Author Topic: B33 Clutch and Gearbox work  (Read 268 times)

0 Members and 1 Guest are viewing this topic.

WayneBergman

  • Blue Star
  • **
  • Posts: 58
    • View Profile
B33 Clutch and Gearbox work
« on: 04 November, 2021, 16:28:53 »
I have pulled my gearbox off the bike and the dismantled the clutch as I will want to sort out a few issues in the spring with a slipping clutch and a neglected gear box. I have question please, this is my first attempt at a dive in like this ………
As I won’t be putting the gearbox back on the bike because parts are still to come maybe not arriving until the new year but I do want to make sure some of the parts I have already arrivred are correct or will work for my bike. The bike is a 52 BSA B33 plunger and the cutch is a 6 spring. The parts shown in the photo show my old clutch center next to the new center. The new clutch center is supposed to be off of a B31 according to my supplier and the part number I used in ordering was 66-3906, it was in stock and I have it now but the issue is the 6 pins are slightly shorter like about 1/4" shorter. Should I be concerned? The new driving and friction plates arrived and they all fit nicely to the clutch center and chain wheel but not sure if I just go with fewer friction and driving plates to make it all work? Length of new clutch center pins is 1.94".

Also one more question please the gearbox main bearing shown in photo, I would like to pull its seal off to see if I have the correct replacement bearing supplied. The replacement bearing is OD 2.835” but not sure the best way to pull the old bearings seal out. I am guessing the seal will get wrecked in the process ? .....thanks in advance for any tips on the above.......wayne



Jim S

  • Blue Star
  • **
  • Posts: 68
    • View Profile
Re: B33 Clutch and Gearbox work
« Reply #1 on: 04 November, 2021, 22:59:28 »
Hi Wayne
The parts book is a little confusing, but 66-3906 Is for a B31 and 66-3903 Is for B32, B33 B34 and Clubmans. I don't have any experience with running a B33 with 1 less set of clutch plates, but I would try to stay with the parts book configuration.

What is wrong with your old clutch center? If it is the photo on left, it looks good to me.

WayneBergman

  • Blue Star
  • **
  • Posts: 58
    • View Profile
Re: B33 Clutch and Gearbox work
« Reply #2 on: 05 November, 2021, 04:13:23 »
Thanks Jim, the old clutch center has one of its studs with what looks like a saw cut half way through its diameter. No idea how this would have happened but the studs strength has for sure been compromised. I have a little tig welder and if I had a new stud I could easily tack a replacement stud in place but I have not found a part number for the stud or found a source for a single new stud so I just ordered the whole clutch center based on numbers from the BSA parts book.And yes the parts book I have is confusing for sure, for instance some of the bushings I would like to replace in the gear box - the parts book implies for the B33 you have to buy the gear and its bush as a whole unit which is pricey and yet the parts book implies other models like the clubman you can buy just the bush so kind of confused but learning as I go. :) Thanks for the input Jim, appreciate it. ........wayne

Pete C

  • Royal Star
  • ***
  • Posts: 234
    • View Profile
Re: B33 Clutch and Gearbox work
« Reply #3 on: 05 November, 2021, 07:17:06 »
If I remember correctly the clutches are different for the B31 and B33 in that the latter has more plates and so the basket and centre are deeper and hence longer studs.
A cut in the end of a stud may be so that a screwdriver can be used to stop the stud turning when adjusting the spring tension if the stud has come loose in the centre.
If you are fitting a sealed bearing you can always remove the seal on the inner side to allow oil to get to it.

idie

  • Golden Flash
  • *****
  • Posts: 757
    • View Profile
Re: B33 Clutch and Gearbox work
« Reply #4 on: 05 November, 2021, 10:00:11 »
The B31 had 3 driving plates the B33 had 4 and the twins had 5. This accounts for the different depths of the clutch basket. I run my B33 with the 5 plate basket, easier to get.
« Last Edit: 05 November, 2021, 10:03:14 by idie »

Jim S

  • Blue Star
  • **
  • Posts: 68
    • View Profile
Re: B33 Clutch and Gearbox work
« Reply #5 on: 05 November, 2021, 16:01:37 »
I would have a go at salvaging the original part that you have using a modified bolt.