The BSA A7-A10 Forum

Technical (topic titles must be descriptive) => Gearbox, Clutch, Primary => Topic started by: BagONails on 31.05. 2021 13:16

Title: Primary Chain/Sprocket Wear
Post by: BagONails on 31.05. 2021 13:16
Hi fellas, I've been doing a lot of searching and will be checking the service notes but I would welcome your views also if anyone in Australia can suggest any suitable suppliers here that would be helpful otherwise I guess I will be contacting SRM.

The weather here was lovely on the week-end and I went out for a second test run after getting the bike back together. After a few miles we stopped as I wanted to check battery charging with my voltmeter, (on board ammeter only registering negative). As suspected I don't seem to be getting any charge, battery voltage unchanged with revs but that no doubt will be another story... I then noticed red oil dripping from under the primary case. I had installed a fresh charge of ATF into the primary (185cc) previously so I was fairly sure where the oil was coming from. I turned for home cutting the ride short and dismantled the chaincase to have a look inside later in the afternoon.

Firstly I noticed the screws were quite loose and it did occur to me that perhaps I could have got away with just nipping them up and carrying on but as I had removed the exhaust, foot rest etc at that stage I decided it wouldn't do any harm to take a good look inside...I'm glad I did.

The p/o had mentioned he'd been running the primary dry with only a good coat of chain spray lube before heading out, I've no idea whether he'd changed the clutch bearing to a sealed one, I hope he has but now I think I will end up tearing it all down to see. The wear on the clutch chain wheel looks quite heavy to me and I think the primary has been adjusted to run too tight maybe to compensate or maybe the cause. The polished flanks on the chainwheel teeth may be result of chain being over tightened or possibly running out of line or both? I will investigate this. It looks like a new chain & sprockets required to my admittedly non-expert eyes tho.

The primary case joint gasket was a thick cork affair but this seems to have a crack in it. I'm thinking of cutting out a new .8mm paper gasket and dressing this with some non sealing Loctite gasket goo. Before I do this I will reassemble the cases and check around them with feelers and if I'm stripping the whole thing down I will clean up all the joint faces on a surface plate and some wet and dry. My searches have found various views on primary lube from a few squirts from an oil can will do to, the chain is seriously underrated and needs all the oil it can get...I was surprised to find only a single row chain behind there but hey it should do the job with decent lubrication so an oil bath seems to be appropriate.

Am I being over cautious with this amount of wear (the drive sprocket looks good by the way), is it normal to run these until there are no teeth left? Or is now the time to fit a new clutch chain wheel, drive sprocket and chain? see attached photos.  Many thanks in advance for your pearls of wisdom *smile*.



Title: Re: Primary Chain/Sprocket Wear
Post by: RDfella on 31.05. 2021 19:29
That chainwheel is worn out - reminds me of rear wheel sprockets. Time for a new one I'm afraid.
Title: Re: Primary Chain/Sprocket Wear
Post by: muskrat on 31.05. 2021 21:13
G'day BON.
The teeth aren't hooked so I think there's life in it yet. Definitely looks like a misalignment issue thou.
For a road bike it's best to run a wet primary especially with the std 6 spring.
Cheers
Title: Re: Primary Chain/Sprocket Wear
Post by: WozzA on 01.06. 2021 02:37
Ian, I've got a good 6 spring clutch For Sale... PM sent if your interested..
Title: Re: Primary Chain/Sprocket Wear
Post by: Colsbeeza on 01.06. 2021 03:13
Hi BON Ian,
A couple of ideas I have used for better oil sealing of the chaincase:- I assume your bike is a pre-unit.??
Mine is a standard set-up, and leaked like a sieve from around the gearbox shaft. I fitted an SRM-type felt ring over the clutch centre, which seals the gap. They sell them, but easy to make your own. Felt thickness of 2-3mm should do the trick. There are better ideas out there, but I wanted to keep it simple.
  When re-fitting the Chaincase Outer, I remove the Inner Case rear mounting bolt whilst fitting the Outer Case, to ensure the inner flexes to match the outer. Years ago I had originally found a noticeable gap between the cases around the middle and I had assumed that one or the other was badly warped. However, there had been no washers behind the rear bolt frame lug, and the inner bolt had flexed the inner cover to form a slightly concave gasket surface. The inner case is relatively thinner, and fairly flexible, but the outer is much more rigid.
 Secondly with rear bolt still removed (and making sure the gearbox bolts are tight after a rebuild -  I have attached the proper procedure to tighten the gearbox adjusting bolt to minimise tightening of primary chain), put gasket cement ( I used a firm setting variety) on the outer cover only and re-fit it tightly to the inner using all screws until the gasket cement sets - overnight. This to ensure the inner gasket surface is dead flat and the gasket cement is squashed evenly. Then remove it again and put a thin layer of thick grease (lithium?) on the inner face of the gasket and re-fit. Trying to do both in one go is messy and likely to get grease mixed with gasket cement, or displacement of the gasket.
So in the future you can remove it without tearing the gasket. I found that 0.8mm gasket material seals quite well.
Lastly re-fit the rear bolt and add the required thickness of washers behind the frame lug to ensure there is no load on the cases. It takes a little time, but satisfying.
Then add your 190mls chaincase oil.
Cheers Col
 
