Impact wrench (Rattle Gun)

[Tigerfeet]

I 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?

[limeyrob]

I 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.

[Derek996]

I 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.

[rhyatt]

I 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

[Oldgoat54]

A 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

[limeyrob]

If 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.

[iansoady]

A 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:

[NClark]

I've used a Ryobi battery rattle gun on classic bikes and cars for years. When undoing stubborn nuts, I always go carefully, starting on the lowest of its three torque settings and increasing if necessary.

It hasn't failed to undo a tough fastener yet, and neither has it caused any damage.

Nigel