primary drive sproket puller?

schwantzz · Post by **schwantzz** » Sun Jan 01, 2012 9:15 am

I am trying to remove the primary drive sprocket to replace a leaking crank seal but the little blighter won't shift.
I ground down some old 3 leg pullers to get in behind the sprocket and got a fair amount of tension on it before giving the end of the puller a sharp tap with a hammer but it just won't shift. I then applied some heat to the sprocket but still can't shift it. I had the nut on the thread as precaution and the pressure on the puller was starting to damage the end of the crank, any more and i'd have problems.

Any suggestions as to what to do now? Perhaps somebody could suggest a better set of pullers I could buy. Mine are old and slightly bent so weren't pulling 100% straight.

If all else fails I'm thinking of grinding the sprocket off but this is a last resort. Bit too risky!!

1608 · Post by **1608** » Sun Jan 01, 2012 10:18 am

Sorry I can't offer any practical help. But, I'm intrigued as to why the sprocket is so tight. If anything, in time the splines on the sprocket would normally wear sufficiently for the sprocket to practically fall off.Somebody with experience in this matter will be along shortly no doubt.

itma · Post by **itma** » Sun Jan 01, 2012 11:18 am

what sort of bike would help.

John Donne · Post by **John Donne** » Sun Jan 01, 2012 12:44 pm

If you look on page 27 of the factory Norton twin cylinder manual, you will see the heavyweight engine sprocket extractor on the right hand side. This was made to remove the engine sprocket, for all Norton heavyweight twins, and it should still be possible to buy it from either Norvil, RGM, Hemmings, or Russell Motors. This is some thing that all Norton twin owners should have as part of their tool kits. I bought my one from a Norton main dealer, back in the 1970's and it is the genuine factory tool. May be Andover Norton also still produce it. Normally tthis sprocket puller fits behind the sprocket, tighten up the puller, then tap the end of the adjuster, and the sprocket should break its hold on the crankshaft. The sprocket is only held on with a woodruff key, so it may have been put on with a Locktie sealer, if the key way was loose. To have to apply heat means there must be some thing wrong with the way it was fitted in the first place. I have checked my T.J.Wassell catalouge and it is not listed by them. The Norton factory part number was EST/12 and was called an engine sprocket extractor.

John Donne · Post by **John Donne** » Sun Jan 01, 2012 12:45 pm

As you live in Northampton, you could take it along to Mick Hemmings, who would be able to remove that engine sprocket for you.

itma · Post by **itma** » Sun Jan 01, 2012 1:54 pm

New years resolution, read the title of the post first you old fool.

Norton engine sprockets are on a taper
so this leaves all sorts of possibilities for trouble, some kind of gloop or other botch.

I would get hold of a decent three leg puller, preferably the hydraulic type and heat the sprocket as much as you can, seeing as you are resigned to scrapping the sprocket; heat will break the seal of most kinds of loctite and glue.
I'd would also add more protection to the end of the shaft, as well as keeping the nut on. place a bit of steel strip over it, recessed for the business end of the puller.

I have removed dozens of Commando engine sprockets over the years and never had any bother, that are not that precise a taper.

and of course there is the old dodge of when the puller is as tight as you dare, give the end of the puller a bloody good whack with a heavy hammer, but keep well to one side as if that shifts it, it will let go with a bang.Edited by - itma on 01 Jan 2012 1:57:13 PM

schwantzz · Post by **schwantzz** » Sun Jan 01, 2012 3:30 pm

Thanks for the replies - It's on my G15CS (I didn't put the bike make as I'd posted in the G15 Forum).
I'll have a look for that Norton tool. As for fitting I don't think it has ever been removed before. In fact I don't think the side casing has ever been off.

A trip to Mick Hemmings would be one possibility but like you say it's good to have the tool for these jobs in your kit.
However knowing how much force I have already put through it with no success I am considering welding a tube to the sprocket over the crankshaft to screw a large slide hammer into.

1608 · Post by **1608** » Sun Jan 01, 2012 3:35 pm

Ahhh! a taper and woodruff key. The sprocket has probably moved on the shaft causing the W-key to bite into the sprocket. Try seeing if the sprocket can be turned / driven clockwise on the shaft a tad and if so it might just release it on the W-key.
Just read your last post, I wouldn't be tempted to use such lateral force as none of the engine or casings are designed to take shock in this direction.If need be you'd be better offgrinding thesprocket off with an angle grinder.Edited by - 1608 on 01 Jan 2012 3:39:33 PM

schwantzz · Post by **schwantzz** » Sun Jan 01, 2012 6:41 pm

Good news - It's off !!!
A friend had a superb puller which just fitted on. I screwed the nut on the shaft the wrong way round then made up a small spacer to push against so I didn't damage the threads on the shaft at all. A good serving of heat - some muscle and a good blow with the hammer and it eventually gave in.
There was no damage to taper or keys, I guess it'd been on there 44 years and didn't give in easy!!
Also managed to remove the seal with no dramas by drilling a tiny hole and attaching a little slide hammer so I'm all ready to fit a replacement. I'll probably go for a new primary drive chain as precaution.

itma · Post by **itma** » Sun Jan 01, 2012 6:44 pm

excellent the system works.
For removing oil seals I have a little Snap On tool, with a wiggle hook on the end , originally meant for loosening rad hoses I believe, it works very well on oil seals .