Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing Rear Axle Noise

Weather fine today so I thought - go for a spin or service the Morgan. Decided that servicing was the moral alternative.

Plus4 M16 with a Salisbury axle. Starting at the back, I jacked up the rear end (used axle stands) with the intention of running the engine in gear to warm up the axle oil prior to change while messing around in the cockpit.

Started up, put her into 2nd gear and gently let out the clutch. A curious, temporary grunching noise from behind, but all seemed fine until I realised that the offside wheel was spinning nicely, whilst the nearside wheel was turning much more slowly and occasionally stopping briefly.

I switched off, dropped the car to the floor and went for a drive - which is what I should have done in the first place but didn't trust myself not to get sidetracked by driving and forget about servicing.

Have not noticed anything strange in normal driving, so, my question is, is there a problem pending and should I worry about erratic wheel spinning?

I had a similar experience running my BMW shaft drive bike with the rear off the ground. I believe the noise is caused by backlash in the transmission, it only becomes evident when it is running with no load, and is normal. If I recall correctly, it is not advisable to run the transmission without load like this.

Regarding the wheels rotating at differing speeds, this will be due to the differential and I think is also normal. No doubt someone with more technical knowledge than me will be able to elaborate.

Colin

You might want to check for a binding brake on one side?

Anyway - much more fun to warm the gearbox and diff oils up by going for a

That was my first thought as well, Graham; but also, a differential is designed to operate under load, so unloaded any slight difference in frictional resistance would have an effect.

Bud
__________
2003 - 4/4

Exactly!

As Graham says, it could be a binding brake and a open (or normal diff, not Limited slip)

when a vehicle with an open differential meets a lack of traction, it directs power to the wheel with the least amount of resistance. The result is the wheel on the traction-less surface spins free, while the opposite wheel of that axle on the better traction surface provides little or no power.

ps I like the reg. number of your new 4/4 Graham.



Bud
__________
2003 - 4/4

Yup. At least it is a little bit distinctive (though slightly overshadowed by the colour!) - though not as much as RTA.
Probably should be on a 4-seater though!

Many thanks all. I'll check the brake for binding as part of the service. After reading all the dire warnings about Salisbury axles and there being no spares avaliable if they break (particularly on GoMog) I have to say I feel more than a little relieved.

Don't take everything you read on GoMog as gospel...
While it is a very useful resource, not everything is 100% correct (though it is a lot better since a certain amount of editing took place recently).