divil

I've been chasing this problem for a while and I've posted about it before. My steering has around an inch or so of movement from the centre that has no effect on the car. It's not loose exacty, it feels springy or spongy.

My understanding is that this is normal when the car is off due to the torsion bar in the steering rack. I have another rack off the car and I can see this clearly - even with the locking bolt installed I can still turn the input shaft a few degrees each way, and it springs back to the center when I let go.

But...is this play supposed to disappear when the system is under pressure? For me, it does not. It's there when I'm driving. It makes it really annoying to drive on a somewhat straight road where you have to make corrections...it just robs the steering of any feel or feedback.

Can anyone tell me, is your car like this? And does it go away when you start the engine?

Over the last year and a half I've replaced more or less everything: intermediate shaft, rack/bushings, control arm bushings (fronts/caster blocks), ball joints, strut mounts/struts, wheel bearings, tie rods (inner/outer) and tires.

Lately when I learned more about how power steering works, i.e. the torsion bar etc., I started to look more at the pressure side of things. I replaced the pressure seals in my pump and that made no difference. I'm pretty much at my wits end now...the only things I can think of are, blow out the lines with air in case there is a blockage, or replace them, or replace the pump. I am definitely getting power assist, so there is definitely some pressure.

Does it sound plausible that it be a pressure problem? I can't belive the car is supposed to be like this, but I'm running out of ideas/things to replace. Any ideas at all are welcome...thanks!

Here's a video of the behavior. In this video, the engine is off but it's the same when driving:

Tails

I recently had play in my steering, vibration under breaking and I undertook the following:
1. Checked steering mounting bolt for tightness - OK,
2. Renewed tyre (tire) rods and tyre rod ends, as some slack located in inner ball joints adjacent of steering rack - now OK
3. Removed the steering lower shaft with universals and found that universal needle roller outer casings were slack. causing play in steering. Used a small socket of the right diameter, held universal yoke in vice and hammer in the outer roller casing until it all were tight on the two cruciforms. Used a centre punch to re-lock the outer casing in new position (6 off locking metal pieces per outer bearing casing. When steering section removed this locking procedure will be evident.

Had wheel alignment done and steering rack held in centre position via special bolt screwed into access hole in steering outer causing.

On completion the steering is now 100% direct with no slack at all.

Unfortunately still had vibration under braking and the problem turned out that the LHS rotor was running 0.012" out. Had the rotor machined and steering and brake operation now "smooth"

Hope this helps.

1990 944 (951) Turbo S (ROW)

divil

Thanks...unfortunately I've already replaced the universal joints with newly rebuilt ones and it didn't fix the problem. The new ones do already have more play than when I put them in last year, but the situation was not much better when they were new.

I'm still wondering if it could be a power assist problem. The lines coming from the reservoir seem to be in pretty bad shape, especially the one going to the cooler...it looks slightly thinner where it touches the body of the car, like it has collapsed or been shrunk. But I'm definitely getting some power.

The new ball joints are extremely stiff, and the steering has felt heavier since I installed them. That seems to make the problem worse. I would have thought the power assist could overcome that so you wouldn't notice. So maybe that's another symptom of the same issue.

Van

Inner tierod joint?

There shouldn't be play like that. Something is bad or loose.

divil

Inner tie rods are brand new, along with the outer ends.

With the old rack, I was able to pin the rack in the centre using the special locking bolt, and still turn the input shaft by hand, just by grabbing the U-joint and twisting it (this was a brand new U-joint with zero play).

With the rebuilt rack I installed, the behavior felt the same when driving, but I have not checked it in exactly the same way beacuse I had trouble getting the locking bolt to thread in. I'll try that again...but I'm pretty sure this movement is just the torsion bar.

Does yours not have this movement? Is there any difference when it's running vs off?

Van

I currently have manual racks in my cars, but had power racks for many years in both a turbo and an NA, and I never noticed what you're talking about.

I've taken power racks apart, and I don't know what you're referring to as the "rack torsion bar". The input shaft is a helical gear that interlocks with the teeth on the rack shaft. Any movement of the input shaft should translate to the rack moving. The "power" is an "assist" that helps push the rack shaft in one direction or the other - but there's no interruption in the "connection".

It may be worth it to pin the new rack in the center position and then take a closer look at the play you're getting in the steering shaft... maybe one of the spline ends is damaged? Maybe there's something else amiss?

Also, bad control arm joints can cause a "dead spot" in steering.

divil

The torsion bar is between the input shaft and the pinion. When I first saw that I could twist the input shaft on the old rack when it was locked, I thought there must be something major wrong with it...but it turns out that's an essential part of how the power assist works.

This explains what I suspect might be my problem:

Now I have taken the input shaft/pinion assembly out of my old rack, and you can't see that there's a torsion bar between them, but it's in there...has to be.

