The BSA A7-A10 Forum
Technical (Descriptive Topic Titles - Stay on Topic) => Gearbox, Clutch, Primary => Topic started by: bakerlonglegs on 13.04. 2020 10:27
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Hi,
I have a rebuilt (by someone else) gearbox I’m using in my A10 plunger restoration. I’ve put the kickstart back on to try turning the engine and the gearbox over but the teeth on the kickstart spindle and the teeth on the spindle that meshs with it don’t line up. They’re meeting tip of tooth to tip of tooth if that makes sense!
I’ve tried to take a pic, see attached, but it’s difficult to get a clear view. This shows the kickstart lever pushed down as far as it will go, i.e. the teeth are in contact tip-to-tip. I can put the bike in gear, rotate the back wheel until the kickstart does mesh, but then one full push on the kickstart and it’s out again. I’ve not put any oil in the gearbox yet as I’m worried I’ll have to take it apart it fix it.
Does anyone have any ideas why this is happening and how to fix it, or is it meant to be like that?
Many thanks!
Edit - that pic is rotated, I don’t know why. Hopefully you get the gist!
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Looks to me as if the quadrant teeth are displaced sideways in relation to the kickstart ratchet teeth. Also assume the bearings and bushes on the inner cover are all good with no radial movement. Bronze bush inside the ratchet cylinder is present.
First line of your post says it all. Without knowing which year the box is, here are a few possibles.
Early plunger box uses a flat clockspring, outer cover has no retaining nut for the spring, instead it uses just a peg on the inner cover. The quadrant has a splined shaft mounting, spring just hooks over a spline. So if you have an early box of this type, the quadrant may not be in the right place on the spline. It should be level with the inner end of the splines. Here the length of the splines on the kickstar shaft between the inner and outer covers controls the lateral position of the kickstart shaft and quadrant.
Later boxes use the more familiar type of spring, the quadrant design changes, so you get them with pointy or flat top teeth, which the ratchet tooth profile must match. Quadrants have a more positive location, appear brazed onto the shaft in some cases. The design requires a boss on the forging or an added cylindrical spacer to hold the shaft laterally as before.
So, you may have a mix'n match set of bits and all depends on what you have. Simple answer is that possibly the cylindrical spacer is missing that pushes the quadrant towards the inner cover to keep the teeth in line, part 67-3173. It all depends on what quadrant you have. As mentioned some seem to have this spacer incorporated into the machining of the kickstart shaft, so this won't apply, and if this is the case, I'm stumped. In all cases the quadrant locates against the kickstart shaft bush on the inner cover, and something in the design you have should locate it here with no chance of lateral shaft movement.
If I've misjudged the whole issue, similar but incorrect parts from another model are the possible solution. All this assumes the box is assembled as it should be, and the quadrant has not been messed with.
Swarfy
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Swarfcut - thank you very much for your quick and detailed reply. Based on that, I thought it would be a good idea to remove the cover and take a look. Some pics attached, aimed at the points you mentioned. I’ve also taken a pic showing a bit more clearly how the quadrant teeth foul tip-to-tip with the ratchet teeth now that the cover is off - it’s only just!
The quadrant appears lined up with the inner end of the splines. The cylindrical spacer is in place. The spring is just held onto the cover by a peg, the other end hooks onto a spline as you said.
Any more thoughts greatly appreciated!
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And one of the kick start spindle
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Second photo - the k/s pinion on the main shaft is very very badly worn and needs replacing - also check the bush on which it rotates.
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Well I got that one wrong. Parallax error? Julian has the answer, and I can see now the box has an early flat spring type cover. Yes, the ratchet pinion is badly worn.
I pulled the cover off my Longstroke box. This has the flat spring and flat topped quadrant teeth. There is no sign of a brazed joint, mine is just pressed on to the shaft.
From experience, the later spring is an improvement. If the flat spring is not tensioned tightly enough, the outer coil of it will bear on the ratchet assembly...clicky- click it goes as you turn the mainshaft by hand. Flat spring also jumps the splines, and assembly is awkward and possibly a bit scary if it slips.
Your shaft looks OK, Quadrant in the right place. Somewhere on the Forum the various parts and numbers have been debated in detail. Later plunger cover, etc plus matching pinion to suit the quadrant are a straight swap. Later S/A kickstart parts and matching pinion will also fit the later plunger cover, or your early cover if you modify the spring peg.
Swarfy.
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Thank you both for your replies. I’ll replace the ratchet pinion then. Which leads to another question (sorry! *red* )......
The ratchet pinion is now out of the gearbox, see pic. The teeth have flat sections in the recesses between each one, which matches the flat tops of the quadrant teeth. The hole is 23.8mm/0.937”. My parts book says the number is 67-3168. However the first website I looked at suggested that part number has a 3/4” hole and the part number with the larger hole, as mine, is 67-3376. However, when I find 67-3376 on line the teeth have V-shaped recesses. Errrrrr......
Again, any advice appreciated here!
