Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing Changing diff oil

Actually, the proper way (logic) to find the right fluid levels is to jack both ends of the car equally. Good for diff, gearbox, motor oil, and coolant which are most often checked at the same
time. It is also the best way to save your suspension when it is storage for more than a few days. 4 jack stands. Jack from the rear first.


Well done Montegue. One important note. Regardless of what the MMC Handbooks say, BTR fluids contain, their insistence, a friction modifier.
Without it, their later axles (post-1999 especially) start chattering at you and occasionally worse. If you like "Westway", simply buy their friction modifier from
them and add it. It is ideally contained in the fluid you buy, but it can be added at any time. All friction modifiers ultimately come from a single source I have
been told.

gmg

Obviously if you use a diff oil that's designed for a traditional plated type limited slip diff, as I did.



There's no need to use a friction modifier, because it's been put in the oil for you already.

The BTR limited slip diff in my TVR Chimaera did over 80,000 miles on this oil, that's four 20,000 miles changes BTW, so I feel confident in its quality.

I am sorry. A. It is not on the specification sheet of the product you picture. When in doubt (the spec sheets are legal engagement and therefore a better source than a phone call. B. We
live in an era where salesmen have a tendency to tell purchasers what they want hear. A brief tour of the internet under 75-140, 80, or 85-140 will find you more fluids without the additive as with.
C. Or an inadequate amount of the stuff. D. Lastly, Westway gives a gratuitous warning to add their fraction modifier to many of their fluids. READ the last note in their description you posted.
Just above Product Benefits.

As for your TVR's BTR, what year was it? BTR only insisted on the additive after they altered these axles in 1999 (from memory). I was on the receiving end of an angry lecture from a DANA
AUSTRALIA (who ultimately makes the thingies) engineer personally involved in the axle design. I had complained that the correct fluid was not available in most of the world and fluids cannot
be shipped. He would not give me an alternative. However, he did tell me that BMW used it in their 3000 series and that I could buy it, in North America, from BMW (for a incredibly silly price.
which I have done for 22 years. He also mentioned it was good for 50,000 miles. I change mine (with the BMW fluid) every 20,000 miles. Until that point, I merely check the level every service.[/i]

So why take a risk? But, whatever your decision, good luck Montegue. It is our duty to try to help/protect fellow owners.

gmg

P.S. 9 times out of 10 you are fine with just the Gear Oil even with the post 1999 (?) sintered cone versions. It is the 1/10 that causes concern to all of this type axle manufacturers.

Sorry, but the spec sheet referred to above is for the standard non-lsd diff oil and not the specific LSD oil that Montegue has purchased. The label on the bottle is quite clear to see.

Given none of us are getting any younger, I've zoomed in on the label on the bottle to make it easier to see



The Westway Lubricants website describes this oil as being a fully synthetic SAE 75w140 premium limited slip differential oil that includes a high quality limited slip additive for LS differentials.

Synthetic 75w/140 Gear Oil is a very high performance, thermally stable synthetic gear oil designed to meet the demanding requirements of light and heavy duty commercial vehicles and highway equipment. Blended from synthetic base fluids and incorporating an advanced technology additive system to deliver excellent shear stability which maintains performance over the life of the product as well as excellent antifoam, anticorrosion and antirust properties.

The low temperature fluidity offers improved fuel economy and increased protection at start-up, synthetic 75w/140 offers high performance for axles and reduction gears, recommended in lubrication systems where filters are added and used in high loaded gears and drivetrains requiring API GL-4 or API GL-5.

You can study and purchase it on their website here:

https://www.westwayoils.co.uk/products/75w140-lsd-synthetic-gear-diff-oil-gl-4-gl-5-limited-slip

The two litres I needed was a very reasonable £32.00 delivered to my door.

I trust this is clear


NB: My Chimara left Bristol Avenue in 1996, TVR fitted BTR differentials from 1995 on after transitioning from GKN diffs, excluding the rare HydraTrack diffs seen on some Cerberas all were traditional plated limited slip differentials, a design that originated in the USA and first appeared on Packards in the mid 1950's, plated LSDs have been around for 70 years so its hardly new technology!

BTR is an Australian company BTW, but ultimately a division of the American final drive giant Dana who have been building traditional plated limited slip differentials since the late 1950s supplying the likes of Chrysler and many others. What Dana dont know about LSDs isn't worth knowing, indeed it was Dana who jointly developed the additives with oil experts Chevron in the 1960s that have been included in all LSD spec diff oils since then.

FYI the additive pack is there to help limit plate chatter and has been in existence for at least 55 years, since then when buying any reputable LSD specified oil meant it also contained the LSD additive pack. However, do check this by reading the label, hopefully my above zoomed image of the label on the LS specified oil I selected helps show it clearly does contain the additive?

(shrug) Thank you for the new image Deejay.

However, it should be remembered that I spoke to and wrote BTR with the same spec 20 years ago...that one was from Amsoil a classy US supplier. As I noted, they angrily rejected it for their axles
they were providing the MMC post-1999. The recommended only one fluid and wouldn't budge. (At that time it was Castrol SAF-XJ) and they were intractable, insisting any other would be considered a
warranty violation. I have been using it since. With such infrequent changes needed, even a long distance mogger such as I didn't think the BMW price (their Part# 83 22 2 282 583) unwarranted, though
I personally think they were hooey. By the time the axles are shipped from Australia to the UK and then overseas (even back to Australia) they are very costly, with shifting costing as much as the axles! And
it was recently posted by Simon that Morgan BTR have ended..like the Salisbury. That being said this is not the best source of info. It should be checked with Brian Gateson (Techniques) I shall do so.

The right (current) Castrol fuild BTR recommends is available in the UK, Europe and Downunder. It is not available easily everywhere else. The question is who do you follow (trust is another issue)
entirely, an aftermarket fluid suppliers or the axle manufacturer. It has been twice superseded by newer Castrol products. Currently, Castrol TRANSMAX Limited Slip LL 75W-140 Fully Synthetic Hypoid
Gear Oil which is considerably cheaper than BTR! (though not as cheap as the aftermarket.

That being said, in almost 30 years, I have not seen more than 2-3 BTRs fail, unlike most Salisbury variants. Two of these were not using the Italian additive and the last was being used in an abusive
fashion. IMHO, BTRs, are FAR too heavy for a sports car..especially compared to the wonderful (mostly UK) Salisbury 12HA . So with all this as a background, I decided to stick with BMW/BTR insistence.
Perhaps I am too cautious...but it makes no sense to take risks with hard-to-replace main components.

Of course, this is merely my perspective.

gmg

Correct me if I'm wrong...but I thought the later BTR axles that MMC used had cone discs for the Lim Slip element with really strong springs that set the static pre-load, unlike the Salisbury 'plates'

Anyway, if that Westway stuff can handle the torque in a GTR diff...nuff said !

Just did mine. i've used both, this time transmax, both with added friction modifier. 4x changes in 4.5 years, can't say I noted any specific improvement over another, but you can tell when it's getting close to 25k miles and needing a change! Likewise gearbox oil, changed at the same time.