OIl leak from kick start

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MATTT

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Jan 5, 2010
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found out why there was no oil in the gearbox then :)

its leaking out of the kickstart shaft,looks like the oil seal is inside the casing?

just wondering if theres an easy way to get to it,as in just the outer casing removal and replace the seal

just worried in case the gearbox gears fall out when i undo the side case!

thanks
matt
 
MATTT said:
found out why there was no oil in the gearbox then :)

its leaking out of the kickstart shaft,looks like the oil seal is inside the casing?

just wondering if theres an easy way to get to it,as in just the outer casing removal and replace the seal

just worried in case the gearbox gears fall out when i undo the side case!

thanks
matt
Click to expand...

There is an outer and inner cover. You just need to remove the outer cover. Nothing will fall out, just oil.
 
MATTT said:
found out why there was no oil in the gearbox then

its leaking out of the kickstart shaft,looks like the oil seal is inside the casing?
Click to expand...

Unless your Commando (or its gearbox) spent quite a while laying over on its R/H side then is highly unlikely that all the oil will have leaked from the kickstart shaft seal?


MATTT said:
just wondering if theres an easy way to get to it,as in just the outer casing removal and replace the seal

just worried in case the gearbox gears fall out when i undo the side case!
Click to expand...


No, there's nothing to worry about, just remove the kickstart shaft, remove the outer cover and replace the seal (a 'quad' or 'x' ring seal works better apparently) although the case can be modified to take the proper 850 MkIII seal?).

However, what does concern me, is that you seem intent on putting the gearbox back into service without a full strip down?

I would urge you most strongly to reconsider, if that was what you are intending to do?
As a bare minimum, you need to inspect and change the layshaft D/S bearing if it is found to be a standard ball race?

Replacing all the old springs could save you a breakdown too, especially the ratchet spring, if it breaks then the box will be stuck in whichever gear it's in when it breaks, and while you're at it, the kickstart pawl and 1st gear bush are probably best replaced, along with all the oil seals?
 
hi there
sounds like not too bad a job then

i only noticed the oil was really low when i went to change it last week and hardly any came out

so this leak must have been why,its proably got worse as the bikes not been on the road for 3 yrs

as for a complete gearbox strip and rebuid,i wasnt planning on it as i know the prev owner well and it was running fine so i dont feel the gearbox needs rebuiding..famous last work i know! as it will proably break now !

i will just fit the seal and run it as im hoping to get it all up and running when the brake master cylinder comes back in 3 weeks time
 
Mattt, L.A.B.'s remarks are not simply the throwaway comments of someone who can rebuild an AMC box blindfolded behind his back whilst subjected to white noise. These boxes can and do fail catastrophically, in particular the layshaft bearing. If this happens, there is a grave danger (and to steal a line from the NOC 'Service Notes' this means a danger that can rapidly lead to the grave) that the box will lock up.

This results in a situation which is known technically as 'Up shit creek, paddling with your hands' It is to be avoided at all costs.

The Commando box has no nasty shims and circlips to misplace and is virtually impossible to put together incorrectly using instructions freely available on the internet.

I second wholeheartedly Les's suggestion that you really take the opportunity to examine the box now. It has had a known oil level problem and even without this can fail. If the box had only leaked whilst stationary, there would be a big sticky puddle underneath it and the garage would smell of cat's piss. If not, then it's likely that the bike has been run like this.
 
Mattt, where are you located? Gearbox rebuild is really not difficult, and as pointed out, there are GREAT online directions, with pictures (in Old Britts.com "technical" section). If you're in the Boston area, I'd be happy to help if you are queasy about going it alone. Been there, done that, got the tools.
 
hiya there

im in the uk in surrey

i hear what your saying about the dangers of the box failing
i will have a chat with my dad , as he part owns the bike and see what he thinks,also i will chat to my friend who owned the bike and see if he ever had the box rebuilt

i do think though most of the oil has come out whilst standing , not whilst it was ridden due to its being in long term storage
he used to just start the engine and not ride it and the last time it was taxed was about 6 yrs ago i think

i will have a look at some of the gearbox threads and see

i assume the gearbox comes out without having to remove the engine though?

thanks again for all your help

matt
 
MATTT said:
im in the uk in surrey
Click to expand...

Matt,

Why not add that information to your profile? As it often helps if we can see at a glance where members live.


MATTT said:
also i will chat to my friend who owned the bike and see if he ever had the box rebuilt
Click to expand...


What you really need to know is whether the layshaft drive side bearing has been upgraded to either a roller bearing or the special phenolic cage high spec. ball bearing as recommended by Mick Hemmings?


MATTT said:
i assume the gearbox comes out without having to remove the engine though?
Click to expand...


