97urS6

I just had a used rack installed (taken from a 2007 A8)... as well as having a few issues when I got it back (see one of my previous threads for that story)... but now I'm noticing something kind of odd. The turning radius has changed from the previous rack... let me explain: when I turn the steering wheel full all the way left vs fully turned right there is about 90 degrees angle less... and thus a larger turning radius going left vs the radius going right?

How is this possible?

Makes me think, I should check the reading in VCDS for the steering angle sensor! I will check that out later and provide an update.

target39

You're short steering to one side. If the car still drives straight with the steering wheel straight ahead, your steering rack may not have been installed/adjusted properly. You should have 2.78 turns lock to lock. An adjustment via the tie rod ends should fix the issue, i.e. moving the left tie rod end closer to the steering gear and the right tie rod end farther so the center point of the steering gearbox yields a pair of front wheels pointing forward instead of slightly left.

I would check the rough distance between each tie rod's lock nut and the end of the rubber boot that covers the inner tie rod and see if there's a large discrepancy. They should be very similar if the steering gearbox was centered prior to installation.

97urS6

Checked VCDS, on ABS Module, Measuring Block 5... which shows the Steering Angle Sensor reading. Dead Center is exactly 0.0 degrees. Fully turned left it reads 412 degrees. Fully turned right it reads -560 degrees. Quite the difference!

The other interesting point, is that when I turn the wheel fully left, it comes to a hard stop at 412 degrees, like the rack or something is hitting something solid. But turning the wheel all the way right, it seems like there is nothing hard at the end, it just seems that is as far as the rack will push that tie-rod... a bit of a spongy feel right at the end. I'm wondering if something is getting in the way down in there??? Should be able to see that if I could get it up on a hoist... will be bringing it into the mechanic who did the rack on Friday... will keep everyone updated.

MP4.2+6.0

Sounds like something definitely wrong. Putting aside things like eccentrics and keyed/splined shafts that often only allow one bolting position, if rack or steering column are not mated up at correct index location, presto the issue--as in yours could be about 75 degrees off (half the difference). Another possible I suppose is a combo of the steering wheel is bolted up wrong on the shaft end AND the toe was set wrong at same time so one masked the other--or how an error was (sort of) dialed back out from a wrong column to rack bolt up to begin with. Thus, all this would point back more generally to some error during rack install.

Failing any of those install problems, at some point you have to otherwise conclude the used rack was defective. If from a junk car, more likely to me it was again an install issue. If it was a rebuilt one, could be a rebuilder error in either assembly or the set point they positioned it at if there are not separate instructions for calibrating it on install. Having just done a Delco steering box on an old GMC, those instructions were very clear not to play with adjustments or position, which meant burden was also on them to pre set it correctly on center.

97urS6

So I took the car back to the mechanic who did the Steering Rack. An interesting point that they brought up is that the steering column can only fit on the steering spline of the rack one way... meaning that it could only be on correctly or off by 360 degrees. I took a look at the old rack spline and I see what they mean. The spline has 2 flat surfaces and a slot where the tightening bolt passes through, so he was in fact correct, in that the steering column can only go on one-way.

Now that being said, there must be some good reason why we are getting short steering angle to the left. It was suggested that maybe the rack in itself might be at fault (and yes it did come off a 2007 A8 that was hit in the rear), but I think if you look at the range of motion that it currently has, it does seem that it can move almost its full 1000 degrees of throw. With 412 degrees on the Left side plus 560 on the Right side (and actually, if you push it all the way, you can get 568 degrees)... giving a total of 980 degrees of throw... which I think is quite good and probably means the rack is ok?

So that suggests it is back to some installation issue... is it possible that they aligned it with the tie-rods vastly shifted to the right? One side being screwed almost all the way in and the other side all the way out, and just remounted the steering wheel to be center, when in fact it was off by about 80 degrees?

Anyways, the mechanic is going to take it to his alignment shop next week and see what turns up there?

97urS6

Here is a pic of the original rack's steering spline.

mishar

There is a centering screw, actually cap that has to be removed and centering screw put instead. It will hold the rack in the center position while wheel alignment is performed. Last think is removing the steering wheel and positioning it properly. Check Bentley or ElsaWin for pictures.

Mister Bally

Either the manufacturer's procedure wasn't followed. or a good, correct part was not used. I would call a dealer parts department or research a genuine audi parts website and verify that the part number of the replacement rack is a valid part that can be used on your vehicle.

In this case, details really matter.

97urS6

This is becoming such a saga of no cooperation by this shop. I took a look at the Bentley and printed off the instructions for "Centering the steering rack". As Mishar suggested there is a short cap bolt that you remove and insert a special bolt to lock the rack at center.

Essentially, the special bolt is just a longer bolt with a pointed end at the threads, that you turn in by hand and the rotate the steering wheel until it hits a groove that marks center. So basically I manufactured one of those bolts for them by grinding the end of an M10 bolt to a nice cone shape point; I also took a picture of where the cap bolt is located (on the original rack that I still have) and the printed Bentley procedure for centering the rack.... and still they say they can't see the bolt from under the car and claim that the rack has to be removed to do this procedure?

Have I completely lost my mind or is this place just full of idiots? I told them that access to that centering bolt is from the driver side wheel well... their comment was that all of the hoses are in the way and they can't get to it without removing the rack?

Has anyone actually done this centering procedure with the rack installed, with all hoses attached? Well, the procedure says to turn the steering wheel to find the centering groove, so obviously it has to be installed!!! But maybe one of the hoses has to be removed?

MP4.2+6.0

I haven't done an Audi rack since about 1990 on an Audi 5000. But on D3 and a variety of others I did adjust the rack. The nut for that is right where the steering shaft comes down to meet the rack. At least for that, you can get in there--just barely--with hoses attached and all. Easier for that if you just unbolt tie rod end, which gives a bit more access. But by the time you reach at deep in as the steering shaft, you are essentially doing it blind/by feel, and the wrench rotates maybe 15 degrees max. Thus with an open end wrench, I literally have to flip it over each 1/6 or a turn to take advantage of the angle on the wrench so it become 1/12 of a turn effectively, and the wrench is 6+ inches long. If the centering bolt goes in anywhere near as deep as the steering shaft, I can't imagine getting in nearly that deep with a bolt between fingers trying to stick it in somewhere. With the tie rod assembly completely out of car (unbolted from rack), that would open up a bit more working room. Getting clamps back on inside of tie rod boot where it attaches to rack is no fun though either. Don't ask me how I know...