Strange 911 steering problem
 

I'm the new owner of a 1988 911 Cab and have an unusual steering problem. The problem is that in slow (10 mph or less) sharp turns, the front of the car bumps from side to side, but makes no unusual noises. Visual inspection of the front-end reveals no bent items or recent work. Wheels bearings good, wheels straight, car drives straight, and tire wear appears normal. Any ideas? Thanks in advanced, Will

It could be the tires. Sometimes separation of the plies will cause the tread to move side-to-side under extreme turns. This would not be outwardly visible on the tires.

Another thought, does your car have posi-tracion? If so, you might be feeling the clutches in the differential doing their thing.

Thanks 930turbo. The tire idea could very well be the problem. Do not have posi-traction. Thanks again, Will

Different toe settings?

Problem update-
Temporarily swapped rear and front wheels. No help.
Playing with the toe adjustment found and that the problem went away with a extreme toe out condition, but the car didn't want to drive straight. I'm now thinking that I might have a "toe difference angle" problem which there is no adjustment for other than replacing defective parts. I have noticed a small amount of play (adjustment/alignment) in the positioning of the steering rack with it's two bolts loosened. My question is this loose positioning of the steering rack normal?

Re: Strange 911 steering problem
 

I noticed the same on mine...there's a little play in the bearings but not enough to cause such a loud and noticable bump...I'm thinking front bushings??. My 4 wheel alignment specs are on the money and the car drives straight as an arrow. The car is in hibernation 'till I move to the new house so I won't be doing any investigating 'till then. Hopefully you will have diagnosed yours by then and made my life easier..

Is it possible your rack is not centered while the wheels/steering wheel are? It is possible your rack was setup a few teeth off center.

Is the front lowered way beyond stock ?

What rim and tire sizes ?

Update-
The steering rack is centered.
Riding heighth set to factory specs.
Front wheel is 6X16 with 205/55
ZR16 tire
Rear wheel is 7X16 with 225/50 R16 tire

All stock parts

So then I would say either wheel bearings or front bushings...only other thing that comes to mind is that my tires are old and VERY hard. My car is slightly lowered, has turbo tie rods and stock wheels... I plan to change the tires and replace bearings in the spring, maybe that'll fix it. Strangely enough, my Audi used to do this with 18" rims but not as bad..?. My previous '88 Carrera did it also and I presumed wheel bearings as they had a lot of play.

Have you checked the universal joints in the steering column?

Mine had a defective joint (old and rusty) that also caused a noise and kind of a bump in the steering wheel due to a pit in the one bearing races of the universal joint. - always at the same angle of steering wheel turn.

It was obvious when the car was on jackstands and someone turned the wheel while I had a finger on the joint - clear as daylight.

Not trying to highjack here but I think Will and I have the same problem. It's not in the steering joint.....If you back the car out of the driveway and then turn opposite lock and move forward there's a loud bump and you can feel the car jump...almost like turning full radius in 4wd with diff lock on...hey, maybe it's the LSD causing it????..again, my Audi with Quattro sometimes did the same thing but less noticeable. Will, do you have LSD ?>

Update-
Steering universal joints check good. Do not have a LSD. When problem occures no sound is made.

Anything more on this I also have this problem. Inotce it mostly backing ouf or pulling into parking spaces( slow sharpe corners)

Thanks
Mark
1986 911 Targa

Update-

No fix yet. Mine also does it when backing up. Lately I have been suspecting old tires on front and rear causing the problem. Are your tires old?

I am not sure how old my tires are. I have only had the car about 8 months. I also thought about the tires because I did not notice it until after it started to get colder.

Mark

You guys with this problem aren't, by any chance, getting tire rub on the inner fender panel? Or something else?

My SC has brake cooling ducting (hardly stock stuff) which restricts how far I can turn the wheel without a tire grabbing it. Feels like what you describe, though I don't recall any of this before I added the ducting (which doesn't really have quite enough room).

I just live with it. But this is a long shot for a stock street car.

Walt Fricke

Update-

No tire rub. Problem starts at about half way max steering wheel turn in both directions.

Has the car been lowered? If so you might want to install the little spacers that raise the steering rack up

Will, did you check your front bushings yet?... I'm in the middle of buying a new house so I haven't even put much thought into the problem recently but that's the first thing I'm going to check. My tires are old and very hard so I'm hoping that's the problem but something tells me it's not. The closest I can describe it is that it feels like the wheels almost fold under the car slightly on hard left or right turns.

Since the wheel bearings are good, the steering is good, the car tracks straight in a straight line, I'd guess worn tie rods or ball joints.

If the car has been lowered have you thought about the ol bump steer kit?

Update-

The car has not been lowered and is at factory specs.

Another update....
New tires fixed this problem for me...and the car rides a 1000 times smoother.

my 77 acts the same with the track tires on the front. (MPSC 225/50x16 on 16x8 Fuchs- 911 offset)
the problem goes away when I put the street tires back on (Kumho ESTA 205/50x16 on 16x7 Fuchs)
I think it has to do with the size of the contact patch, stiffness of the sidewall, and the age of the components.

Bill K