>
>This weekend after a nice drive to the beach, our '66 MGB developed
>a rear axle clunk. :( The clunking happens when changing gears on fast
>acceleration and when breaking (and sometimes when turning corners.)
>So I was wondering,
>1) what is the most common cause of this sort of clunking?
> I suppose it could be a loose wheel, since we did take the
> right rear wheel off that day to clean and grease the
> splines. We haven't checked out this possiblilty yet, but
> because it started clunking after driving about 60 miles, it
> doesn't seem too likely, although the sound _is_ more audible on
> the passenger's side of the car.
>2) is it something we can fix ourselves? We don't have much in the
>way of tools -- a couple of jacks, a socket set, and a parking space
>(no garage :( )
>3) if we can't fix it ourselves, how much might it cost to have it fixed?
>4) how bad is it to drive on anyway? (will the rear axle just fall off
>one day? )
>Hoping for a positive prognosis,
>Lydia Gregoret
>gregoret@cgl.ucsf.edu
At last, someone with the same problems that I have (Including no garage!)
My 69 MGB has had rear axle clunk since the day I bought it nearly three
years ago. I can think of quite a few things that can cause this. First
there is a possible bad universal joint. There are two of these in the
driveshaft and they can clunk like heck when they go bad. Bad U-joints
are fairly common. A new one costs about $25 and should not cost more
than $ 30 or so in labor to install. You can do it yourself, but you
usually need a large vice to do it with (I used one at work when I replaced
one of mine a year and a half ago). The driveshaft also has a splined
joint in it that can wear out. Mine has quite a bit of play in it. This
is quite rare unless the car is very high mileage (mine has at least
120,000 miles on it, I don't exactly because the car came with a broken
speedometer cable and I know the guy who had it before me drove it that
way for months!) The only cure for a bad driveshaft spline that I know
is to get a different driveshaft. Moss wants near $ 200 for that puppy
new! I suggest checking with local wrecking yards first if you need one.
Next in line is the differential itself. Worn bearings in the differential
will cause clunking. There was a short writeup in a Moss newletter a while
back that dealt with this that I can dig up if you like (just send me
email). Problems here are rare, but often very expensive. The gears here
have to be set to close tolerances or they will wear very quickly. New
gears are also close to $ 200. Usually if you have problems in the
differential, you will get whirring or grinding noises as well as clunks.
Next there are rear wheel bearings at each real wheel hub.
These are fairly cheep, and a little more common a problem,
still they don't fail very often. When they do go bad, usually the associated
seal starts to leak and your rear brakes get covered with differential oil
which will eventually get all over the rear wheel and tire as well. This
is not fun to clean up :-(. The last thing left is the wheel itself. If you
have disk wheels, make sure the lugs are all tight. If you have wire wheels,
then check your splines. Mine are about shot. I had the car up on a jack
a few months ago and found I could twist the drivers side rear wheel back
and forth about 1/8 of an inch without the center hub moving at all!
I am told that wheel wobbles some as I drive down the road, earning the
car the nickname "Ol' wobbly wheels". I know I need new splines, and I
should probably replace that wheel at the same time. Every time a new
british car parts catalog shows up in my mailbox, I immediatly check the
prices on new MGB rear wheel splines. One hundred and seventy dollars each!
I just can't bring myself to spend that kind of money on a part that no one
can even see for a 20 year old car. A new top, OK, people can see that and
a few might even notice, but a rear wheel spline? I suppose that one day
push will come to shove and the spline will strip out completely and I won't
be able to transmit much power to the ground anymore and I'll have to do
something, but hopefuly this won't be soon. Another source of clunks is any
of the rear suspension attach points. Look for lose nuts and bolts on
anything that looks like suspension. As far as isolating any of the other
trouble spots, I'd start by putting one of the rear corners of the car up
on a sturdy jack stand and twisting the rear wheel back and forth while
listening for the clunk. Whatever the clunk comes from is your problem.
You can fix most of this yourself, but none of it is what I consider "easy".
The lack of a garage is a real drag. Some of these things are fairly
cheep, some are real steep, kind of a mixed prognosis.
I hope this help, and good luck!
Andy Haber (andyh@hdw.csd.harris.com)
Harris Computer Systems Division, Ft Lauderdale, FL
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