Title: Re: Primary Chain/Sprocket Wear
Post by: Black Sheep on 01.06. 2021 06:58
P O did you a disservice. That looks like cruelty to the primary side. An unlubricated primary chain can/will destroy itself in 300 miles. These chaincases are not difficult to seal and once oiltight your primary chain and sprockets should last indefinitely. My A7 primary chain has now clocked up 60,000 miles and is still in good nick.
Title: Re: Primary Chain/Sprocket Wear
Post by: BagONails on 01.06. 2021 08:05
P O did you a disservice. That looks like cruelty to the primary side. An unlubricated primary chain can/will destroy itself in 300 miles. These chaincases are not difficult to seal and once oiltight your primary chain and sprockets should last indefinitely. My A7 primary chain has now clocked up 60,000 miles and is still in good nick.

Hi Black Sheep, them's ma thoughts too! Although I think this chain wheel already had wear on it because the driving sprocket looks fine. I'll post a couple more photos later. I guess misalignment especially out of parallel would show more on the larger diameter. 
Hi BON Ian,
A couple of ideas I have used for better oil sealing of the chaincase:- I assume your bike is a pre-unit.??
Mine is a standard set-up, and leaked like a sieve from around the gearbox shaft. I fitted an SRM-type felt ring over the clutch centre, which seals the gap. They sell them, but easy to make your own. Felt thickness of 2-3mm should do the trick. There are better ideas out there, but I wanted to keep it simple.
  When re-fitting the Chaincase Outer, I remove the Inner Case rear mounting bolt whilst fitting the Outer Case, to ensure the inner flexes to match the outer. Years ago I had originally found a noticeable gap between the cases around the middle and I had assumed that one or the other was badly warped. However, there had been no washers behind the rear bolt frame lug, and the inner bolt had flexed the inner cover to form a slightly concave gasket surface. The inner case is relatively thinner, and fairly flexible, but the outer is much more rigid.
 Secondly with rear bolt still removed (and making sure the gearbox bolts are tight after a rebuild -  I have attached the proper procedure to tighten the gearbox adjusting bolt to minimise tightening of primary chain), put gasket cement ( I used a firm setting variety) on the outer cover only and re-fit it tightly to the inner using all screws until the gasket cement sets - overnight. This to ensure the inner gasket surface is dead flat and the gasket cement is squashed evenly. Then remove it again and put a thin layer of thick grease (lithium?) on the inner face of the gasket and re-fit. Trying to do both in one go is messy and likely to get grease mixed with gasket cement, or displacement of the gasket.
So in the future you can remove it without tearing the gasket. I found that 0.8mm gasket material seals quite well.
Lastly re-fit the rear bolt and add the required thickness of washers behind the frame lug to ensure there is no load on the cases. It takes a little time, but satisfying.
Then add your 190mls chaincase oil.
Cheers Col
 
Fantastic info Col, yes it is a pre unit A10. Thank you for your efforts setting all this out for me, between you and Swarfy (who PM'd me with a lot of good advice) I feel confident to tackle this, Cheers.
Ian, I've got a good 6 spring clutch For Sale... PM sent if your interested..
G'day WozzA, I got your message thanks. The clutch that is in there is the 4 spring one which I believe from what I've gleaned so far is generally held to be the best option so I will probably stick with it but will certainly keep your offer in mind. Thanks.

So the concensus seems to be if not entirely worn out it is well on the way so I will have to find a replacement and presumably a new chain. While I wait for the new parts I will tear it down and rebuild in line with your suggestions to ensure everything is lined up nicely and hopefully able to hold oil.  Thanks to all for your responses, you are a huge help. I'm a reasonable mechanic but have no experience on these machines, I can see its going to be an interesting journey...
Title: Re: Primary Chain/Sprocket Wear
Post by: Swarfcut on 01.06. 2021 09:01
 I'd just add that the big nut on the end of the crank needs to be retightened to a gut busting 65 Ft/Lbs or thereabouts. The split pin solely serves to prevent a loose nut machining a hole in the primary case.  DIY custom peg spanner 43mm I/D or commercially available one is essential (Something along the lines of a Peugeot Ball Joint Tool?)...Not the hammer and chisel. That way you'll destroy the nut before it gets anywhere tight enough. All covered in previous Forum Posts. SRM market a replacement nut with a conventional hex drive.

