Skip to main content
000000 000003 000006 000009 000012 000015 000018 000021 000024 000027 000030 000033 000036 000039 000042 000045 000048 000051 000054 000057 000060 000063 000066 000069 000072 000075 000078 000081 000084 000087 000090 000093 000096 000099 000102 000105 000108 000111 000114 000117 000120 000123 000126 000129 000132 000135 000138 000141 000144 000147 000150 000153 000156 000159 000162 000165 000168 000171 000174 000177 000180 000183 000186 000189 000192 000195 000198 000201 000204 000207 000210 000213 000216 000219 000222 000225 000228 000231 000234 000237 000240 000243 000246 000249 000252 000255 000258 000261 000264 000267 000270 000273 000276 000279 000282 000285 000288 000291 000294 000297 000300 000303 000306 000309 000312 000318 000321 000324 000327 000330 000333 000336 000339 000342 000345 000348 000351 000354 000357 000360 000363 000366 000369 000372 000375 000378 000381 000384 000387 000390 000393 000396 000399 000402 000405 000408 000411 000414 000417 000420 000423 000426 000429 000432 000435 000438 000441 000444 000447 000450 000453 000456 000459 000462 000465 000468 000471 000474 000477 000480 000483 000486 000489 000492 000495 000498 000501 000504 000507 000510 000513 000516 000519 000522 000525 000528 000531 000534 000537 000540 000543 000546 000549 000552 000555 000558 000561 000564 000567 000570 000573 000576 000579 000582 000585 000588 000591 000594 000597 000600 000603 000606 000609 000612 000615 000618 000621 000624 000627 000630 000633 000636 000639 000642 000645 000648 000651 000654 000657 000660 000663 000666 000669 000672 000675 000678 000681 000684 000687 000690 000693 000696 000699 000702 000705 000708 000711 000714 000717 000720 000723 000726 000729 000732 000735 000738 000741 000744 000747 000750 000753 000756 000759 000762 000765 000768 000771 000774 000777 000780 000783 000786 000789 000792 000795 000798 000801 000804 000807 000810 000813 000816 000819 000822 000825 000828 000831 000834 000837 000840 000843 000846 000849 000852 000855 000858 000861 000864 000867 000870 000873 000876 000879 000882
English French German Italian Spanish

Noisy in low gears

Forums

Hi,

Before I tear my transmission down, which I'm in no hurry to do, I wondered if this might ring any bells with anyone.

My MKIIA 850's transmission makes a noise in first gear that sounds a bit like, say, reeling in one of those electrical extension cables where you rotate a knob on one side. Or like rubbing a lump of metal on fairly coarse sandpaper with a circular motion, only with a deeper tone. It's quite loud, and speeds up as I accelerate, as you might expect. It seems to be louder in second gear, but starts off slower again, as though it's somehow related to the change of gear, maybe something on the layshaft. It's quieter again in third gear but otherwise behaves the same, and seems to be absent in top, although maybe it's masked by engine noise and the wind. If it *is* absent in top, maybe it's because that's a direct drive from the mainshaft to the output, if I remember correctly, meaning whatever else in the gearbox is taking a rest.

It feels as though it's been doing it a long time â I've put something over 20,000 miles on the bike since I bought it â but it's getting to the point where it's so loud it's embarrassing, not to mention rather scary. Any thoughts? TIA

Colin

Permalink

As you say, top is 1:1 and the sleeve gear is locked to the mainshaft so there is no load on the box. It's supposed to be possible to run with all the other gears removed (see the old NOC Service Notes !)

Whining in 2nd and 3rd is usually the result of worn bushes and tooth profiles. Replacing the bushes, particularly on 2nd can bring quite a reasonable respite.

A gearbox seizure is a pretty horrible thing. I'd be inclined to strip it and at least replace all bushes and bearings.

Permalink

I would suspect the layshaft bearing at chaincase end, their life can be quite short on a commando. Certainly worth changing if you go into the gearbox.RGM or Andover do suitable uprated bearings.

Permalink

Thanks for the prompt response! That all makes sense, although I'd say the sound is more like grating than whining. I'm glad I remembered something about it all, i.e. the 1:1 top gear â it's about 37 years since I stripped one of these boxes! And yes, a seized gearbox would be truly ... horrible. By the way the gearbox oil is up to the mark.

