How do i loosen the front sprocket nut

[nickodemon]

I have taken sprocket cover off and noticed the front sprocket is worn, so i thought i would replace it. I have put the bike in gear and applied the back brake. Using a 36mm socket and a long handled socket wrench i can't get it to budge. I have tried an impact driver with the socket also.. The bike has 43'000 miles and it's the original sprocket   Any good tips on getting the foccer off?

[Freck]

Put a bar through the back wheel across the swing arm (with some rags to stop damage) and turn the wheel so that the spoke is against the bar.
Flatten off the retaining washer and undo the nut.....voila!


Mine wasn't too tight but still needed a fairly long breaker bar 


Steve

[slappy]

I put a piece of wood through back wheel across the swingarm, mate sat on bike and very long ,about 3 foot, piece of pipe on wrench just managed to shift it, thought the wood was going to snap!

[nickodemon]

I think i will get a bit of 25mm galv tubing from work to extend my wrench and put wood through the wheel.........

[Val]

I think i will get a bit of 25mm galv tubing from work to extend my wrench and put wood through the wheel.........

I have used nice solid wodden hammer handle in the back wheel wrapped in old T-shirt.


I've tried with breaker bar, 60cm breaker bar I've got was not enough for the old nut, I bought FFA Concept Steel Round Tube, (W)30mm (L)1m from B&Q:

http://www.diy.com/departments/ffa-concept-steel-round-tube-w30mm-l1m/254227_BQ.prd

The best £9 I've ever spend. Removing the old sprocket nut was very easy with it.

Here it is in action:

[Fazerider]

Don't use an impact driver on the sprocket nut.
The force of the hammer blow goes straight through to the bearings of the output shaft.

[nickodemon]

It won't matter if it is used straight on. The sprocket gets pressure from the chain pulling so me using an impact driver dead straight to the sprocket won't damage anything as the force is sideways just like the pressure of the chain, as impact drivers rotate just like the chain does... The force of the impact driver is used to rotate the impact driver, it won't damage the output shaft because it doesn't put pressure against the output shaft.

[PaulSmith]

It won't matter if it is used straight on. The sprocket gets pressure from the chain pulling so me using an impact driver dead straight to the sprocket won't damage anything as the force is sideways just like the pressure of the chain, as impact drivers rotate just like the chain does... The force of the impact driver is used to rotate the impact driver, it won't damage the output shaft because it doesn't put pressure against the output shaft.

Ehhh no... That is not how impact drivers work.

Some of the force of the hammer blow driving through your bearings is translated into rotational movement to loosen the nut, and some of it isn't. They are your bearings so it is your choice but there is a reason why everyone else uses a breaker bar and not an impact driver for this job.

[nickodemon]

I only tried it once. I didnt sit there hammering like a mad man   I will be using a longer breaker bar than the one i have, as i obviously tried that first before trying it once with the impact driver.

[PaulSmith]

Breaker bars:

https://clusterhq.com/2014/09/11/state-zfs-on-linux/

[mr self destruct]

It won't matter if it is used straight on. The sprocket gets pressure from the chain pulling so me using an impact driver dead straight to the sprocket won't damage anything as the force is sideways just like the pressure of the chain, as impact drivers rotate just like the chain does... The force of the impact driver is used to rotate the impact driver, it won't damage the output shaft because it doesn't put pressure against the output shaft.

Ehhh no... That is not how impact drivers work.

Some of the force of the hammer blow driving through your bearings is translated into rotational movement to loosen the nut, and some of it isn't. They are your bearings so it is your choice but there is a reason why everyone else uses a breaker bar and not an impact driver for this job.

More details here:



Does show a certain amount of force is applied along the axis of rotation regardless whether the nut's being tightened or loosened.

[Falco9]

I used almost every trick in the book to remove my drive sprocket with no success. Using the longest breaker bar I had only resulted in the wood stopping the rear wheel turning snapping...
With no other options available I borrowed a battery powered impact driver and the nut came off in approx 2 seconds..... I've bought one now and I'll use it again for this type of work. I think sustained use of a an impact driver might "eventually" damage a bearing but a couple of seconds??? I'll take my chances.

Of course had the wanker who owned the bike before me not used tons of Loctite on the nut I wouldn't have had the problem in the first place 

[PaulSmith]

Now you have fixed the locktight problem, you wont need to use the impact driver again so your bearings should be safe.

[Fazerider]

Powered types like that should be perfectly OK to use on the drive shaft... for some reason I'd assumed the OP had used one of the manual ones.