Vibration and oil leak from primary chain

Hello:
I´m new in the forum, I own a Norton Commando roadster 850 MKII from 1973, I have this bike from 1985, and two years ago I restored the bike , specially the engine, I´m from Spain , I sent my cylinder head to U.K. for big valve conversion, new seats for unleaded fuel, my crankshaft to balance, new pistons, new camshaft, etc. and now I have a big vibration problem than never had before, I fitted new head steady and new MKIII isolastic mountings, but still vibrates all the way from idling speed to high revs. The engine leaks a lot from the outer part of primary chain case close to the gearbox and from the cranckshaft. The engine sounds more brave than ever, good, but the bike in the stand moves, shakes, when You speed up and the ground vibrates underneath the bike.
Now I´m dismantling the primay chain complete, and I don´t know what to do, to dismantle whole engine again to check crankshaft, seals etc. Could anyone give me advice?. Thank You very much .Alfonso

My advice would be to remove the custom head steady and put the stock one on first. Then adjust the isolastic collars two "holes" at a time until the vibration improves. I found that the initial adjustment instructions that came with my MKIII isos were way too tight.

As for the oil leak, the common places to leak from in the primary are the rubber o-ring cover seal, the plastic grommet around the alternator wires and sometimes the felt seal behind the clutch.

Alfonso,
Are you saying the vibration is serious? Does it get worse with higher revs? Maylar is correct about the Mk3 adjustment. Do not rely on instructions for correct clearance. I suggest you unscrew the adjuster until you get the 008 to 010" (0.20-0.25mm) clearance and count the no of adjuster holes to achieve this. A very tight front mount will transmit a lot of vibration. The rear seems to have less bad effect in my experience. Also did the front mout assemble easily to the engine and frame? If the mount is under tension because the front bolt is not aligned with the rubbers and frame tabs this can also increase vibes.
All this assumes the crank was balanced correctly? Who did the work?
For your oil leak, is this chaincase oil or is engine oil coming into the chaincase through the drive side seal? Check that the seal is the metal cased type and not the rubber outer covering (outer diameter). Also check that the crank keyway has not damaged the seal during assembly. I did that this year for the first time ever!! It will only take a tiny cut for the seal to leak.
Buena suerte.

Also as I learned from the more expierianced members here when oil was coming from my primary side, if the bike has "wet sumped" the oil can seep past the crank shaft seal into the primary. If it's over filled it will leak out the felt seal behind the clutch basket. Drain your primary to the correct level & see if the leak stops. Mine did.

RTV alternator wire exit, if there's more oil in primary, main seal failed, make sure outer primary is flat. Use a torque wrench set to 25lbs on ISO bolt after checking clearance. :!:

Sounds like you may need a new crankshaft seal, especially if you just got the bike and don't know when last replaced.

If you can find a way to fix the vibration problem - great. If not then the best way to eliminate your Norton vibration problems once and for all is to cure it at the source - those heavy pistons. The answer is lightweight pistons and longer rods. Its a great feeling having a smooth running Nort and you don't have to worry about reliability of the cases and crank bceause the shaking forces are lowered to a safe level. Join the riders who are converting their valued classics.

see them at the new http://www.jsmotorsport.com web page


Jim Schmidt - helping to create reliable, smooth running Nortons

What I here you saying is that after an extensive bottom end rebuild (and top end) you developed a serious engine vibration that previously did not exsist. You then swapped out the engine mountings (ISO's )to help the vibration problem but it did not change. Is this correct? If so, I suspect main bearing issues. Possibly a bad installation assuming that they are new or loose journals or exsessive end float? When you ride down the road, what is it like. Sounds like you may be fearing the worse.
Validate your isolastic settings and the procedure to accomplish this.

Concerning the oil leak at the primary, changing the crank seal is easily done when the clutch basket and the engine sprocket is removed. The reason for the seal failure and excessive oil in the primary can be surmised as the oil pump needing refurbishing. Also verify that your breather curcuit is clear and plumbed correctly.

To avoid confusion, You should start another topic to separate these issues and address them individually, unless the drive side mainbearing is so bad that oil is blowing by. God forbid.

When you get that primary off and the old seal picked out, see if you have and noticable movement by hand at the crankshaft. God forbid.

Thank You to all of You ¡
I started last week the engine of my Commando, I fired the engine at the first kick, more or less after four months storaged . After a few minutes, it begun to leak oil from the inner side of the chaincase inner half and gearbox , dropping oil close to gearbox countershaft sprocket constantly, the mistery is the oil level inside primary chain was normal. The oil that comes out was black, the engine oil was 20/50 new I´ve just changed before start the engine.I saw after dismantling the whole primary chaincase, oil coming out from crankshaft oil seal. May be broken main bearing oil seal?, or it is a matter of high pressure inside the crankcase?. I´m thinking about dismantling the whole engine to take out crankshaft to send to balance properly, but I don´t want to make a mistake.
I´m so disappointed with my bike at this moment.

