Forum

[p]

EP 90 has similar consistency to mid range engine oil - viscosity is measured differently hence apparent numerical difference - so what you use in the engine should also suit gearbox. I use 15/40 diesel engine oil because I've got a drum of it, same for gearbox, engine and primary chain case.... been okay for 20K miles, so guess it's suitable. Even though it's a detergent oil I find it remains clear and golden long beyond usual change time - so I've extended that to "when I get round to it".Only the gearbox requires occasional topping up as it loses a little, and I've contrived a dip stick to make this easy, only mod is a breather hole in filler cap to prevent any pressure forcing oil out. 350 iron bullet yr 2000.

[Clement]

Thank you all for the replies and suggestions.To keep you posted: EP90 (extreme pressure) as mentioned by some of you, contains phosphorus and sulfur compounds in sufficient levels to be potentially corrosive to yellow metals - so I drained the stuff out.ST90 is not always easy to get so I have simplified things by refilling with 20W50 as suggested (same as engine).

The clutch has currently Type F automatic transmission fluid in it (as per suggestion Pete Snidal). I am not happy with it: it seems to slip after starting up but comes right when engine heats up. I am tempted to drain and probably put 10W30 in.

Clement

[Leon Novello]

If you don`t like grease, and 90 gear oil is not satisfactory, there is always 140 gear oil; sort of half-way between the two. If the clutch slips with ATF type F, it`s not the fluid, I would be looking at the clutch.

[Rattlebattle]

Millers do an SAE 50 oil specifically for gearboxes that have phozzy bronze bushes. I used it in my pre-unit Tiger 100. Although SAE 50 it has similar viscosity to EP 90. As has been mentioned the ratings for gear oil and engine oil are not the same. Fast postal service direct from Millers if there’s no local supplier.

[Rattlebattle]

Sorry, that should read Morris, not Millers. I blame early onset senility...

[Presto]

There is plenty of good informed opinion that says that concern over bronze bushes and the like and modern gearbox and engine oils is misplaced and that no damage or such minimal damage is done as not to be worth worrying about. It is also worth noting that with their straight-cut gears and very low performance levels that these 4 speed gearboxes are subject to very low levels of stress and virtually any decent engine or gear oil will be satisfactory. But of course we will ignore all that and want to put in the ‘best’!

[OldBoy67]

You are correct Presto. This is from the Jack Gray article on rebuilding a Crusader in the Technical Notes section of this very web site: "For lubricating the gears 20/50 or EP90 works well, although some owners think that EP oils attack the bronze bushes in the gearbox. This question was put directly to Castrol a number of years ago for their opinion and quote the following from their very friendly reply. 'Firstly, the question of EP oils attacking Phosphor Bronze. This, like many myths is founded on a
modicum of fact, but certainly doesn't apply today. Early EP oils relied on the excellent, but highly active. load-carrying ability of sulphur and sulphur chlorides. Although these were effective with steel they did attack 'yellow' alloys and so could not be used where bronze was present. However, the advance of technology saw the introduction of more stable EP products (based on sulpho-phosphorized terpenes) which become active only when requiredhen required - i.e. when the gears are under extreme pressure. When the bike is sitting in the shed they will be completely inactive!"

[Presto]

Thanks OldBoy67 - and remember that Jack wrote that article over 50 years ago. What he said about the suitability of 'standard' oils and bronze bearings etc is even more the case now, with the continued development of all oils.

[Clement]

Final post to keep you up to date. I blamed my slipping clutch (and stiff handling of Albion gearbox) on ATF type F oil until somebody pointed out that I should look at the clutch. I thought that the clutch had to be alright because the clutch adjuster assy (halfway down the cable) was almost screwed in - indicating a short cable with still plenty of adjustment to go. The previous owner had also assured me that everything was okay. I ordered new clutch plates regardless and unbolted the clutch cap; bolts overstretched needing replacement; to my surprise the bonded plates had about nothing left;as I pulled out the plates one by one I pondered about the mystery of the clutch cable which seemed to still have plenty of adjustment in it. The mystery was solved when, after pulling out the 24 segment friction plate (and coming to the last plate furthest away from me) this dished plate was mounted back to front: the raised centre was facing away from me instead of facing towards me. With new clutch plates in the gearbox felt a lot better, especially changing gears. So much for me replacing the shifter assy a few months ago to overcome gear changing problems.Needless to say (Leon) that I refilled the primary case with 420 mls Type F automatic transmission fluid.......Thanks to all for helping me along.

Clement