Strut bearing failure? - Type 44

[Max Hoepli]

I hear a boing boing noise from the rear left of the car when driving
slowly.

Max


----- Original Message ----- 
From: "E. Roy Wendell IV" <erwendell at mac.com>
To: <quattro at audifans.com>
Sent: 26, December 2006 17:10
Subject: Re: Strut bearing failure? - Type 44


> >
> >> What are the symptoms of a bad strut bearing?
> >>
> > Poor steering feel. Possibly some play in front end. Harsh over bumps.
> > Alignment may deviate.  Higher turning effort.
>
> Not entirely true for the type 44. There will be no play in the front
> end as the "strut bearing" is more correctly a "spring bearing". The
> only thing it does is support the weight of the car resting on the
> spring while allowing for its rotation. The strut rod is in no way
> supported by the bearing and is in fact stationary while the strut
> tube rotates around it.
>
> The common symptom is a "boing boing" sound as you turn the steering
> wheel which is caused by the spring winding up and then releasing. By
> turning the steering wheel you rotate the strut housing , lower
> spring seat, and spring. The upper spring seat, supported by the
> bearing, should follow along but with a sticky bearing it won't until
> a significant angle difference between the top and bottom spring
> seats causes enough internal force to develop in the spring to
> overcome the drag. You might find that the steering doesn't want to
> return to center by itself after a sharp turn.
>
> The surefire troubleshooting step is to jack the car up, take off the
> wheels, pop off the tie rods, and turn the strut by hand. The motion
> should be relatively easy and smooth. Because of the preload on the
> spring there will still be plenty of load on the bearing to show any
> faults although it is of course less load then when the car is
> sitting on the wheels. Due to the mechanical advantage of the
> steering rack, especially if the engine is running and power steering
> active, I don't think you can feel a bad bearing at the steering wheel.
>
> I've taken apart a few very worn out bearings where there was little
> to no evidence of  grease, the balls and races were all pitted, rust
> abounded, and contamination in the form of dirt was profuse yet the
> bearing still rotated. Oddly enough, all the bearings I've taken
> apart show signs of the balls having pounded into the race with such
> force as to render it no longer smooth. Even if the bearing is
> cleaned and regreased it still won't rotate smoothly. Short of the
> spring compressing to the point that the coils stack up solid and
> transfer a huge load into the bearing I am at a loss to explain this.
> The bump stop on the strut should stop the spring from compressing to
> that point and in every type 44 front end I've taken apart so far the
> bump stops have been intact. I suspect that the design of the bearing
> itself is inadequate for the load. The balls aren't caged and there
> seems to be too few of them such that large gaps open up between
> adjacent balls. On my most recent suspension rebuild I actually added
> a couple of extra balls to each bearing and so far nothing drastic
> has happened but I have no idea yet as to whether the bearing life
> will be increased.
>
> Dirt contamination of the bearing is often caused by poorly fitting
> dust shields that sit on top of the upper spring seat. These get
> warped over time and no longer keep dust out of the bearing area. The
> bearing itself isn't really sealed, rather the metal bits (top race,
> balls, lower race) sit inside of an upper and lower plastic case that
> snap together. The fit of the male upper housing into the female
> lower isn't all that tight. I'm only pointing this out so that you
> can consider ordering new ones along with the bearings. The strut
> boots will likely be shot as well so many times the best option is a
> complete kit.
> >
> >> The symptom I'm experiencing is a grinding feel and sound.  It only
> >> occurs
> >> during very low speed turning, as in parking the car, with the
> >> steering
> >> cocked fully to the left.  Does not occure when turning right.
>
> This doesn't seem right as a bad bearing can't really become a one
> way device i.e. it should have the same drag and therefore symptoms
> in both directions.
>
> >> No
> >> other
> >> wierdness is evident yet.  The car in question is an 87 5ktq with
> >> about 180k
> >> miles, and the original strut bearings.
>
> They are undoubtedly shot at this point. Like many parts on the type
> 44 they seem to have a 100k life span at best.
>
> >>
> >> The part I'm talking about is part # 431412249D ... the ring shaped
> >> thing
> >> that is accessible only upon complete removal and disassembly of the
> >> front
> >> strut.  This is >not< the strut mount ... metal and rubber thing
> >> secured by
> >> three bolts..
> >> If it is the strut bearing, what am I risking by delaying
> >> replacement?
>
> Other than some steering system drag I don't see any safety hazard as
> long as you know about it. In any case,  none of the parts in
> question can really escape and fall off and as discussed the wheel
> will still be properly located by the suspension.
>
> Roy Wendell
> erwendell at mac.com
> Too many type 44 tq
> A pair of MR2s
>
>
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