Author Topic: B33 plunger centre stand  (Read 305 times)

0 Members and 1 Guest are viewing this topic.

Greenfield

  • Royal Star
  • ***
  • Posts: 239
    • View Profile
B33 plunger centre stand
« on: 09 March, 2021, 13:20:42 »
I need to renew the pivot on the centre stand of a B33 plunger. I need the stud 65-4728 which shouldn't be a problem, but sourcing the pivot tube 29-4840 is not proving easy. I've tried Drags, Hawkshaw and KMc, can anyone suggest anywhere else?
It's quite a simple part to make as long as you have a lathe; but I don't!

Calum

  • Royal Star
  • ***
  • Posts: 121
    • View Profile
Re: B33 plunger centre stand
« Reply #1 on: 10 March, 2021, 09:50:57 »
The stand on my B31 plunger has a bronze bush in it through which the stud passes, not sure if this is original or not (probably not as whoever had fitted it hadn't drilled through for the grease nipple!) It came with the bike, but unattached and with the old pivot seized in and cut off. I shelled it out and removed it, reamed the bush back to something like and made a new pivot pin to suit. As usual, the frames were worn so I made top hat steel bushes to go into the frame holes which were dressed until they fit nicely and the pivot bolt passed through with minimal play. Worked nicely in the end, and saved me welding the frame holes up.

I can turn you a bush in steel, bronze or whatever you like. Where abouts are you?

Cheers
Calum

EDIT: thinking about it is the tube supposed to be a crush tube so the stud tightens up hard on it and the stand pivots around it? Possibly. I can't remember what I did to get the nuts to tighten now. The bush was so tight in my stand I assumed that where it should be. Would also explain the lack of grease hole in it if the tube is supposed to be stationary with the frame (oops!)
« Last Edit: 10 March, 2021, 10:32:07 by Calum »

Greenfield

  • Royal Star
  • ***
  • Posts: 239
    • View Profile
Re: B33 plunger centre stand
« Reply #2 on: 10 March, 2021, 11:49:12 »
Thanks Calum
The stud is 7/16" and goes through the centre of the pivot/spacer tube. When you tighten the nuts the tube is gripped onto the lugs on the frame and the stand pivots around it. The dip in the centre of the tube receives the grease from the nipple which should then lubricate the friction surfaces. The grease nipple on mine is clear but has not received any grease for may years, hence the wear.
I've made a few more calls to suppliers this morning to no avail.
There is wear in the frame hole and in an ideal world it all needs work or completely replacing. Bushing the outer parts of the spacer would certainly help but the original spacer would need skimming to remove uneven wear.
Thanks for the offer. What are your thoughts? I live in Chepstow but the post works well.
« Last Edit: 10 March, 2021, 11:54:05 by Greenfield »

Calum

  • Royal Star
  • ***
  • Posts: 121
    • View Profile
Re: B33 plunger centre stand
« Reply #3 on: 10 March, 2021, 12:02:46 »
Yes can make one of those and post it to you no problem. When I sat and looked at it with a fresh set of eyes it was obvious how it should work - my original assessment was based on what I had inherited from a previous owner (which is obviously wrong, although it does work) but when I mentioned it earlier or became obvious how it should be.

Let me know the length, OD and ID and I'll turn one out of some steel.

Cheers
Calum

Greenfield

  • Royal Star
  • ***
  • Posts: 239
    • View Profile
Re: B33 plunger centre stand
« Reply #4 on: 14 March, 2021, 12:52:26 »
I don't know how to add this pic to the original post so hence the separate entry.
The picture shows the top of the stand with spacer tube. The tube looks shorter than the top of the stand due to perspective, when it is in fact a little longer. The offset grease nipple hole feeds to the edge of the tube waist.

Calum

  • Royal Star
  • ***
  • Posts: 121
    • View Profile
Re: B33 plunger centre stand
« Reply #5 on: 17 March, 2021, 13:04:59 »
Can't attach a photo to a PM it seems!