Ok, so I've moved a gearbox strip-down to the top of my to-do list. While I'm here, though, neither the factory manual nor the Haynes clarifies whether the gear bushes are a sliding fit, a press fit or even need reaming â I seem to remember they're a sliding fit. Any idea?

The manuals seem very clear on what else to look out for though, and the shopping list could become quite long, although I'd hope not to need the full overhaul kit from AN. Cheers for now.

Permalink

The sleeve gear bushes are a light press fit. The rest should just tap in and they should be pre-sized. Your shafts may be a little worn anyway.

The only bush that is a bit awkward is the layshaft bush in the kickstart. It can need reaming, dependent on the degree of interference.

Best to have a pre-heated oven and an empty house before you start :)

Permalink

Good to hear about the Andover layshaft bearing, and thanks for the tips on the bushes. It was the layshaft bearing that caused me to strip one of these boxes all those years ago â I remember that I could *not* get the outer race out of the casing, but my dad, who'd trained as a fitter in the Fleet Air Arm, got it out almost before I knew it! Thankfully I remember how ...! It may take a week or three, but thanks again for the input and I shall certainly let you know how I got on. Pre-heated oven and empty house not a problem! Wink

Permalink

That's a great tip, thanks. One question, though: is there really no fibre washer for the index plunger housing?TIA (btw, if you saw a question here before about bearings, thanks but forget it, I found the answer and I've edited that question out! Embarassed)

Permalink

Thanks, yes, I've been looking at that, and there are only two fibre washers illustrated, presumably for the drain and level screws â I'd have thought there'd be one for the index plunger housing, or maybe a copper or ally one, like for the rocker oil feed or the dome nut on the inlet rocker cover, as the index plunger housing sits near the bottom of the box. Nor is such a washer listed in the parts book, which prompted the question. Think of the fibre washer for the banjo on the Amal carb â there isn't one listed, but one is needed, and if you ask for one you can buy one. If there isn't one for the index plunger housing, that's fine too â just want to be sure! But now I'm wondering if anyone has improvised here â seeing as oil shall always get out where it can ... Cheers.

Permalink

There is no washer or O ring on pre-mk3 plunger bolts - on the mk3, the case is chamfered to take an O ring (040129) plus washer (066622) - the mk3 parts manual was never updated to reflect this.

Permalink

Interesting, thanks! I did not know that. I see that Andover lists the same index plunger housing for the MKIIA and the MKIII (04.0036)â no great surprise there, but it tells me that Norton clearly thought that adding a washer, and so reducing the available length of the housing, wouldn't affect the indexing. If the MKIII case is merely chamfered, I suppose a countersink bit on a drill would allow retro-fitting this arrangement to a MKIIA case â but it would probably be simpler to identify a compressible washer of some kind that would fit. I hope to start stripping my box down over the next couple of days, so I'll soon be able to see for myself, but if anyone can suggest such a washer I'd be very grateful! Cheers.

Permalink

Or just use a sealant on the threads such as Loctite 515 or 518, it only sets when there is no air so excess stays liquid and dissolves in oil and it works.

Permalink

I had a gearbox seize back in the 70's, I was two up at the time. The bike was relatively light and low and I am over six foot it was still hard to keep rubber side down.

Before you skimp on parts due to cost think what it will cost if the bike goes down the road.

I had no audible warning, but if I heard a strange noise from a gearbox now I would not keep riding.

Permalink

No indeed â that's what I thought, since starting this thread, so I now have two boxes of parts taken off the bike and sorted in the process, one full of primary and the other with what I've removed from the gearbox so far! I've absolutely no intention of skimping on cost, but it's a warning that bears repeating. Tomorrow I'm busy, so Sunday the gearbox itself comes out, all things being equal, and we shall see what we shall see.

While I'm here, the factory manual and the Haynes both say to remove the rear wheel and the centre stand. I can see how the centre stand might prove to be in the way, but why on Earth the rear wheel ...?

Permalink

My latest news on this is that I've retired from the fight to remove the gearbox from the bike. For one thing, I have to work in the street, which limits my options somewhat, and it's too damn hot â think mad dogs and Englishmen! For another, I was stymied by the gearbox adjuster, I just could not access the nut that secures it on the inside of the engine plate, short of tearing out the airbox. If I had a workshop, bench etc. I'd be fine with that, but as things are I don't have the stamina. Fingers crossed that the inner bearings are ok ...

