Date: Mon, 12 Aug 1996 22:47:57 +0100 (BST)
From: "D.J. Walker" <djw12@leicester.ac.uk>
Dear All,
The problems with this Commando gearbox, i.e. the shifting of the kick
start lever and the tendency for the wheel to turn when kicked over in
neutral indicate serious problems with the layshaft. Your lack of apparent
compression is also worrying. Can you hear the breather pipe sucking and
squelching inside the oil tank as you kick the engine over. This sound
should be produced if you have anything resembling a pair of pistons inside
your engine. If you can't hear it, then your primary drive has severed:
you are not turning your engine over. A broken chain would be a cheap explanation
for this, but given the gearbox symptoms, appears unlikely.
I'll be honest, this post does little to address your immediate problems: you're going to have to crack that gearbox open, and what you find inside will almost certainly be self-explanatory, as to the cause. The symptoms you describe are not caused by minor faults.
This post is merely intended to clarify the way the AMC gearbox works to those new to it.
The AMC gearbox is a tremendously strong design, and obtains its compactness by running several shafts coaxially, one inside the other, in a way that is familiar nowadays, but which was fairly new when this gearbox first appeared.
The mainshaft runs above and to the rear of the layshaft. It is supported at its outer (right-hand) end by a composite ball-race bearing, at its inner end by the interior surface of the slevegear shaft, which in turn, rotates inside a composite roller-race bearing in the gearbox inner shell.
The layshaft is supported at its inner end by a composite bearing housed in the gearbox inner shell. At its outer end, it runs _inside_ the Kickstart shaft, coaxial with that shaft, on a bronze bushing which sits inside the hollow core of the kick-shaft.
If the layshaft gets misaligned, it will bind on the inside of the kick start shaft, causing both shafts to turn, as though they were one. This is most likely caused by disintegration of the layshaft composite bearing at the inner end of the layshaft.
Under normal circumstances, drive is transferred from the mainshaft to the layshaft via a set of sliding gear couples, and thence to the slevegear by the layshaft "top" gear pinion.
(If I get any of this wrong, get straight onto it, and point out the error of my ways!)
First, here are the two sets of gears, drawn schematically:
Mainshaft Gears
Sleeve gear (f)
Final drive sprocket
3rd (s)
/
/
2nd (f) \
__ /
_ /
1st (s) \
\__ |--|
/_\
\
\__ |--|
|__|
|/ \|
\__ |--|_
__|__|__ | |________________ | _ | Mainshaft
.-|--|-. .-|--| |_ |_ |__|__| _|--|
- - - - - - - -||/ \| passes thru
| |__| | | |__| _| _|| ||_
|_|__| _ _ _ _ _ _ _ _|| | ---->
`-|__|-' `-|__|_| |__|--|__|
| |________________||\_/| here, to the
__
|__| |__|
|--|
| | clutch basket
|--| __
|__| |__|
|\_/|
|_ | _|--|
__ |__|
\_/
Kick || |_|__|___ _|--|__
__ Layshaft inner
Shaft\ || _| | _| _||--|
| .-|--|-. end, composite
in \|| |_|--| |_ |_ |__|
| | |__| | bearing here.
here. || _|__|___| ||__|__|
`-|__|-'
_|| |_|__|
|__| /
|__| |__|
/ "Top" (s)
|__| /
3rd (f)
/ 2nd (s)
1st (f)
Layshaft Gears
The lands for the dogs have been left-off, on the relevant gears, owing to lack of space in ASCII. Those of you reading the next bit will have to imagine the gears moving back and forth by telekinetics, or something.
The code (s) after a gear signifies that it is locked to the shaft it turns on via a set of splines. The code (f) signifies that it can freely rotate on a smooth bronze internal bush, and is not, itself, locked to the shaft on which it spins.
The 1st gear pair, and the layshaft "top"/slevegear pair, never move, and remain in constant engagement with each other, whatever the gear selection. Layshaft 1st, and the slevegear are not splined and are thus free to turn on their shafts unhindered, unless they are locked into place by sliding the neighboring gears up to mesh with them.
When the Kickstart shaft is turned, its ratchet paul springs free of its housing in the gearbox outer shell and engages on a keyway built into the inner circumference of layshaft 1st gear, causing this gear to rotate. The layshaft doesn't turn, because 1st gear is free to rotate on it when in neutral. Rotation of layshaft 1st gear turns the mainshaft 1st gear, turning the mainshaft with it, and so too the clutch basket at its far end, turning the motor over.
