Morris Minor Owners Club

Why is it that when my car is acellerating, in fact whenever the engine is actually driving the car forwards, I get a kind of 'moo' noise from the back end.

Not exactly like a cow, more like an extended Mmm with an Oooh at the end!

Is this the sound of a worn diff?

yes probably the diff. if you free wheel and it goes away its the diff.

Yup, thats it exactly, I guess my next questions are ...

How do I work out how long I have left?

Am I better replacing the diff, or is it worth taking it apart to find the worn parts and replace them individually?

How hard is it to fit a diff from a Marina?

How do I go about checking a 'new to me' diff to see if its better or worse than the one I already have?

i would'nt worrie about it. diffs very realy completly fail, they just get louder, you will change it when it gets on your nerves. unless you are very good at enginering, and have full workshop facilites you will not be able to repair it. diffs from other vechicles will mess up your gearing, speedo reading, that is if they fit. i dont get involved in parts from other cars. checking a diff can be tricky. look for wear on teath, the amout of free play, condition of oil seal. the noise comes from a bearing inside there, and it needs to be tested under load, if its second hand

Its very rare for a Minor diff to fail they can humm along forever and they only tend to get changed if they suffer from a major oil leak or if the owner gets fed up with the noise, the problem with buying a recond diff as Willie will tell you is that a lot of places cant set them up properly.
Its not worth taking it apart to replace parts as you will not have the specialist eqipment to set it up properly.
A Marina diff will not fit, you would need to fit the whole axle, and that involves changing the spring mountings etc and the wheel pcd will be wrong although it can all be done.
Without trying it in a car I am not sure, you could look for obvious wear but I dont think that will show things like humming up unless the bearings were completly shot.
Can you live with it if its not too bad wait until it gets worse, as for how long that takes the answer is how long is a piece of string.

its probably got years left in it.

That's a relief, well at least now the blue morris has a name ... we're going to call her Daisy ... as in the cow ... as in the noise

Daisy ... as in the cow

Not as in silly old MOO from the TV series.

Dunno ... what TV series do you mean?
(I try not to watch too much TV, it rots my brain!)

Till Death Us Do Part, with the main character being Alf Garnet (sorry Alain but showing my age here)

Ah, I remember ... the racist one ... yeah, I hear that was pretty good, but I think I was a bit too young at the time to really 'get it'.

Same goes with 'Rising Damp', 'Steptoe & son' & to some extend 'Only fools & horses' ... very funny I'm sure, but never did quite get on with them.

I much preferred 'Not the Nine O'Clock News', and of course the dear old 'flying circus' (although that could be pretty variable at times)

My diff doesn't moo, as much as hum gently... I think it's in B flat, but I can't be sure... Shame it's not A Minor, really...

Hmm... I'll get my coat... ;)

WELL, I know all about noisy diffs! I have just fitted the fourth
one in my convertible in my search for a quiet one! I did fifty
miles in it and then took it out and fitted the old one because it
is quieter. What I have managed to do today is find a supplier
of EP 140 oil. Obviously that is thicker than our recommended
EP 90 diff oil but seems to me the only way to quieten down
the units since,as I have said before, i cannot find anyone who
can set them up properly so that they are quiet. I will see if
the EP 140 makes a discernable difference.

heres an idea. ready for this. ive never done it my self, not the sort of thing one does on customers cars, but it works. mix sawdust in the oil.

i tend to just turn the radio up....works every time!

vulc

The sawdust bodge was what the unscrupulous did when
they were selling a noisy old wreck,not the sort of thing
we clean living lot would do. I understand that Oak was
better than Mahogany!!

Further to the whining diffs problem,I discovered,whilst
tracking down some EP 140, that there are at least two
additives available which are specifically for gearboxes
and rear axles. One is from STP, the other is by Molyslip.
They both state that 'hum' will be reduced and the Moly
one says that it should not be used in auto boxes or
limited slip differentials which suggests that it decreases
friction significantly. Any one tried either of these??

yes once is serviced a morris. we changed diff oil. when car went home it was humming. of corse it wasent humming when it came in

Did fifty miles today with the EP 140 differential oil in.
It definately DECREASED the whining so I consider it was
worth trying although there was a slight drag on the
car until the oil had warmed up (it was a very cold frosty
morning). This Castrol oil is a 'GL4' class which means
that it contains exactly the same percentage of the additive,
(Sulphur/Phosphorus), which gives the anti wear protection
as the normal EP 90 so there should be no problems there.
The improvement has saved me having to fit a 200 Watt
radio anyway!

I don' need a radio - if I had one loud enough to drown out the engine, I'd be deaf...