Weirdness in power steering

[thehackmechanic]

For the 35 years I've owned my '73 3.0CSi, the steering has never been silky-smooth and centered like it is on my Bavaria. I don't believe this is a mechanical play issue or an alignment issue. I've been through the steering and suspension, and replaced center track rod, tie rods, idler bushings, etc within the last ten years. Before I drove the E9 to Vintage at Saratoga a few weeks ago, I checked out the car on the lift and found no mechanical steering play or binding. I also reset the front toe to zero, and while it made the car feel a little less twitchy, it didn't change the fundamental problem.

The root of it appears to be the power steering, which DOES groan a little. In addition, it almost feels like it takes a half a second to engage when you turn the steering wheel. This was worst when, after Saratoga, I drove on back roads heading east to Manchester VT, and the uneven pavement and steeply-crowned roads exacerbated this feeling.

I removed the power steering belt, and to my surprise, I don't feel any binding or any lateral or axial play in the pulley of the pump. Nonetheless, I bought a used "100BAR" from a 633CSi on eBay. I was about to swap it, but it turns out to have a LOT of lateral (fore-aft) play in it, so I'm looking to return it. So I don't have that to try.

The cylindrical filter under the tray at the bottom of the reservoir looks okay. It's hard, but they're hard even when new. It doesn't look shriveled up like the one was in my Bavaria. With the filter installed, I can see some motion of the fluid, but not a lot. With the filter removed, I see more motion of the fluid. I can't remember if I drove it with the filter removed or not. I have ordered a new filter.

I probably should try driving it with the power steering disconnected (the belt off) to see if it loses the schizophrenic feeling in fully manual mode.

Any other ideas? I'd really like to get to the bottom of this.

Thanks.

--Rob

 

[thehackmechanic]

UPDATE: I drove the car this morning with the power steering pump disconnected, and to my surprise, it doesn't change what I feel in terms of the car feeling darty on crowned roads. So I guess this is either an alignment issue or a steering box issue.

 

[tferrer]

Try to find a manual rack and ditch that whole, heavy mess. They are easy to drive without power steering and the benefit is good feel and easy oil changes!

 

[HB Chris]

I think you need a tiny amount of toe-in.

 

[Gransin]

My coupe was twitchy as soon as it wasn't on perfect asphalt. It's hard to describe the feeling, but it seemed to be all over the place and you couldn't take your eyes of the road for more than a second.
Played with different toe settings, tried different wheels, went through the suspension/steering several times but couldn't find anyting wrong.

This left me no other option than to mess with the adjustment screw on the steering box. I loosened the nut while holding the screw in place, then turned the screw until I could feel some resistence (approx 20° in my case) backed off a tiny bit and tightened the nut. Went for a test drive and had a return to center problem. Stopped and backed off a tiny amount again - better but not good. I repeated the backing off by a tiny amount a couple of times until I didn't have the return to center problem anymore and now the steering feels like a new car compared to how it was before.

If you overdo the screw, it can/will lock the steering - so be careful if you try this!

 

[Blinkling]

I second the recommendation to take a little bit of pressure off the Danger Screw.

I think a lot of owners (myself included) have tightened the Danger Screw to try to eliminate play in the steering system assuming that sloppiness was the cause of the imprecise feeling. Tightening the screw meshes the gear teeth in the box more snugly. But any friction at all between the teeth at “center” overwhelms the delicate balance (mere ounces of force) between the car centering itself and minute movements of the driver’s hand.

There will always be a little bit of play in the steering column because of how the valves in the steering box work. It's hard to explain the mechanism without drawing it. But if you and the hydraulics are both overpowering a bit of friction during the delicate balance it could feel like two people steering at the same time. You're kind of fighting the car for control of tiny movements.

 

[Erik]

Tires?

This was the cause of "steering" issues I experienced. "Steering" is fine, tires were bad.

 

[thehackmechanic]

Thanks folks for the input. I'll look at the steering box adjustment.

In the meantime, the plot has thickened a bit. I was aware that my right front tire has a bit of asymmetrical wear on the inside edge. I just checked the specs from the last time I had a commercial alignment, and the right front wheel shows substantially more negative camber than the left front. Granted, this was quite a while ago, and the car has had changes since then (Alpina 16-inch open lugs, 205/55ZR16 tires, and springs from which I cut a coil to settle the nose down), but I'm curious if uneven camber is what wore the right tire, and the combination of the uneven camber and the worn tire is what I'm experiencing. I think I'll start with a camber measurement and swapping the tire out and see where I am.

Thanks again.

--Rob

 

[adawil2002]

I had uneven wear on my right outside tire running fixes negative camber plates, after 9300 miles it was almost bald. VSR checked the measurements of the car & everything was in spec. The alignment showed the camber was not even side to side. It was corrected with adjustable camber plates to get equal negative camber on both sides. Left is -1°, Right is -1.6.

 

[Blinkling]

We want to see what the tire looks like! Put a face with a name for this steering gremlin.

