| Author | Message | |||
     Hameed Noor Mohamed New User Username: hameednoor Post Number: 5 Registered: 12-2006 |
New Silver Spur 1990 owner. 125,000 kms. My car gives out a humming noise from the rear between 60 - 100 km speed. Its a constant hum. It comes on as soon as I touch the gas and disappears when I am coasting. I recently changed my tyres. Bridgestone. Still no change. The resonating hum remains. A couple of guys are suggesting it is the differential noise. Any quick cure or do I have to live with this hum on the highway... Thanks | |||
| Gerry Acquilano New User Username: miatasportscar Post Number: 6 Registered: 12-2006 |
Sounds like worn ring and pinion gear. Change the oil and live with it, very expensive repair. Although I have heard lots of "NO's!!" on using additives, Wynns Friction Proofing has stopped the whine on one of my customers Shadows. Don't think I'm promoting this product, but I have personally seen the noise dissappear after using it. Only once mind you, but the noise dissappeared. Richard Tracey would not agree, nor will I recommend it, or ANY additives of any sort, but again, I saw the results just once. Can't hurt to try it. | |||
| David Gore Moderator Username: david_gore Post Number: 683 Registered: 4-2003 |
Hi Hameed, Suspect your climate will also contribute to this noise due to the high ambient temperatures you experience. This will thin the oil and also increase clearances between the crown wheel and pinion. I would be interested in taking the car out in the cool of the night with your current oil, letting the car cool down for an hour or two and seeing if there is any reduction in the noise until the diff warms up with use. The standard differential oil specification is Castrol EPX80W-90 however you might like to try a more viscous oil such as Castrol EPX85W-140 which Castrol recommend for temperatures above 30deg Celsius. See data sheet below for more information:
Kind regards David | |||
| Hameed Noor Mohamed New User Username: hameednoor Post Number: 6 Registered: 12-2006 |
The temperature in my area is HOT. It is winter and in the cool of the morning, its about 20 celsius. Havent noticed much of a difference in noise during the cooler times. Do I have to take the car to a mechanic to change the differential oil or is it something i can carry out. Not sure if I want to try additives. Thanks for the info anyways. Hameed | |||
| Bill Coburn Moderator Username: bill_coburn Post Number: 844 Registered: 4-2003 |
The Factory in my experience has not made a consistently quiet final drive since the Mark VI Bentley! That was a relatively small casing and as with the whole following series a fairly conventional internal mechanism. The Cloud's casing got bigger and that's when the trouble started. Being of Aluminium it expands and contracts fairly readily. While usually quiet when they warm up you will often get a hum. Come the Shadow with a much bigger case and the problem got much worse. Diffs set up perfectly would hum when they got hot to varying degrees and the trouble persisted until the end of the line. The supposed theory is that the expansion of the casing simply alters the various settings and that makes for noise! Early in the Shadow production they even experimented by rigging seat motors into the casing so that gear settings could be varied while driving. A visitor allegedly inquired why there was a cage on the Facory floor full of new differentials - he was told quietly that they were for the American market - selective assembly. There is nothing to be done - put up with the noise, change the oil when you change the engine oil - it uses little oil and takes but a few minutes to do and you are then providing the best environment for the little diff gremlins to do their work! | |||
| David Gore Moderator Username: david_gore Post Number: 684 Registered: 4-2003 |
Hi Hameed, You can do the change yourself but you will need the right male socket [I think they are a square taper and my friend BBC will correct me if I am wrong] to undo the plugs for draining and filling the differential. A plunger oil pump makes filling the diff easier if you are on your own - otherwise you can get a helper to pour the oil into a funnel + connecting tube while you position the tube to fill the differential [or vice-versa if appropriate] - just kink the tube to stop the flow when the differential is full. I would try the EPX85W/140 as I think this will quieten things down as far as practicable for you. | |||
| Bill Coburn Moderator Username: bill_coburn Post Number: 845 Registered: 4-2003 |
Well Hameed, I can help with the method. The plug needs a 13mm hexagon allen key although these were supplied in the small tool kit with the car. If the bean counters axed them by 1990 you will have to buy one from a tool shop. Getting the oil in is much simpler these days. Castrol of which I am a great fann markets its axle oils in litre containers with a pull up spout. You can poke that in the filler hole and squeeze the bottle - much simpler. Be sure to drain the axle when it is hot after a good run! | |||
| Hameed Noor Mohamed New User Username: hameednoor Post Number: 7 Registered: 12-2006 |
Thanks guys. Just drove up to the local lube shop and they replaced the differential oil with Shell 140. 5 min job. US$15. The noise is still there but at least I have a well lubricated differential. I have a missing problem and am starting a new thread on that. |
Castrol EPX Oils