Topic: CB500 Rusted Stuck Front Sprocket. Help!

[Cleric40]

Hi all,

I'm in a predicament with removing my front sprocket. I am trying to replace because It's rusty and I am changing chain and sprockets. As you can see in the pics, the sprocket is super rusted onto the shaft and I can't get it budge one bit. ( I have cleaned it up as best I can so far and it's still nasty)

I have tried everything I can think of and every suggestion I have read including the following

1. PB blaster for 2-3 days now. Applying everyday.
2. Heat with torch and lightly tapping (don't want to transfer too much shock)
3. Gear puller(s)-- I have broke two and bent one puller
4. Homemade penetrating oils: Acetone and ATF.

nothing's even making it budge a tick!

I'm to the point of just bolting the retainer back up and letting it be, but I really would like to avoid this.

Anyone have last suggestions on how to get this sucker off?!  Any help or crazy tricks would be greatly appreciated.







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[oldhatt45]

Cleric40,

Looks like a lot of RUST built up in there.
Have you tried using a wire wheel on the visible rust??
Maybe if you get the exterior rust off, then sprocket could slide out instead of having to fight its way over that exterior rust???
Also, after getting the exterior rust off, tap with a hammer (lightly) while squirting something like liquid wrench into the joint where the sprocket meets the mainshaft??

Don't know if it will help, but keeping my fingers crossed.

Charlie

[MoMo]

Had  a similar but not so bad situation once.  Used a good puller and lots of tapping with a brass mallet to break free some of the internal rust, plus pb blaster and heat.  tighten the puller , tap , tighten, tap, on and on but it eventually broke loose... good luck with it....Larry

[Cleric40]

Thanks guys,  I will try to get ANOTHER puller and hope it doesn't break or bend...

I've tried wire brush in there but maybe time to step it up to a wheel.

I've though about pouring coke cola on it as I've heard the acid in it is pretty tough on rough.

Any one else have any hidden old timer tricks?
 


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[MoMo]

Thanks guys,  I will try to get ANOTHER puller and hope it doesn't break or bend...

I've tried wire brush in there but maybe time to step it up to a wheel.

I've though about pouring coke cola on it as I've heard the acid in it is pretty tough on rough.

Any one else have any hidden old timer tricks?
 


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The heat I used with the puller and brass mallet was a propane torch applied to the sprocket to try and cause it to expand...Larry

[Damage Inc]

Just a thought,
Make a slide hammer that bolts into the 2 threads.
Use with heat on sprocket
Or perhaps a puller, where a  steel plate bolts into the 2 threads with a larger bolt in the centre that screws against the shaft.

[calj737]

You must first destroy the rust before a puller or other mechanical lever will remove that sprocket without causing damage. You can use CLR (Calcium, Lime, Rust) cleaner. Pour it onto the shaft and allow it to eat the rust. Follow with some heat, applied to the sprocket near the seam. It will take more heat than you think.

Rap the sprocket around its face, on the teeth, while heating to help break the bond. Then a puller will easily draw the sprocket off. Obviously treat the shaft when the sprocket is off.

[SOHC4 Cafe Racer Fan]

Expect to get that sprocket VERY hot to where its starting to glow.  Don't be afraid to give it some impact (not the shaft) on the face and teeth.  This will help separate the rust bond. 

Don't forget to handle the sprocket like a hot potato when it comes free.  It'll stay hot longer than you think.

[754]

Tap it one side then the opposite..back and forth rust should start showing at the join.
 Use common sense if the bike moves over on centrestand you are hitting too hard.

They usually float on there,  so you have layer of rust built up where it joins

[Cleric40]

Great suggestions guys! I didn't think of CLR. I tried cola today but hard to get a lot on there (dang gravity!)

Many suggestions for heat. I have been using my torch but being cautious because I don't want to burn/melt the seal behind sprocket.

How hot is safe?


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[Cleric40]

I finally got it off. 5 pullers later!!!
Thanks for everyone's help.

What would you guys suggest to put on shaft splines to prevent this from happening again, a light coat of waterproof grease? Or something else?


Here's the end result before cleanup


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[MoMo]

congrats,  bike cleaning and chain lube should help to prevent another problem...larry

[754]

Is it an aftermarket sprocket? Looks like there was no clearance. On the OD of the splines..