Gear Box Help Please!

phillyskip · Feb 19, 2014

My 72 Norton project bike has a leaky gearbox. When I assembled the box I used new gaskets and seals .....also used silicone sealant on the gaskets. Torqued all fasteners to spec. It leaks like a sieve. Will lose 5 to 6 ounces in no time flat. Help Please.....Skip

Hobot · Feb 19, 2014

What level of oil as easy to over fill and where are the leaks seen? I feel so much better about my own fumble fettering with your post but maybe some damage over looked rest of us ain't had to deal with. Hillbilly first fix would be just dump some black pepper inside.

pete.v · Feb 19, 2014

Well. let's get specific. Inner cover, outer cover or other?

There no pressure here so their must be something obvious.

Other than at the kickstart shaft oring and a little at the shifter oring, these things do not leak to speak of.

You bset offer up any and all detail if we are to help.

texasSlick · Feb 19, 2014

+ 1 with PeteV.

Surely with a leak as you describe, there should be some clue as to the source. Wipe all surfaces clean, place a clean paper or corrugated paperboard under, and observe!

We are waiting for your report.

Slick

Ibex · Feb 20, 2014

pete.v said:
Well. let's get specific. Inner cover, outer cover or other?

There no pressure here so their must be something obvious.

Other than at the kickstart shaft oring and a little at the shifter oring, these things do not leak to speak of.

You bset offer up any and all detail if we are to help.

Surely there is some pressure forming when the gearbox warms up in use. There is a pin-sized hole in the inspection cover to vent the gearbox, and pressure will build up if all seals are good and the hole is blocked with grime/metal polish etc..

Hobot · Feb 20, 2014

The pin hole in the fill cap is likely not needed d/t the venting of cable entry and the dry venting past non existent seal of the main shaft open ended sleeve bush well above oil level not to mention the clutch rod at either end. I have on a few occasions over filled going by manual listed amounts to have a mess of few extra oz of lube everywhere till it sought its natural level which I no longer exceed, nor can I exceed for long as it flows out to normal level by time engine fully warmed on the fly.

pierodn · Feb 20, 2014

pete.v said:
Well. let's get specific. Inner cover, outer cover or other?

There no pressure here so their must be something obvious.

Other than at the kickstart shaft oring and a little at the shifter oring, these things do not leak to speak of.

You bset offer up any and all detail if we are to help.

+1 with kickstart shaft oring.

concours · Feb 20, 2014

Oil leak 101, clean thoroughly, observe. Ride 100 yds., stop, inspect. A gusher like you describe should be easy. Leak at rest (NOT drainage)? Or only underway? Where does it seem worst? Chain side? Sleeve gear seal riding on a nice smooth surface? Sealant used on splines, sleeve, sprocket? Sprocket nut properly torqued?

myjota · Feb 20, 2014

Hobot I must disagree about vent hole. I had a gearbox made from various sources and it pumped its oil down the mainshaft into primary chaincase and leaked from every seal once it got hot. Took an age to discover that there was no breather in the inspection cap. Probably a mk3 cap on an right hand change box.

Hobot · Feb 20, 2014

Ok myjota then you had exceptional well fitted cable entry and will keep my little hole clean on AMC's. Ani't yet checked if the TTI has vent provision. On your report evidence I might try a vent to manifold to stifle the weeps of heated travel. Someday all the Commando's will be fully fettered and only need a wipe off now and then...

phillyskip · Feb 20, 2014

All....thanks for your comments. The leak seems to be coming from the area around the 7th stud on the inner gearbox. That is the one exposed on the outside. I've tried both dry gaskets and gaskets with sealant. The bike is not complete so I haven't ridden it yet. I'll check the plunger area as well. I thought I had this problem solved after I replaced the gaskets the second time ,but a leak developed after about a week. I'm hoping that I don't have some hairline fracture in the gearbox housing. When I got this bike as a basket case it had two gears missing teeth and a twisted layshaft. Something awful happened in there during it's lifespan.......Thanks,Skip

Hobot · Feb 20, 2014

Something awful happened in there during it's ifespan.......Thanks,Skip

Oh oh another one with a bad history. You are on you own to find the damage in cover or hole or could just extra goop around it, next time, and wipe excess off and cross fingers.

pete.v · Feb 20, 2014

Philly
Based on that information, I might think that, if not a hairline crack, they may be tweaked or have a depression or two. True up all mating surfaces. I'll bet if applied to a layout plate, there will be some rocking.

I hate to think it, but the shell may be the surface that needs truing. You may be able to just pull the studs and apply a flat to it to check. It seems the shell could be more vulnerable to catastrophic force than the inner cover.

I know It seem like alot of work when you are so close. Good thing you have a good circle of supporters.

phillyskip · Feb 20, 2014

Pete the one thing that I have learned from my years of rebuilding/restoring bikes is that it is a natural tendency to want to quicken the pace when getting to the end of a project to "get it done" .We must resist that urge. Now is the time I'll slow down and and get the "end game" as good as I can get it.

I'll stay on this gearbox as long as it takes to figure it out and fix it. It will be apart tomorrow and I'll report back with my findings. I'm new to Nortons so this is the pound of flesh Pa Norton wants me to pay for all of my years with Triumphs!...........Thanks,Skip

toppy · Feb 20, 2014

hobot said:
Ok myjota then you had exceptional well fitted cable entry and will keep my little hole clean on AMC's. Ani't yet checked if the TTI has vent provision. On your report evidence I might try a vent to manifold to stifle the weeps of heated travel. Someday all the Commando's will be fully fettered and only need a wipe off now and then...

Fully fettered !!!! just need a wipe over!!!!!! Hobot that is without doubt the the most crazy idea you have very had

Hobot · Feb 20, 2014

Yes sir toppy I've even had a couple of fully fettered Combats, for a time, just my drool to wipe off. Philly your stick with it attitude is food for my soul to feed on when my turn into another AMC let down approaches. This time the kicker thing a ma gig quit gigging but not in a manner it has before so nothing for it but dig in again and see what else it worn out too, again. I swear each time I'm going to do it right the first time, ugh.

B+Bogus · Feb 21, 2014

If the oil is coming from one of the stud locations it's possible that the main casing has cracked across the stud hole and oil is migrating via the stud - especially as it has 'a bit of previous'

phillyskip · Feb 21, 2014

That's what I'm thinking the possibility of a crack where the lower left hand stud and exposed nut are located. If that is the cause I'll "JB" weld it on the outside for now and do a real fix when the weather warms up . It's cold in the shop right now.

Hobot · Feb 21, 2014

Philly around here JBW is looked down on so best refer to it as cold welding like I do...

Biscuit · Feb 21, 2014

" fully fettled" That is pretty funny Hobot, but actually my bike is fully fettled....for days or a week on end until it on it's own volition becomes "un-fettled. Then it's fettling time again. (this is my new favorite phrase). In the morning with a scheduled service or repair I will put my glasses on, roll up my sleeves and declare " Let the fettling begin"! Conversely, if I should break down or stall miles from safety I will stand back, squint at my bike and say "fettle you Norton".
By the way "fetter" , according to Webster, means "to restrain from action or motion". In which case, yes, many Nortons are "fully fettered

Gear Box Help Please!

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