The BSA A7-A10 Forum

Technical => A7 & A10 Engine => Topic started by: Steverat on 12.01. 2019 20:05

Title: An odd ring
Post by: Steverat on 12.01. 2019 20:05
This is a hardened steel ring, 30mm inside diameter.
It bears inscriptions SKF and HUP209.
I found it in the bits box which came with Josef's bike, it might or might not be related!

Does anyone know what it is?
Is it a vital engine or gearbox part for an A10?
Title: Re: An odd ring
Post by: Greybeard on 12.01. 2019 22:08
I don't recall having one of them on my bike.
Title: Re: An odd ring
Post by: Steverat on 12.01. 2019 22:18
It would have to go in a heavier part of the machine, most of that is already assembled:-
Title: Re: An odd ring
Post by: duTch on 12.01. 2019 22:22

 
Quote
..I don't recall having one of them on my bike...
....me either

 30mm is the same size as the drive main journal, so maybe was an unnecessary bodge behind the cush sleeve...either that or a neatly self-destructed bearing *conf2*- otherwise no idea
Title: Re: An odd ring
Post by: RichardL on 12.01. 2019 22:30
Take a look here. I'm not sure what the extra ring is for, but it's part of the NUP209 bearing.

http://www.rfq-bearing.com/bearings-NUP-209-ECM-SKF-NUP-209-ECM.html

Richard L.
Title: Re: An odd ring
Post by: berger on 12.01. 2019 22:30
I went to the pub I am now a witness to an assault  *pull hair out* *bash* *whistle* skf is skefco or skefko as I understand bearing makers *beer*
Title: Re: An odd ring
Post by: Greybeard on 12.01. 2019 23:15
Take a look here. I'm not sure what the extra ring is for, but it's part of the NUP209 bearing.

http://www.rfq-bearing.com/bearings-NUP-209-ECM-SKF-NUP-209-ECM.html

Richard L.
Ah, so you think that 'H' is an 'N'

Is it that bit on the right of this picture?
Title: Re: An odd ring
Post by: RichardL on 13.01. 2019 00:51
Gotta be. Maybe a different take on the drive-side bearing?

Richard L.
Title: Re: An odd ring
Post by: duTch on 13.01. 2019 05:04
 
Quote
.Ah, so you think that 'H' is an 'N'..

 I think the 'H' is definitely an 'N' , but I thought the 'U' is an 'O'....(NOP 209  NE). .. easily *conf2*

 Ps bergs- this was done while doing a quick potato/ ponytail/ pistol/ stupid spell suggestions- friggin *PITSTOP* at a *friggin pub*


Title: Re: An odd ring
Post by: Steverat on 13.01. 2019 05:29
The H could be an N but the U is a U
Title: Re: An odd ring
Post by: Swarfcut on 13.01. 2019 09:30
 Steve, I reckon GB's diagram nails it as part of a possible answer. The design appears to allow the rollers to stay in the case, the crank pokes through and the ring is the inner part of the outer axial support for the rollers. If we are right there should be a nice even witness mark around the  periphery of the ring where the rollers have been.  As a design alternative it is a clever trick, avoiding damage to the cage and rollers as the inner race is taken on and off to shim up and set the minimum running clearance to the face of the timing bush, as once assembled there will be no end float apart from the axial clearance in the bearing as the rollers are  supported "top and bottom and both sides" The only weakness is the ever critical tightness of the big  nut pushing the inner cush drive sleeve and the ring hard up against the bearing inner. If you still have the original main bearing to hand, see if the ring fits.

  The only other part that looks remotely like that ring is the rear sprocket hub collar, 67 6078 which fits in the centre of the brake drum/sprocket, around the rear spindle. No need to remove this on a regular basis, most are "rusted" in place into the drum. It is just a plain metal ring, no posh numbers. If yours is in place, then this mystery bit is spurious to your build. Otherwise this part may have been fitted there as a codge.

  Admiring your hard work and attention to detail. Josef is in for a treat.

  Swarfy.
Title: Re: An odd ring
Post by: RDfella on 13.01. 2019 16:48
Indeed it is the inner ring of a single row cylindrical roller bearing. Cannot see your number, but NUP 206 had a 30mm ID and a 38.5mm OD. SKF is a major bearing manufacturer.
Title: Re: An odd ring
Post by: chaterlea25 on 13.01. 2019 17:54
Hi All,
That type of bearing is used on the timing side of T140 engines
Cannot remember the bearing number offhand though??
John
Title: Re: An odd ring
Post by: Servodyne on 13.01. 2019 18:34
It certainly looks more like a NUP206 to me.
With this type of bearing you wouldn't need to shim the crank as this bearing will control the end float. Probably the bearing to use, if you have an end feed crank and needle roller timing side bearing without an integral ball race.
Title: Re: An odd ring
Post by: Steverat on 16.01. 2019 04:54
Thanks for all the research and ideas gents. Yes it does have some rubbing contact on the other side but not in the location which GB’s diagram might suggest. In any event I am convinced now that it was on the drive side main which is no more. I shall keep it as a smooth key fob and a reminder of the possibilities when I do my next engine.