Talk Morgan Forums Morgan Sports Cars Classic Morgans (pre-CX) BTR Axle noise

I see there is some advise about oils for the BTR axle but....... I developed a sort of moan or groaning noise when making very tight turns so I changed the oil for Valvoline
75w-140 synthetic for LSD. Which shouldn’t need any friction modifier added but the noise continues, what oils are other BTR owners using ?
Thanks Dave

Castrol Syntrax 75w-140 LS oil.

The oil in a modern diff is usually for the life of the car and unless there are problems or oil loss is not normally changed. Perhaps for cheap insurance it could be changed at 100,000 miles or 150,000 km. Up to you but the intervals are normally very long unless the diff is subject to very heavy use or contamination such as may happen in 4WD vehicles that often ford rivers and/or operate in severe conditions.

If you are getting a noise from the diff area it would definitely indicate that there is a problem. It is notoriously difficult to understand just where a noise may be coming from in a Morgan. The fact that it is happening in tight turns may indicate some other point of stress or physical contact, even something as simple as the tail shaft touching the inside of the transmission tunnel. I had this problem in hard right hand turns until I fitted the 5 link suspension.

I use Morris transmission oils which are used by the factory and I change the oil every couple of years. The lsd darkens the oil, which is why I choose to change it. If you get a noise which resembles a loose wheel, add a bit more friction modifier.

Peter,

I think you are confusing bad advice from some manufacturers and garages winging it on diff oil changes for facts.

Any investigation of used oil analysis on diffs shows that at around 30,000 miles there is in the region of 300 to 400 parts per million of wear metal in the oil and if you check the viscosity, the oils are in most cases well below their lower limit.

With you having a liking of Jaguars, certain versions of the around 2003 XKR had a specific Shell diff oil only available for Jaguar dealers that was "filled for life". There was no accessible drain plug. The oil had specific additives to prolong it's life. No I did not find any UOA of these diffs.

A few years later Jaguar went back to having fill and drain plugs on their diffs. i think the reintroduction of these facilities on the Jaguars speaks volumes.

Volkswagen and Ford are at it again on their smaller cars with "filled for life" gearboxes and reports of the oils proprieties at say 50k miles are not good. In saying that the car is probably with it's second or third owner and therefor the manufacturer is now off the hook due to missed services on that one.

Sigh....gone are the days when a handful of sawdust would quieten the noisiest of axles.....

Arwyn

Like Dave I believe in changing the diff oil every major service , usually 2 years but can be sooner depending upon mileage.

The oil that comes out is invariably visibly more contaminated than that going in , so I am pretty sure that I am doing the right thing, although I don't have any oil analysis data to back this up.

As Dave points out, I use Morris Lodexol XFS 80W/140 fully synthetic which already contains a friction modifier.

I believe that BTR recommended an oil change at 50,000 miles , unfortunately the oils you have recommended are not available here ,but I may look harder for the castrol syntrax .
I drove a couple of I hour trips yesterday day and the noise is no longer present once warm but returned when cooled ,
I have ordered friction modifier from Summitt racing which strangely varies from $9 to $90 for a 4 oz bottle ? And I will add a couple of oz and see what happens ,
The many different offerings state that it’s for “clutch type” differentials , Whereas the BTR is a cone type but the materials I would imagine are similar .
Btw the oil that came out was very dark but no visible metallic ie bronze in it .
Dave

I use Castrol Syntrax which is meant to have some friction modifier, BUT after a change, the diff made a noise like sticking brake calipers when reversing on a turn. I was advised to add 70mls of redline friction modifiers and this solved the problem - blissfully quiet ever since!!!