I'll definitely take a closer look...not ruling anything out yet.

I have freshly rebuilt ball joinits and new front control arm bushings (caster blocks are about a year and a half old). The new joints are noticeably stiffer...if anything it has added to the issue.


EDIT...here's a video I took of my old rack demonstrating the movement. The rack is pinned - look at the number of teeth visible on the right, you'll see the rack does not budge as I rotate the input shaft in either direction:

divil

OK I had a closer look. Everything seems perfectly tight. There is zero slop in the tie rods, control arms, ball joints and struts. There's a tiny bit of 12/6 movement in the wheel bearings since I had them checked and adjusted by a mechanic. I have a bad *rear* bearing, which might be contributing to the generally vague handling, but obviously not to the numb steering feel.

The u-joint pinch bolt at the rack is super tight. I can't check the upper one without removing a lot of stuff, but I'm pretty sure it's tight given what I'm seeing - I put a camera under the car to see what the lower u-joint is doing when I rock the steering wheel, and it looks to me like the there is no movement disappearing before the rack.

When I get a chance to clean up the threads I'll install the locking bolt and try to get a good video to show what's happening.

Still thinking of a pressure problem, I disconnected the cooler and blew compressed air though it. There is definitely no restriction there. The fluid was very slow to drain from the return hose when I pulled it from the cooler however, but I don't know if that's significant.

It's obvious to me now with 2 racks exhibiting this behavior that if I simply drove with no power assist at all, I would have a big dead zone in the centre of the steering due to the way power steering works. I don't know why everyone with a depowered rack doesn't complain about this, but I have found a lot of threads referencing it and discussing shimming the torsion bar stops to overcome it. I definitely do have some power assist though...so the question is, could I have enough pressure to make steering relatively easy, but still not enough to make it feel tight?

Jfrahm

I do not know if they do anything when they rebuild racks to re-set the pinion depth. In the 944 power racks this does not seem to be adjustable as it is in manual racks and some power racks on other cars. I suppose when the rack wears you get some worn teeth in the middle of the rack and more wear on the pinion, and some of that could be taken up with a re-do of whatever ZF does to set this depth at the steering rack factory.

If you set the pinion too deep you would get clash at the outer, less worn areas of the rack teeth.
I have two racks and as per the other thread I installed one that is a lot less sloppy. I understand some slop is needed to allow the power system to function, but how much is too much? The rack I pulled out is annoyingly sloppy.

-Joel.

divil

Hmmm I had forgotten some of the details of my previous thread..thanks for reminding me

So maybe I just have 2 badly worn racks. The old one doesn't feel worn...with no load on the rack, there is no perceptible play. I had to pin it to find the source of the play...that's what made me think it's all down to the torsion bar. Do you know if yours was like that?

V2Rocket

There is a definite zone in the center of the rack travel where moving the wheel an inch or two in either direction has no effect on the actual steering direction of the car.

...perhaps it might be worthwhile to see if another car's steering rack could be fitted to the 944...? Miatas use a similar design...or maybe 986/996 P-cars would be a good option...

divil

Are you saying this is normal, in your experience?

V2Rocket

i've felt it in a lot of 944s.
i think it's a typical wear symptom.
it could be addressed largely with the U-joints IMO but the rack wear can't be really fixed...

VirginiaF1

Hi Divil..
While I always defer to the veterans here, I will offer my own findings:

1. My '88 n/a just today passed Virginia State Safety inspection where they closely inspect Tie Rods, Ball Joints, Steering Shaft, Bearings & Bushings, etc..

2. My steering wheel has always exhibited what I see in your first video
(ie: about 0.5 inch of free movement left & right of center)

3. BUT when I mimic your video test, my wheel emits no click/clunk sound that I hear from yours.

4. Under power, my steering wheel has that 1 inch of deadzone from center.

5. I always thought that Autobahn-bred German cars bake that "Sneeze Factor Deadzone" into their racks for 150+ mph running.

6. FWIW, My 2000 Audi A4 also had a 1/2 inch deadzone left & right.

Subscribed..
mike

divil

Thanks, that's helpful to know.

Regarding the clunk noise in my video...I think that's just the steering lock stops. I don't hear the irritating "bing" noise in that video so I think I probably didn't have the key in. I just did the test again with the steering lock off and there is no sound like that.

In the dead zone, does yours feel loose or springy? Mine is not what I would call "loose", in that I feel progressive resistance, like I am compressing a spring, from the moment I move it, even the tiniest bit. It just doesn't have any effect the car when I'm driving.

Funny thing is, looking at my other car (1998 Audi A6), it does seem like it's kind of similar in the centre, it does have that springy zone, but I think it's smaller...hard to tell though. It definitely feels a LOT better to drive...it has a much sharper, more positive feel, despite being a bit over-assisted.