_ Mainshaft
1st gear turns |"""|
_
TURN / \ \ _
| | / \
MAIN | _. _| |________________________|
| | TURN CLUTCH
SHAFT \_/| |_ _________________________
| . _ | BASKET
|_| /
| | |\_/
__\
| | Mainshaft turns |
|
TURN / / ___||
|...|
KICK | .------___||____________________ \
SHAFT | | |_________________________|
Clutch basket
| `------___||
\
\_
/ || \
/ |_| Layshaft (stays still)
Kick-shaft
\
Layshaft 1st gear
(turns with kick-shaft)
When first gear is engaged, the dog on layshaft second gear slides the gear outwards (rightwards) until the crescent-shaped blades on it's outer face bind with the circular holes on the inner face of layshaft 1. Since layshaft 2 is fixed on it's shaft by splines, layshaft 1 & 2 now turn as a pair, turning the layshaft as a whole with them. The two are turned by the mainshaft 1st gear, and transfer drive in to the "Top" gear, fastened at the far end of the layshaft. This turns, rotating the slevegear, thus turning the final drive chain.
This is shown below. 1st gear selected, drive goes down the mainshaft to mainshaft 1st gear, over to layshaft 1st, which is locked to the layshaft by being coupled to layshaft 2nd. Drive then transfers up layshaft to layshaft "top" pinion, which transfers it back across to the sleeve gear.
Sleeve gear } Turn at
_
/
}- different
| |
_______/ Mainshaft } speeds
___| |______________________|---------|_____/
---| |----------------------|_________|-----'
|-| layshaft
| .-------'
| |_ <-- 2nd gear shift |-|
_| | |-.________________.-| |-.
-| | |_|----------------|_| |_|
| |_|
|_|
|_| \
"Top" gear pinion
\ \
\ Layshaft 2 }_Locked
Layshaft 1
} Together
Second and third gears select in a similar way to each other. In second, the freely rotating mainshaft 2nd gear is locked to its shaft by being coupled to the splined mainshaft 3rd gear pinion. Drive is transferred from mainshaft 2nd to the splined layshaft 2nd, along the layshaft to layshaft "top" pinion, and over to the sleeve gear, as before.
Mainshaft 2nd
}__Locked
\ Mainshaft 3rd}
Together
\
\_ _
\_|
| | | Slevegear
|
| | | |__________/
______| | |_________|------------|______
------| | |---------|____________|------
|_|
| | .----------'
|
|_| |-|
_____| |___________| |__
-----| |-----------| |--
|_|
|_|
/
/
Layshaft 2nd
layshaft "Top"
The 3rd gear selection is similar to the above: drive is transmitted off the splined mainshaft 3rd, to the layshaft 3rd, which can freely rotate, but which is here locked to the layshaft by being forced into combination with the tabs on the splined layshaft 2nd gear. Drive is then delivered to the layshaft "top", and thence back to the sleeve gear.
The layshaft and layshaft "top" pinion, play no part in the drive during 4th gear selection. Instead, mainshaft 3rd gear is slid along the mainshaft until the tabs in its interior end engage with the tabs on the right-hand end of the slevegear. By this method, the smooth-bore sleeve gear is locked to the mainshaft by being mated to the splined mainshaft 3rd. Drive now travels direct to the slevegear via the mainshaft. Both are locked together and turn at the same speed, as a unit.
Layshaft "top" pinion still turns, of course, turning the layshaft with it, but it does no work.
Mainshaft
_
3rd gear shifts -->
_| |
/
| | |__________
/
|
_______________| |------------|_____________ |
| _. ---------------|
|____________|------------- | _.
\_/|
| | .----------'
\_/|
`-| |
/ `-'\
Mainshaft 3rd Slevegear
Locked together and turn as one
Thus four gears are available using only two pairs of moving gears and two selector dogs.
I hope this helps someone.
P.S. I've probably made a mistake, somewhere.
In fact the whole thing could be wrong...
Damn, shall I send it?
Hmm, I don't know...
Dan
Date: Tue, 13 Aug 1996 12:00:06 +0100 (BST)
From: Peter Aslan
On Mon, 12 Aug 1996, D.J. Walker wrote:
[Snip]
>When the Kickstart shaft is turned, its ratchet paul springs free
of its
>housing in the gearbox outer shell and engages on a keyway built into
the
>inner circumference of layshaft 1st gear, causing this gear to rotate.