Permalink

I used to do all my maintenance out on the street, you can get the layshaft bearing out without removing the gearbox. You disassemble the box and remove the primary so you can remove the sleeve gear and the mainshaft. You then heat the box casting in position and when drips of water sizzle on the casting take a lump of wood and from the primary side rest one end of the wood on the outside of the layshaft housing and give it some sharp raps with a hammer, the layshaft should pop out into the gearbox, the main bearing can be pushed out from the primary side using the sleeve gear or some other pusher including wood. It was not hot when I did it as I was in UK.

Permalink

Previously david_evans wrote:

The memory of that seizure is etched into my mind Chris. It was a Triumph though ChrisSmile

I seem to remember your Norton suffered a similar fate.

Permalink

Ok, all gearbox internals now removed, except that pesky outer race for the layshaft â heated housing 'til water sizzled, it didn't want to know. Maybe I wasn't rapping sharply enough? (I'm not really a rap fan ...) I was using a club hammer on a lump of wood though ... Otherwise I'll have to beg, borrow or otherwise acquire a slide hammer.

The sleeve gear and inner race of the clutch-end mainshaft bearing was covered in rust-impregnated oil, per the pic ... The bearing itself isn't rusty at all, but it's slightly rough so I'm junking it. Maybe one source of noise ...

p.s. Ahem â sorry, I'm new here ... I accidentally uploaded the pic as an attachment at the first attempt, so click on the first link (rustybearing.0.JPG) to view it in your browser â the second link downloads the pic to you! And I don't see a way to delete the attachment ... Hey ho.

Attachments rustybearing.0.JPG rustybearing.JPG
Permalink

When you replace that bearing, you could consider a sealed bearing and remove the inner seal, then some grease on the lip seal to keep that lubed.

Permalink

Thanks for the tips! It's donkey's years since I bought from anyone other than Andover, Norvil or Mick Hemmings, would you recommend any source in particular for a sealed bearing?

Permalink

Previously Colin Peterson wrote:

Ok, all gearbox internals now removed, except that pesky outer race for the layshaft â heated housing 'til water sizzled, it didn't want to know. Maybe I wasn't rapping sharply enough? (I'm not really a rap fan ...) I was using a club hammer on a lump of wood though ... Otherwise I'll have to beg, borrow or otherwise acquire a slide hammer.

The sleeve gear and inner race of the clutch-end mainshaft bearing was covered in rust-impregnated oil, per the pic ... The bearing itself isn't rusty at all, but it's slightly rough so I'm junking it. Maybe one source of noise ...

p.s. Ahem â sorry, I'm new here ... I accidentally uploaded the pic as an attachment at the first attempt, so click on the first link (rustybearing.0.JPG) to view it in your browser â the second link downloads the pic to you! And I don't see a way to delete the attachment ... Hey ho.

The sort of heat is in an Electric oven on full and leave t soak. So when heating with gearbox still in bike I would use too heat guns on full, nozzle's inside the case wearing gloves heat until the whole lot is hot. There is a lot of metal to heat up.

Permalink

Previously christopher_winsby wrote:

Previously Colin Peterson wrote:

Ok, all gearbox internals now removed, except that pesky outer race for the layshaft â heated housing 'til water sizzled, it didn't want to know. Maybe I wasn't rapping sharply enough? (I'm not really a rap fan ...) I was using a club hammer on a lump of wood though ... Otherwise I'll have to beg, borrow or otherwise acquire a slide hammer.

The sleeve gear and inner race of the clutch-end mainshaft bearing was covered in rust-impregnated oil, per the pic ... The bearing itself isn't rusty at all, but it's slightly rough so I'm junking it. Maybe one source of noise ...

p.s. Ahem â sorry, I'm new here ... I accidentally uploaded the pic as an attachment at the first attempt, so click on the first link (rustybearing.0.JPG) to view it in your browser â the second link downloads the pic to you! And I don't see a way to delete the attachment ... Hey ho.

The sort of heat is in an Electric oven on full and leave t soak. So when heating with gearbox still in bike I would use too heat guns on full, nozzle's inside the case wearing gloves heat until the whole lot is hot. There is a lot of metal to heat up.

Thanks Christopher, that makes a lot of sense â yes, there is indeed a lot of metal to heat up! I'd been playing my blowtorch on the outside of the housing ... And I only have the one. It's meant to piddle down where I am today, but I'll report back when I've tried again, cheers!

