Primary Chain/Sprocket Wear

[chaterlea25]

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 best to leave the shaft in place
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

[BagONails]

Hi John,
Now hang on a minute, I thought I was the one asking the questions around here?! 
(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!

[BagONails]

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

[chaterlea25]

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

[berger]

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

[BagONails]

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...

 

[Swarfcut]

  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

[BagONails]

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

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

[Swarfcut]

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.

[BagONails]

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!   

Ian

[morris]

While at it, a SRM sprocket nut is a worthwhile upgrade to prevent oil seeping out via the mainshaft/final drive gear

[chaterlea25]

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

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

John

[BagONails]

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. 

[BagONails]

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

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  and dare risk being struck down by the great one eyed rivet counting Beezer gods in the sky...