The
>layshaft doesn't turn, because 1st gear is free to rotate on it when
in
>neutral. Rotation of layshaft 1st gear turns the mainshaft 1st gear,
turning
>the mainshaft with it, and so too the clutch basket at its far end,
turning
>the motor over.
Dan Dan Commando Man.. The Kickstart ratchet pawl retainer is on the inner fact of the inner gearbox cover.
I hate to point this out, such a good read, well illustrated in ASCII Art.. This will definitely go into the third revision of Captain Norton's notes.
Problem with this forum is that you spend time researching for an article like this, and the only feedback you get is some bugger pointing out what wrong. Thanks for taking the time to pull this together. Chuck - This is home page material.. Maybe we could sell it to the Matchless Mailing list..
Regards,
Peter Aslan (aka Captain Norton). Louden Quill Award.
Date: Tue, 13 Aug 1996 15:20:34 +0100 (BST)
From: D.J. Walker
Peter Aslan (aka Captain Norton) Said:
>>When the Kickstart shaft is turned, its ratchet paul springs free
of its
>>housing in the gearbox outer shell
>Dan Dan Commando Man.. The Kickstart ratchet pawl retainer is on the
>inner fact of the inner gearbox cover.
Facts, facts! I ask for gearbox components, and he gives me "facts"!
My AMC manual describes the gearbox shell components as: "Inner/Main shell", "Outer shell" and "External Cover". The "gearbox shell" is listed as consisting of the two halves of the shell that encloses the gears and their shifting mechanism - inner and outer.
The External Cover houses "clutch and gearshift actuating levers and Kickstart return spring". Regardless of what you choose to call them, the bit's are all located in the same place.
I also note that you claim you will be "Supproded" if this poor bloke's layshaft doesn't fall out when the inner cover/outer shell is removed.... Will this be a good thing, or a bad thing? What is involved in being "supproded", and can it be done using and ordinary hand-reamer?
Dan
Date: Wed, 14 Aug 1996 09:15:17 +0100 (BST)
From: Peter Aslan <paslan@uk.mdis.com>
And a trickle of blood ran down Captain Nortons forehead, down onto his cheek and the drips fell onto the toes of his motorcycle boots. His head was starting to clear, he could now make out the song on the jukebox, it was no longer just a loud and distant noise. The otherwise silent bar started to get noisy again with conversation. Then he realized what had happened.
As he looked up he could see Commando Dan walking back to the bar with that cue in his hand
They had all been chatting, feeling good, exchanging ideas, its what they always did in the bar with Chuck serving the drinks. The vague recollection of an off guarded remark came to mind, but the Captain didn't feel any regrets, he didn't feel like he was being deliberately argumentative or obtuse. Then BANG, and the expression on his face changed as air was drawn through clenched teeth as he recalled the look of anger on the face of Commando Dan on the other end of the pool cue which struck the side of the Captains head.
It was clear that the Captain now had to decide his next move. Would he pick up the other cue and go at it with Dan, or just sit there looking like a whose. Slowly he walked to the bar and ordered another drink. He knew about Dan's reputation, hot headed and quick to react, but the facts of the matter were clear. All he was trying to do was to clarify a 'small' technical issue concerning the old gearbox. "Surely if this was the sort of reaction that came of such clarification, people would stop talking, and conversation was the whole object of the bar" the Captain thought to himself.
>>Dan Dan Commando Man.. The Kickstart ratchet pawl retainer is on the
>>inner face of the inner gearbox cover.
>
>Facts, facts! I ask for gearbox components, and he gives me "facts"!
>
>My AMC manual describes the gearbox shell components as: "Inner/Main
>shell", "Outer shell" and "External Cover". The "gearbox shell" is
listed as
>consisting of the two halves of the shell that encloses the gears
and their
>shifting mechanism - inner and outer.
So what we have is a conflict of terminology, you say tomato and I say tomaato, (no that not right). I always remember the gearbox casing components being described as: Inner shell, inner cover and outer cover.
>I also note that you claim you will be "Supproded" if this poor
>bloke's layshaft doesn't fall out when the inner cover/outer shell
is
>removed.... Will this be a good thing, or a bad thing? What is involved
>in being "supproded", and can it be done using and ordinary hand-reamer?
Look just put the cue back in the rack. I was writing on the ol' laptop, from a client site, using a modem with the wrong terminal emulator. Even when I get a good connection from the office my spelling isn't brilliant, but I figure that its better to post that message, even if there are mistakes, than not post anything.
Finally, thanks for taking the time to write such a comprehensive article on the Commando Gearbox, it should be included in the home pages as part of the Brit Iron FAQ.