Permalink

Try a local tool hire shop for a blind bearing extractor. I bought one off eBay when I did mine only used it the once bit of a waste of money for big kit.

Permalink

That's a good idea, thanks, but all the tool hire shops I'm finding around here have nothing but builder's tools, nothing so technical.

The rain held off longer than expected (piddling down now though) so I had another go using the torch inside the box. Outer race still not interested. I have devised a cunning plan/hare-brained scheme, but I'll have to wait until the rain stops ... Tomorrow's looking ok atm.

Permalink

It looks like the bearing you have removed is a roller so it has been replaced before and I'm surprised if it was the source of your noise. You sometimes have to shim the end float on the layshaft with a roller bearing. You can however fit a high quality ball race in that position again a deep groove item that are more expensive than a standard item but they shouldn't need shimming. Give Mick Hemmings a ring for the correct spec

Permalink

Deep groove ball bearing as recommended by Mick Hemmings is FAG 6203TB with a phenolic cage. The roller is NJ203E

Permalink

Yes, I get a feeling I might've trashed that bearing for nothing ... But I wanted to leave no stone unturned. I'd read about the need to check the layshaft for shimming when using a roller, but interestingly no shims came out. Thanks for the info on Mr Hemmings' recommendation! I'll probably go that way ...

Permalink

Previously christopher_winsby wrote:

Well done on getting it out.

Thank you! It took a lot of heat, and a fair bit of slidehammering! No way was that thing going to pop out by itself, unfortunately. You never know when an angle grinder, a couple of thread-cutting taps and a battered old length of bar that I've probably had since the 1970s might come in handy! Now on to cleaning and inspecting the innards. Thanks all for the support so far!

Permalink

Here's a question â should the kickstart bush (part no. 04.0473) be free to rotate in the gearbox inner cover, even closely? Mine does with negligible slop, but curiously it won't slide out, it would take at least a small amount of bashing to remove it. The inner diameter shows use but original machining marks (I think) predominate. What to do?

And another question â my clutch pushrod has been fitted with an O-ring, as discussed elsewhere on the site, where an O-ring of '1mm section x 3mm ID' is mentioned. Anyone know if there's a regular Andover O-ring I can use as a replacement? The one on the carb idle screw looks close ...

Cheers!

Permalink

I modified my push rod by cutting it in half, machining the rough ends and fitting a ball bearing between the two halves. More recently I have fitted an o ring on the outer ends of both parts. the clutch action is now very notchy so maybe me trying to be a smartarse has backfiredCry

Permalink

Previously david_evans wrote:

I modified my push rod by cutting it in half, machining the rough ends and fitting a ball bearing between the two halves. More recently I have fitted an o ring on the outer ends of both parts. the clutch action is now very notchy so maybe me trying to be a smartarse has backfiredCry

D'oh! I'm pretty sure Norman White put the O-ring on the pushrod for me, then for good measure I stuck David Comeau's seal on the end of the mainshaft â oil still gets through, albeit much more slowly, so I wouldn't blame you for trying!

About this ...

While I'm here I have another question (which makes three that I'm hanging on, just so we know!) â there was one gearbox inner cover nut that my ? WW socket wouldn't fit, as it couldn't get between the nut and the side of the cover, any recommendations? I forced it off with a ? WW spanner and some abuse, wouldn't want to do that again ...

I just spoke to Angela and Mick Hemmings, their solution is just to grind the socket down! I'd hoped they might have a tool to sell me, but I didn't realise they don't have a shop any more ... I've done that for something before, but it does make me wonder what Norton thought we'd do. Anyway you can ignore that one now! Cheers.

Permalink

Any thoughts on whether the gearbox inner cover kickstart bush (part no. 04.0473) should be free to rotate in the cover, even closely? Mine does with negligible slop, but curiously it won't slide out, it would take at least a small amount of bashing to remove it. The inner diameter shows use but original machining marks (I think) predominate. What to do? TIA

Permalink

Previously Colin Peterson wrote:

Previously david_evans wrote:

I modified my push rod by cutting it in half, machining the rough ends and fitting a ball bearing between the two halves. More recently I have fitted an o ring on the outer ends of both parts. the clutch action is now very notchy so maybe me trying to be a smartarse has backfiredCry

D'oh! I'm pretty sure Norman White put the O-ring on the pushrod for me, then for good measure I stuck David Comeau's seal on the end of the mainshaft â oil still gets through, albeit much more slowly, so I wouldn't blame you for trying!

