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gearbox oil level

Technical help for Series one, two and three Lambrettas. Models include the Li, Li Special, TV, SX, GP, Serveta and API/SIL models

gearbox oil level

Postby bluebob » Fri Jul 13, 2018 4:29 pm

I have always refilled the gearbox oil up to filler hole level.i believe this is 0.7 l.i read somewhere recently that 0.5 is enough,and sometimes the larger amount can cause too much pressure.the reason I ask is that on this engine I have twice had slight problems with overheating ,with a bit of oil coming out of the filler plug,and up through the gear selectorrod,past the o ring.both times I put this down to other factors and the problem went away both times .any thoughts please?
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Re: gearbox oil level

Postby CHRIS in MARGATE » Fri Jul 13, 2018 4:49 pm

0.7 on rebuild and 0.5 on oil change is what I always do.
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Re: gearbox oil level

Postby Scooterdude » Fri Jul 13, 2018 5:23 pm

Ive only been in to scooters for a couple of years but this has always puzzled me. People always say fill the gearbox with 700ml, but replace with only 500ml ?? When ive drained what i know to be 700 I always get 700 out :o and i dont check the level via the level plug, what i do is dip a certain screwdriver in the filler and 700 registers exactly 1 inch on the screwdriver, saves risking stripping the level plug thread. Ok carry on...
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Re: gearbox oil level

Postby nickw » Fri Jul 13, 2018 5:39 pm

I do as Chris says above. To create pressure you refer to you'd have to put a lot of oil in surely?
Not sure how you get 700 mls on draining but then again I never measure the drained oil. This is not a Lambretta factory guide but came about years ago (probably through the racing fraternity) because when you drain the oil and then put back a fresh 700 mls technically it would be too much because the old oil sticks to the clutch and gearbox. Obviously not 200 mls worth. Sticky also put it in his manual. Personally I don't worry about it. The oil leaking from the plug and the gear selector arm is more reminiscent of a crankshaft oil seal failure.
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Re: gearbox oil level

Postby Scooterdude » Fri Jul 13, 2018 5:44 pm

Just relating to my relative inexperience with the job, i use an old measuring jug to drain into so thats how i know what does or doesn’t come out.
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Re: gearbox oil level

Postby rossclark » Fri Jul 13, 2018 6:21 pm

Having had my chaincase off and on and drained it a couple of times this week I measured in 700ml at the start when I drained it the first time I put it back in the bottle and it measured 600ml so there was still about 100ml floating around in the casing so I just put the 600 back in.
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Re: gearbox oil level

Postby Scooterdude » Fri Jul 13, 2018 8:29 pm

I put a small piece of wood under the left hand stand leg and leave to drain overnight, probably why i get it all out + all of the oil-bourne particles and crap.
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Re: gearbox oil level

Postby Warkton Tornado No.1 » Fri Jul 13, 2018 8:56 pm

I vary between using the oil level plug as a guide & using 500 ml if it is a refill, but, in general, the oil doesn't tend to have a hard life unless the engine is really being thrashed (as in racing)

The leakage experienced will not be due to the crankshaft seal failing unless accompanied by white smoke as the seal (if fitted correctly), has the lip facing the crank, so will tend to admit oil into the bottom end.

The problems stated will most likely be due to worn gear selector shaft/plain bearing bushes with a poor 'O' ring/thrust washer/slack fit (vertically) & the filler cap having little or no wire mesh which acts as a filtered breather but also stops oil trying to escape.

The gear selector shaft should have virtually no play up & down. If there is any movement, oil will find it's way out past the 'O' ring.

The filler plug can be replaced or repacked to prevent loss, unless you are using a really light oil (as some of us do) in which case a piece of clear tubing can be fitted onto the round section & taken up by the fuel tank to act as a catch 'reservoir'

I hope that all helps....
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Re: gearbox oil level

Postby bluebob » Fri Jul 13, 2018 9:43 pm

thanks for the replies.i was just curious after reading about using 500ml as opposed to the standard amount.never heard that before(and I cant find it to doublecheck).I have only ever used the level hole for reference,although measuring out a dipstick is not a bad idea if obstructed by exhaust.
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Re: gearbox oil level

Postby Fast n Furious » Sat Jul 14, 2018 1:05 pm

I use a whole litre in mine without any problems whatsoever.
I do so to ensure that the mainshaft roller bearing doesn't get starved when riding at sustained motorway speeds.
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Re: gearbox oil level

Postby davej » Sat Jul 14, 2018 1:16 pm

Mate of ours only used to fill up to the level plug, Enderd up with the clutch getting hot and not working properly
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Re: gearbox oil level

Postby Warkton Tornado No.1 » Sat Jul 14, 2018 2:01 pm

Fast n Furious wrote:I use a whole litre in mine without any problems whatsoever.
I do so to ensure that the mainshaft roller bearing doesn't get starved when riding at sustained motorway speeds.


I really enjoy reading different, reasoned opinions on various factors about enhancing the performance of our favourite, Italian shopping machines, but I wouldn't agree with using more oil than necessary. I hope that my response is not offensive, but seen only as an attempt to achieve balance ;)

I have been fortunate to have designed very high (two metres or more) complex, industrial gear trains that utilise an 'oil bath' system that was, in reality, an oil 'shower'

Although the oil was pumped up to a top tray with holes to drench the enclosed components below, the need for that was questionable as the gears that were dipping into the sump always ensured that EVERYTHING within the confines would get drenched with lubricant. The only real need for a pump was on start up, but it also gave opportunity to cool the oil, if necessary, via a heat exchanger. In fact, too much oil could be adversary as oil retains heat so much more than, say, water, which sheds it's heat so much better, & the reason it is used universally for automotive cooling. I know that Suzuki flirted with oil cooled engines for a while, but don't know that they do now, for that reason.

I reason that Innocenti will have optimised the amount of oil & the complex internal structure of the crankcase cover to gain the best combination of lubrication & heat transfer & my own take on any improvement would be to look toward a better oil for any improvement in heat transfer, rather than increase the quantity. To that end, I no longer use ST90 as I consider there are far better alternatives that have proved reliable in all the engines that I have been involved with over the last decade or so, & I now have settled upon an oil that some would, no doubt, not believe could work in a wet clutch scenario.

I doubt the Lambretta engine receives any harsher treatment than in a racing environment, rather than a consistent, sustained load, & I have yet to witness the failure of any of the bearings within the transmission, though I have known my fair share of other components fail, but not due to inadequate lubrication! :roll:
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Re: gearbox oil level

Postby Fast n Furious » Sun Jul 15, 2018 3:26 am

You can't really use more gear oil than is necessary in a Lammy. If you do put too much in, the excess spews out of the breather, leaving you with a right clean up job when you get home. :evil:
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