It isn't entirely necessary to remove the gearbox to do this work, but you may need to tilt the engine forwards in the cradle slightly before you can get the gearbox out?
 
i will try to find that out then

i need to have a look through all the papaerwork 1st to see if theres any stuff in there


thanks Keith,nice to know and your only up the road too....

dont worry i wont turn up in the dead of night with a brown paper bag full of gearbox internals that i cant get to fit back in ! :)
 
This thread has been really interesting as it has caused me to pause and reconsider my plans. I had not planned to disassemble my gearbox due to the low mileage on my bike (3400 on a 69). My only real concern had been the fact that it's been sitting for a number of years and something could be frozen by rust as opposed to worn out. I really don't want to disassemble anything I don't have to (the project has already gone way beyond what I expected) but I want even less to go back and take the thing apart again after it's been reassembled (after having ridden out some dreadful occurance). :shock: Given the concerns expressed by those much more knowledgeble than me, that might not be the best choice.
It's currently disassembled to a bare frame with the engine/gearbox still in. The front iso is out so the engine is supported by the headsteady and a wooden block. As I recall, the manual shows the engine/gearbox coming out as a unit. Is this necessary? as it looks like it would take a strong back for that much weight, or is it possible to just get the gearbox out around it? Also, is there a standard re-build kit available from Mick Hemmings or must the parts be purchased individually?
 
Gearbox can come out by itself, and given it's a PITA when the bike's fully assembled, now is the ideal time to do it.

No idea about parts on your side of the pond but Mick Hemmings would be a good guy to contact about them. I used his gearbox video as a guide to rebuilding my box and it was quite helpful.
 
well
decided to heed advice and strip the box

ive left it for a while whilst i rebuilt the front caliper and had the master cylinder resleeved as i didnt like the idea of the bike in too many bits !

so today i took the gearbox outer cover off to be sent away for the 2 oil seals to be machined/fitted

i need to get a whitworth set of sockets,anyone know the size of the nut on the mainshaft as the sets all seem to go up to a 5/8 i think it was or if not i can buy a bigger set with more than 7 in it

ive undone the inner case bolts and by gently tapping it ive broke the gasket seal and managed to gently pull it away by a about 3 mm

i had to leave it there as i ha to get home, but it did seem well stuck in there,although ive not undone the mainshaft nut yet

im going to try and get the layshaft out with the box still in the bike,is this a bad idea??
 
MATTT said:
anyone know the size of the nut on the mainshaft
Click to expand...

Hexagon should be 1/2W (or 9/16 BS). Although I think either a 15/16 A/F or 24mm socket would be close enough?


MATTT said:
i had to leave it there as i ha to get home, but it did seem well stuck in there,although ive not undone the mainshaft nut yet
Click to expand...


Yes the nut needs to come off first.


MATTT said:
im going to try and get the layshaft out with the box still in the bike,is this a bad idea??
Click to expand...


No, there's no problem, if the layshaft bearing is the original ball race, then the layshaft can often be a fairly tight fit in it, but that can be used to advantage, as the layshaft is used to pull the bearing from the case,-once the case has been heated, and doing this in situ can make it a little more difficult to apply sufficient heat to the casing around the layshaft bearing-unless the inner primary case is removed.
 
Instead of replacing that worthless oring with another, here is a simple and effective solution.
You must still pop the case off. Then heat the case around where the oring is with a propane torch or heat gun to pop out the kickshaft bushing. You can buy this seal Timkin #240731, seal number 9815
1.25 x 1 x .125 at your local oilseal dealer for around $6.00.
 
Hi Mattt,
I'll put in my two cents worth of info. I did my layshaft bearing replacement a few years back and was able to do it with the tranny case still in the bike, I can't remember but I think the I had left the primary case assembled (IE mainshaft still intact). I was able to pull the old bearing out using a small slide hammer with a bolt screwed into the end of it. I had ground the head of the bolt just thin enough to be able to get it behind the inner race of the bearing, then alternating side to side slowly tapped it out. Carefully applied heat with a propane torch and/or heat gun makes things go easier, and if you can fashion some sort of bearing driver for install purposes that will also help imensely.

GB
 
thanks for the tips regarding the slide hammer

regarding the seals i was going to send the outer cover off to get it machined and replace both seals with better ones

ive found a 24mm socket but the nuts tight enough that the engine just turns over when you try to undo it

hoping not to have to get the box out still as the mainshafts looking like im going to have to lock it in place somehow to stop it turning
 
MATTT said:
thanks for the tips regarding the slide hammer

regarding the seals i was going to send the outer cover off to get it machined and replace both seals with better ones

ive found a 24mm socket but the nuts tight enough that the engine just turns over when you try to undo it

hoping not to have to get the box out still as the mainshafts looking like im going to have to lock it in place somehow to stop it turning
Click to expand...

Air impact wrench will get it off.
 
Well got a long wrench and a couple of quick pulls and its off

got the layshaft out with the bearing stuck on the end of it , just need to work out how to get it off the shaft now

the bearing had a name on it,i cant remember now im home what it said,spoke to RGM and was told it was a standard roller bearing but a good quality make
it looks fine but ive ordered a new one along with a gasket set and the improved x type o rings seals

couple more things i need to know,do i fit the new bearing onto the shaft 1st or loctite it into the casing and push the shaft in afterwards?

im hoping the shaft wont need shims as ive not got a dial indicator,is there a way to feel how much play there should be? not an accurate way i know,the RGM guy said it may well not need shims but how will i know without using a guage?

checked all the gears and they are fine,only thing im replacing is the kickshaft pawl which is worn

thanks again
matt
 
While it is out, take a good look at the bushings in the gears and their fit to the shafts. Now is the time to replace any worn ones. Pay particular attention to the sleeve gear. It should have at least two bushings.

If the gearbox did much mileage without sufficient lube, these bushes could need replacing.
 
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