Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing 2010 Roadster diff noise

Hello everyone. It has been years since I posted here but i lurk here regularly and use the forum for its wealth of info.
This time I have a question I didn't find the answer to.
We are in Italië with the Morgan, drove there from Holland.
I have always heard a noise, a whine, presumably from the diff, when going through tight corners. This noise got worse while going up and down the passes in the alps (Stelvio and a lot more) The noise is louder, and starts at less steering. Sometimes now with a rattle at full lock.
I thought about getting a local garage to change the oil in the diff. But when I looked this morning I found only one large hex plug half way up the rear cover. No drain plug.
Any idea's on what the noise might be. Should I wory about finishing the trip? And how to change the oil without the drain? Does it need to be siphoned out maybe?
Regards, JJW&M

If it's a BTR limited slip diff the rattle on full lock is likely the LSD clutches. This can be cured with a friction modifier oil additive. I used Redline 75W90 full synthetic LSD oil which contains the modifier, to cure similar issue.

The drain plug on this axle looks very much like one of the casing screws, the one at the bottom obviously.

As Richard said the LSD clutch can get noisy when the oil starts to break down and loses its "friction modifier" properties.

The drain plug is the very bottom bolt in the centre of the back cover and can be a bit of a bu**er to get out but a good mechanic with a long spanner should manage it. I changed the axle oil in my 2010 Roadster before I did the Austrian run earlier in the year including the Grossglockner pass etc and it made a big difference.

I tried the Redline that Richard mentioned and it was very good.

Can't be certain that it will cure your problem but worth a try.

Correction, i found the drain plug, a small square plug at the bottom of the cover. It is hidden by the panhard rod. That will have to come off. Now off to find that good mechanic ;-)

You say a square plug but mine was a hexagon bolt head and I could get to it with an spanner without removing the Panhard rod.

Morgan being Morgan, yours could well be different to mine even though only a year apart with the same axle

Firstly are you sure that the noise is emanating form the diff?

I say this because often noises from that general area result from the prop shaft hitting the transmission tunnel. I agree that this would probably be more of a rattle than a whine, but it might be worthwhile checking while the car is up on the ramp to change the oil. It is very diffcult to do from the top as you really have to remove the seats, some upholstery and the tunnel to check. Not something you want to be doing whilst on holiday.

Well done. It is hard to see if you don't know where to look.Seems at a glance to be merely another backplate bolt.

I have never heard (save once) of a BTR failure unless the wrong fluid has been used. BTR is very precise on that.
What was in there and what does the Italian mechanic want to use?

It does not take a good mechanic to drain a BTR. Merely someone knowledgeable enough to use the right fluid.

L.

Thanks for the replies. I think you are right, it is hex not square. It felt square searching from above but I later looked at some pictures I took and it showed up hex. I tried two garages in Siena but they would not touch it. I also found that the diff is quiet when cold and only gets noisy after while. Tempted now to finish the trip and get service at home.
Alternative would be to go back to Florence and get the Morgan dealer there to change the oil.
Cheers JJW

On my 2006 Roadster one of the rear suspension hangers broke on the alp passes. That let the prop shift hit the tunnel on had bends. You can easily see that as the damper will be loose.

The symptoms you describe are the diff, especially the clicking around slow corners, it's worse when hot as the oil is even thinner, diff oil changes are often overlooked during a service because of difficult access, you may potentially have 10+ year old oil in there

Make sure the new stuff is a known brand and states LS grade (for limited slip)

If you are going to attempt yourself, DON'T drain it until you have tested you can get the refill plug out which is hard to access, on the back of the diff case about half way up