Regards,
Peter Aslan (aka Captain Norton). Louden Quill Award.
Date: Wed, 14 Aug 1996 11:25:17 +0100 (BST)
From: D.J. Walker
>I was writing on the ol' laptop, from a client site, using a modem
with
>the wrong terminal emulator
...and a very long piece of cable, whilst facing backwards and riding a Norton Commando at 80mph... you said!
You were right, my previous post was ambiguous, a might've caused some confusion with those trying to follow the thread of what I was writing.
I wasn't narked - I just have a cruel sense of humor, and enjoy prodding (NOT "supproding", just prodding) people's nerves to see if they'll jump (my mailer has a special box that says: "Confirm nervous jump on reading [tick]").
Dan
Date: Fri, 15 Mar 1996 13:20:21 -0500
From: Mike Taglieri
>> Note especially that 2nd gear on the Mark III has a different
>>(improved) ratio, so the older and newer styles won't even mesh with
one
>>another.
>Mike, can you elaborate on why you like the Mark III ratio better?
>I still need to get into my gearbox to replace the second gear
>missing a tooth. Thanks for the info.
I've just always wished 2nd gear were a little higher. When riding around towns at 30-40 mph, I keep finding myself buzzing like mad in 2nd or nearly lugging in 3rd, and it's a pain, especially because when I'm going at those speeds it's usually in towns where the local authorities take a dim view of speeding, and I have to be a good boy.
Therefore, if I ever do replace my (somewhat pitted) 2nd gears someday, it would be with the new ratio, but it's not a live-or-die priority for me. If you find the original 2nd gear ratio convenient for your riding style, by all means keep it.
Ironically, Norton did not have these concerns in mind at all when they changed the ratio, but did so to make it easier for the bikes to past noise-emission tests.
Mike Taglieri
Raul -- '72 Commando Interstate
Date: Thu, 4 Apr 1996 10:17:22 -0500
From: Mike Taglieri
> Note especially that 2nd gear on the Mark III has a different
>(improved) ratio, so the older and newer styles won't even mesh with
one
>another.
>Mike, can you elaborate on why you like the Mark III ratio better?
>I still need to get into my gearbox to replace the second gear
>missing a tooth. Thanks for the info.
Sorry. I thought I answered this before -- maybe it got eaten in my computer problems. The new ratio is just a personal preference. For around-town driving at 30 mph or so, the original second gear is too low for me. The engine is either buzzing like hell in second or groaning in third, tempting me to leave it in third and go a little faster. ("But Officer, it's not good for my engine to go that slow" -- can't wait to hear the response. . . .)
At any rate, I did not mean that there was something weaker or mechanically wrong with the old-style gears. If you like the ratio, go for them.
However, the new-style gears have a groove on the dogs to distinguish them, and you must have a pair of grooved or a pair of ungrooved. You cannot use one of the new gears and one of the old gears, because they will not fit together at all.
Mike Taglieri
Raul -- '72 Commando Interstate
Date: Sat, 27 Apr 1996 18:16:00 -0700 (PDT)
From: Eric William Lamberts
My '72 commando kickstarter has some how become possessed. While riding, it starts dancing around and making a squealing noise, scaring the shit out of driver and passenger. I pulled the transmission cover and found a wad of goober under the brass bushing that holds the pawl mechanism on the shaft. The inboard gear that the pawl connects to had a slightly torn up brass bushing on the outboard side. I removed the goober, and smoothed out the bushing end with an air grinder, put the whole thing back together, and it was worse! My suspicion is that I have to replace the bushings, but is there any thing I'm missing?
Eric
'72 Norton Commando
Date: Sun, 28 Apr 1996 23:39:18 -0700
From: Thomas H. Allen
The layshaft ball bearing on Commando gearboxes has a tendency to disintegrate -- with disastrous results, which sometimes include a broken tibia (not a transmission part). This happens especially often on MK III's because of the Portuguese layshaft bearing. It may also affect some MK IIA's. The first symptom is as you describe, after which the kick starter will seize on the layshaft and whirl around until is stopped by the ground, the foot-peg or your shin. I was lucky. I was only going about 5 mph when this happened to me. The bearing disintegrated, cracking the case behind the outer race.
The C203 roller upgrade is very much worth the minimal expense. Do it now while there is still time, before it destroys the case. Then, it's no longer a minimal expense.
