ET: Engine (Twin) Rapide Gearbox - Very 'tight' gearchange

greg brillus

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VOC Member
Some of the new gears available can be a snug fit.............I had one recently that the diameter of the dogs were near the same size in OD as the ID of the mating gear, and this was 1st gear too. I ground a bit off the OD of the sliding gear and all was well.............If I'd assembled it as it was, first would have been a right bitch to engage and perhaps stick when changing to 2nd. When compared to an original gear the diameter of the dog engagement was a lot smaller this on the G 10 gear causing the binding of the dogs on G 9. Again this being first gear..............
 

Peter Holmes

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VOC Member
Hi Peter, the parts came with the bike. I bought the Rapide as a reconstruction job.
The gear cluster is new. I found that the selector arm was fouling the quadrant plate so made an adjustment. I can now get 2,3 & 4th gear but not neutral & first. Very frustrating.
That could be the problem, lots of parts have been made over the years for Vincents by lots of different people, some of it good, some of it not so good (accurate) That is why the club decided to get accurate drawings and specifications done so we no longer have to play the parts lottery, I have also found Maughans to be excellent, the problem could be, and please note I am only saying could, not is, that the parts do not fit that well with each other, Trevor also tells us that some bikes came out of the factory brand new with gear selection problems, it is a difficult one. one thing is for sure, it is far better to make sure that the problem is totally sorted before any serious use, a locked up gearbox when rattling along would not be a lot of fun.
 

bmetcalf

Well Known and Active Forum User
VOC Member
Do you grind them freehand on a bench grinder or a more sophisticated method?

Some of the new gears available can be a snug fit.............I had one recently that the diameter of the dogs were near the same size in OD as the ID of the mating gear, and this was 1st gear too. I ground a bit off the OD of the sliding gear and all was well.............If I'd assembled it as it was, first would have been a right bitch to engage and perhaps stick when changing to 2nd. When compared to an original gear the diameter of the dog engagement was a lot smaller this on the G 10 gear causing the binding of the dogs on G 9. Again this being first gear..............
 

greg brillus

Well Known and Active Forum User
VOC Member
I just took a bit off the outer diameter of all the dogs with my linishing belt. These gears were supplied by the Voc spares co..........I pretty much take nothing for granted when fitting new parts, always need to check for fits and clearances, it was in fact the G 10 that had the issue and I could not see an easier fix. Some may complain about parts not fitting correctly, and that copying parts cant be difficult, but the variation from one bike to another makes this very difficult. I think people who struggle to understand this have not had much experience with restoration of anything old.
 

litnman

Well Known and Active Forum User
VOC Member
When you have bunch of gearbox parts, nothing is handier than Trevor's gearbox simulator. Interesting how cam plates can make a big difference in the way they shift.
Gearbox simulator.jpg
 

Phil Arundel

Well Known and Active Forum User
VOC Member
I also noticed that the outer race of the cover plate lay shaft bearing stands proud of the cover plate by about 3mm . Should this be so?
Could it be restricting movement of the lay shaft? Thus restricting end float of the lay shaft or am I clutching at straws? Maybe not as I can achieve 2,3 & 4th gears.
At this rate I will be taking the crankcases to Maughans to be sorted aaaah
 
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Bill Thomas

Well Known and Active Forum User
VOC Member
Morning Phil, What did you do to change the problem from the high gears to the low gears ?.
That bearing does not sound right, Just checked my spare, Mine is 20 thousands of an inch proud, Is yours the right bearing ?, Check the numbers on the bearing with the book.
As Vibrac said, The ends of the layshaft are not the same !, The right gear has to go on the right end !.
If you put it the wrong way round, The outer cover does not go in far enough.
Cheers Bill.
 
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