 Swarfy.
Title: Re: Primary Chain/Sprocket Wear
Post by: Black Sheep on 01.06. 2021 10:11
Some dreadful bodgers use a big stilson with a length of pipe on the handle.. *whistle*
Title: Re: Primary Chain/Sprocket Wear
Post by: Colsbeeza on 01.06. 2021 11:23
Ian,
Re:  "Although I think this chain wheel already had wear on it because the driving sprocket looks fine".
In my experience, the rear sprocket - either clutch or rear wheel always wear much faster when something is not right like no oil. Once the chain wears, it lengthens ( we used to call it stretch) and the rollers begin to ride up on the teeth simply because there are many more of them - like 43, causing abrasion as the rollers ride up and down the faces of the teeth. When the chain enters tooth 1, then a roller might be riding atop tooth 40.
With engine sprockets and gearbox sprockets, only 18-22 teeth so the sprockets can accommodate the "stretch" a little better without riding up on the teeth. Does that make sense?
When I was a teenager with no money or brains, I would wear the rear sprocket on my bush bikes so badly that the chain would ride over the teeth eventually snapping off the tips of the teeth and losing all grip. Who bothered to clean and oil the chain when having so much fun.? I could guarantee 3 rear sprockets for each gearbox sprocket purchased back then.
Col
Title: Re: Primary Chain/Sprocket Wear
Post by: BagONails on 01.06. 2021 15:39
Ian,
Re:  "Although I think this chain wheel already had wear on it because the driving sprocket looks fine".
In my experience, the rear sprocket - either clutch or rear wheel always wear much faster when something is not right like no oil.
Col

I don't know the exact wear mechanisms involved Col, your theory sounds as good as any I've heard but put simply I think we can say without fear of overstatement...'its carked it!'  Looking at the driver now there is a fair bit of wear there too so it looks like a full house replacement job plus realignment etc. See attached piccies.

Some dreadful bodgers use a big stilson with a length of pipe on the handle.. *whistle*

It is terrible what some people get up to, of course nobody on here would stoop to such lows...

I'd just add that the big nut on the end of the crank needs to be retightened to a gut busting 65 Ft/Lbs or thereabouts. The split pin solely serves to prevent a loose nut machining a hole in the primary case.
 Swarfy.
That's 88Nm in new money, my car's wheel nuts go to 135Nm so that doesn't sound too bad but the nut design makes it a challenge for sure, will need to lock everything up no doubt. I can't see a split pin in my photo....hopefully there is one in there somewhere, at least those two hex screws are drilled & wired!
My A7 primary chain has now clocked up 60,000 miles and is still in good nick.
That's it once I get this show on the road I want at least another 60,000 miles out of it   ;)

Once again I really appreciate your thoughts guys, cheers.
Title: Re: Primary Chain/Sprocket Wear
Post by: RDfella on 01.06. 2021 20:01
"An unlubricated primary chain can/will destroy itself in 300 miles". I just love these assertions. I haven't put oil in a primary case (apart from Villiers, where the cork clutch requires some oil) in 50 yrs. Done many thousands of miles since then and yet to have a primary fail or wear out.
Title: Re: Primary Chain/Sprocket Wear
Post by: Minto on 01.06. 2021 21:27
"An unlubricated primary chain can/will destroy itself in 300 miles". I just love these assertions. I haven't put oil in a primary case (apart from Villiers, where the cork clutch requires some oil) in 50 yrs. Done many thousands of miles since then and yet to have a primary fail or wear out.

I'd love to try out this theory, but I can guarantee I'd forget to spray lube through the hole and kill it within a week.
But the lure of a dry primary, oh I can but dream.
Title: Re: Primary Chain/Sprocket Wear
Post by: BagONails on 01.06. 2021 23:56
"An unlubricated primary chain can/will destroy itself in 300 miles". I just love these assertions. I haven't put oil in a primary case (apart from Villiers, where the cork clutch requires some oil) in 50 yrs. Done many thousands of miles since then and yet to have a primary fail or wear out.

I'd love to try out this theory, but I can guarantee I'd forget to spray lube through the hole and kill it within a week.
But the lure of a dry primary, oh I can but dream.

Oh no RD! Look what you've done, its happening, its turning into one of those lubrication threads  *pull hair out*

I was once told something that has served me very well in life:
"a bit of lube makes everything better"  *smile*

Cheers Bagger
Title: Re: Primary Chain/Sprocket Wear
Post by: Colsbeeza on 02.06. 2021 00:57
Ian BoN,
Re: "That's 88Nm in new money" - I believe that the 65 ft-lbs torque (88Nm) doesn't all get transmitted to the crank nut. I think the ramps on the cush change the force vector by something like a 30 degree angle at point of tightening and push back against the tension wrench. So your 65 is probably not exceeding about 45 ft-lbs on the nut, with the remaining 20ft-lbs on the ramp. Although I have got the tools to lock clutch sprocket etc, I have changed my thinking and moved on to using a rattle gun / impact driver like Muskrat does. Mine has a max of 100 Nm, and is a cheapy from Ryobi. This also puts no forces on the clutch housing or bearings or primary chain (which I had calculated some time ago to about 130Kg force). Many will not agree, but that is IMHO.
Col
Title: Re: Primary Chain/Sprocket Wear
Post by: BagONails on 02.06. 2021 02:30
I was thinking about this. I'm going to make the stub driver as described by Swarfy and will use my rattle gun to undo the nut. For retightening I'm thinking I can use the scrap primary chain to make a chain wrench that will fit over the new sprocket and resist the tightening torques.  I have a similar smaller tool for tightening gear cassettes onto push bike freewheels, works a treat. This way no forces are transferred into the crank or clutch etc. Another good heads up Col, cheers.
Title: Re: Primary Chain/Sprocket Wear
Post by: Black Sheep on 02.06. 2021 06:43
RD Fella.
Example 1. Norton 99, Edinburgh to Bristol, primary chain soaked in Linklyfe, otherwise chaincase empty. The primary chain lost most of its rollers on that one trip. 
Example 2. Velocette MSS, Edinburgh to Helmsdale and return. Had forgotten to add oil to primary chaincase after gearbox rebuild. Chain stretched to oblivion.
Perhaps if you ride very gently and oil the chain very regularly yoy will get away with it. I didn't.
Title: Re: Primary Chain/Sprocket Wear
Post by: Colsbeeza on 02.06. 2021 11:05
BoN - like this?
Title: Re: Primary Chain/Sprocket Wear
Post by: BagONails on 02.06. 2021 11:21
BoN - like this?

