• Welcome to the website of the Vincent H.R.D. Owners Club.

    Should you have any questions relating to the Vincent H.R.D. Owners Club, or Vincent H.R.D. motorcycles in general, please contact Graham Smith, Hon. Editor and Webmaster by calling 07977 001 025 or please CLICK HERE.

    You are unrecognised, and therefore, only have VERY restricted access to the many features of this website.

    If you have previously registered to use this forum, you should log in now. CLICK HERE.

    If you have never registered to use this website before, please CLICK HERE.

1935 Series A 500 Burman BAP Gearbox questions


ClassicBiker

Well Known and Active Website User
VOC Member
Got a question for all the Series A aficionados out there. I've been helping a local section member and club member with his Series A single. Prior to my involvement he had another refurbish his gearbox. Yesterday after finally getting new clutch springs I installed them and thought it a good idea to make sure I could select all the gears. I can find only two gears and I am not sure about what I think is neutral. My friend's confidence in the gearbox is less than absolute as the individual responsible for rebuilding it also supposedly rebuilt a motor for another bike he owns, but that turned out to be a fallacy. To be fair the re-builder has suffered a stroke a little while back. Now you know the history to my questions.
1) How many ratios does the BAP gearbox have. Looking at the Alternate part list he I believe it has four.
2) How do I time the shift mechanism? The fact that the neutral indicator on the shaft didn't even remotely line up with the indicator on the box is what made me want to check in the first place.
3) Are there any major pitfalls or issues I need be aware of? I'm having my friend pull the cover to see if there is anything obviously wrong. If he doesn't find anything glaringly obvious then I'm digging in.
4) Sources of information please? I haven't begun looking, but if anyone can point me in the right direction, it would be much appreciated.
Lest anyone be under the misapprehension that I am doing all this for totally altruistic reasons, I'm not. I've got a vested interest in this. Once this is up and running I've been promised to be able to take it for a ride around the block a couple of times and some photos with it. So the stakes are high here!
Thanks
Steven
 

Robert Watson

Well Known and Active Website User
VOC Member
The internals are the same as a post war box. There is a specific place the shifting mechanism has to be when it is assembled. If no one posts it up in the next few hours (I am just heading out for a bit) I will look it up and take a scan of it and post it up for you.
 

MartynG

Well Known and Active Website User
VOC Member
Got a question for all the Series A aficionados out there. I've been helping a local section member and club member with his Series A single. Prior to my involvement he had another refurbish his gearbox. Yesterday after finally getting new clutch springs I installed them and thought it a good idea to make sure I could select all the gears. I can find only two gears and I am not sure about what I think is neutral. My friend's confidence in the gearbox is less than absolute as the individual responsible for rebuilding it also supposedly rebuilt a motor for another bike he owns, but that turned out to be a fallacy. To be fair the re-builder has suffered a stroke a little while back. Now you know the history to my questions.
1) How many ratios does the BAP gearbox have. Looking at the Alternate part list he I believe it has four.
2) How do I time the shift mechanism? The fact that the neutral indicator on the shaft didn't even remotely line up with the indicator on the box is what made me want to check in the first place.
3) Are there any major pitfalls or issues I need be aware of? I'm having my friend pull the cover to see if there is anything obviously wrong. If he doesn't find anything glaringly obvious then I'm digging in.
4) Sources of information please? I haven't begun looking, but if anyone can point me in the right direction, it would be much appreciated.
Lest anyone be under the misapprehension that I am doing all this for totally altruistic reasons, I'm not. I've got a vested interest in this. Once this is up and running I've been promised to be able to take it for a ride around the block a couple of times and some photos with it. So the stakes are high here!
Thanks
Steven
Take a look at this video - covers all your questions.
and if you still have questions read the attached article.

Martyn
 

Attachments

ClassicBiker

Well Known and Active Website User
VOC Member
Martyn,
Thanks for posting that video and the pdf. I just watched it and I think given what my friend's gearbox is doing I think I know where the re-builder went wrong. We'll see if I'm right.
Thanks for the help. I'll keep everyone posted.
Steven
 

ClassicBiker

Well Known and Active Website User
VOC Member
Okay so it was as I suspected after seeing video MartynG posted. When we took the outer cover off we discovered the box was really miss-timed. We followed the steps in the video to time it. Before that I turned the selector shaft to make sure it would rotate an select all gears. It selected all four gears and neutral. So on went the cover timed as in the video, between 2nd and 3rd gear. Into 2nd, no problem. Change to 3rd, fine. Change to 4th, okay. Back to 3rd good. Back to 2nd, nope won't go. Cover off again, re-time, try it again. same result. So we tried something different. Timed it between 2nd and 3rd. Into 2nd, no problem. Into neutral, good. Into 1st, good. Back to neutral, good. 2nd, good. 1st good. 2nd good. 3rd, fine, 2nd, okay, 3rd, good, 4th good. Back to 3rd, fine. 2nd, not going to happen. Tried this a couple of times. Once I go to 4th, I can return to 3rd, but then I'm stuck. Back and fourth from 1st to 3rd is fine. Once I hit 4th I can't go back beyond 3rd. So I thought the ratchet or pawl were worn. So I repeated flipping the pawl over. Figuring if I went to first and couldn't get beyond 2nd it was the pawl. If it remained the same the problem was with the ratchet. The problem remained. Examination of pawl and ratchet shows nothing out of the ordinary other than the springs look rather ominous and old grease (so much for the expert rebuild). New springs are on order and the grease will be cleaned. A new pawl has been ordered just in case, the hole and slot looked okay but the play seemed excessive. The alternate A series parts list has a part cx056 selector cover shown. This appears to be missing. It appears to fit between the selector spring box (bottom photo) and the outer cover. Looking to be a piece of sheet metal in the outline of the spring box of the selector mechanism. Is it imperative to have this and what is the most like thickness of material. I should also note that if I left the out cover off and held everything just so, gear selection up and down was not problem. So I believe that the problem lies with the ratchet and pawl. Opinions of the appearance of the ratchet teeth, the pawl, are invited. As are any other likely sources of the cause of the problem. All help and suggestion gratefully accepted and appreciated.
Steven IMG_0258.JPGIMG_0259.JPGIMG_0260.JPG
 