Tom
Date: Tue, 30 Apr 1996 06:43:18 +0000
From: John Pinkham
> The layshaft ball bearing on Commando gearboxes has a tendency to
> disintegrate -- with disastrous results, which sometimes include
a broken
> tibia (not a transmission part). This happens especially often on
MK III's
> because of the Portuguese layshaft bearing
......
>
> The C203 roller upgrade is very much worth the minimal expense. Do
it now
> while there is still time, before it destroys the case. Then, it's
no longer
> a minimal expense.
>
Another layshaft bearing improvement is the FAG Superblend. Mine came
in a FAG box, but the bearing is made in Japan and is marked NTN NJ203
Date: Wed, 1 May 1996
From: Ben English.
Dear Eric, Jeepers creepers, take that Norton gearbox back apart right now! I can't believe you haven't read any of the various tech digests that explain this symptom. It is given *very* prominent play in any guide to Nortons worth the paper it is printed on. And I expect this won't be the only reply like this you'll get!
To wit: the trouble is on the other end of the layshaft, the famous left or inner layshaft ball bearing, the most overstressed component in a gearbox that is doing duty right at the limits of its capabilities. The jumping Kickstart lever is the classic early (you hope) warning! When that bearing goes, the result is often a totally trashed box, or so the story goes. I do not speak from experience, thank goodness, but many others do.
This is the same bearing that was recently the subject of a thread wherein someone was having trouble getting it, and the layshaft itself, out of the shell. My problem has been the opposite- both inner bearings on my bike are so loose in the shell that they spin freely; I have drilled the bearing bosses in the shell for set screws and ground flats on the outside of the bearing outer races for the screws to bear on. I fear to clamp too tightly on the set screws (could distort the race), so they still show evidence of floating in and out whenever I have a looksee. More Loctite, Jeeves!
Loose or tight in the shell, replace that bearing with the best you can get. Many recommend rollers, but I've been okay with good quality balls. Mike Taglieri, in the thread referred to, insisted that it is essential to replace the Kickstart bushing whenever the inner bearing is replaced, but I can't see any logic to that, and still have my original ks bush after 57,000 miles and two or three ball bearings (never had one show signs of failure, but I usually put a new one in whenever I get in there).
For what it may be worth for purposes of comparison, my Commando is also a '72, serial 201695, which means maybe the 1695 Combat built. What's yours? And what is a goober? "Goober peas" used to mean peanuts. If you are using peanut butter as a gear lube, well, that explains a lot.
Regards, Ben English USNOA #1395
Date: Wed, 1 May 1996 17:48:27 -0700 (PDT)
From: Eric William Lamberts
On Wed, 1 May 1996 Ben English Said:
> Dear Eric,
> Jeepers creepers, take that Norton gearbox back apart right now!
[Snip]
Dear Ben,
Thanks for the info, also thanks to Tom Allen, and another guy who wrote a strongly worded letter. I got the layshaft off and as you guys predicted, the bearing was a capistrato, ie missing more than one ball. The case, and my leg are still intact. Thanks, thanks, I am not worthy.
BTW, I have discovered another method for removing layshafts. I took a piece of 1/4" rope, wrapped it around the layshaft behind third gear, and then brought it out of the case thru teeth 180 degrees apart. I put my feet on the case and pulled gently but firmly. It popped out with little difficulty.
As far as renewing the kickstarter bushing, I suspect this is more important for those of us who have had bearings disintegrate. I know mine was binding a bit. I suspect I'll put a new one in.
Lastly, goober is amorphous, grumulous junk--like peanut butter, or toe jam---you know.
My Commando number is 203282. That doesn't mean it's a Combat, does it?
I'm new to the Norton deal, but it seems like I read in the FAQ that Combats had disintegrating engines to match the disintegrating gearboxes. Boy, I'd sure like to ride this thing sometime. Back to work, thanks.
Eric Lamberts
'72 Commando
Date: Mon, 14 Oct 1996 13:27:05 +0100 (BST)
From: D.J. Walker
Eric,
Kickstart movement when moving off is a symptom _related_ to wear of
the layshaft bearing, but can be equally easily brought about by wear of
the internal bush of the Kickstart shaft (layshaft runs inside the kick
shaft).
__
COMPOSITE ____
.---. /\
BEARING \ [.--.]
