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Comet gearbox

redbloke1956

Well Known and Active Forum Website User
Non-VOC Member
Hi to all, I am just trying to sort through some issues on my 51 comet, the gearbox that is fitted has the following number stamped on the case G97L49 and the gearbox I purchased is stamped G42E52 and near that is B525 can anyone shed any light on these two boxes:
I assume that the 49 and 52 are years of manufacture? but that is as far as I get. Can anyone tell me if I should expect great differences in two comet boxes.
Thanks Guys

Kevin Dennis
 

chankly bore

Well Known and Active Forum Website User
Non-VOC Member
I don't know everything about Comet gearboxes,but I believe the letter before the year denotes month of manufacture;i.e.G97K51 is November 1951.If yours is a G42 prefix check the mainshaft length and precise details of the clutch hub mounting.Please post any details on this site as the more information that is available,the fewer errors will be made.Notwithstanding that,if a little knowledge is a dangerous thing I'm bloody toxic! Cheers mate, F5AB/2A/7945 since 1972
 

redbloke1956

Well Known and Active Forum Website User
Non-VOC Member
I don't know everything about Comet gearboxes,but I believe the letter before the year denotes month of manufacture;i.e.G97K51 is November 1951.If yours is a G42 prefix check the mainshaft length and precise details of the clutch hub mounting.Please post any details on this site as the more information that is available,the fewer errors will be made.Notwithstanding that,if a little knowledge is a dangerous thing I'm bloody toxic! Cheers mate, F5AB/2A/7945 since 1972
Thanks Chankly, that's a good start mate! What in particular is important about the G42 that we need more info about it?
 

chankly bore

Well Known and Active Forum Website User
Non-VOC Member
Burman parts diagram

The Burman BAP gearbox was also used on 600c.c. and 650 c.c. Panthers.I have inspected a known original Panther that has G42K53 as a serial number.Panthers had a larger diameter clutch as well and may have had a different final drive sprocket/clutch wheel offset.The original Comet mainshaft has been measured by a mate who had one to hand.It is 287mm. overall.As i said before this stuff needs searching out.Does anyone out there want to contribute more information? Cheers, F5AB/2A/7945 The gearbox diagram on thevincent.com depicts G97 as the Vincent Comet gearbox
 
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timetraveller

Well Known and Active Forum Website User
VOC Member
I have in my possession an A1 sized drawing of a Burman gearbox. There are three drawings on the sheet; 1) is a section vertically through the box and clutch 2) a horizontal section through the box and clutch and 3) a section through the clutch lifter mechanism. The drawing is dated 1973 so I assume that it is for post-war gearboxes. It would be possible to get the whole thing copied at a professional copy shop and then the copies posted to those who are interested in these gearboxes. The drawings are what I would call 'general assembly' drawings in that they do not show dimensioned details of individual components so they may be of limited use. If anyone is interested in this then please contact me at my personal email address enw07@btinternet.com. There would be no charge for this other than the cost of the copies and the postage. Payment would have to be via Paypal for overseas customers.
 

Bill Thomas

Well Known and Active Forum Website User
VOC Member
Hello Kevin, We had something about this a little while ago, If you put into Search on the home page " Comet gearbox " And go to page 5 and look for " Bap Gearbox on Ebay " They tell you that one mainshaft is longer, Good Luck, Bill.
 

redbloke1956

Well Known and Active Forum Website User
Non-VOC Member
The Burman BAP gearbox was also used on 600c.c. and 650 c.c. Panthers.I have inspected a known original Panther that has G42K53 as a serial number.Panthers had a larger diameter clutch as well and may have had a different final drive sprocket/clutch wheel offset.The original Comet mainshaft has been measured by a mate who had one to hand.It is 287mm. overall.As i said before this stuff needs searching out.Does anyone out there want to contribute more information? Cheers, F5AB/2A/7945 The gearbox diagram on thevincent.com depicts G97 as the Vincent Comet gearbox
Hi Chankly and others, I ordererd a clutch actuating rod and the arm that pushes it (still waiting on g'box manual for correct nomenclature) from VOC and they don't fit into the G97 gearbox mainshaft (vincent box ...see above) but DO fit into the G42 box mainshaft?
am confused!!!!!!! any ideas???
 

chankly bore

Well Known and Active Forum Website User
Non-VOC Member
So,next thing to do is measure the mainshaft. Is it 287 mm.overall? Then measure the boss on which the clutch hub sits, with reference to the Comet gearbox article mentioned by Bill Thomas.I think he mentions a boss about 59/64" deep,and I think the splines go all the way through the abutting shoulder.Let us know what you find!Cheers, F5AB/2A/7945 Why exactly does the rod not fit? Too short?Too long?Wrong diameter hole or rod?Is the operating arm installed back to front?Is there a 1/4"ball or 1/4"x1/4"roller between the thrust fork and the pushrod?So many chances after 60 years of unidentified frogs and idiots leaving you with monumental dramas.
 
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timetraveller

Well Known and Active Forum Website User
VOC Member
Message for redbloke1956 is that your A1 size print of the Burman gearbox is ready if you still want it. I sent a email to that effect but perhaps it did not get through. I will need a postal address. I have also looked out a handbook on Burman gearboxes that covers models from the old three gear ones up to and including BA type boxes. As I have no knowledge of such boxes I have no idea if this hand book is likely to be of use. I could scan the handbook and email images to anyone interested but could not do that with an A1 sized drawing.
 

redbloke1956

Well Known and Active Forum Website User
Non-VOC Member
So,next thing to do is measure the mainshaft. Is it 287 mm.overall? Then measure the boss on which the clutch hub sits, with reference to the Comet gearbox article mentioned by Bill Thomas.I think he mentions a boss about 59/64" deep,and I think the splines go all the way through the abutting shoulder.Let us know what you find!Cheers, F5AB/2A/7945 Why exactly does the rod not fit? Too short?Too long?Wrong diameter hole or rod?Is the operating arm installed back to front?Is there a 1/4"ball or 1/4"x1/4"roller between the thrust fork and the pushrod?So many chances after 60 years of unidentified frogs and idiots leaving you with monumental dramas.

Thanks chankly, sorry the new rod is too large in diameter and is the same diameter as the new clutch operating plunger (which came with a roller not a ball) will pull clutch off tomorrow and investigate further.
Kevin
 
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