Substandard parts.

Started by Janacek, 11 Apr, 2026, 11:23

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Janacek

Had several new parts on my B31,and most are ok.
However I fitted a new kickstart ratchet pinion and kickstart quadrant and new folding kickstart lever and cotter pin.
The first thing that happened was the threaded portion of the cotter pin snapped off as I was tightening it.The folding kickstart jammed against the silencer and as the exhaust pipe is against the bottom rail it can't be moved.The ratchet pinion has started to jump a tooth,and although the quadrant looks ok,the ratchet pinion has some burred teeth.This has only been on for a couple of months and I have only ridden three times.
These are of course aftermarket pattern parts and I strongly suspect that the material and accuracy are below the original spec.
Are original new,old stock genuine BSA parts available anywhere? Or a supplier of parts that are definitely up to spec?

Derek996

The thread and nut aren't meant for tightening the cotter pin, only for retaining it. When fitting a cotter pin, tap it in fully from the opposite side until it is fully home then tighten the nut to a sensible torque which be about 9-10Nm for the 1/4" threaded section.
The kickstart lever apparently has an incorrect offset, not unusual for pattern parts unfortunately. I can't comment on the quadrant and ratchet pinion although I suspect thay are not up the standard that they should be. New old stock parts are now very hard to find.
1948 BSA ZB32 Competition
2015 Ducati Scrambler Classic
2017 Ducati Supersport 939

neil1964

Afraid the kickstart clearance will be by trial and error.
The kickstart ratchet problem is two fold:
Early quadrants (OEM ones have splined shaft and removable quadrants these and matching ratchet gear have flat top teeth.
Later ones have pointy teeth.
Mismatch these and wear is dramatic. Added to that bear in mind that quite a lot of Indian supplied ones are made of hard cheese.
Cotter pins also an issue (also seem to be made of cheese!). I have guillotined two so far on my DBD34 600 kickstarter and suspect the one at the moment is going same way (warning seems to be you notice kickstart is a little loose on the shaft, despite washer and spring washer, so you tighten nut - a week or so later the pin shears).  I notice this phenomenon again this week as I have been using bike for commute to work. I grabbed a spare pin and suitable spanner and kept in my jacket pocket.  I've got a Barleycorn ss one on my off-roader and that is very secure, so just bought two more ready to find next pin is on its way when I grab time tomorrow!
So I suggest Barleycorn ss cotters and try Kidderminster MC for ratchet gear once you have confirmed flat vs pointy quadrant (these don't seem to wear).
Beware eBay sellers and part numbers as they mix them up assuming all the same.
Good luck.

V500

A lifetime ago when I was interested in pushbikes and riding them through the countryside (but before those new-fangled cotterless chainsets were financially available) we used to file the cotter pin to fit nicely. The thinking was at some point, probably sooner rather than later, the cotter would need to be removed again to change the cranks etc.
Trying to pull them home with the thread or knocking five bells out of them to make them fit was severely derided.
Clearly it must still go on on BSA's as my Goldie has witness marks on the gearbox end cover where someone was a lousy shot with the ball-pein hammer..

limeyrob

Pattern parts are often poor metal and poor fit but that makes fettling even more critical. I file and trial fit cotter pins then tap them home. For crucial parts I try to find good original used parts as I know they are well made.
This is not restricted to BSA or even bikes, I have the same problems with an old Land Rover, if you get a good set of brake drums you hold on the them!

scifi

Am I correct, that bike Cotter Pins had to be put in a certain way around, so they would tighten in normal use..?   I think the hole in the crank was also larger one side than the other.

idie

Make sure the kick start quadrant and pinion have the same tooth form. They either have straight teeth or rounded. Mix them and if they don't  jam they will tear themselves to pieces.

Janacek

Thanks for the replies.Mismatched teeth on the qúadrant and pinion would explain the rapid wear. I wasn't aware that they could be different.I will check tomorrow to see what I fitted.
When I order a new ratchet pinion I will make sure it matches the quadrant.

limeyrob

I put the cotter pin so the wide part of the flat is on the high load part when you kick.

Janacek

On scrutinising my ratchet pinion and ratchet,it appears that the slipping kickstart is caused by a rather worn ratchet.
Tried Draganfly but they are on backorder which means probably never,and Classic bike shop doesn't have one.
The part number on Draganfly's list is 67-3167,and looking on the internet there are a few suppliers of the ratchet,but the part numbers don't match up with the Draganfly list.The numbers that the internet suppliers quote are 66-3079 and 66-3080.
Although these are advertised for B31/33,I am unsure about them.
Am a bit stuck as to what to order,so any advice will be welcomed.

Derek996

For the swinging arm gearbox the 1954-54 parts list shows:-
Ratchet pinion : 66-3080
Kickstart ratchet : 66-3079
Kickstart quadrant : 15-4121

But the 1958 on parts list shows:-
Ratchet pinion : 687-3376
Kickstart ratchet : 67-3167
Kickstart quadrant : 42-3160

The 1957 A10 parts list shows the same as later B31/33.

I would reckon that as long as all three items are of the matching type you should be ok.
1948 BSA ZB32 Competition
2015 Ducati Scrambler Classic
2017 Ducati Supersport 939

JulianS

The parts 66 3080, 66 3079 and 15 4121 are for the M type gearbox, used on the M20/M21/M33 and pre swinging arm B31/B33.

For swinging arm B31/33 the parts were the same as for the A7/A10. They were modified in 1955, the attached shows the pre and post modification part numbers. The quadrant was changed again later, I think to one piece rather than a spindle with detachable quadrant, that is the 42 part number in post above.  The ratchet 67 3167 was not changed.

Derek996

Quote from: JulianS on 14 Apr, 2026, 15:49 The parts 66 3080, 66 3079 and 15 4121 are for the M type gearbox, used on the M20/M21/M33 and pre swinging arm B31/B33.
You are correct. I was looking at the wrong diagram.  :'(
1948 BSA ZB32 Competition
2015 Ducati Scrambler Classic
2017 Ducati Supersport 939

idie

So long as you fit as a pair you should not have a problem.

neil1964

#14
To be clear he later (pointy):
Ratchet gear 67-3167 that is compatible with
Quadrant 42-3160 (GS scrambles - ie same as B31/3) or
Quadrant 42-3163 (GS Clubmans 42-3163 for forward canted kickstart).

The earlier (flat top)
Ratchet gear 67-3168
Quadrant 67-3178

Ratchet 67-3164 (that goes on the end under the lockwsher and nut is the same for both.

If pushed I have spare flat top (two piece) std quadrant in good condition but the only decent flat top pinions I need to keep!