I need to remove the cotter pin, to allow access to the outer timing case.
My first attempt with a small G-Clamp, with suitable sized steel bushing over the cotter head.... resulted in a bent g-clamp.
Looking at posts here and RR it seems like next attempt should be a suitably sized drift and careful angling of the hammer swing, with the the nut screwed back so it is just proud/level with the end of the cotter. The nut faces down-ish/backwards on mine. So probably should take the exhaust off to get the drift straight.
Advice welcome, particularly on how to avoid damage. I am a bit concerned that whacking the cotter damaging the shaft mechanism and case hole.
RR mentions using aluminium drift, so should the drift be softer than the cotter?
If the cotter is really that tight then prepare to replace with new when removed. I wouldn't bother unscrewing the nut slightly first as cotter pins are as soft as cheese, and the whacking it'll need would destroy the threads anyway.
A hammer and drift should do the job easily enough.
Beg or borrow a ball joint splitter. Works every time.
Good point. I have dug out a straight push ball-joint press and I can use the bush in conjunction with it....once I remove the exhaust and gear change lever. It has a finer thread than the G-clamp and is more robust and should not bend.
I did once try using this on some bicycle cotter pins. It failed. I struggled to get it stay in line ( in that case) and push straight. Hopefully with the bush over the head of the pin I'll get a more stable fit to push straight.
Have just been looking at cycling forums, I see advice from names I trust saying that well stuck cotters can resist presses like these, requiring tonnes of pressure. It cites the importance of keeping the forces directly in line ( via presses or blows with a drift) and that a series of small sharp impacts (rather than huge wallops) with the crank arm braced against a concrete floor with a thick walled tube,is the most reliable approach with stubborn cotters. If my cotter nut was facing forwards I could do this by tying the kick-start arm in a position parallel to the floor ....er but it isn't......so lets hope the ball joint press works.
So far no one seems very concerned that striking the cotter with a hammer has a risk of damaging the kick-start shaft/mechanism or outer case shaft hole. This surprizes me. I can envisage that if only light taps are required ( as Rupert R suggests) that this risk is be low enough.......I can't see how it wouldn't be a risk with a well stuck one like this.
I think the cotter pin should be fitted with the nut forward, so that the thick end of the pin bears the force of the kick.
If it is fitted the wrong way round it may be that the thin, threaded, end has distorted and jammed.
If this is on a C15 or similar , the nut is forwards.
The wedge of the cotter comes in from the rear side of the kick start lever.
Modern cotters are rubbish material.
Sometimes you may need , during the punching process , to jiggle the kickstart lever a shade.
Nice long punch , I leave the nut just engaged on the thread on the cotter then place the punch into the recess .
The nut keeps the punch from shooting off
As said, most cotter pins these days are very soft. As a last resort, carefully centre op and drill out with progressively larger drills. Once you've got up to 1/4" or so it'll probaby fall out.
I recently discovered cobalt drillswhich make short work of most things and are only a few quid from toolstation and the like.
It's a B40
It looks like the ball joint splitter I have probably isn't usable even with the exhaust off, due to
a) not having enough reach to get over the crank/arch in the kick-start/ & it's too wide to rotate and use it otherwise,
b) there being very little flat edge on the lever either side of the C-P head to securely locate the clamp end without it wiggling out of alignment. If someone has used a press of some form successfully and can share a picture of the press I would seem useful.
Have been considering a vice, with a socket/steel bushing over the cotter head.....But my bench vice is big and supporting it in the right position looks challenging.
I sourced some replacement cotters from a motorbike shop that says they are suitable and not soft (only time will tell). The one in-situ will be 1997 at the latest. If I get this one off a replacement will go back in nut forward. However I am very disinclined to use hammer and drift to anything other than one attempt with light blows.
If you hit it with a light hammer several times, all you will do is bend and flatten the threaded portion, a bit like riveting it in place.
Much better is a very strong hit with a 3 pound hammer, in a direct line with the pin.
If the kickstart has rotated into the pin, you could try levering the kickstart backwards, the opposite way to starting. Be Careful as this presses against the ratchet back-stop.
