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G: Gearbox New Gearbox: Help Needed


ehb86

New Website User
VOC Member
Hello everyone,

I'm in need of some advice so this seems like the best place to start. I'm a long time overseas (USA) VOC member and read the forum and MPH regularly, but haven't posted before, or if I did I don't remember. I'll do my best to explain my problem and hope for the best. Thanks in advance for any help, it would be much appreciated and sorry for the long first post/request.

I've owned my Shadow since the mid eighties and rode it a fair bit but several years ago I started having shifting problems and jumping out of gear problems so I pulled her apart and removed the gearbox for inspection. The gears generally had a lot of wear on the dogs and I decided to just replace all the gears and shafts and start from new. I put this engine together originally in about 1985 and times were tight so I used everything I had available in the way of original parts, some may have been beyond their time, but it worked well for some time.

I recently purchased all new gearbox gears, shafts, shifting forks, cam plate etc. and reassembled the gearbox. I still have the gearbox cover off and I've been checking that I can shift through all the gears with the gear position indicator. The problem is that shifting from first to second or first to neutral is almost impossible with the indicator lever. If I tap on the cam plate with a screwdriver gently, I can nudge it eventually into neutral or second, once in second it shifts easily with the gear indicator to third and fourth and back down to second. Once in second again, it is impossible to do with the shift indicator and I don't want to damage the pinion and have to split the cases.

There was a couple of year time lag from when I disassembled the bike until I recently got all the parts together and I don't recall if I used to be able to shift into first and second without the engine running easily or not? I believe that I used to be able to shift all gears by hand with the indicator lever if I just spun the rear wheel a bit, as I said, now it will work fine from second on up and back, but from first to second or second to first it's just too tight.

I've backed the cam plate spindle out a turn and a half or so to be sure it isn't putting pressure on the cam plate, all the gears and forks move easily on their shafts and are well lubricated. I'm at a loss, or maybe I'm expecting too much and need to put it together and fire it up and get everything rattling around good? I also put my old cam plate back in and it is still the same result. So, I'd be grateful for your suggestions or thoughts. Again sorry for the long post and thanks for your consideration.

Best regards,
Mark
 

Robert Watson

Well Known and Active Website User
VOC Member
A couple of things come to mind. The first is that new gears and shafts etc coming from likely different periods of manufacture don't really know each other. You need to lock them in a room and make them play together. I recently put a new 5 speed in my early B and it shifted quite stiffly to start with. I think the new detent and spring running on the new camplate was a part of that. After a very short while it started to behave in a civilized manner.

I would put it together and try it first, and I know it might mean taking it apart again but then you would have a better idea of exactly where it was having an issue.

The other thing to check is that the lay shaft is in the right way around as the spline section on one end is just a very small bit longer than on the other end and they can be put in backwards. Get the gears in the correct order and see how they fit for depth on each end,

When all that fails, and if you have no Vincent help in the neighbourhood just put it in the back of a pickup truck and bring it 8 miles North of your northern border and I'll help you sort it out!

Robert
 

greg brillus

Well Known and Active Website User
VOC Member
I have had several instances now with new gears mostly from the VOC spares co where the first gear sliding gear G 9 hangs up on its mating gear G10. The problem is the OD of the dogs on the sliding gear are larger in diameter than they should be and they just grab on the inside of the G 10. If you simply linish down the outside of the G 9 dogs just a whisker this will allow the two gears to mesh with no resistance. Ihave had the same trouble where G 8/1 slides into G7 but not as often. I'm pretty sure this will be your trouble..........Also as Robert has pointed out, the detent plunger/spring can be too stiff on the cam plate. If the cap G 37 screwed into the top of the G 2 cover plate is backed out a turn or so, this helps a lot. remove the spring and squeeze it till it coil binds in the jaws of a vice. This will shorten the spring by about 2 mm ....... this is enough to relieve the excess tension on the plunger, and make it shift much easier. Good luck and keep us posted........... Greg.
 

Bill Thomas

Well Known and Active Website User
VOC Member
Morning Mark, If you can tap the Cam plate, Does that mean that the gearbox round outer cover is still off ?,
It needs to be fitted fully fitted to line everything up, I think.
If and when it is fitted, Try not fitting the the detent spring or leave it a bit loose, Just to try it on the bench.
Good Luck, Bill.
 

chankly bore

Well Known and Active Website User
VOC Member
Also while you are at it check that there is no side loading on the G50 plate where the selector shaft goes through the little ball race G41. It can be pushed awry by the E80 battery platform nuts.
 

ehb86

New Website User
VOC Member
First off, thanks very much to everyone for great suggestions and such quick help. I'm going to try to answer questions in order.

Robert, putting it together and getting them to settle in was kind of where I was headed. The layshaft is in correctly, I measured it on assembly after reading about that length difference in another thread here before I started assembling. I'm going to go check out the G9/G10 and G9/G7 mating per Greg's suggestion and if all is well there I think I'll reassemble and try running things in a bit. Also thanks for your generous offer of help. I would definitely take you up on that if I can't get it straightened out.

