Lay Shaft Bearing? Really???

In October of 09, I had some transmission work done on my MK III. I noticed the kick starter would move on acceleration from a stop. The work included an upgraded lay shaft bearing and a couple new bushings. Since then I believe I have put less than 2,000 miles on the bike (That is another story all together). A couple of months ago I returned from a 100 mile ride and noticed the kick starter moving when I started from a stop again. I parked the bike until my mechanic can free a space to look into it. This week I decided I needed to verify that the kicker was really moving when I start out.

When I first started the bike all was solid. There was no movement in the kicker. I even locked up the brakes and loaded the transmission with the clutch and engine. I took the bike out for a ride and noticed, as the transmission gets hot, the kicker starts moving under first gear load. I can lock the brakes and create the kicker movement with the engine and clutch.

Is there something I am missing? I am assuming this isn't normal and I am afraid to ride the bike for fear of blowing something up. What should I look for, or am I reading too much into this?

Sounds iritating , First thing I would do is get the gearbox oil turbulent with a small drive then pull the small gearbox drain plug and drain the oil into a pan ,visually inspect the oil in god light for metal particulates, searching for grey-silvery metal or fine brass bits. Get back to us with results. Clear oil would be good.

Perhaps the kickstart spring needs a bit more tension.

Cash

I rode the bike around my neighborhood this morning hopefully enough to stir the oil in the transmission. I drained the oil and found lots of gold glitter in the bottom of the pan. It was mostly very fine particles, but there were some flakes as well. I also found a couple slivers of a dark grey or black metal material. Forgot to try them with a magnet.

Kicker shaft spring tension: I had a friend hold the kicker back a bit while I had the bike under load. He said he could feel some resistance in the mechanism when he tried to move it back and forth a bit.

That is all I have been able to figure out so far.

Bueller?? Anyone???

calbigbird said:

I drained the oil and found lots of gold glitter in the bottom of the pan. It was mostly very fine particles, but there were some flakes as well. I also found a couple slivers of a dark grey or black metal material. Forgot to try them with a magnet.

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Maybe the layshaft 1st gear pinion is rubbing against the inner end of kickstart shaft or the timing side layshaft bush (insufficient end play?)?

Or the layshaft 1st gear bush has moved and is rubbing against the end of layshaft bush, or the 1st gear bush could be breaking up?

I would of said exactly what LAB did but I thought the tranny had recently been renewed. The weakest wear item it the too commonly seen photo LAB left, though they can completely break up soon after that still half way functional state. There is danger of popping out of gear when going slow for neutral engine drag/power load and drop your ass with tail sling out the blue.

Its a tedium job to fit new bushes so is tempting not to bother if still shifting or not dragging kicker down.

There is one other possibility I don't know if could do this, if primary chain/belt is thermally straining the main shaft to put a bow in it length to bare on lay shaft and kicker?

THanks LAB, I guess I won't really know until it gets torn down - again. RATS!!!

Put in clean oil and try a ride again ,if trouble persists teardown and new bush(s) The 1 st gear bush is so delicate and could be breaking up causing jamming. Any way you look at it that puppy is comin' apart. Sorry ,get back to us.

My bike worked fine, although the sleeve gear bushings were worn. It's a project but worth it. Here's some info I found at NOC I think. There's some info on the circlip too.

"Sleeve gear bushes are always coming loose-sometimes the outer bush moves inwards to the centre of
the sleeve gear-then all you need do is to Loctite a new bush in the end. Leave the old one in and it will
prevent the new one moving inwards, i.e. fit three bushes in your 750 a la 850. Sometimes the bush
moves outwards and gradually mills itself away on the sharp edges of the circlip which locates the clutch.
That’s worse because eventually the bush disappears completely and all the pull of the back chain comes
on the sleeve gear bearing. No wonder the bearings come loose. Often the first sign of sleeve gear
bushes going -is striking "gold" in gearbox or primary drive oil, watch it! Here the answer is to buy two
new bushes and a clutch location shim (060894 or 060895). Push both bushes-Loctited on the outside--
into the sleeve gear--the middle one stops the outer from moving in-and then put the shim loose on the
shaft to avoid the bush wearing on the circlip even if it does move. It is an advantage to grind the outer
edge of the shim so it will pass through the hole in the primary case (or file or even clip it away with tinsnips
to about half the radial thickness).

