Advance-retard mechanism

Well Anna, thanks for explaining, But I have undone the nut, it has come away from unit without taking it with it, now the nut or bolt wont come right out & it wont do go back in that is pull itself back in.

Have you any ideas whats going on?

Cheers Jim

Previously Phil Hannam wrote:

Once the ATD has come away from the magneto you should then be able to pull the head of the extracting bolt back another 5mm. Then by continuing to turn this part clockwise it should extract itself free of the ATD body. See attached photos.

The extractor bolt goes back into place by pushing in and turning anti-clockwise because it has a left-hand thread.

Thanks Phil,

Picture shows bolt like it is, I have had no joy in tapping it off with some heat, have done some damage to spring hanger so I shall have to find replacment. I still have to get it off & think I shall have to make some sort of extractor, but at least now I know it will come off in the position its at, I was begining to wonder if the bolt end had come off making it still locked on.

Cheers Jim

Previously barry_carson wrote:

Hi just wondered if there is any in and out ( end play ) movement on the shaft if so get two small levers about 6 inches long or so behind the cog not on the teeth then lever the cog outwards holding the pressure on tap the shaft Centre inwards with some sort of punch or similar.dont apply to much pressure just enough to stop the shaft moving inwards when tapping it .get something smaller diameter than the shaft keep clear of the thread. assuming the bolt is out of the unit and the chain is removed. baz

Thanks Baz,

Bolt is out, & I have tried similar to what you suggested but it didn't release, I am now making an extractor. cheers jim

Previously Phil Hannam wrote:

I am almost running out of ideas with this problem.

My next suggestion is to pour some neat coke (cola) into the centre of the ATD and let it soak for 24 hours. This is a mild acid and it should get into the taper joint and eat a minute amount off each surface. It is well known in the motor trade as a freeing agent. If you can somehow tilt the ATD so that the fluid remains around the joint for as long as possible or keep topping up the level.

A puller of some sort might seem a good idea but these ATDs are very flimsy and apart from the hardened sprocket will probably bend very easily.

Another possible.......an expanding concrete anchor bolt down the centre might give a better opportunity to lever the ATD away from the taper.

I am still a little surprised that a sharp dose of heat has not worked. On one of my old my bikes, that had a stuck ATD, I just pulled out the bolt and aimed a gas torch down the hole for about 30 seconds. The damn thing then jumped off the magneto shaft.

Thanks Phil for all your help, I am going to make an extractor, all else has failed will keep the coke to final solution. cheers jim

Previously David Cooper wrote:

Jim I'm not entirely sure... has the sleeve bolt come out? And I'm not sure how much you know about these things so please forgive me if I state the obvious. It wasn't obvious to me when I first met one, I do know that.. The bolt in the middle is a sleeve bolt with its thread inside its end. Normal right hand thread holding the unit onto the shaft. But outside its barrel it has a left hand thread which is not engaged when it is in place. So when it is unscrewed (antoclockwise) it comes slack off the shaft. Then the back of the LH thread meets the back of its counterpart inside the unit . It is turning the wrong way so it does not engage so now it pulls the unit off. If you really want to remove the bolt, it now comes out with clockwise turns If it is now slack but not puling the unit away, I imagine the LH threads are damaged. So maybe you could lever under the bolt head and turn it clockwise so as to extract the bolt leaving the unit in place. Then maybe try a plain bolt in the threaded hole - but it is LH thread. That must be why my PO tapped the inside of the unit (in place I suppose). It shoudf then be possible to simply run a plain bolt up the inside of the newly tapped thread to pull it off. Since the shaft is not affected, the old sleeve bolt could be re-used to hold it in place. Much as I respect Phil's mass of Norton Knowledge, I'd be wary of chemicals in case they provide a permanent weld.

Thanks Dave,

I am going to make an extractor based on the photo you sent, not going to tap unit, going to use left hand peddle spindleoff bike which will fit threads, a s/h oneif I can find one & just drill hole in centre & tap it for a long enough bolt to fit which will (hope) pull it off. cheers jim

Previously robert_tarr wrote:

Hi All,

Stuck yet again!!

Self extracting bolt didn't do what it should, Phil kindly advised heating & tapping to remove, but it wont come off, does anybody have any more ideas how to release this please.

Many thanks Jim

RESULT.

A/R mechanism off now, what a job I have had!

Making extractor from LH pedal was a nightmare, I knew it was case hardened so heated it red hot with blow torch (not hot enough) I managed to drill as big as 1/4" hole with difficulty then resorted to sticking a small bolt packed out with nuts & washers to give projection into hole & just wound it in.

I expect you professionals are horrified. Thanks for all your help!!!

Previously Phil Hannam wrote:

Result..........well done!!!

How about taking some photos and putting together a short article to go in Roadholder. Your bit of bodging might be of help to other NOC members.

Will see what I can come up with.