.

Looking back over the past few years, I'd be a lot happier if I'd installed manual R&P Tiger steering. About half the steering effort of the manual Alpine with good feedback and wheel return.

IDK, maybe I should be made to go sit in the curmudgeon corner.

Bill

[JackMcCornack]

To be fair, builders should keep in mind that steering effort is the sum of many factors.

And one factor is caster. I was going crazy searching for those last 2mpg that would take me up to 100 miles per gallon on my streamlined diesel Locost, and I backed off the caster and toe to zero, and boy is the steering light. The only issue (and I've put umptythousand miles on it now, and it's really a non-issue, it's just strange) is the steering doesn't self-center at all -- if I take my hands off the wheel, it keeps doing whatever it was doing before I let go; if it was going straight, it keeps going straight, if it was turning, it keeps turning. I'll admit mine is pretty extreme, but reducing caster by some reasonable amount will lighten up your steering by an equally reasonable amount.

[terryjr]

How do electric PS units act if the power is disconnected? I assume like a depowered hydraulic unit? Would hope that it doesn't freeze up.

I asked a similar question on DF kit car forum, they use these in there cobalt based kit cars. I was told they get super stiff, much more so than a hydraulic system when belt falls off. I was hoping to put it on a relay and switch on for parking lots/driveway and switch back off while driving.

http://dfkitcar.com/forum/index.php?thr ... post-12314

[C10CoryM]

The only issue (and I've put umptythousand miles on it now, and it's really a non-issue, it's just strange) is the steering doesn't self-center at all -- if I take my hands off the wheel, it keeps doing whatever it was doing before I let go; if it was going straight, it keeps going straight, if it was turning, it keeps turning.

Self centering is actually the reason Caster is built into the suspension. Most people would not be happy with zero Caster.... Trade off is heavier steering and less stability at (very) high speed. I'm a little surprised you gained MPG by reducing Caster: I'd expect the constant steering inputs would lower MPG.

As far as EPS feel goes, you really shouldn't be able to tell the difference between a good EPS and a good hydraulic assist. Either system will give you a little flex in the torsion valve/sensor compared to manual steering but I can honestly say I have never noticed it in my Yaris (which has done street, track, tons of autoX, winter TSD rally). Yaris has speed variable assist, and it works quite well at giving feedback at all speeds. When getting out of the Seven and driving the Yaris home the steering in the Yaris still feels responsive/firm. The brakes feel like a giant marshmallow (despite working very well), the clutch is absolutely phantasmal, but the steering still feels good! With EPS off, steering is no heavier than if it was a manual rack and, again; no P/S system should regularly operate w/o the assist working. You'll have to flex the torsion valve/sensor every steering input until it bottoms out before the rack will move. Not good for the driving experience, nor the rack.

Cheers.

[JackMcCornack]

Interesting comments, Cory.

Self centering is actually the reason Caster is built into the suspension. Most people would not be happy with zero Caster....

It was odd at first, and I do warn people before I let them drive it, but so far, no complaints. Driving a Locost of any sort is such an unusual experience for the muggles that they don't notice such subtleties as caster, but for those folks who are used to going from turned to straight by letting the wheel slide through their fingers, boy would they be surprised.

Trade off is heavier steering and less stability at (very) high speed.

Stability didn't seem to be an issue--it still went where it was pointed--but then, top speed is 90 mph.

I'm a little surprised you gained MPG by reducing Caster:

Also zero toe and zero camber. I don't know what specific in my zero/zero/zero alignment made the difference...and of course I could be kidding myself...but it did seem to be worth a percent or two. Not as big a difference as turning off the headlights.

70 mpg was easy, and the Lalo body took it to 90, and I got to 95 mpg with some obvious stuff (like a full length smooth floor) but man, that last five miles per gallon was a workout.

I'd expect the constant steering inputs would lower MPG.

I don't think it has added to my steering input, and can't see why it would. Explain please?

[TRX]

Some years ago I set my car to zero caster. It was quite interesting to drive; feather-light steering, and if you let go of the steering wheel in a long turn, the car would keep turning. I grew to like it quite a lot. I wound up dialing camber back to zero static for street driving, and got rid of the toe-in.

I warned my wife before she drove it the first time. She wasn't sure she liked it until she went back to her car, whereupon she wanted me to set her car up that way too.

Bear in mind most drivers are used to cars with a *lot* of self-centering force, and I've driven some with power steering where the effort to keep the wheel turned was more than most manual steering cars I've driven.

If you're used to something that tries to break your fingers unwinding when you let go of the steering wheel, neutral steering is probably *very* strange.

[BBlue]

When I started this project, the car had about 2.75 degrees caster. My problem was keeping the damn thing between the telephone poles. Changed camber and toe, which helped a little, but was not the answer. It became drivable when caster was pushed up into the 5-6 degree range. What am I doing wrong? I don't think it thing would drivable at zero caster. At lower settings, it acts like it has a bad case of bump steer.

Bill

[JackMcCornack]

Yes, TRX, that's exactly what I experienced -- thank you for showing me I'm not crazy*.

BBlue, my guess is you have a substantial amount of wheel offset, which made small imperfections in the road surface change your heading, and then there wasn't enough camber to straighten it out again. But that's my guess, YMMV, and no animals were harmed testing this hypothesis.**

* Which is a notoriously difficult condition to self-diagnose.
** Okay, one squirrel, but it was an accident.