Stripped lay shaft nut on output shaft

[amamet]

I have a feeling that the lay shaft nut may be too rounded over for me to get off. Granted i don’t have the proper tools for the job right now, I’m just wondering what can be done if it is too rounded over

[Tom H]

Get the right size deep socket and grind/sand it down so that there is no taper in the tip. That MAY get it off. That is what I did for a good nut. I can find the size latter if needed. I THINK??? it was a 27mm. Measure or wait to be "fairly" sure.

Tom

[pehayes]

I tried to look at the pics carefully.  It seems that the external collar may have been punched into the splines in several places.  Get those all free to start with.  You really need to work with a deep, 6-point socket so that you make contact with the hex flats rather than with the hex crown tips (which are now all gone).  If you can't get enough grip to release that nut free from the shaft then I have no idea how you would proceed into the future.  A specialty EDM or Spark Erosion shop?  Could be costly.

Look carefully at all those splines.  Look from directly aft with a bright light.  ONE of those spline grooves goes down into the shaft much further than the others.  At the bottom of that one groove, behind your damaged nut, lies a steel bearing ball.  The collar  you see which is peripherally outside of your damaged nut and which rides against the surface of the rubber seal is actually an external portion of the speedometer drive gear.  The ball bearing in the groove merely acts like a woodruff key and keeps the speedo drive gear from spinning on the shaft.  It MIGHT be possible to drill or punch cut the damaged nut down through that one deep spline groove.

Now would be a good time to pull the other portions of the speedometer drive.  See the brass hex above and right of the output shaft.  Pull that housing.  Careful, it has a hardened steel thrust washer.  The thrust washer may come out with the surrounding body or it may come out with the central worm drive shaft. Once the worm drive shaft it out, probe down to the bottom with a magnet.  There should be a second,  hardened steel washer below the bottom of the worm drive shaft and resting on the cast aluminum shelf.  Just make sure to get all those bits out of the way.  The speedometer drive bits look like this:

https://hmb-guzzi.de/Speedometer-drive-5-Speed-Gearbox-Revised-version

I have heard that earlier 5-speeds may have  had only one hardened thrust washer.  This picture shows two.  One is  hard to see between the black gear and the silver housing.  The other is loose and goes over the beveled tip end.  You can't install it all as one piece since the lower thrust washer won't pass the larger drive gear on the output shaft.  You have to carefully reach in with a probe wire and slide the lower thrust washer into position on the support shelf.  Then  you can install the worm drive gear and probe it into the center of the lower washer.

I can't attest to this but I think it will work.  I do know that it is possible to remove the rear cover with the output shaft and all its associated parts still in place in the cover.  Remember, the output shaft is held into its carrier bearing by your damaged nut and the carrier bearing is merely pressed into the rear cover casting.  Once opened, it may then be possible to press forward on the output shaft and thus push the output carrier bearing and these speedo bits forward out of the cast cover.  The nut and speedometer drive are smaller than the carrier bearing and so should all press forward with the shaft.   I'm just not sure if there would be any further interference from casting area around the speedometer worm drive hole.  I don't have a 5-speed cover handy.  I do have a 4-speed rear cover.  Same output logic.  And it surely looks like the shaft/bearing/speedo would all press forward out of the casting once the rear cover is free from the transmission.  Once you have the shaft free of the rear cover it would then be a simple Dremel job to slice and split and remove the output shaft nut.  Likely you would also have to slice and destroy the speedometer drive gear body which surrounds the damaged nut, but those are all cheaply replaceable parts.

Patrick Hayes
Fremont CA

[Doug McLaren]

As Patrick suggests it is possible to drill down into the nut and split it. I had to do exactly that many years ago. You'll need a decent bench drill, slow and steady wins the race.

[Kiwi_Roy]

Yes the locking ring is punched into the spine to lock it in place, drive something in there to bend it back out again, an old screwdriver perhaps.
While you are there might as well refurbish the box with new bearings and seals.
I can highly recommend John Noble's "Inside the Lemon Box"
http://www.thisoldtractor.com/guzzitech.dk/pdf/gearbox-rebuilding-john-noble.pdf
If you are going to order some parts replace the Pawl spring, mine broke in two while I was working on the box, I think it must have been cracked.

[LesP]

Being to far away location wise this (6 point) socket would most likely get it off with pressure applied to the top of it so it could not rise..

I think the trick (already posted ) is to get a 6 point on there and in a way that it can not rise ruining what is left of the hex.
If you were careful (and the punched sections are raised from the spline as posted) you might be able to undo the nut the fraction it needs to break the torque with a chisel or heavy pin punch but there would be no going back after that (The shaft would need to be stopped from turning)... It could be tight or it might not be so tight at all.

