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EP or Not EP - that is the question

Technical help for all early models, A, B, C, LC, D, LD, E & F models

EP or Not EP - that is the question

Postby Ranburetta » Sun Jan 13, 2019 5:43 pm

Should the SAE140 oil for the D/Ld final drive be EP or non EP flavour?

Thought I should ask rather than risk suffering the slings and arrows of outrageous fortune.
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Re: EP or Not EP - that is the question

Postby Fast n Furious » Sun Jan 13, 2019 11:38 pm

Any power train that has a "wet clutch" will not like EP oil grades. Causes clutch slip and associated consequential problems. ;)
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Re: EP or Not EP - that is the question

Postby Tractorman » Mon Jan 14, 2019 10:31 am

Fast n Furious wrote:Any power train that has a "wet clutch" will not like EP oil grades. Causes clutch slip and associated consequential problems. ;)

I thought it was due to the additives in the EP oil had a detremental effect on phosphor bronze/brass bushes. This was told to me at a tractor mechanics course many years ago but the application in question did not have a oil immersed clutch. So I'll go with your theory.
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Re: EP or Not EP - that is the question

Postby Fast n Furious » Mon Jan 14, 2019 12:49 pm

Sulfur containing extreme pressure additives can cause corrosion problems in gears with parts made of bronze, brass and other copper alloys when high temperature environments are encountered.
I would question if a lammy gearbox would reach the elevated temperatures necessary for this to happen?
It will affect the clutch plates though.
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Re: EP or Not EP - that is the question

Postby jbcollier » Mon Jan 14, 2019 3:23 pm

GL4 gear oil does not affect brass/bronze and is used in Land Rover transfer cases. It's not easy to find but it is available. I use Pennzoil 75w-90 GL4. The most readily available gear-oil is rated GL5. It is used in limited slip diffs with clutch packs, though sometimes with an additive. I have used GL5 rated gear oil in many, many Vespa and Lambretta (chain-drive) gear-boxes with no problem. There isn't much bronze in the later Lambertta/Vespa gearboxes. No effect on the clutches.

Bevel drive Lambrettas are a different matter. They do have a number of bronze bushings in the gear-box, typically have long periods between overhauls, and are often neglected between overhauls. I would not use GL5 in a D/LD gearbox. Fortunately, you are not supposed to. It specifies 30 weight engine oil, changed frequently. You do use gear oil in the final drive (120 weight IIRC) and EP additives are very important there. You could use a GL4 gear oil in the D/LD gear box. It would work very well (much better for the bevel gears so you wouldn't have to change it so often) and is only slightly heavier than the specified engine oil. Gear oil viscosity is measured differently from engine oils: 80w90 gear has roughly the same viscosity as a 40 weight engine oil.
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Re: EP or Not EP - that is the question

Postby Steve J » Tue Jan 15, 2019 8:25 pm

+1 on that! As long as the oilseal between the two bearings in the pinion group is sealing properly, the EP oil in the final drive won't get anywhere near the bronze bearings in the gearbox. Just about the only bronze or brass components in the final drive are the inspection plug and the level plug, so using GL5 oil in there shouldn't cause any real issues. I always used Castrol 140EP oil in the final drive, never had a problem with that.
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Re: EP or Not EP - that is the question

Postby Ranburetta » Wed Jan 16, 2019 8:08 pm

Thanks all for your helpful responses.

I shall invest in EP140 for the final drive.
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