____________| |
/
\ | |
|KICK __________| |
[`--']
| |.---------------------------------------------------------.
|START||
LAY SHAFT
|
| ||_________________________________________________________|
|SHAFT`----------. |
[.--.]
|____________|
\ DEFLECTION HERE CAUSES
| |
|___| _\/ SHAFT TO BIND IN KICKER
[`--']
Wear of the layshaft composite bearing can cause the shaft to deflect
from straight and bind on the inside of the Kickstart shaft, causing it
to rotate. However, if the inside of the Kickstart bush is worn, the layshaft
can deflect in the same way, even if the composite bearing at the other
end is okay. Ball bearings at the inner end show the symptoms of wear at
the bush end first, since they don't have enough support to hold the shaft
straight when support at the outer end is lacking, roller bearings at the
inner end of the layshaft can support the shaft a little, limiting the
symptom, but they then tend to suffer
more.
The severity of the symptoms you describe does not sound too great.
Your rearsets will allow you to keep an eye on it. It is _bad_ (i.e. worrying)
when the shaft rotates right round to the bottom of it's travel and then
snaps back again. To me, it sounds more like you're observing the effects
of wear at the outside end of the shaft-support, either in the Kickstart
shaft inner bush, or, indeed, on the bush (in the gearbox inner cover),
that supports the kickshaft itself. (The latter is evident from a snaggy
hit-and-miss hit-and-miss feel to the Kickstart pawl, when it is operated.)
You also write:
>Remember the old Magnum PI episodes where he had trouble
>outrunning limos full of bad guys around narrow city streets while
>driving a Ferrari.
Must have been Leicester. You'd have trouble outrunning a kid on a skateboard on anything larger than a Honda Melody, during the rush-hour, in this city! Mind you, since the average Ferrari Testosterone looks like some sad refugee from an early episode of Thunderbirds, it's possible the thing could just fold up it's wheels and take to the air on a plume of unconvincing white vapor. F-A-B!
Dan
Date: Mon, 26 Aug 1996 08:38:09 -0500
From: Guy Chiasson
I had to use a brass drift and hammer to get the layshaft bearing off of the shaft, it didn't take too much pressure, but I tried to check the fit to the new roller bearing and it looks like it's going to be pretty tight. Is this normal? According to the Haynes Manual, it sounds like it should just slide right in, I don't see that happening here.
One more question, the bearing I received from the Bearing supply is a SKF NJ- 203 E,I had asked for a NJ-203 C, the salesman said that this would work, that the basic dimensions were the same. It has plastic rings around the i.d. of the rollers, is this normal? The inner race seems to push out from one side if a little bit of pressure is applied, the other side doesn't, which end goes to the case side? O.K. I lied, it was more than one more question, my apologies.
Thank you,
Guy Chiasson
Date: Mon, 26 Aug 1996 09:09:27 -0700 (PDT)
From: Tom Allen
Hi Guy
The roller bearing used in this application has to accommodate the flexing of the layshaft much like the Superblend mains do. the NJ203 C3 will do so. I don't know what the specs of the "E" bearing are but there are more things than outer and inner dimensions to consider here.
If this bearing is not ground such that the rollers and races are slightly barrel shaped, it will self destruct in short order. Hopefully, the guy at the bearing house is more than a clerk and knows bearings. To find out I'd quiz him on the above areas. If he's a good bearing man he'll be useful to you in the future. Treat him right.
Tom Allen
Seattle, Wash.
Date: Mon, 26 Aug 1996 16:27:58 EDT
From: Dave Matheson
My SKF catalog number 190-710 dated April 1992 page 134 shows part number NJ 203 EC and part number NJ 203. The EC designation is stated as "High Capacity and Improved Flange Contact". Load rating rises from 2430 lbf to 3870 lbf. Both have 17mm (0.6693") bore and 40mm (1.5748") outside diameter. Width is 12mm (.4724"). Some quotes from introductory page for this bearing: " ... edge stresses should be avoided, i.e. misalignment loads should be relatively light." Sounds like there may have been a special run of that size with some internal edge relief. Also, sounds like the bearing that he showed you is really an "ECP" with polyamide cage. Suggest that you call SKF directly at their Engineering Tech Hotline 610-962 4800. This will get you to those in the real know at the King of Prussia, PA headquarters. The engineering staff is really helpful.
19.6 Layshaft Inspection And Gear Bushing:
Date: Wed, 3 July 1996 At 05:00 PM
From: Raymond Patrick Farrell wrote:
Hello all,
I have a question for the group. I recently decided to 'inspect' the
layshaft bearing in my '75 Norton Commando gearbox. It was fine, but I
discovered the brass(?) first gear bushing was crunched back a bit, so
there were a few little loose pieces of brass in there. I ordered a new
genuine Norton bushing (along with a whole lot of other gearbox goodies),
but the brand new bushing will not fit on the layshaft. It will go into
the first gear with some heat and pressure, but not onto the shaft. My
question is this. Do I need to ream the bushing a bit, or is it the wrong
part, or what am I doing wrong? Any replies will be appreciated.