[Kiwi_Roy]

This is how I held mine, an old clutch plate and a piece of aluminium strap. Put the box in top gear to do the output shaft.

To hold the box while torquing the nuts bolt it to an 8 x 2 (the strap is out of sight)

[LesP]

I did some Sunday baking for mine.
Half machined Acetyl then pressed the old hub in, bake until you hear the ring (slide) drop off the hub.
I used the stock type ring fastener on the input shaft.

I remember the struggle in the beginning, nothing is to much trouble these days to make things easier, but of course I feel the pain (pita) of those days reading this thread.

[Old Jock]

As Roy said and others

1) The layshaft nut still has the staking ring bent down in place, it's at about 12 and 9 O'Clock in the 2 respective pictures, you'll need to force that up first.

2) It looks like the nut is indeed rounded and the hex that can be seen is the section that's covered by the shroud on the end case

3) As said by others you can split it with a cutting wheel by going along the deep splines so you don't muller the thread. I had to do this a while back on a Sporti, with the box in situ. It's not a fun exercise but perfectly doable. Cut in as far as you dare then either cut all the way throug to split it or cut in sufficiently deeply to weaknen the nut then a jewellers screwdriver or a pointy tool on the split and batter it with a hammer until it starts to move.

I actually used a Dremel with a small router head to cut it as I didn't have a wheel short enough to get access and it was softer than I thought. Just what I did

https://wildguzzi.com/forum/index.php?topic=100237.msg1585318#msg1585318

John

[amamet]

for those saying use a deep socket, say I get a good bite, how do I keep the shaft from spinning as I try to remove it? put it in gear?  I know there's a through socket available from mgcycle then the shaft can be held with another tool they sell or part of a ujoint clamped in  a vise or something.  I have standard tools and cannot mill, lathe etc..
thx
allen

[Stevex]

for those saying use a deep socket, say I get a good bite, how do I keep the shaft from spinning as I try to remove it? put it in gear?  I know there's a through socket available from mgcycle then the shaft can be held with another tool they sell or part of a ujoint clamped in  a vise or something.  I have standard tools and cannot mill, lathe etc..
thx
allen

Impact driver will get it off without having to hold the splined shaft, that's what I used. Came undone in a couple of seconds.

[Old Jock]

Put the gearbox into 1st (I think) you're looking for the max movement on the input for smallest movement on the output to reduce the torque if I have it correct. If I've got it the wrong way around then it's 5th

I'd wholeheartedly agree with using a 6 point socket, I usually use a long 6 point impact socket on that nut as it grabs the flats, a 12 point grabs the corners and is not up to the job, as that nut is at a zillion torques 

Is the box out on the bench or in the bike (I'm guessing in the bike)?

IF the box is out the bike

You'll need to put on the clutch hub and use a tool like Les P showed you in the bottom picture, I'm in the UK and got one from Stein Dinse, it wasn't that pricey as I recall.

Either that or magic up some other ingeious method to stop the clutch hub turning.

If the box is in the bike

Put the bike into gear and try it.

I'd initially put the socket onto the nut and try it, the engine should hold it sufficiently to give you an idea if the socket is biting or the nut hex has been rounded beyond redemption.

If the socket does bite on the nut I doubt you'll be able to lock the shaft sufficiently to get it off, the engine will most likey start to rotate.

You could then also drop the pan and extender (if you have one) and  jam some wood between the crankcase side and the web on the crank to lock the engine. Personally I wouldn't try to hold it on the Alternator nut as you could damage it or undo it, I can't remember which way the engine turns when you turn that shaft anticlockwise

I magnified the picture and I'm sorry to say it looks very similar to mine when I was in this position, however if it does bite then perhaps you've been lucky

 



When you look it appears like there is enough hex to get a grab on it with a socket. Unfortunately that's not the case as the section with the hex still showing is inside the recess in the gearbox endcase, so you cannot get a socket in there.

Dremel and a router worked well for me but as I said it's not a fun thing to do and takes a while as you need to go at it pretty slowly and carefully to ensure you don't damage the layshaft threads. If that happens then you're into a strip and need to find a layshaft (expensive, a hassle and a prolonged delay). When I cut the nut off, the box was in situ in the bike with the swinging arm removed. I'm about average with tools (on a good day)

EDIT Just to add once all the stakes have been levered up but (if you do attempt to try and cut the nut) as suggested by Patrick already I'd try with a flashlight or something like a toothpick or even a needle or whatever your probe of choice is, push it up through all the splines. You will find one is longer than all the others (it's used to hold the speedo locking ball) and then cut the nut at that slot. The ball might get damaged but it's just a small ball bearing and you should be able to get a replacement if you need (but I think it would be Ok).