 

[stphers]

Hope everyone knows that there is no adjustments on the frt end of a coupe except for toe. You have to go to adjustable camber plates to get any adjustment but if that is what you need to do to get camber right, I would really start looking for something bent, usually a strut, can't always see it ( look closely where the tube part of the strut goes into the steering arm, look for any uneven distancing around he base of the tube to the steering arm, if you find there is more on one side than the other, bent strut ) You can also elongate the 3 strut mounting holes to get more -camber

Camber is much more of a wearing issue rather than a steering problem but it can if they are both out again, something could easily be bent Now, Caster is a major effect on steering pulling but cannot be adjusted Caster helps the car steer straight, best example of this are shopping carts, look at the wheels on them, they are mounted so they actual "trail" the path that they are going on, no matter which way they point to when starting, they will always spin to be in that trail position If you look at the mounting point, you see that the wheel is not mounted center but towards the frt of the wheel at a slight angle That is a very simple explanation of caster If the caster is out, the car will pull important that it be within specs But again, not adjustable

Last thing is toe, all cars run a little toe in, not at 0 straight ahead. The reason that you need slight toe in is because of what they call a pneumatic trail, the wheels or actually the tires want to follow a path so if you have a car with too much toe in, it will "plow " a bit too much toe out, and you have a real crazy steering car as that "pneumatic trail " of the tires are pushing in 2 different directions, worse on uneven roads I remember a couple of years ago, I did a ton of work on a 71 2800CS and a lot of it was in the frt end, the alignment shop is about 4 -5 blocks away so I didn't bother too much with eyeballing the toe, it was toed out, what a lot of fun to drive, goes everywhere but where you want the car to go Toe is also a major wearing problem if not done right I usually set them at about 1/8 " toe in

Now, if you have lowered the car, you may be running into bump steer. Try to imagine that you have a round disc attached at the top and bottom by arms to the frame. Now as none of these parts can change length as the wheel moves up and down ( what a wheel does as it drives down the road, going over uneven pavement ) so the wheel moves up and down in an arc, now, remember that the steering arm is attached and also, cannot change length, so, as it the wheel goes through that arc, the toe will change because the distance with all the steering components are fixed. If you lower the car too much, the steering arms/tie rod assembly are now in a position where they will cause even more toe in change. The steering arms/tie rod assemblies should be as level as possible with the proper weight of the car on them while just sitting on a level surface. This can be fixed by using a special bolts to hold the inner tie rod end to the steering arm usually up higher than the steering arm to get the back some of the proper geometry to get back to minimum toe changes when going through bump and rebound

Lowered 911's are notorious for this ( and no one leaves them at the factory settings ) it compounds the problem when running much fatter tires as well Look at a Porsche site and see how many different things that are available to fix bump steer in them

Understanding frt end geometry and checking it properly is not for everyone, it is more complicated than just some numbers on a sheet. The new alignment machines are great, IF, the guy running it, knows what he is doing, trouble is that most shops look at alignments as money makers and good to sell suspension and steering parts but few guys really, really know what the hell they are doing I am done with alignment shops, I made my own set up to check the cars using string ( string can't bend or arc ) You can buy magnetic camber/caster gauges that will fit to our cars , not cheap but not out of this world for price I made my own set up to measure toe and to check that all 4 wheels are going in the same direction

So .now , that I have totally confused you, time to go and get some more done on a 71 2002 ti that I am restoring for a fellow

Thanks, Rick

 

[bluecoupe30!]

Wow, that is a textbook's worth of explanation in a short paragraph. Great info Rick. That ti will turn out perfect, That I am sure!

 

[Krzysztof]

Hope everyone knows that there is no adjustments on the frt end of a coupe except for toe. You have to go to adjustable camber plates to get any adjustment but if that is what you need to do to ...

Great article!

I'm pretty sure this text can be a technical article available out of the forum section!

 

['69 2800cs]

I do my own alignments with string and corner balance with borrowed scales.

The 911 has adjustable everything and my coupe has camber plates front and coil overs front and rear.

The symptom of dartiness on crowned roads I’ve found to be mismatched caster from side to side. I mean, positively EVIL to drive when they’re off.

Thats why I think adding alignment adjustments front and rear are worthwhile even if you don’t track the car. These old tubs are not straight and being able to dial things in is a nice benefit.

 

[teahead]

Checked whether the frame is straight?

 

[Honolulu]

A long time ago, the u-joint on m steering shaft got rusty of something, and made a very stiff spot in the rotation of the steering wheel. Markus Glarner was a member then are revealed the problem. I took the joint out and nearly boiled it in ATF (heat gun under a tin can) and it's been good since. The hot ATF was intended to penetrate the joint, and seems to have done the trick why simply dipping it would not.

Lately a lot of loud groaning from the pump. Last time it did that, draining at the pump and refilling with new juice did the trick.

I too changed the filter back in the day, when it was the subject of considerable discussion, but it made no difference at all.

 

[eriknetherlands]

Could it be related to a worn top mount? Don't they rotate partly, being connected to the strut? Not sure how the top mounts are constructed, but if they have a bearing to transmit the pushing forces while allowing the rotation, it could be that the bearing has developed dimples, giving the balls inside a certain position they will prefer to occupy?

 

[thehackmechanic]

Following up on this after a couple of weeks. Thanks for the input, folks.

As I said above, I drove the car with the power steering pump disconnected, and the darty-ness on crowned roads remained, so it's not a power steering issues as I first thought

As requested, here's a photo of the right front tire showing wear on the inside edge. It's not that dramatic, but a tread depth measurement shows that the innermost tread groove has 5/32″ of depth, whereas the rest of the tire has 7/32″ or 8/32″.

I bought both an inexpensive camber bubble gauge and an inexpensive digital inclinometer and took some careful measurements with them using a straight piece of 1/2" square steel tubing cut to fit lip-to-lip on the outside of the wheels, and both gauges do indeed show that there's about a 1 degree difference in camber between the right front and left front (left is about -0.8, right is about -1.7). So it makes perfect sense to me that the uneven camber is wearing the inside edge of the tire, and both the uneven camber and the uneven wear are causing the dart-y feeling.

Man, those J-Mac 191716-1J adjustable camber plates are pricey ($380/pair). The Ground Control ones are about the same. Short of elongating the holes in the shock towers (which even The Hack Mechanic wouldn't do these days on an E9), does anyone know of any other options?

Thanks.

--Rob

 

[sfdon]

A great (not just good) alignment shop will hydraulic jack the strut back into compliance.