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#11
Singles / Gear Selection Problem
Last post by NClark - 25 Oct, 2026, 13:53While I'm generally very pleased with my recently acquired 1961 B40, I've found an intermittent problem with gear selection. Starting off in first and going up through the gears is fine, but sometimes when coming down through the ratios, first and second will not engage.
When this happens the gear lever is almost locked solid, with very little movement. Changing up and down between third and fourth is unaffected, perfectly normal, but second and first are unavailable. This problem seems worse when engine and 'box are cold.
Stopping (without turning off the engine) often allows the lower gears to be selected after a few prods of the gear lever. Once warmed up, the lower gears will select on the move, though the slower the speed, the easier the third down to second change becomes. Once down into second, changing down to first isn't a problem.
Please can I ask if anyone has experienced similar symptoms, or what the cause could be? I'm wondering if there's an issue with the detent plungers engagement with the cam plate?? But I'm hoping not to need to dive that deep into the gearbox!
Nigel
When this happens the gear lever is almost locked solid, with very little movement. Changing up and down between third and fourth is unaffected, perfectly normal, but second and first are unavailable. This problem seems worse when engine and 'box are cold.
Stopping (without turning off the engine) often allows the lower gears to be selected after a few prods of the gear lever. Once warmed up, the lower gears will select on the move, though the slower the speed, the easier the third down to second change becomes. Once down into second, changing down to first isn't a problem.
Please can I ask if anyone has experienced similar symptoms, or what the cause could be? I'm wondering if there's an issue with the detent plungers engagement with the cam plate?? But I'm hoping not to need to dive that deep into the gearbox!
Nigel
#12
Singles / Re: Impact wrench (Rattle Gun)
Last post by iansoady - 25 Oct, 2026, 13:24A sprag as it's known. This is using a bit of flat alloy bar on my ES2.
And this using a bent bit of bar to hold the worn out gearbox sprocket:
And this using a bent bit of bar to hold the worn out gearbox sprocket:
#13
Twins / Re: A65 rebuild
Last post by MITCHELL - 25 Oct, 2026, 13:15Mark at c&d autos doesn't recognize and has never been asked for them so I think I'll just carry on and ignore them. Thanks.
#14
Singles / Re: Impact wrench (Rattle Gun)
Last post by limeyrob - 25 Oct, 2026, 13:07If the clutch and primary chain are still on an open ended spanner diagonally between the clutch sprocket and engine sprocket works well. I have a bit of bronze bar I use to protect the teeth but a spanner works because you can get one the right length.
#15
Singles / Re: Impact wrench (Rattle Gun)
Last post by Oldgoat54 - 25 Oct, 2026, 12:58A colleague has often used one on old Seagull outboards (problems exasperated by age in a salt water environment) when nothing else will work. Doesn't seem to round-off damaged nuts (if six flat impact sockets are used) like some spanners/sockets seem to. Nothing to lose in trying!
P
P
#16
Singles / Re: Impact wrench (Rattle Gun)
Last post by rhyatt - 25 Oct, 2026, 12:46I used one plenty of times on cars , but never on a bike.
I've used wood down between the crank halves to lock the crank , preferably to in gear and rear brake.
I wonder why it's so tight
I've used wood down between the crank halves to lock the crank , preferably to in gear and rear brake.
I wonder why it's so tight
#17
Singles / Re: Impact wrench (Rattle Gun)
Last post by Derek996 - 25 Oct, 2026, 12:28I bought this Clarke rattle gun a few years ago to undo the rear wheel nut on the single sided swinging of my then Ducati about 13 years ago. They are tightened to 230Nm and are almost always impossible to undo with a breaker bar, even with a long extension.
I've used it for loosening all sorts of nuts on bikes and it's never let me down. There other battery powered ones and the market and they often turn up in Lidl and Aldi at very reasonable prices. Great for undoing clutch centre nuts, flywheel nuts and crankshaft pinion nuts. Bear in mind though that you have to be able lock the shaft to torque the nut back up again on reassembly.
I've used it for loosening all sorts of nuts on bikes and it's never let me down. There other battery powered ones and the market and they often turn up in Lidl and Aldi at very reasonable prices. Great for undoing clutch centre nuts, flywheel nuts and crankshaft pinion nuts. Bear in mind though that you have to be able lock the shaft to torque the nut back up again on reassembly.
#18
Singles / Re: Impact wrench (Rattle Gun)
Last post by limeyrob - 25 Oct, 2026, 10:42I think the short answer is "tell us how you get on" 
The forces have to go somewhere whether you use a large breaker bar or a rattle gun so it should be OK.
The forces have to go somewhere whether you use a large breaker bar or a rattle gun so it should be OK.
#19
Singles / Impact wrench (Rattle Gun)
Last post by Tigerfeet - 25 Oct, 2026, 10:28I am just about to wrestle with the crankshaft pinion nut on the TR25 (B25)- with the main issue being how to hold the engine. Then I will be removing the sludge trap and flywheel bolts.
I have used various tools and methods in the past for these operations - but it struck me that I have never used a rattle gun on them - or seen it advocated. Is that because rattle guns simply weren't around?
I had a part to undo on my F650 BMW that was notorious for being difficult. So I borrowed a pal's lowest power rattle gun (he had three sizes) and it came straight out. So now I am thinking I should use the same tool on the crankshaft. (It has five torque settings so I will start at the lowest.) Can anyone think of a reason why I shouldn't?
I have used various tools and methods in the past for these operations - but it struck me that I have never used a rattle gun on them - or seen it advocated. Is that because rattle guns simply weren't around?
I had a part to undo on my F650 BMW that was notorious for being difficult. So I borrowed a pal's lowest power rattle gun (he had three sizes) and it came straight out. So now I am thinking I should use the same tool on the crankshaft. (It has five torque settings so I will start at the lowest.) Can anyone think of a reason why I shouldn't?
#20
Singles / Re: Fitting the later B25 cast...
Last post by JulianS - 23 Oct, 2026, 21:42The third fixing is not used when fitted to earlier engines. It does work fine, I converted my (now long gone) Starfire following Ruperts most excellent book years back. This is the service sheet.