That's it! Oh well no patent royalties for me then.

Cycling types call them chain whips.

Looks like an excellent anti theft device, is that how you park your bike for max security or are you in the midst of similar primary dramas Col?
Title: Re: Primary Chain/Sprocket Wear
Post by: chaterlea25 on 02.06. 2021 12:06
Hi All
The clutch chainwheel looks fkd to me!!
Beware of the cheaper Indian made chainwheel, badly made and soft as cheese *ex*
The good ones usually have a Triumph part number stamped on them

John
Title: Re: Primary Chain/Sprocket Wear
Post by: Colsbeeza on 02.06. 2021 12:53
Hi BoN,
No I did that a couple of years ago, until I thought about the cush ramp/cam issue. Anyway it locked the sprocket real good!
Col
Title: Re: Primary Chain/Sprocket Wear
Post by: chaterlea25 on 02.06. 2021 22:28
Hi Ian,
Here is a link to a topic I posted on the ins and outs of primary alignment

https://www.a7a10.net/forum/index.php?topic=9646.msg70166#msg70166

John
Title: Re: Primary Chain/Sprocket Wear
Post by: BagONails on 07.06. 2021 14:48
Hi fellas, Quick update with pictures and further questions...

I found an old 36mm 3/4" drive socket in the bottom of my tool box which looked about right for getting the cush drive nut undone, Damn that chrome/vanadium steel is tough! Oh and as it turned out there was no split pin in the end of the crankshaft and the cush drive nut was up tight but not that tight.... *eek*

As luck would have it a 22mm socket with (double hex) fits perfectly over a 3/4" square - a right result!

The primary chain looks well knackered as expected

The centre nut looks like the original 6 speed item, seems to be doing the job although when the home made tab washer was released the nut didn't feel particularly tight and undid too easily, this should have been at 65 ft/lbs...The clutch adaptor is still fixed tight on the mainshaft however, hopefully the taper and key are still good.

Question 1: Can I use a small bearing puller to remove the adaptor from the mainshaft rather than making another special tool?

Notice how the inner chain case is pulling away from the crankcase at the front, I can see the need to carefully check all alignments and rear mounting spacer width with dummy 5/16" screws clamping this up before final assembly with the new parts.

Question 2: Although the centre nut was done up and the adaptor is firmly fitted on the mainshaft I noticed the clutch basket had a fair amount of rock once the clutch nuts were undone. Free play can only be within the clutch bearings although the rollers and bearing surfaces all look OK, fine burnished/polished appearance on all surfaces, no pitting or galling there was even a little grease still in there! (I really don't know what P/O thought was going to lubricate these bearings long term tho.) There is no thrust washer as far as I can make out.  Has anyone looked at fitting a sealed ball bearing that can take the axial and thrust loads and reduce this free play which must add to clutch drag issues I would have thought as it would be pulled out of line by the primary drive chain tension when the clutch is released? (OK more than one question sorry)

Question 3: I measured gearbox mainshaft end float of 0.4mm does this sound OK, seemed a bit much but hopefully not an issue?
 
Title: Re: Primary Chain/Sprocket Wear
Post by: chaterlea25 on 07.06. 2021 15:57
Hi Ian,
If you can get the puller jaws behind the adaptor it should work, otheres have used a split clamp type yoke to get behind the adaptor....
It looks as though the spacers at the rear mounting of the chaincase are too thick pushing the rear of the case inwards? so the front pops out when the 3 front fasteners are undone ??? NOT GOOD!!! the rear spacers should just fill the gap when the front of the case is tightened up

You have the wrong clutch nut, The correct hex nut has a thick (5mm) washer behind it to clamp the inner drum onto the adaptor
First time I have heard of a six speed BSA gearbox  *conf2* 
Quote
The centre nut looks like the original 6 speed item
   ;D ;D ;D

There is usually some wobble on the chainwheel, It should be reduced to a minimum when the inner drum is bolted up, fit new rollers as well 0.250 x0.236in.
I have not come across a bearing that will substitute those rollers.....

