Front Sprocket nut

[Mac1508]

Hi Guys,

not finding much on this one, changed my chain for first time, bought bike a week ago, it was pretty rough. But came to the front sprocket removal and I dont have anyhting to remove this lock nut thing.

is there a specific tool or technique? I removed those two small 10mm bolts but then that centre locking nut seems to require some toothed socket

[Mississippi Bullfrog]

That looks like the splines of the drive shaft on my phone. It looks pretty neglected so the drive cogbis probably seized on the shaft. Put plenty of lube on it and maybe a bit of heat as well. Don't go bashing it with a hammer. 

[Ian Frog]

As @Mississippi Bullfrog said put the hammer away for a bit.

Lube then heat is correct.

You have removed the 2 small bolts that secure the plate that slides over the splined output shaft and that assembly is what retains the sprocket.

In theory you just lift that washer from the shaft and wriggle the sprocket off.

All that is holding you back at the moment is corrosion so lube heat and repeat.

Cheers

Ian

[Mississippi Bullfrog]

From my days of restoring 1970's cars which were generally rust buckets...... If you're working on a bike that looks pretty rusty you're going to come across this problem of freeing off corroded parts. Get yourself some PlusGas penetrating fluid. 90% of seized bolts come loose with that alone and it works quite quickly. For the remaining 10% give it another dose of PlusGas followed immediately by a squirt of WD40. WD40 alone isn't much use other than on lightly seized parts but as it is a dispersant it drives the PlusGas into corroded parts better. 

 

I worked on some cars which were heavily corroded and only one bolt (an upper suspension bolt in a 1971 Viva) refused to succumb to PlusGas + WD40. Sometimes soaking it overnight works wonders. Heat also works buy just be cautions if you're recently applied WD40 because it's inflammable. 

 

As said above, don't go hammering it but you can tap gently, just enough to break the rust seal. Many light taps are better than one or two big whacks. Sometimes a puller can help for this kind of thing.

[Nick the wanderer]

Try rotating the plate that you have taken the bolts out of on the shaft. Think bayonet light bulb. 

[Simon Davey]

Once it's had a good soak with penetrating fluid, What about using a bearing/clutch puller? 

[RideWithStyles]

as the others say, remove chain, remove small bolts and plate, pent liq, big long shaft flat headed screw driver behind sprocket and in front of case pull the driver at a 11 to 2 contact points a bit then spin the sprocket a bit so your now lifting what would have been 11 to 8 ooints and just keep moving it round bit at a time.

[Phil1]

Another option if you're really struggling is to cut the face of the sprocket down one side with a grinder, just away from the output shaft, it'll significantly weaken it and allow it to be split and just pull straight off. 

 

Like the image, and if you're really really struggling then do both sides 

 

 

Edited March 24, 2024 by Phil1

[Mac1508]

ah cheers guys, yeah I swapped chain and rear sprocket, but left this alone till I was certain what I was dealing with. glad I asked

yeah the two wee bolts came out with some tender care, but just wasnt sure on middle bit. perfect no need for special tools will give her a good soaking once weather clears up

[Mac1508]

yeap right enough, there was a Shim infront, with matching teeth, shifted teh shim off the spline the a wee love tap and some oil on sprocket and she came easy enough

cheers guys