Quote from: hoogerbooger on 20 Dec, 2024, 18:24 I sourced some replacement cotters from a motorbike shop that says they are suitable and not soft (only time will tell).
It's intended that cotter pins are soft as they're meant to be filed to achieve a snug fit.
As said, you need to welt it once not tap it ten times.
Quote from: V500 on 21 Dec, 2024, 09:50 Quote from: hoogerbooger on 20 Dec, 2024, 18:24 I sourced some replacement cotters from a motorbike shop that says they are suitable and not soft (only time will tell).
It's intended that cotter pins are soft as they're meant to be filed to achieve a snug fit.
As said, you need to welt it once not tap it ten times.
.... and also support the back with another heavy hammer.
Hi,
There are 'oversize' cotter pins available but they do not seem to be any better a fit.
Dave.
Radco in the Vintage Motorcyclists' Workshop suggested filing a taper oh a HT bolt but my feeling is this wouldn't leave enough thread engagement. Never tried it though. TBH I loathe cotter pints - splines/serrations have their issues as well but I prefer them.
Hi,
I suppose anyone with a lathe could modify the harder bolt and then turn the correct size for thye threaded bit.
Dave.
Thanks for the advice all.
I've done some practice on my bicycle with stubborn cotters. The design of the my ball joint press is a problem.
It failed squirrelling out of alignment.
So not having a thick- walled pipe I drilled a recess in a length of hardwood and with a second block on the concrete floor set it up to brace the pedal arm against the floor. Screwed nut up so flush with end of threaded end, selected a drift to fit the width of the nut. Even after heating the cranks, plusgassingand waiting for several hours and tapping crank with hammer to try and help release the bind I only got one out......eventually. The marking/distortion on the cotter face was surprisingly small given the amount of welly that was needed to get it out and the axle looked virtually unmarked.
I can't brace the kick-start lever against the floor (as the cotter is the wrong way round). I'm certainly not going to use the strength of hammer blow on the kick-start that was needed on the bicycle. So after New Year I'll remove my bench top vice and work out how to support it to have a go using that.....but will first try it with the remaining bicycle cotter.
Quote from: iansoady on 21 Dec, 2024, 13:05 Radco in the Vintage Motorcyclists' Workshop suggested filing a taper oh a HT bolt but my feeling is this wouldn't leave enough thread engagement. Never tried it though. TBH I loathe cotter pints - splines/serrations have their issues as well but I prefer them.
Good job we're all different. The only issue I've ever had with cotters is when they're too stubbornly in place, but I'll live with that rather than stripped/worn splines any day. Cotter cranks are cheap and reliable and don't wear.
What Radco suggested may work as a get-you-home temporary repair but the cotter thread isn't concentric to the shaft, so won't be an easy or very effective adaption.
I agree with @iansoady
You are less likely to do damage by drilling the guts of the cotter pin out first, you will probably not have to drill it all out as the heat (and whatever cooling fluid you use when drilling) will loosen it.
As your cotter is installed the wrong way round drilling the body (vs the thread will be easiest, I think).
I've managed to buy stainless steel oversize cotters for one of my bikes as it is actually the K/S hole that has gone slightly oval vs the shaft worn, should probably get a new lever, but it seems to be holding for now.
UPDATE
proved pretty easy with a the ball joint splitter pictured. Only had to remove the foot-rest to get a position where the force was fairly straight and the splitter didn't try to wiggle it's way out of place.
I'm guessing it would have come out with a hammer and punch, without too much welly, if I had been brave enough.
Quite surprising to me is how small the dints are on the cotter face. Can feel with the finger nail but very slight. Shaft recess looks nice and unmarked, but then that is presumably much harder.
I have a spare, but looks like I can use this one again. I presume I try to dress out the small dints on a sheet of emery paper on glass or carefully file......and put it back in nut forward this time.
Hi,
Be very careful cleaning up the face as it does not take much too slack and it will go too far through.
Dave.
noted. It already didn't have much head showing.
Quote from: hoogerbooger on 13 Jan, 2025, 19:34 noted. It already didn't have much head showing.
I'd always fit a new cotter pin.
If it is a long way through why not buy one of the O/s ones. Easily available. Draganfly do them.