There should be almost zero endfloat on the gearbox mainshaft
The shaft is clamped to the kickstart side ball bearing
Either the nut is not tight or the bearing is worn  (All else being OK)

John
Title: Re: Primary Chain/Sprocket Wear
Post by: BagONails on 08.06. 2021 13:58
The correct hex nut has a thick (5mm) washer behind it to clamp the inner drum onto the adaptor

Yes I found a different nut and washer and tab washer listed, the thick washer is dished so it clamps the hub back against the shoulder on the adaptor I take it.

If you can get the puller jaws behind the adaptor it should work, otheres have used a split clamp type yoke to get behind the adaptor....

it worked a treat thanks!


There should be almost zero endfloat on the gearbox mainshaft
The shaft is clamped to the kickstart side ball bearing
Either the nut is not tight or the bearing is worn  (All else being OK)

John

Oh gawd the trail of destruction leads on into the gearbox... *work*

After taking the inner primary off this evening I turned it over to look at the back and found the final drive chain has been milling away at it because the case has been flexed so far over by the huge spacer at the rear mount. This could have turned into the mother of all oil leaks  *eek*

 I also found the nut holding the final drive sprocket was loose, only the very tired looking tab washer was holding it on. And so it continues!
Title: Re: Primary Chain/Sprocket Wear
Post by: Colsbeeza on 09.06. 2021 03:03
Hi BoN,
 If the inner case is saveable, I recommend the approach that I took.
First - check that it mates well with the outer case.
Secondly - place a straight edge along the gasket surface of the motor and measure the stand-off at a couple of points along the gearbox/engine mounts. This is to check that the engine is square with the frame and mounts.
Thirdly - screw the inner case to the engine using the 3 studs and check that the clearance behind the rear mount is only a mm or two.
Between these checks you may find (probably will) the inner needs some panel beating. I laid it down on the bench with some rag underneath and gave it a few strategic whacks with a rubber mallet. A good eye helps decide just where to whack it. It was surprisingly pliable and no hint of cracks or damage. At your own risk of course! Then a final check that the inner and outer mating surfaces don't have any large gaps.
Step 4 - If all fails, look for another inner case.! ;D
Col
Title: Re: Primary Chain/Sprocket Wear
Post by: BagONails on 13.06. 2021 06:21
After removing the outer cover on the gearbox I found the K/S nut to be tight and I can see the mainshaft and the inner bearing race moving together. I measured 0.4mm (0.016") end float so this now appears to be wear in the bearing itself.  The kickstart gear is also showing a fair amount of wear.  At this stage I don't want to get into a full gearbox rebuild and my test rides so far have not shown up any obvious issues apart from some difficulty finding neutral. It was quiet and gear changes were smooth enough, no whining or jumping out of gear etc. I suppose I should ask at this point what are the likely symptoms of a worn mainshaft outer RH bearing and how much of an issue is it in fact?

I'm considering now following the service sheet 311 which says I can pull the mainshaft out of the gearbox as an assembly complete with the inner cover, after removing one more screw. This should then allow me to undo the kickstart nut, strip everything change the bearing and the kick start gear (if I can get one) on the bench while leaving the rest behind in the shell.  Reassembly is simply the reverse of disassembly...now where have I heard that before *eek*

It would be good to hear from anyone who has done this and what issues may be hidden for young players, it all sounds too easy somehow...
Title: Re: Primary Chain/Sprocket Wear
Post by: Swarfcut on 13.06. 2021 08:27
 To swap out just that ballrace, the inner cover and bearing can come away after the mainshaft nut and kickstart ratchet, pinion, bush, spring and washer are slid off. This leaves the mainshaft in place. This procedure is outlined in Service Sheet 209, for Plunger boxes.

 If the clutch is already dismantled the mainshaft can be removed complete with the inner cover as in Service Sheet 311. With the mainshaft gears left in situ, replacing the mainshaft may prove a challenge, lining up the splines. Easier on a loose box, more tricky perhaps with the box still on the bike.  Both Plunger and S/A boxes share similar layout, and on the face of it the dismantling procedures should be the same, but as they say there are more ways to skin a cat, so proceed as to what suits the situation.

 Outer race is a press fit in the inner cover. Warm the casting and it will drive out easily. New bearing in the freezer, warmed case and it will fit with no drama.  Check the seating for wear and also the condition of the retaining spring steel snap ring. When replacing the inner cover, ensure the selector shaft is lined up with its location in the inner cover. Unintended  pressure on this shaft will break away the retaining grubscrew location adjacent to the chain sprocket.

 Kickstart gear comes in two variants of tooth profile. If replacing, make sure it matches the quadrant teeth. All explained in previous Forum posts, it's just a matter of searching.