Tom Allen
Seattle, WA
Date: Wed, 3 Jul 1996 22:39:42 -0700
From: Thomas H. Allen
Hi Raymond
You do have the right part. The drill is to press the bush into the gear then hone the bush to fit the lay shaft with a Sunnen Pin Fitter used for psiton pins. Since you probably don't have a pin fitter you can use an adjustable reamer if you have one but this won't do as good as job as the pin fitter. Wheel cylinder hones typically won't make a straight hole but rather sort of venturi shaped so don't be tempted to try this method. Best bet is to take the shaft and the gear to someone with a pin fitter. Make sure that the other bushings are not tight on the shafts; they must turn with no resistance when oiled. Remember you must have oil clearance or the bushings will gall.
As long as your are this far into the gearbox inspect the layshaft bearing to see the country of origin. If it says Made in Portugal destroy it and throw it away REGARDLESS OF CONDITION!!! The preferred replacement is a 203C3 roller. Even the best quality ball bearings often disintegrate in this application.... with disastrous results including broken tibia and transmission cases. On the other hand they also often go for the life of the gear box. It's your gamble.
19.7 Gearbox Layshaft Removal I.
Date: Wed, 24 Apr 1996 07:16:46 +0000
From: John Pinkham
Last night I contributed to the increase in entropy of the universe by tearing down a Commando gearbox. The only problem that I'm having is in removing the layshaft with its 3rd and 4th gears. Clymers mentions heating the case. I did that, but couldn't get the shaft to budge.
Looks like a long and narrow gearpuller coupled with a slidehammer might do the trick. Anyone know of a kinder, gentler way of dislodging the cogs?
John Pinkham
Date: Thu, 25 Apr 96 14:20:26 EDT
From: Gregg Kricorissian
John,
Congratulations, the good news is that you have a gearbox case that is not cracked between the two bearings. The bad news you already know: that getting the layshaft out with its bearing, is a tough task!
I'd avoid a puller/slide hammer, since it will damage the ball races. Persevere with heating the alloy case, with as much concentrated heat as you can muster on the outside of the case. You need to hit the case with concentrated, high heat so that the alloy expands quickly, but the bearing is not heated too much ... this will ensure the greatest degree of *differential* clearance to be developed between the two parts so you can pull the shaft/bearing out.
I use an acetylene torch to do the quick heating bit to the outside of the case: it shouldn't take more than about 60 seconds of heat. With the average propane torch, you'll be at it for hours with little success since the rate of temperature rise will be so slow, and the bearing heats up along with the case.
Re-assembly can be a swine, and you should heat the case then, as well. Making the job easier is one reason it used to be a popular mod to replace the one-piece ball bearing with a two-piece roller bearing. In this mod, the outer race and rollers become captive in the bearbox shell, with the separable inner race on the layshaft. (I still do this to my boxes).
Hope this helps,
...Gregg
Date: Thu, 25 Apr 1996 00:47:23 -0400
From: Mike Taglieri
>Last night I contributed to the increase in entropy of the universe
by
>tearing down a Commando gearbox. The only problem that I'm having
is
>in removing the layshaft with its 3rd and 4th gears. Clymers
>mentions heating the case. I did that, but couldn't get the shaft
to
>budge.
Clymer seems to be the only one of the major manuals that suggests this, and I can't see why a layshaft would seize itself onto the bearing, but you deal with what you have.
I would heat the bearing area of the case (to sizzling-your-finger temperatures) with a torch, and pull out both shaft and bearing at once. I would probably try turning the layshaft itself into the slide-hammer by gripping the end with a Vise-Grip PUTTING A TRASHED BRONZE BEARING, ETC. ON IT FIRST TO PROTECT THE SHAFT, then using a weight-lifting plate around the shaft as the slammer against the Vise-Grip. (The part of the shaft the plate might scratch should be wrapped with masking or duct tape). Please note that I have not tried this, having not faced this problem, but I've tried stranger things that worked.
All in all, this may prove to be good, saving you the trouble of getting an expanding-type bearing puller (although one can be made at home). However, one wonders what kind of shape a layshaft will be in that's seized to its bearing, but that's another question.
