gearbox oil ?

[waterworks]

Is this a suitable oil for a 102 ?

[Oyster 49]

The oil needs to emulsify with water when the water gets into the box. If it does then I'm sure it will be ok. Straight 140 grade is the best.

85-140 grade indicates the oil goes thinner when hot, however the seagull gearbox should not get hot. People go on about gear oil for seagull, the most important thing is to get some in there, and change it regularly!

[headdownarseup]

Straight 140 is what was recommended by BS. It's quite thick and sticky and doesn't really pour like thinner oils will.
This 85-140 looks like it might be a tad thin in my opinion, HOWEVER, some oil (even if it's the wrong stuff) is better than NO OIL at all.

Suck it and see. If it leaks out too quick then try and find a thicker oil. The thicker the better really, but remember the oil must at least mix with water to some degree.


Jon

[Charles uk]

The oil specified by BS for non sealed gearboxes was SAE 140!

[hippy]

Just a thought but is there no way of sealing the gearbox? Gearboxes on any other vehicle ordinarily don't run on a water/oil emulsion. As there are only two places that water can actually enter the box it can't be that hard surely. If so you could run on any box oil really. Coupled with crank seals could probably bring these units a bit more up to date. Just a thought....

[Hugz]

The later sealed ones run 90. The early ones run a runny grease at about 320 (360?) viscosity. Ships stern tube oil is designed to emulsify.

https://lubes.exxonmobil.com/MarineLube ... e-oil.aspx

[Charles uk]

There's a challenge for you Hippy, come up with an easy way of sealing a Seagull 3.5:1 40+ gearbox, that the average Seagull user with a small workshop, could do at home!

This could turn into a very interesting thread with a few brain waves!

[hippy]

Not saying I could come up with it for the average seagull user but sure it can be done. I am fortunate enough to have a lathe, miller etc so if it could be done cost effectively I would be happy to do it for others. If anyone has any shot gearboxes for the cause I'd be more than happy to address this. Don't really wanna pull my motors down at this time of year, sure you guys understand.

[Collector Inspector]

Use that oil if readily at hand.

Check before every use on a transom.

Check that it turns to brown with no clear water after using and removing lower cap screw etc.

Attention and all will be well

BnC

[hippy]

Realistically the teeth on the gearbox wheels only need the finest coating of g/box oil to prevent wear. If you set up can provide this all is well. Whether emulsified or not this is the only requirement. I once built a trike using a bevel box in the final drive train. The bevel box had less oil the say a century gearbox and ran fine without cooling (like an outboard has) with well over 100bhp going through it. I think it is too easy to over think the specs, and although its a different set up the physics remain the same. If you have enough oil in your box to coat the teeth whether emulsified or not you will be fine.

[Charles uk]

The teeth will run virtually dry but try that with a bronze bush & a stainless prop shaft or a steel pinion shaft, let alone the thrust washers!

[hippy]

Fling covers this much in the same way the bores of an ICE. It appears in the boxes I have been into that there is a cut out in the cap to supply the rear bush and the front supplied from the driving gear fling. All I was indicating was that the oil would be less critical than some put heed to. As long as most of the bits have a fine coating all should be good. As I mentioned previously I have put (a specified 111bhp) through a bevel box (which is all a gull box is) filled only a third full and moving perhaps about 450kg of trike at motorway speeds with no ill effects. As we all possibly know 140s sticks like the proverbial poo to a blanket, provided there is a supply (even a small one) the box will be fine. If the box could be sealed I see no reason why a much lighter oil couldn't be used.

[hippy]

Ok Charles, quick question as I don't have one to hand. How is the drive shaft held in the bush at the top of the gearbox? Is it assembled and the drive gear pressed on? Can't make out from available schematics as to how the shaft and bush assembly fit and stay together. Is there a roll pin/collet affair as in the other parts of the box?

[Charles uk]

Varies depending on the box design.

[hippy]

Just pulled a 40 box down and would be more than feasible to put a seal at the top and behind the prop. Smallest rotary seal I can find at quick notice is 18mm OD and only 3mm deep. The 40 box would more than accomodate this both top and bottom seals with very little engineering. Can't speak for other boxes as I have none that aren't attached. Will have to speak to my bearing/seal man to get best sizes but this was after just a quick search on ebay. More than happy to try it on mine and see if its viable. If so I'd be happy to help others out. 140s isn't cheap and pretty sure price of doing it could be offset after a couple of seasons and a cheaper oil.