nkt267

Well Known and Active Website User
VOC Member
Okay so it was as I suspected after seeing video MartynG posted. When we took the outer cover off we discovered the box was really miss-timed. We followed the steps in the video to time it. Before that I turned the selector shaft to make sure it would rotate an select all gears. It selected all four gears and neutral. So on went the cover timed as in the video, between 2nd and 3rd gear. Into 2nd, no problem. Change to 3rd, fine. Change to 4th, okay. Back to 3rd good. Back to 2nd, nope won't go. Cover off again, re-time, try it again. same result. So we tried something different. Timed it between 2nd and 3rd. Into 2nd, no problem. Into neutral, good. Into 1st, good. Back to neutral, good. 2nd, good. 1st good. 2nd good. 3rd, fine, 2nd, okay, 3rd, good, 4th good. Back to 3rd, fine. 2nd, not going to happen. Tried this a couple of times. Once I go to 4th, I can return to 3rd, but then I'm stuck. Back and fourth from 1st to 3rd is fine. Once I hit 4th I can't go back beyond 3rd. So I thought the ratchet or pawl were worn. So I repeated flipping the pawl over. Figuring if I went to first and couldn't get beyond 2nd it was the pawl. If it remained the same the problem was with the ratchet. The problem remained. Examination of pawl and ratchet shows nothing out of the ordinary other than the springs look rather ominous and old grease (so much for the expert rebuild). New springs are on order and the grease will be cleaned. A new pawl has been ordered just in case, the hole and slot looked okay but the play seemed excessive. The alternate A series parts list has a part cx056 selector cover shown. This appears to be missing. It appears to fit between the selector spring box (bottom photo) and the outer cover. Looking to be a piece of sheet metal in the outline of the spring box of the selector mechanism. Is it imperative to have this and what is the most like thickness of material. I should also note that if I left the out cover off and held everything just so, gear selection up and down was not problem. So I believe that the problem lies with the ratchet and pawl. Opinions of the appearance of the ratchet teeth, the pawl, are invited. As are any other likely sources of the cause of the problem. All help and suggestion gratefully accepted and appreciated.
Steven View attachment 19981View attachment 19982View attachment 19983
I had something similar last week on a 1951 Comet..It turned out that one of the 3/16" rollers for the cam shaft had dropped into the box and was jamming every now and again..I have a few spring boxes as spares so will check the plate later..john
 

MartynG

Well Known and Active Website User
VOC Member
Oh. You do need the spring box cover plate - there should be 2 of them, one each side, if I remember correctly.
 

nkt267

Well Known and Active Website User
VOC Member
The thickness of the inner plate,the one one the opposite side to the one in the picture, is 32 thou. My parts list only shows the one cover plate for the springs..John
 
Last edited:

greg brillus

Well Known and Active Website User
VOC Member
Does anyone know the difference between the mainshafts of a pre and post war Comet. The shaft I have here from the "A" Comet I'm rebuilding looks very similar except for an extra collar inboard of the stepped spline for the clutch. It's just that I need another one to suit another gearbox I'm building again, for a pre war Comet. Cheers.....................Greg.
 

ClassicBiker

Well Known and Active Website User
VOC Member
Thanks for all the replies. Doug has ordered new springs, all four, ratchet, pawl, and cover(s). I think he only ordered one, but it shouldn't be to difficult to copy and make another. So we are on hold until parts arrive.
Steven
 

A_HRD

Well Known and Active Website User
VOC Member
Does anyone know the difference between the mainshafts of a pre and post war Comet. The shaft I have here from the "A" Comet I'm rebuilding looks very similar except for an extra collar inboard of the stepped spline for the clutch. It's just that I need another one to suit another gearbox I'm building again, for a pre war Comet. Cheers.....................Greg.
Greg,
The thicker part of the shaft (which comprises the 4 inch long splines and the bearing surfaces for the output gear) is approx 6-29/32" long on the A Comet and 7-1/8" long on the C Comet. Consequently, the overall length of an A Comet shaft is approx 11-1/8" and a C Comet is approx 11.300". I stress 'approx' throughout because I have witnessed small variations.... (1/64 - 1/32ths).

Peter B
 

Top