Edit - I see what you mean about the debate on part numbers!
https://www.a7a10.net/forum/index.php?topic=10382.0
Maybe I need a new ‘pointy’ quadrant to go with a ‘pointy’ 3376 pinion?
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Apologies to forum members, this is the day of my most daily posts ever. Somewhat embarrassing but here we go.
In an ideal world, replacing the worn pinion, its supporting bush and matching profile quadrant gets the bike back on the road and a confidence of trouble free miles ahead. As with other gear teeth, mixing old and new parts never give the ultimate long term utility.
The mainshaft diameter is the same on all boxes, but as you have found, there are variants in the bush OD and pinion. V shaped teeth are later, if my Longstroke flat top quadrant is original. So a V tooth quadrant with an early type splined shaft would do, I'm thinking "middle to late" plunger box, and early S/A, if you want to retain the original cover and flat spring. These boxes retain the splined shaft, but have a conventional spring. Later cover brings wider choice for replacement, later spring, plain shaft.
So the options are cheap to expensive, and the decision is probably the hardest part of sorting this little problem.
Swarfy
Additional.
1949 Longstroke Gearbox part numbers Quadrant 67-3165
Ratchet 67-3158
Pinion 67-3159
Sleeve 67 3160
These are the parts used up to 1950 which your early type box may have and should be direct replacements. Finding them may prove difficult.
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Thank you Swarfcut! Advice and part numbers much appreciated *beer*
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Hi.
I was working on a 52 gearbox a few weeks ago, and needed a ratchet pinion (flat top)
I had quite a job sourcing one *sad2* (they said it was the last one in stock)
Good luck with the search for one
John
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Maybe try Mike Reilly in Brisbane Aust as he has NOS gearbox gears.
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Hi,
I thought I would provide an update as to where I’ve got to on this. A company called De Groot in The Netherlands sold me a new ratchet pinion, under part number 67-3168. Very easy to deal with and the part arrived quickly given the lockdown. It has the inside diameter of 24mm and square gaps between the teeth. It’s much better than the old one but the kickstart lever still jams about half the time. I’m going to wait until I get a chance to ride it then see if that frequency changes.
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Hi,
I thought I would provide an update as to where I’ve got to on this. A company called De Groot in The Netherlands sold me a new ratchet pinion, under part number 67-3168. Very easy to deal with and the part arrived quickly given the lockdown. It has the inside diameter of 24mm and square gaps between the teeth. It’s much better than the old one but the kickstart lever still jams about half the time. I’m going to wait until I get a chance to ride it then see if that frequency changes.
Get most of my parts from them. Very correct and easy people.
Ideally you'd change the ratchet and quadrant as a pair.
Had the same issue. Only changed the ratchet but it kept jamming every now and then. Replacing the quadrant with an item from the same supplier cured that
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maybe you could lap the old with the new using a bit of grinding paste??? or replace the other part as Morris suggested which is probably the best way out....
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I really shouldn't browse the forum you know, this post prompted me to go through the kickstart stuff and also any new bits I'd bought earlier - surprise! it looks like I have a worn "pointy" quadrant and I've bought a "flat top" pinion *sad2*, so I decided to browse further and can see lots of earlier discussions on the subject, but can somebody summarise what goes with what regarding year of manufacture please?? eg I have a '56 A10 s/a with a 2 piece quadrant that I think is pointy but could just worn pointy! all the stuff out there now seems to be one piece flat tops, hence I guess why they supplied the flat top pinion (years back now, so cant change if I wanted to)…..
Also, there's been no chat about replacement rachets, are they all the same regardless of the pinion type? the reason for asking is that the new flat top pinion really doesn't mesh that well with the old rachet, again could just be wear I suppose, but is the rachet part of the change too??
Finally, the bush that the pinion sits on, seems to have worn a lot because its actually stuck inside the old pinion (free to rotate/wobble around, but doesn't slip out), or is this because somebody earlier has overtightened the mainshaft nut and squashed the bush (I think I read that somewhere in another post)??
thanks for your thoughts and ideas, its been quite eye opening as I travel down the rebuild path (at last!!), cheers
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Jules, If you are sure it is a flat top pinion, a flat topped quadrant from an early plunger box should fit. A "one piece flat top " should do, finding the flat top pinion is the hard part.....no problem for you.
1947/53 Ratchet 67 3167 Pinion 67 3168 Bush 67 3169
Quadrant 67 3178 Plunger Box, "Flat Top" Quadrant
1954/57 Ratchet 67 3167 Pinion 67 3376 Bush 67 3169
Quadrant 42 3160 S/A and Plunger Box "Pointy Top" Quadrant
Data taken from published parts lists. Both boxes use a common kickstart assembly from S/A introduction.
On the face of it, for these model years the cylindrical pinion bush and ratchet remain the same, changes confined to quadrant and pinion tooth form.
The early longstroke box has a flat top quadrant and pinion, so by my reckoning any flat topped quadrant from any year pre-54 should match your flat tooth pinion. Part numbers change to accommodate minor variations in quadrant construction, splined or plain shafts, but the essential dimensions and fit are the same. As the flat top form was only run for a few years, this may explain the apparent surplus of quadrants and shortage of pinions. As long as pinion and quadrant tooth form match as a pair, they will fit. A pointy tooth quadrant matches a V root pinion, flat top quadrant matches flat root pinion.