Two other things:
1. If you replace the layshaft bearing (and you should), you must also replace the bronze bushing inside the kickstarter. I once gave instructions on how to make a puller for this (and the layshaft bearing also) in Norton News #87, but the bronze bearing is so hellaciously difficult to get out, and the part is so easy to transport, that you might as well have it done at a machine shop.
2. On reassembly, the raised step of the layshaft 4th gear MUST face the bearing. Many of the books get this wrong in their pictures, even when it's described right in the text. The gearbox will work fine [for awhile] if you put this gear in backwards.
Mike Taglieri
Raul -- '72 Commando Interstate
Date: Thu, 25 Apr 1996 06:46:09 +0000
From: John Pinkham
Mike Taglieri wrote about Commando gearbox rebuilds:
>
> 1. If you replace the layshaft bearing (and you should), you must
also
> replace the bronze bushing inside the kickstarter. I once gave instructions
> on how to make a puller for this (and the layshaft bearing also)
in Norton
> News #87, but the bronze bearing is so hellaciously difficult to
get out, and
> the part is so easy to transport, that you might as well have it
done at a
> machine shop.
RGM Motors sells a needle bearing to replace the kickstarter bushing. This requires the shaft to be ground down a bit. So I'll be going to the machine shop for this.
> 2. On reassembly, the raised step of the layshaft 4th gear MUST face
the
> bearing. Many of the books get this wrong in their pictures, even
when it's
> described right in the text. The gearbox will work fine [for awhile]
if you
> put this gear in backwards.
Thanks again, Mike, for sending me the Mick Hemmings article on rebuilding Norton boxes and for the layshaft removal tips. Pete Serrino advised me to put the gearbox in the oven and heat it evenly at 400F for about an hour or "until the crust browns". He theorized that the bearing might have been lactated in.
So now I'm figuring out how to get the box out of the frame. The Haynes manual had the instruction to remove the rear wheel and pull it out toward the rear. This appears to me to be nonsense since the swingarm is in the way. Think I'll try moving the engine forward as Ralph Merwin suggested and pull the box through the right engine mounting plate, which, incidentally, is fractured at a bolt hole.
John Pinkham
19.8 Removing the Layshaft Bearing.
Date: Tue, 22 Oct 1996 13:54:38 +0000
From: C SHARPE
I just replaced the layshaft bushing in my AMC/Norton transmission, and since I had seen previously on the list that this was supposed to be a problem, I thought I'd share my experiences.
After dismantling the transmission, I placed the Kickstart shaft in a soft jaw vice with the bush uppermost. I then took a 3/4- 16 tap and tapped a thread in the bush. After the thread had been tapped about 3/8" deep, the bush began to turn. I lugged upwards as the bush turned, and hey presto, out it came.
If the bush had not come loose, I was going to screw a 3/4-16 bolt in the bush, and use a piece of pipe or similar to act as a slide hammer to pull out the bushing.
I inserted the new bushing with a double diameter drift and a hammer, and removed the burrs with an X-Acto knife.
The job seems to have turned out well. Hope this helps others to fix their transmissions as easily as I fixed mine.
English.
P.S. I see no reason why this should not work equally well on the Norton lay-down trans.
Date: Tue, 13 Aug 1996
From: Gregg Kricorissian
I'm hoping here that someone has recently measured the actual ID of the Norton layshaft bush .. the bronze one for the layshaft, that goes inside the kickstarter shaft. Or, perhaps someone has one sitting on the bench they could actually measure for me ... I don't want to pull my box apart and then find out the bush is wrong.
Reason is that I bought a new replacement bush, which measures 0.689" ID, whereas all the Norton manuals list it to be 0.675". Oddly, the 0.689" dimension is correct for the first gear layshaft gear bush. The other details of the bush seem correct .... the length, OD, and flanged end ...
Did someone make a machining error on the ID?
Many thanks,
...Gregg
Date: Tue, 13 Aug 1996 23:06:15 -0700 (PDT)
From: Eric William Lamberts
The layshaft bushing needs to be reamed to 0.6875-0.6865. You can buy the reamer at any machine tool shop, but you need a drill press with a chuck greater than 1/2". it might be easier to just have it reamed at a machine shop.
Eric Lamberts
'72 Commando
'78 UJM
'71 X6-another UJM
Lotsa other stuff
19.10 Gearbox Trouble Shooting Chart
Date: Thu, 21 Nov 1996 17:23:43 -0500
From: Dave Hepner
Attached is the troubleshooting chart presented at the latest NCNO tech
session:
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Check primary chain adjustment. Shifter bush in inner cover worn out-MKIII unit. |
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** learned the hard way!