 Swarfy.
Title: Re: Primary Chain/Sprocket Wear
Post by: berger on 13.06. 2021 11:29
swarfy's first way of doing this is the way to go leaving the mainshaft in the box otherwise the selectors and gears may move making it a bit awkward on re assembly. when pulling the inner case away keep your thumb on the mainshaft end to prevent it pulling out and letting these bits slip out of place.
Title: Re: Primary Chain/Sprocket Wear
Post by: BagONails on 13.06. 2021 12:07
Thanks guys, my main concern was how tight the mainshaft would be in the inner race of the bearing which would be a problem for disassembly and reassembly with the new one but if not too tight then leaving the shaft in situ sounds like the go, I will find out in the morning *smile*
Title: Re: Primary Chain/Sprocket Wear
Post by: chaterlea25 on 13.06. 2021 16:21
Hi Ian,
Pulling the mainshaft can allow one of the gears slip out of the selector fork, hard to see if it's the in er one, then a locked up box *eek* best to leave the shaft in place *ex*
The sliding plate in your pic looks  non standard? With a boss at the sprocket side
Can You post some close up pics from either side?
Now is the time to check out the condition of the drive sprocket and seal in the gearbox along with the main bearing and sleeve gear bushes
I wonder why the case was pushed in so far? Was it to allow the clutch to seat on the taper? Does the sliding plate fit onto the adaptor scroll or does it have a seal that rides on the gearbox shaft???

John
Title: Re: Primary Chain/Sprocket Wear
Post by: BagONails on 14.06. 2021 11:40
Hi John,
Now hang on a minute, I thought I was the one asking the questions around here?!  *fight*
(Only Jokes folks very grateful for the input and the interest.)

The sliding plate in your pic looks  non standard? With a boss at the sprocket side
Can You post some close up pics from either side?

So you spotted that then, I'm sure P/O has put this on backwards with the riveted on plate against the felt washer, that plate weren't slidin' nowhere!

In fact due to the worn out chain wheel and very worn primary drive chain the gearbox is quite a long way back and the riveted centre piece was partly across the edge of the hole in the rear primary case. I've attached photos of the plate and the adaptor as you can see it has been rubbing hard on the mainshaft.

I have ordered amongst other things a chainwheel/clutch basket, new adaptor, new center hub and new rollers so we will see how all this fits up. There was significant movement on the chainwheel in the old assembly and due to a lack of lubrication, I can see significant wear on the original adaptor where the rollers were running so decided to replace everything that could affect this. It has been running with the wrong centre nut and no flanged washer so I think things were being pulled well out of line by the engine torque and this has caused a lot of the chewing away on the sprocket side you can see in the previous photos. The alignment currently is actually pretty good, within about 0.5mm with a quality steel rule edge on along the drive sprocket and sighting from above along the dismantled empty chainwheel/adaptor assembled back on the mainshaft.  I only hope the replacement parts will be comparable but we will worry about that when they arrive.

I've added a picture of the gap I am getting now at the rear mount to the frame with the inner case reattached at the front and this is without the new gasket in there. The gap is about 2mm, and that is the spacer that was in there, its about 8.5mm thick... and I was disappointed it was leaking!
Title: Re: Primary Chain/Sprocket Wear
Post by: BagONails on 14.06. 2021 12:20
Part 2!
In which we answer more of John's questions hopefully...
Now is the time to check out the condition of the drive sprocket and seal in the gearbox along with the main bearing and sleeve gear bushes
I wonder why the case was pushed in so far? Was it to allow the clutch to seat on the taper?

The final drive/gearbox sprocket has been removed and this is a shot of the back of the gearbox. I've not cleaned anything and you can see the glistening pieces of aluminium swarf stuck all over everything from the drive chain milling away the rear primary case - noice! The good thing is that the gearbox had plenty of reasonably clean oil in it and most of it was inside rather than outside. The main bearing and seal appear to be OK I can only feel bare perceptible movement in the bearing same goes for the sleeve between the inner mainshaft end and outer constant mesh gear. There was a little oil around the sprocket at the back but this must come through the sleeve and the splines I guess and can't be stopped as far as I can see.

So the covers both came off easily enough and I am pleased to find little sign of P/O having ventured this far. The gaskets were old and very thin more like  a fine paper than the usual. I have found the kick start pinion in rather a sorry state, it looks like the pointy version, while the quadrant has truncated teeth and looks like new, its as if the pinion is purposely designed to be sacrificial although it's not so cheap to replace.

I also found the kick start quadrant stop was loose (despite having both a split washer and a star washer on the back!) and was slowly chewing its way through the cover, you can see the ovalised hole in the housing. I'm thinking to fix this I need to spot face the inside of the housing and put in a non standard  steel washer as the stop is slowly disappearing further inside the housing each time it gets re-tightened.

Finally I'm not sure this bearing was correct? Why would you put a sealed bearing in there when its running inside a sealed box with plenty of lubricant sloshing around? In fact its possible this has been causing oil starvation to the layshaft bush which sits below. There is a drilling which appears to be situated to benefit from oil coming through the bearing above and running down the face to be collected by the drilling and feed the layshaft end bearing in turn except this wouldn't happen with a sealed bearing I don't think?  Having said all that All the bronze bushes I can see and get to appear in pretty good nick with no visible wear ridges. I think this box might have been reconditioned at least once in its life...

Finally a quick peek inside, not much room for fingers in there, glad I sought advice on here before pulling its guts out as I can now see how difficult it would be to fiddle things back into place when it is on its side like this in situ.  Once again thanks for the good advice fellas.