Alfonso, as pvisseriii asks,

Did the bad vibrating start as soon as the rebuilt engine was started, or

Have you had the rebuilt engine running without it vibrating badly prior to just recently?

I owned my bike since 1985 , two years ago I finished with a friend´s help a whole restoration of my bike. After put all bits together , firts kick was so hard, because so much compression, I broke a new kickstar; I was riding about 1000 km. feeling the bike vibrations more than ever, and oil leaks, from the beginning of engine new life. I had to weld petrol tank crack.

Rebalanced crank? Not really neccesary on a Commando.....don't know who did the job but if they don't have Norton experience maybe they did something incorrect like assemble the crank cheeks onto the wrong sides of the flywheel?

Remember when checking the frame isolastics that the bike is not up on the centre stand and just use the side stand or hold it up on a box. I found that I needed to wind out the iso adjusters a quarter turn and take the bike for a ride and then come back and undo another quarter turn until it got smooth at 2500.
The .010" gap is immaterial with vernier isos, set it until you are happy.

Mick

Alfonso, from what you have said, there are only two obvious causes of the vibration from the work you have had done(without actually being able to look at the bike), which have already been mentioned by other posters.

The crank balancing was done incorrectly, or

The isolastics are too tight at one of the three mounting points. Is the head steady that you fitted a standard Norton head steady, or an after market (improved) type?

Who balanced the crank, and to what % was it balanced?

Hello guys:
I´ve sent cranckshaft to balance to Mick Hemmnings (but I don´t know % of degrees), with conrods, and new pistons that I bought from Him. Metz Porting worked in my Cylinder head, making Big valve conversion, gas flow, new valve and seats for unleaded fuel and repaired exhaust threads. A friend of mine helped me to fit all parts together. We could made something wrong, never knows, by now I´ve just taken the engine out from the frame to dismantle and check cranckshaft, I´m thinking about sending it again to check the balance to England (P & M) Whom made a good job with my brother´s Triumph Rob North replica.
Thank You.

A Commando engine is shaking all the time. If there are destructive effects on the cycle parts (and the rider !) then it must be bridging the isolastic gap.

Have you checked the primary case and fittings thoroughly to see that everything is correctly assembled and not contacting the cycle parts ?

Years ago, I rebuilt mine in a hurry and finished it the day before a long trip. Unfortunately, I had powder coated the frame and engine cradle and these softened and came loose on the motorway. The roughness, noise and vibration convinced me of a main bearing problem but to be honest by that stage I was damned if I was going to stop on the hard shoulder so I rode on to the next services. I looked down as I rode in and saw the chaincase contacting the footrest hangar.

I really would suspect some sort of 'bridge' over the rubber mountings.

alfonso420 said:

The engine sounds more brave than ever, good, but the bike in the stand moves, shakes, when You speed up and the ground vibrates underneath the bike.
Alfonso

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Alfonso, All Commandos shake and dance around on the centerstand when running. It's not considered a good idea because the stand really isn't up to it. And all Comando engine/trans/cradles shake within the frame, a lot. I like 79x100's diagnosis that something is binding or making contact with the frame. Setting up the headsteady and iso's is a major production and there are many ways they can be made to do exactly what you describe. Anything on the bike that can be shaken loose and vibrate will, centerstand, tanks, ect. I'd think about going over the bike stem to stern before going into the motor.
P.S. I found that if you can place your fingers on the primary cover and the Z-plate with the engine running you can feel if something is hitting even though you can't hear it.

I've had holed pistons, blown head gaskets and plug wires come off,
but nothing made my Combat shake to the teeth like a pebble
caught between front mount and and steel skid plate.
I though frame had broken by a rod about to finish breaking.

I was shocked by how easy a screw driver in a front mount tab
hole can flex the tab and maybe twist the tube some.
I think a good part of tweaking each iso gap is to account
for the slight angling of these tabs to bind on engine side.
It worked ok prior and nothing mentioned should make your
steed shake so, but normal engine motion connecting to frame.

hobot

Hello:
Last saturday with a friend of mine dismantled the engine, we took out the crankshaft with conrods. Pistons, crankcases, mainbearings, etc., all looks good, Timing side good too. I realised that I did not change rear isolastic mounting, front iso and head steady are new; breathing may be ok because in the timming side it has two holes, different than 750 model.
I´m thinking about fitting an anti sump valve, to avoid the oil falls into the engine. I´ll send the crankshaft to check balance, and I´m thinking about change my old conrods to a new Carrillo conrods, but I don´t know if the bike will be better or be an expensive waste of money. I want my bike to road not to race, but I only owns one Norton and I would like to have it top of the line.
Best wishes
Alfonso

Stay with the factory rods then, magnafluxed and maybe polished and
shot peened, lighter and cheaper and not a weak link in road worked
Norton.

hobot

front iso and head steady are new;

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This may be a clue. The Norvil headsteady needs very careful setting up and can also contact the tank if its a Roadster. I see yours is a Roadster. Take a look at the underside where the mount could be touching. From what I have read it does increase vibration to a point where it is noticeable at higher revs.