Swarfy.
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ok Swarfy, appreciate you taking the time for me *smiley4*, but you have me thinking now about "pointy" vs "flat top" and I thought I'd mastered it! The new pinion (from C&D yonks ago) says it 67 -3376 on the bag, but it looks like its got a flat top on the teeth!! is the difference subtle or obvious, any body have a pic of each??
and "pointy" is correct for s/a, hmm....I think I'd better get a new rachet too then because it doesn't seem to match the new pinion very well, plus a new bush, I cant understand why the bush doesn't just slip out its clearly worn, hence my question about how tight to do up the mainshaft…. cheers
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same here jules with the flat bits, I went through mine the other day and noticed removable ones and fixed ones , also pointy bits and flat bits. the flat bits being in the bottom of the ratchets and the tops of the quadrants , and the pointy bits in the bottom of the ratchets and top of the quadrants
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Yes, 67 3376 is the later pinion so should have V shaped tooth roots to match a pointy tooth quadrant. So in fact yours is not, as I thought, a rarer earlier pinion with the flat roots. Sorry, just barked up the wrong tree, and an unworn pointy quadrant should do the job. Suppose it hinges on a mis- understanding in the description of what's flat or pointy.
bergs nailed it better than me, but that's the answer.
Swarfy.
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thanks Berger/Swarfy, things are getting clearer by the minute and I think a picture is worth a thousand words, so here's a few pics showing the meshing of the old bits with new pinion - are they "pointy" or "flat head"?
I'm thinking there might be a bit more life in the old pinion and quadrant yet, maybe?
I'm concerned about the meshing of the old ratchet with the new pinion (doesn't look so well meshed as the old parts)?
I'm concerned about the meshing of the old quadrant with the new pinion (maybe jamming potential)?
I'm planning on a new bush which should certainly help with meshing stability, the old one is well worn/barreled actually, hence my question about overtightening ie what is tight?
No more questions, thanks for your help with this, cheers
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Jules Just pulled the cover off an early Plunger box, kickstart return spring is flat clockspring type. Quadrant design has splined shaft, pressed on quadrant with flat top teeth.
Pinion has 17 teeth, with distinct flat area between the teeth roots. Ratchet teeth mesh fully.
Your new pinion looks to be a worse match than the original parts! The teeth have a more straight sided profile, maybe flat roots. It looks almost right for my early type quadrant. C & D miss pick?
My pinion has worn quadrant teeth, but the ratchet teeth mesh to the roots, less a bit of wear, your new pinion looks almost pre-worn.
Swarfy
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Additional Few more pix. Plunger box, early type. Features a Quadrant with flat top teeth, splined shaft, pressed on quadrant, clock spring return, anchor peg (not nut and bolt) retains the spring. Outer cover has no grease nipple on clutch arm spindle
On this box, Mainshaft nut looks a bit suspect, hanging on by a thread. Pinion badly worn and ratchet spring support washer between pinion sleeve and bearing is missing.
What other mishaps shall we find inside? Nice bit of sediment there, but no nasty noises or metallic bits in the oil, so looks a good 'un. Thinking about the bearing, an open type here must catch a fair amount of material worn from the ratchet pinion.
Swarfy
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Hi Swarfy, yep definitely looks like the new pinion is flat topped/bottomed, more suitable match for your quadrant in pic vs my quadrant which looks more pointy with the bottom of the pinion less flat too *eek* *sad2*, but the mismatched ratchet shape is a worry, it looks like they missed the back relief/chamfer to allow the ratchet to slide further in *eek* *sad2*, maybe fixable with a small grinder if I get desparate….
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Jules, your pinion looks like this one as regards ratchet teeth. Maybe a case of mistaken identity at C & D.
https://www.ebay.co.uk/itm/NEW-BSA-M20-M21-B31-B33-RIGID-PLUNGER-KICKSTART-PINION-66-3080-1938-62/143257291483?_trkparms=aid%3D1110006%26algo%3DHOMESPLICE.SIM%26ao%3D1%26asc%3D20200513093106%26meid%3Deda32ddc550642feb8b06131271e9257%26pid%3D100005%26rk%3D5%26rkt%3D12%26mehot%3Dlo%26sd%3D322577000971%26itm%3D143257291483%26pmt%3D1%26noa%3D0%26pg%3D2047675%26algv%3DSimplAMLv5PairwiseWebWithBBEV1Filter%26brand%3DBSA&_trksid=p2047675.c100005.m1851
Despite appearances, this parts inventory is mainly Indian. A,B,M Series gearboxes share common design concepts, but there are detail differences. Draganfly's online parts catalogue offers hours of free entertainment!
Swarfy.
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yep, I think you could be right Swarfy *sad2*, I'll hold off anything further until I get the new bits from Mike, then see if I can make a silk purse out of a sows ear ! cheers