Mike said:
Lots of good advice here. First off, definately not cv joints
or PS pump. Reason is gets louder with right
hand cornering, but quieter with left hand. to the point of
disappearing altogether with a modest amount
of LH cornering. There is absolutely no play on the bearings at
all, even when levered from underneath the tyre with a crowbar.
But I am coming round to suspecting the NS bearing again. Part
of the problem is the parts cost. If this was a 20 squid
bearing it would have been replaced asap, but at more like 110,
or 150 fitted Its a little on the dear side to be fitted on the
off chance.
Firstly, for the OP and anyone else reading, my previous reply
was to help the OP explore any related possibilites, and either
rule in, but more likely rule them out.
Faulty wheel bearings do not have to have any play at all to
indicate a failure. Play (excessive, more than any that is
specified, I hasten to add) is however "one" very positive
indication of bearing failure. Also, the Mark 1 HomoSapien, as
amended etc, may not be able to induce play in wheel bearings,
even with the aid of levers, but the forces of 1½ tonnes of car,
multiplied by the centrifugal forces when cornering, would be
able to induce play. A great visualisation of this, when TV
cameras are mounted near the wheel / tyre area on motor racing
cars, the amazing deflection in the tyre which can be seen during
cornering - to the un-initiated, it looks as though the tyre is
gonna roll of the rim!
It may be a posibility that the garage damaged the new bearing
whilst fitting it. They could have tried to install it at an
angle, or more likely (and sadly, quite commonly) applied force
to the inner bearing race. Applying force on the inner race
during fitting usually totals the bearing before the car turns a
wheel on the new bearing.
Was it an OEM bearing kit they fitted, or a pattern part? I
would go back to them and request they re-do the bearing with an
OEM - the bearing also incorporates the ABS wheel speed sensor
(which also provides data for the speedo and odo), which is why
they are so flippin' expensive. Whilst chatting to a trusted
local independent mechanic, he told me of problems and
difficulties with ABS / ESP systems after other customers had
non-genuine ABS incorporated wheel bearings fitted by other
garages (and himself, he admitted), which were only corrected
after re-fitting OEM bearings. Apparently, the bearing housing &
sensor only needs to be slightly out of calibration for it to
send "different" data to the ABS and speedo ECUs.
The comments about the diff are valid, but as I said, they
cannot be heard outside the car when it is run off the ground
(jacked up on ramps)
It is very often the case, of not being able to hear noises
outside the car, but they become very obvious inside. Firstly,
most modern cars are usually very well insualted against external
environmental sounds, so other noises, such as wind noise, noise
from other cars, etc will be numbed or eliminated. Therefore,
any noise directly "attached" to the car will appear to be louder
(remember the classic experiment of two empty baked bean cans
connected with a long piece of (taught) string, and used as a
primitive telephone). Secondly, a car interior is actually quite
a good amplifier to any sound connected to it (although hi-fi
accoustics are poor, and v.difficult to achieve). That is why
many sounds seem much louder inside a car, when they may be quiet
or inaudible from the outside.
A combination of shitty weather and an inescapable commitment
meant that it will now have to wait while next weekend
before I can have a look at it again, but if the mounts turn
out to be ok I think i will bite the bullet and get the NS
bearing removed.
Mike
BTW, I cant remember if I said this before, but when both front
wheels off the deck the NS is a fair bit harder to turn than
the OS.
theres also a sort of gentle rubber squeaking sound from the
NS. Its been commented that its just the cv gaiter, but if that
was so then chances are it would do it on both sides. I dont
think its the brakes drakking a bit as it went straight on the
ramps from a 10
mile drive and there was no appreciable difference in
temperature between the discs.
If one front wheel is harder to turn than t'other, check you dont
have a binding brake caliper / seized brake pads. Push the
calipers/pads clear of the discs on both sides like I mentioned
in an earlier post, and then see if there is any difference
spinning the wheels by hand. You may also have a warped disc.
The rubber sound you mention - the standard CV joint gaiters
(boot) as supplied by Vauxhall are a plasticky type, which do not
make any noise. If your Zaf need a CV joint boot changed, for
whatever reason, someone may have fitted an aftermarket rubber
one, which will make more obvious "rubbery" noise, which would
explain the side to side differnece.