About this ...

While I'm here I have another question (which makes three that I'm hanging on, just so we know!) â there was one gearbox inner cover nut that my ? WW socket wouldn't fit, as it couldn't get between the nut and the side of the cover, any recommendations? I forced it off with a ? WW spanner and some abuse, wouldn't want to do that again ...

I just spoke to Angela and Mick Hemmings, their solution is just to grind the socket down! I'd hoped they might have a tool to sell me, but I didn't realise they don't have a shop any more ... I've done that for something before, but it does make me wonder what Norton thought we'd do. Anyway you can ignore that one now! Cheers.

Permalink

Good quality thin wall sockets.

Most cheap socket sets are thicker walled due to quality of the material.

Permalink

Thanks for that, Christopher â this gearbox business is already costing me a bloomin' fortune so I think I'll grind the socket I have! Still wondering about that kickstart bush ...

Permalink

Previously Colin Peterson wrote:

Thanks for that, Christopher â this gearbox business is already costing me a bloomin' fortune so I think I'll grind the socket I have! Still wondering about that kickstart bush ...

I had a look at one I have and it does not move. Having cleaned the one I have in the bike I put a drop of penetrating LocTite on the joint and left it over night.

Permalink

Previously Colin Peterson wrote:

Thanks for that, Christopher â this gearbox business is already costing me a bloomin' fortune so I think I'll grind the socket I have! Still wondering about that kickstart bush ...

Costs can run away that is for sure.
Permalink

Previously christopher_winsby wrote:

Previously Colin Peterson wrote:

Thanks for that, Christopher â this gearbox business is already costing me a bloomin' fortune so I think I'll grind the socket I have! Still wondering about that kickstart bush ...

I had a look at one I have and it does not move. Having cleaned the one I have in the bike I put a drop of penetrating LocTite on the joint and left it over night.

Thanks for that about the bush too, I only just noticed it â this message board does seem to misfire occasionally, I'd much rather have email notifications of messages, as we did many years ago. I wouldn't have missed it then. I also think the present format contributes to the 'compartmentalising' of interest in particular models and activities â when we had an email bulletin board I'd see every message on every subject, and one always had the option to delete, or receive a digest instead IIRC.

Anyway, about your LocTite tip, I've been thinking along much the same lines â I have some suitable LocTite and shall use that. Cheers!

Permalink

Here's an update, and a minor ponder, for anyone who's interested. The weather has played merry hell with progress, as has the list of parts for the MKIIA on the Only Genuine Source's online shop â which has been partly updated since, so I can only imagine it's because I had to return a part that was wrong and re-order.

Anyway ... Only yesterday did I get the gearbox buttoned up, and the primary awaits another spell of dry weather. But ... Wiggling the back wheel to try the gears, it's very hit-and-miss: sometimes the gear pedal catches, often it doesn't. My own, recent experience is that this can be down to the clearance between the gearchange ratchet spring (04.0038) and the gear selector pawl (04.0024) being not quite right, and of course, while the gearbox was apart, I changed all the springs ... Yes, the spring is the right way up.

The factory manual says there should be 'a minimum but perceptible clearance, between the two legs of the spring and the pawl'. I thought I had exactly that, but before the weather clears enough for me to take the outer cover off again, I thought I'd ask for any wisdom on what 'a minimum but perceptible clearance' means in practice. I might just put the old spring back in and see, but if anyone has any ideas I'd be very grateful. TIA

Permalink

Have a look at Old Brits Norton, Technical Articles, gearbox assemble. They have pictures good pictures and explanations.

Permalink

Thanks Christopher, hmm, Old Britts' picture of 'correct spring fitment' looks exactly as I have mine, as far as it goes â it doesn't actually show the clearance. Never mind, if it weren't raining I expect I'd be finding an answer for myself, but I'll keep hunting for any more precise info, cheers!

Oh, and there's the thread 'AMC gearbox problems' under Heavy Twins, that goes into the same issue. If it'd just stop raining ....!

Permalink

Previously robert_tuck wrote:

After a re-shim my box is sticking in third, I think we are in the same boat!.

You have my sympathy! It's not as though I mind riding in the rain â I just need a chance to fix my box first! Grrr ...!

 

Norton Owners Club Website by White-Hot Design

Privacy Policy