Cheers Ian
Title: Re: Primary Chain/Sprocket Wear
Post by: chaterlea25 on 14.06. 2021 13:01
Hi Ian,
Ok, where do I start my reply?

I can see that the sprocket seal circlips is not fully seated in its groove as the ends are too close together... this is a common issue as the rubber face on the back of the seal can be too thick.   Work around the circlips with a flat punch and see if the circlips seats into the groove

The gearbox bearing is usually open, but I bet if you popped the seal off it's full of oil?
A lot of modern gearboxes use sealed bearings. Make sure the replacement is a quality branded item

The kickstart ratchet gear should match the quadrant, it looks like a pointy gear was fitted? Hence the mash up!!!
The inner bushes are different sizes , was the pointed gear loose on thd bush?
Anyway you need to match them up

I posted a fix for the kickstart stop a long time ago, Do a search for it
(I am replying on my phone so not easy to search) I can look tonight if you can't find it

John
Title: Re: Primary Chain/Sprocket Wear
Post by: berger on 14.06. 2021 13:07
bagonails i can't find the pics of the kicker stop repair my brother did for mine but i think he bored the hole and made a new stop, and made a top hat steel sleeve fitted in the case and a thick washer at the back
Title: Re: Primary Chain/Sprocket Wear
Post by: BagONails on 14.06. 2021 14:27
bagonails i can't find the pics of the kicker stop repair my brother did for mine but i think he bored the hole and made a new stop, and made a top hat steel sleeve fitted in the case and a thick washer at the back

I think I've found it here bergerman during my search for ratchet to quadrant match ups rather than mash ups.
with my compliments:
https://www.a7a10.net/forum/index.php?topic=15587.msg132470#msg132470

It looks like a good solution, I think I could do that, thanks

John said
"I can see that the sprocket seal circlips is not fully seated"
Yep in fact the one I took out today was similar, I think they've been out before. These clips are tricky to remove without over straining them and they can take a set. I will try your suggestion as we don't want him popping out down the track.

"The gearbox bearing is usually open, but I bet if you popped the seal off it's full of oil?"
That would be my expectation, I tried this and found the inner side seal had already been cut out and put back in again! Yes there was oil in there. I will try to get an open bearing to go back in they are usually cheaper and turn more freely too. The bearing is worn but I've certainly seen and heard a lot worse. It would probably run for many more miles but maybe the end float has an affect on gear changes so worth changing it now its out I guess.

"The kickstart ratchet gear should match the quadrant, it looks like a pointy gear was fitted? Hence the mash up!!!
The inner bushes are different sizes , was the pointed gear loose on thd bush?
Anyway you need to match them up"

I've been searching and read many threads but I'm still not sure. Our parts guy here "Mike's Classics" lists 67-3376 and that agrees with the spares list I have. The picture is of a pointy toothed 17T pinion  He also lists a 67-3168 which he says is for Plunger models and not for S/A types like mine, this one has flat topped teeth. So it would seem that my pointy toothed pinion is the correct one. The book also says 42-3160 is the correct quadrant but this has pointy teeth and mine are very flat topped. Maybe I have the wrong quadrant and that has mullared the pinion? The pinion is a lot cheaper to replace however so do I get a truncated tooth version to match the quadrant I have but then I need to change the bush as well which is a good fit with the current pinion. Basically how do we match these correctly is  it pointy/pointy or truncated/pointy or pointy/truncated or truncated/truncated (Quadrant / pinion respectively)

I've not seen your K/S stop idea John but the one above looks pretty good, maybe you have a similar suggestion. The idea of a top hat sleeve sounds right to me. I'll make a new stop pin too while I'm at it.

Back to more searching now...

 
Title: Re: Primary Chain/Sprocket Wear
Post by: Swarfcut on 14.06. 2021 17:13
  Ian.  The quadrant and pinion for all model years share the same basic dimensions as regards bush and shaft sizes and intechange as a pair. Early and late quadrants differ in style and manufacture eg splined kickstart shaft/pressed on quadrant early, one piece brazed up versions on later models. The tooth profile changes too, truncated/flat top quadrant teeth (early) pointy teeth later. Add to that quadrant versions which position the kickstart lever pointing slightly forward and you can see the numerous part numbers which add to the partsman's inventory as this basic box is also used on other models.

     If you have a good quadrant, simply use that with a pinion of matching tooth profile. That's the hard part as it's clear some sellers think one size fits all mistakenly confusing the differing tooth profiles. Mismatches and wear are the reasons for kickstarts that jam. Also true of the previous owner by the look of it, it's a mix, with a good early type flat top tooth plunger quadrant mated to a later pointy pinion.

 Here's what goes with what, all will interchange as pairs on Plunger or S/A boxes.

Plunger        Quadrant 67 3178   with  Pinion  67 3168   Flat top teeth. Fitted up to the 1954 model year.

 With the introduction of the S/A models, the teeth profile changes and the new parts are then used on Plunger boxes as well.

   S/A      Quadrant 42 3160  with   Pinion   67 3376   Pointy teeth. This pair are also shown in my parts list for later engine series DA10 onwards including Super Rocket and Plunger boxes from 1954.

