Loud noise in 4wd--any ideas????

I have a 1993 Suzuki Sidekick. When in 4wd it now makes a loud
clunking noise at random intervals. Feels as if it is under the car.
Front axles are new, hubs are new. My mechanic found some metal bits
in the front differential fluid. He is reluctant to diagnose it
because everytime he is in the car, it won't make the noise! Does
anyone have any ideas as to what it is -- i.e. differential or
transfer case???? Thanks! Please email me if you can -- I'm new at
newsgroups and hope I can find the thread again

Are you driving on a solid surface like cement or pavement? Or loose like
dirt, sand or snow? On a solid surface one axle will turn slightly faster
than the other axle for various reasons, it can start to wind the driveline
up like a spring until something "slips", either a tire against the
pavement, or a car part gives way.


"Judi" > wrote in message
om...
>I have a 1993 Suzuki Sidekick. When in 4wd it now makes a loud
> clunking noise at random intervals. Feels as if it is under the car.
> Front axles are new, hubs are new. My mechanic found some metal bits
> in the front differential fluid. He is reluctant to diagnose it
> because everytime he is in the car, it won't make the noise! Does
> anyone have any ideas as to what it is -- i.e. differential or
> transfer case???? Thanks! Please email me if you can -- I'm new at
> newsgroups and hope I can find the thread again

Thanks "Rusted!" It has happened on solid surfaces -- wet/slushy, and
on ice. Also, sometimes the "clunk" happens after I disengage the 4wd.
This just started last winter after 10 years. Do you know of a way to
fix this? One axle had been new and the other was replaced this spring
in hopes of solving the problem. It sounds and feels terrible and has
to be causing some kind of damage. Thanks!

"Rusted" > wrote in message > ...
> Are you driving on a solid surface like cement or pavement? Or loose like
> dirt, sand or snow? On a solid surface one axle will turn slightly faster
> than the other axle for various reasons, it can start to wind the driveline
> up like a spring until something "slips", either a tire against the
> pavement, or a car part gives way.
>
>
> "Judi" > wrote in message
> om...
> >I have a 1993 Suzuki Sidekick. When in 4wd it now makes a loud
> > clunking noise at random intervals. Feels as if it is under the car.
> > Front axles are new, hubs are new. My mechanic found some metal bits
> > in the front differential fluid. He is reluctant to diagnose it
> > because everytime he is in the car, it won't make the noise! Does
> > anyone have any ideas as to what it is -- i.e. differential or
> > transfer case???? Thanks! Please email me if you can -- I'm new at
> > newsgroups and hope I can find the thread again

As the previous respondent intimated, you should not be using 4WD on any
sort of paved surface. All permanent 4WD vehicles have a differential in the
center which eliminates the driveline tension that would otherwise build up.

When you engange 4Wd in a part time set up, it is assuemed that there
traction is diminished to the point that any drivetrain buildup will be
released by the wheels slipping slightly. If they cannot do that, as on a
tarmac surface, then the tension keeps on building until either the wheels
eventualy slip or somthing pops in the drivetrain.

Thus do not engage 4WD on paved surfaces. I suppose that if the snow is
thick to the point that you are not going to encounter any tarmac, then you
might consider 4wd, but otherwise use it only when off road, eg mud, sand
etc.

Regards
Stephen

I could be wrong about this, but I thought that unless you have locking
differentials (which I'm pretty sure a SideKick does not come with) your
differentials will do there job (allowing axle slip) even in 4wd. I've got a
Samurai, and although there is more resistance to steering in 4wd, there is
not a solid connection between any of the tires. You can drive around and
around in tight circles w/o tires slipping or anything snapping. If any one
tire is off of the ground or looses traction, it will spin freely. This is
why people spend money for limited slip diff's or lockers. Someone correct
me if I missed something.
-Will


"fanie" > wrote in message
...
> As the previous respondent intimated, you should not be using 4WD on any
> sort of paved surface. All permanent 4WD vehicles have a differential in
> the
> center which eliminates the driveline tension that would otherwise build
> up.
>
> When you engange 4Wd in a part time set up, it is assuemed that there
> traction is diminished to the point that any drivetrain buildup will be
> released by the wheels slipping slightly. If they cannot do that, as on a
> tarmac surface, then the tension keeps on building until either the wheels
> eventualy slip or somthing pops in the drivetrain.
>
> Thus do not engage 4WD on paved surfaces. I suppose that if the snow is
> thick to the point that you are not going to encounter any tarmac, then
> you
> might consider 4wd, but otherwise use it only when off road, eg mud, sand
> etc.
>
> Regards
> Stephen
>
>

Will wrote:
>
> I could be wrong about this, but I thought that unless you have locking
> differentials (which I'm pretty sure a SideKick does not come with) your
> differentials will do there job (allowing axle slip) even in 4wd. I've got a
> Samurai, and although there is more resistance to steering in 4wd, there is
> not a solid connection between any of the tires. You can drive around and
> around in tight circles w/o tires slipping or anything snapping. If any one
> tire is off of the ground or looses traction, it will spin freely. This is
> why people spend money for limited slip diff's or lockers. Someone correct
> me if I missed something.

Open diffs will keep each axle from binding up, that is they allow both wheels
on the axle to operate at different speeds (i.e. differential operation). But,
a part time transfer case is typically gear- or chain-driven and essentially
locked, i.e. it allows no differential operation, front shaft and rear shaft
turn at exactly the same speed. Drive in a perfectly straight line and this
works fine. Make a turn and guess what? The rear wheels follow a tighter arc
than the front wheels. A tighter arc implies that the rear wheels travel a
shorter distance than the front wheels (remember 2 * PI * radius). To see this
for yourself, find an empty parking lot with a puddle in it. Drive through the
puddle then make a sharp u-turn. Hop out and look at the wet tire tracks.
Identify the front and rear tracks and see how much tighter circle the rear
wheels follow. So, while the differential in the axle can let one rear (or
front) wheel travel a different distance than the wheel on the other side of
the axle, there is no center differential to allow both front wheels to travel
a greater distance than both back wheels. This is what causes driveline
binding and that is also why its called a part-time 4WD system.

--
Roger

I see what you mean. I was thinking of just a side-to-side diff, I forgot
about front-to-back. Thanks. Sorry for pooing on anyone's input.

-Will