Bearing Clutch Sprocket

[Anthony Duffield]

Commander P53I would be very grateful for some help in removing item 13 bearing clutch sprocket as shown page 10 and 11 of the replacement parts catalogue.During the engine and gearbox overhaul I found the bearing to be very rough and coupled with an occasional slip of the sprag clutch decided to renew both, the sprag came out no problem but try as I might I can only just get the bearing item 13 to move slightly.The explode diagram shows two circlips one is item 16 circlip sleeve internal I can see this one but as it is recessed cannot remove it, I cannot see the other circlip item 14 circlip bearing external.I'm guessing that the offending bearing must go out through the clutch sprocket assembly i.e. into the space where the clutch plates are fitted but when pressing it out in that direction it moves just very slightly just enough as if to take up the movement of a circlip in a groove.I would like to remove the bearing in one piece, I do not really want to break it up to get it out.Any advice will be gratefully received.ThanksTony

[Richard Negus]

Hi Tony,Another of Norton's little jokes! You have to remove the starter sprag outer ring first and then push the bearing and sprag race out from the clutch plate side. There is a conventional circlip in a groove in the outer race of the ball bearingFirst push the sprag ring (and bearing) as far IN as it will go. This will allow you to remove the wire ring circlip which locates the outer race.Then, from the plates side, push the bearing and outer race out together.When re-assembling, push the ball bearing in (as far as its circlip will allow) from the back of the drum.Then push in the sprag outer race as far as it will go and insert the wire circlip.IMPORTANT! Now push the bearing and outer race from the plates side as far as it will go, trapping the wire circlip and confusing the next owner who wants to replace the bearing and/or sprag outer race.Seemples - but not obvious.Alternately, RTFM!R.

[Anthony Duffield]

Richard,Fantastic advice thank you very much.This simple job has had me scratching my head for two nights, as soon as I get home tonight I will following your instructions and will revert with how I get on.Thanks again.Oh and by the way Merry Christmas to you and to all those who read and contribute to this forum.Tony

[Anthony Duffield]

Easy when you know (or are told) howNow to find a 6007 C3 bearing with a snap ring groove!!Tony

[Richard Negus]

My equivalents list suggests that the bearing from a Commando clutch is the same; part number 06-0750Andover Norton are closed now until 4th January but a search of Ebay, for example, should get a quicker delivery if your local bearing stockist can't oblige.Merry Xmas!R.

[Richard Negus]

Just had a look at a few sites offering the Commando bearing, and none of the photos show a groove in the outer race.So Commando 06-0750 / 6007 is not interchangeable with rotary 55-0743 / 6007N.So, what does the circlip actually do? As installed, the bearing is pushed towards the back of the clutch drum so that the circlip doesn't touch anything and doesn't axially locate the bearing in the drum. I suppose in service, the bearing might migrate towards the plates side of the drum until stopped by the circlip. But then the clutch release bearing would be overloaded and the chain sprockets out of alignment.So, is that circlip redundant, only there to make the assembly/dis-assembly more difficult?Please discuss.R.

[Anthony Duffield]

Richard,I would have to check the clutch drum when I get home tonight as I am not sure if the bearing less circlip can move out towards the clutch plates, if it can then I would suggest a means of ensuring that it cannot move axially is required. I found that when pressing the bearing with circlip fitted towards the clutch plates there was approx 1.0 mm movement, I appreciate that this would misalign the primary drive but when taking into account the distance between the drive sprocket and clutch drum would this misalignment be an issue?If the Commando bearing does not have a groove for the circlip SKF appear to produce a 6007 bearing using the American term for a circlip "snap ring" groove.After the New Year I will investigate the availability of a replacement bearing with circlip groove and will let you know how i get on.RegardsTony

[Richard Negus]

Tony,The Commando bearing arrangement has both inner and outer races of the bearing located by shoulders on one side and circlips on the other.I've just remembered that the F1 clutch has a much simpler arrangement; the bearing is pressed into the drum, against a shoulder, from the plates side and the starter sprag outer race is pressed in to the same shoulder from the other side. No circlips, easy to assemble, but impossible to remove the sprag outer race if/when required. "Sorry Sir, you'll need a new clutch drum" - not that one ever has had such a fault.It works that way for the F1, so should work on the earlier clutch too. The only axial load is from the clutch lift mechanism which tends to pull the drum outwards and keep the ball bearing and sprag outer race firmly against the wire circlip.Revised Assembly Instructions.Press sprag outer race into clutch drum until it stops..Fit wire circlip and press outer race back over the circlip until it stops..Press ball bearing in from the plates side until it stops against the sprag outer race.Go on - you know you want to!R.