The BSA A7-A10 Forum

Technical => Clutch, Primary, Gearbox => Topic started by: GuyboA10 on 23.05. 2008 13:15

Title: Bearing recomendations for gearbox/clutch
Post by: GuyboA10 on 23.05. 2008 13:15
G'day, just curious about the appropriate bearings for the mainshaft/clutch end (24-4065)and kickstart end(24-4217). Both were hoffman open types which were removed. Should i stick to the open style, or go the 2RS ( rubber shields) ??. I reckon there is always a chance dirt & metal fragments can affect the open type, so i feel the 2rs is more suitable, is this ok? Also, should i get both bearings with CN ( clearence normal)? I know some people have used C3 bearings on different parts.
The driveside main roller bearing is a hoffman r130 v3 and the replacement is NF206. Does this come in CN & C3? and which one is correct? i'm thinking CN.
cheers, Guy.
ps. my resto is going well, everything is apart and is being cleaned up, polished , de-rusted etc... found i've got near new pistons and nicely polished conrods, also the cylinders look newly bored..beautiful looking!!!  *smile*Step by step and slowly it will be a great bike when finished, cant wait!! But its great fun building it up. cheers..
Title: Re: Bearing recomendations for gearbox/clutch
Post by: dpaddock on 24.05. 2008 23:11
I'd stay with the open bearings and BSA oil recommendations. Drain the oil at intervals based on how much debris you find (can't be much unless you're having a problem - in which case, you're in early innings). It's not always wise to re-engineer the designers' decisions. A magnetic drain plug would be a good thing.
Title: Re: Bearing recomendations for gearbox/clutch
Post by: Brian on 25.05. 2008 02:45
What I do is remove the seals from both sides of the kickstart end bearing but on the drive end I only remove the inner seal. When I put the final drive sprocket on I put some grease between this seal and the proper one. This effectively gives you a double seal. I have been doing this for many years and have bikes that have done many thousands of miles and it has worked perfectly. With the bearing clearance I use SFK Explorer series bearings which are a finer tolerance bearing but unfortunately I dont know exactly how they are rated, a bearing company should be able to say. Once again I have had no problems with them. Good luck with your rebuild.  Brian.
Title: Re: Bearing recomendations for gearbox/clutch
Post by: Rocket Racer on 16.03. 2016 04:55
Having rebushed layshaft and sleeve gears, I was in the process of replacing the  SC  gearbox bearings and was quite surprised to find the old Hoffmann that came off the layshaft was a C3 clearance bearing.
The question is should I fit another  C3...  *conf*
Title: Re: Bearing recomendations for gearbox/clutch
Post by: duTch on 18.03. 2016 10:23

 I had an issue like that when I replaced my Gutzzi driveshaft bearing at the uni-joint. Can't remember all details, but I think I was inadvertently given a C2 (?) from the bearing shop.
 When it heated up, th bearing tightened up more than the interference fit factor, and the bearing spun on the uni-joint and flogged it (x2or3) out leaving me with an unnerving vibration, so 'C' factor depends on careful assessment of the application. *pull hair out*
Title: Re: Bearing recomendations for gearbox/clutch
Post by: chaterlea25 on 18.03. 2016 20:35
Hi
C3 for the crank and gearbox main bearings

John
Title: Re: Bearing recomendations for gearbox/clutch
Post by: Brian on 18.03. 2016 21:27
Just for a bit of info for those not familiar with bearings I thought a small explanation of bearing clearances might help.

C2  -  slightly less clearance than standard
CN  -  standard or normal clearance
C3  -  slightly more clearance than a CN
C4  -  slightly more clearance than a C3
C5  -  slightly more clearance than a C4

I tried to find a chart online that would give some figures in thou's but couldnt.

Dutch, I always fit C4's in Guzzi's.
In my BSA's I use CN in all applications.

The bearing that carries the uni joint in a Guzzi is a tight fit in a steel housing and have quite a lot of "crush" when fitted. The bearings in the BSA's have virtually no "crush" effect.
Title: Re: Bearing recomendations for gearbox/clutch
Post by: duTch on 18.03. 2016 21:51

 
Quote
The bearing that carries the uni joint in a Guzzi is a tight fit in a steel housing and have quite a lot of "crush" when fitted.

 Thanks Brian, I think we worked out that was what was happening- took a couple of U.J's though