Due to its position, the width and depth of the groove is rather diffcult to measure, and although the circlip is circular in cross-section, the groove appears to have a square-cut profile, only wide enough to accept the circlip and is cut to a depth of approximately half the circlip's .047" wire diameter.

With the circlip installed in its groove, the circlip's I/D is: .870". (the bush I/D measures up at .810")

The distance from the end of the sleeve gear to outer edge of the groove is .040"

064991 (850 MkII/IIA single circlip type sleeve gear)"

Dave
69S

Finally I got a bit of a reason for my transmission problem. I took the bike to someone who knows the Norton transmissions. He said, a 4th gear is bad. I also looks as though the bearing on the end of the shaft has pulled out of the race and is allowing end play. This in turn may be putting stress on the end of the kick start shaft. He will replace the 4th gear, replace any bushings that may be damaged and locktite the bearing in the race so it won't move. At least, that is what I think he said. For all I know he could have told me the framis is broken where it connects to the gozenta and the flux capacitor isn't modulating properly as a result.

Short version: the transmission is sick and needs to be fixed. Thanks to all who gave suggestions.

Just curious CBird, who did you take the bike to? Someone in our area that knows "Norton" gearboxes well? Please do tell. Glenn.

If the bearing bore too big, I've never heard of any success with mere locktite, only JBWell. Bad bores have left literally piles of AMC C'do boxes useless but Al scrap at vendors all around the world, I know because i've contacted about all them world wide a few year ago. Altas boxed at half the price solved Peel deal and fit better to boot w/o the dam thick washer to bang about for no good reason. It takes a real machinist to get the bushes fitted so don't feel too guilty to farm it out and ride the booger.

I have to wonder what kind of trans you have there that has a 4th speed gear on the layshaft. Jim

Unfortunately Jim, even the original factory parts book lists 'layshaft 4th' which is a bit odd really as it's taking no load at all when in top.

What should we be calling it ? 'Layshaft first, second and third' ? ' :roll: 'Layshaft output pinnion' ?

I have to say I have never looked at the name in the parts book but you are right they are calling it fourth gear. They must have been standing in front of the bike and started counting on the left to get that because it sure doesn't have anything to do with fourth speed. ??? Most manufacturers call it the drive gear or transfer gear. Jim

comnoz said:

I have to wonder what kind of trans you have there that has a 4th speed gear on the layshaft.

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BSA, Triumph, Norton etc. parts books usually refer to that gear as layshaft 4th (or 5th) or high gear, even though in reality it isn't.

L.A.B. said:

comnoz said:

I have to wonder what kind of trans you have there that has a 4th speed gear on the layshaft.

Click to expand...

BSA, Triumph, Norton etc. parts books usually refer to that gear as layshaft 4th (or 5th) or high gear, even though in reality it isn't.

Click to expand...

Obviously it's because after you try a burnout and strip all the teeth off that gear. Then 4th is all that is left to get you home.

Like I said, I don't really know gear boxes I just tried to relay what I was told. I may have mistaken something.

Final answer

Got my bike back from the mechanic today and here is the final answer. Apparently, the 4th gear bearing was moving in and out of the case and pushing on the layshaft 4th bear. This in turn put pressure on the kick start shaft and caused it to move much like a bad lay shaft bearing. He fit a new bearing by peaning it and using green Locktight. He replaced the main shaft bearing and seal, peaned and use Locktight on the cam plate bushing (was leaking oil out the shaft on the front of the trans case).

Also, on my request, he changed from a 19 to a 21 tooth drive sprocket (my request to lower freeway RPM). I know, a MK III should have a 20 tooth drive sprocket, but this is the way it was when I found it on FleaBay. I only got to ride it around my neighborhood before other priorities took over, but it seems to be running great and shifting perfectly. Hopefully tomorrow or Monday, I will be able to give it a proper ride.

Thanks for all the suggestions given on my original post.