It's also possible to cut the nut in one of the shallower grooves but you won't be able to cut right through the nut without increasing the risk of damaging the shaft. In my case I drilled through using one of the shallower grooves but then had to take a hammer and punch to it as I couldn't drill further without risking damage to the shaft. You can see how far I got in the above pictures, but if I had to do it again (God Forbid) I'd defo try to identify the deeper spline

(there's some more info in the gearbox strip guide I wrote a while back and given in a link by Kiwi Roy earlier in the thread)

Picture of the layshaft below

Impact driver will get it off without having to hold the splined shaft, that's what I used. Came undone in a couple of seconds.

If the nut is partially rounded but not totally gone my opinion (for all that's worth on here) is that an impact will finish the rounding for you. That's the normal way to remove the nut and it's what I'd use if the nut is in good condition, but if it's damaged I think it will do more harm than good

I'm guessing that you will now make sure you remove lock tabs and stakes in future, I'm not trying to be smart I've done it myself and the grief you end up with is on a whole new level.

Just what I'd be doing if faced with where you are now and I have been!!!

Good luck with it

John

[Moparnut72]

Work on old outboards. When I have a stubborn flywheel nut and need to lock the engine. I pull a spark plug and fill the cylinder with nylon rope with the piston at the bottom of its stroke. After trying to compress the rope which it can't do, the engine is locked. No damage to anything, when finished just pul the rope out. An accepted practice in the antique outboard world. Too bad there isn't a little more space between the the nut and the case to be able to use a turned down socket.
kk

[acogoff]

      No milling machine or lathe in my garage. I just have a cutoff saw and a welder and came up with this set up. Just a cutoff 6 point socket welded to a piece of 1/4 steel and an old ujoint to hold the shaft.
   

[Tom H]

Here are some pics for you.





I have never tried it, but if you remove the input shaft spline/gear, a broken U joint may fit. Here is what I use to hold it.





The same flat piece of metal can also be used to hold the flywheel. Use a bolt to the flywheel and hook it over the bell housing stud.

Tom

[Old Jock]

Any update on this?

[amamet]

Ordered sockets from amazon. May get them today I think. Update coming 😺

[amamet]

welp, got the nut off, thx for all the help.  used a cutoff wheel on my grinder to get a nice flat surface on the 27mm socket and then I welded (poorly, but it held) a peice of flat bar to an old clutch plate to hold the spline hub in place

[pehayes]

Were you planning to disassemble the box now that you have the output nut off?  IIRC you complained that the output shaft and nut were floating in and out relative to the rear cover.  That shouldn't be happening.  I suspect that the output bearing has come apart or else the output bearing outer race  has spun and become loose in the rear cover casting.  Only disassembly will prove that.  If that wasn't your symptom, please clarify.

Patrick Hayes
Fremont CA

[amamet]

yup Patrick, output shaft was moving in and out.  I pulled off the cover and the big chunk of metal on the bottom may be a clue.  one of the gear forks is kaput.  ive never been in a transmission before so im going to use this one as a learning tool and look to buy one to put in the bike.  there's no way I'd ever learn to rebuild a tranny without good reason, well I have a good reason now.

[Old Jock]

Well I'm not going to push my "How To" anymore, on the box disassembly and reassembly, it was just something that I thought you may have found useful if you've not been in there before.

The box is actually pretty straightforward and it's a good time to check and shim the selector drum should it need. It makes quite a difference to the change if it wasn't shimmed properly in the factory (and a lot weren't)

Only other thing that will be a pain when pulling it apart is the peg nut to undo the clutchshaft at the front and it's also pretty dammed tight and it too has a locktab washer behind it. You don't need to pull it to get all the other stuff out, but if the bearing on the layshaft is questionable or there is other damage in there I'd be pulling it to check the Clutchshaft bearing too.

I'm guessing you're in the US, if you'd been in the UK I could have loaned you my pegnut socket.

Glad you got the layshaft nut off.

As Patrick stated there should be no play on the Layshaft or the Clutchshaft for that matter. The nuts that retain them pull them up tight into position (that's why the nuts are torqued to a high value) Depending on the amount of play you have it could lead to further damage or in an extreme case the possibilty of the box locking up.

John