   Your picture of the seal and snap ring looks a bit strange regarding the grub screw securing the selector rod. Hope its a trick of the light but it looks like the area has a hairline crack starting. Pay attention to this area, plenty of internet images of what is correct.

 Swarfy
Title: Re: Primary Chain/Sprocket Wear
Post by: BagONails on 15.06. 2021 12:36
Swarfy, I am very grateful to you, there are many threads relating to various kickstart pinion/quadrant queries but nowhere have I found it laid out so succinctly, thank you and I'm sure this information will be useful to many of us in the future. (although it is possible I am the only Klutz on here who doesn't have all this down pat yet!)

My quadrant looks very much like an earlier (incorrect for my bike) flat topped tooth model and has the splined connection so 67-3178 per your table and therefore I should be able to fit the earlier pinion 67-3168 if I can find one. Photo attached shows the quadrant is in amazingly good nick considering the pinion it has been chewing through all this time, even more amazing is the fact I was blissfully unaware until opening the cover as the kick start was functioning very well!

You had me going there with that 'crack'. I have cleaned up the area in question now and donned my best "seeing glasses" and am relieved to report there is no crack present.  The line which had me worried I will grant you appears to be a pattern or moulding joint from original manufacture, I've attached another photo to set your mind at ease *smile*

The snap ring however has lost its snap and is well past its best (it virtually fell out when I started winkling with my screwdriver) I will try and find a replacement, also I guess I should renew the seal if it is possible to insert one from the back. I have resisted pulling the existing one out as it is offering resistance and I don't want to damage it until I know I can put a new one in from this side, it looks like I should be able to.

Once again very grateful for all the help from you guys on here it really is invaluable especially to a newb like me.
Cheers Ian
Title: Re: Primary Chain/Sprocket Wear
Post by: Swarfcut on 15.06. 2021 13:59
Ian. Lots on the Forum about the seal and their variance in quality and accuracy of manufacture. Once the snap ring comes off the seal can be levered out, and a new one can be replaced with a  smear of silicone or jointing compound.  The snap ring holds it all in place and as already  noted the ring needs to well seated in its groove. This is where a sealed bearing would offer a belt and braces solution to an annoying and hard to get to (without major dismantling) oil leak. All gearbox sprockets used with a seal interchange allowing a choice of final drive ratio. Downside is that the speedo will be no longer accurate, always assuming it was the right one to start with.

 That capscrew is a spurious part. Original grubscrew is slotted Whitworth Thread Stud with a tit on the end to engage in a radial stop groove in the selector support rod.

 Good news about the casting, reassembly will get easier from now on. Reckon the hard part is over.

 Swarfy.
Title: Re: Primary Chain/Sprocket Wear
Post by: BagONails on 15.06. 2021 15:07
That capscrew is a spurious part. Original grubscrew is slotted Whitworth Thread Stud with a tit on the end to engage in a radial stop groove in the selector support rod.

 Good news about the casting, reassembly will get easier from now on. Reckon the hard part is over.

 Swarfy.
I'm pretty sure I can find a grubscrew that will be neater and suit/ stand modification. I'm loath to disturb anything there in case something moves tho...

I do hope you are right mate, the interesting bit will be how comparable all these replacement parts turn out to be, could be a whole new set of issues but I will try to not bother you too much!   *thanks*

Ian
Title: Re: Primary Chain/Sprocket Wear
Post by: morris on 15.06. 2021 18:13
While at it, a SRM sprocket nut is a worthwhile upgrade to prevent oil seeping out via the mainshaft/final drive gear
Title: Re: Primary Chain/Sprocket Wear
Post by: chaterlea25 on 15.06. 2021 23:03
Hi Ian,
Here is the link to my repair for the kickstart stop, similar to Berger's but all in one piece
The thread size is increased to 3/8in.
Hard to believe I posted this back in 2010 *eek*

https://www.a7a10.net/forum/index.php?topic=2914.msg19637#msg19637

John
Title: Re: Primary Chain/Sprocket Wear
Post by: BagONails on 16.06. 2021 00:27
While at it, a SRM sprocket nut is a worthwhile upgrade to prevent oil seeping out via the mainshaft/final drive gear

Good idea Morris, and there's me thinking it was a design feature to keep the final drive chain lubricated.  ;)
Title: Re: Primary Chain/Sprocket Wear
Post by: BagONails on 16.06. 2021 09:46
Hi Ian,
Here is the link to my repair for the kickstart stop, similar to Berger's but all in one piece
The thread size is increased to 3/8in.
Hard to believe I posted this back in 2010 *eek*

https://www.a7a10.net/forum/index.php?topic=2914.msg19637#msg19637

John
That's great too, good job John. It is an uncharacteristically poor piece of design by BSA considering the hammering this detail can potentially receive if you are the kind of owner who just lets the kickstart fly back.  I think mine might end up 3/8" BSF if you will allow as I don't possess any BSCY taps or dies as yet...or possibly even M8 with a nyloc nut  *shh* and dare risk being struck down by the great one eyed rivet counting Beezer gods in the sky... *smile*