Greg, thanks for that valuable insight. I'm going to be away from the bike for a few days. I will check the gear mating out when I'm back and report what I find. That sounds like a very likely culprit. It would fit with what is happening very well.

Bill, thank you, I've tried it both ways, cover on it's the same result. Then I've pulled it off to switch out cam plates, etc. and ensure that I can get it to move through the gears with a little help. I've swapped pinions on the cam plates as well to be sure they weren't binding due to height differences, etc.. Thanks for the suggestion though and I'm sure you're correct, the plate takes care of shaft alignment and stiffness.

Vibrac, thank you, I believe I've got it right but never hurts to double check..... a few times with me.

Chankly, I will look at that as well.

Thank you all... I will report back mid week after I've had a chance to check things out.

Mark
 

ernie

Well Known and Active Website User
VOC Member
Mount gears like this to test the smoothness of various operations. If all is well then it must be the detent. But first gear is always stiff on the indicator.
26487
 
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greg brillus

Well Known and Active Website User
VOC Member
The 5 speed boxes have their own "Can of worms" to sort through, including the cam plate spindle that can foul on one of the three selector forks, but the 5 speed selectors are quite different in operation to the stock 4 speed.
 
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Robert Watson

Well Known and Active Website User
VOC Member
One other thought...... A number of years ago there were some gears (IIRC the two outer ones on the layshaft) that were made a little too wide. Just mic the width of the new ones and compare to the old originals. I had some perhaps 20 years ago and I think we just tickled them with a surface grinder...
 

ehb86

New Website User
VOC Member
Thanks Ernie and Robert, I'll add these to my list for Wednesday/Thursday when I'm back and report in.

Mark
 

vibrac

Well Known and Active Website User
VOC Member
The 5 speed boxes have their own "Can of worms" to sort through, including the cam plate spindle that can foul on one of the three selector forks, but the 5 speed selectors are quite different in operation to the stock 4 speed.
Dont say that Greg I have a 5 speed about 1 day from testing...
the last one (1999) I fitted gave no problems back then there was a question about where a spacer fitted but that was fixed. there is a bit of a lack of instruction with the cluster and the photo of the cluster is back to front
Any more info about the can of worms?
 

greg brillus

Well Known and Active Website User
VOC Member
I just bought a 5 speed cluster from the Uk, and like you say, no instructions........That in itself is quite poor in my opinion, not everyone can work out these things. There have been several versions of the 5 speed box that I know of, the ones here started back in the 90's when the RTV's were being created. The cam plates of the variants have all been different, and the ones here need more rotational travel than a stock 4 speed plate. This meant that installing one to an assembled engine was very difficult, as the bevel stop in the roof of the gearbox housing needed modification to allow for this extra travel. The kits made by Quaife don't suffer this issue as they seem to have worked out how to select all gears with the same travel as a stock cam plate. I did have an issue with one where the spindle protruded below the hole in the cam plate bevel gear and this fouled on one of the selector forks, as there is one that passes under this area. The ones from here did not have the small parts that limit the travel of the G 66 AS lever either, probably because of the extra travel mentioned before needed for the cam plate. Like all these mods to these bikes, you have to trial fit everything and assume that some fettling will be necessary........... I'm well use to it now. The 5 speed box which was one of the later ones that Terry supplied for a time, was the one I used in the HRD twin racer I built. I had to carry out some re-shimming of the gears and shaft end floats, this was because the cases had the centers machined from weld repairs that had left a gap in the cases, my guess is we lost about 0.020" from the joint face. Apart from that, the gearbox has performed perfectly and it is fabulous to use, coupled to the Bob Newby belt/clutch kit that we used............ Just for your info Tim, we run 40 weight Morris castor oil in the box. Cheers................. Greg.
 
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Robert Watson

Well Known and Active Website User
VOC Member
I have fitted 2 Quaifes and one of Terry's 5 speeds. The only issue I have encountered apart from the "Check that the shim is in the right place" which probably took less time that them actually putting the shim in the right place, was the spindle sitting just below the cam plate and fouling the center shifter fork.

Quaife I think made the first 5 speeds for Sportspower (John Surtees Co) and the first batch were all close ratio with a tall first gear. Dan Smith got probably the first one sold and made some new bits (as one does) to give it standard ratios. That was pre 1989 as it went into his short rod Shadow from new and it was first on the road in 1989, so they have been around for ,more that 30 years now!
 

Glenliman

Well Known and Active Website User
VOC Member
As an easy trial, you can just back the detent pin spring holder out a bit and see if shifting improves.
I ended up with 2 sealing rings the holder, things were a bit clunky with just a single ring. As others have mentioned, a little extra spring tension here changes operation quite a lot.
Re instructions lacking for the 5 speed- I have a full set of 5 speed instructions from Surtees Sport Power here. If anyone needs these, I could try emailing photos, should be legible.

Glen
 
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Little Honda

Well Known and Active Website User
VOC Member
First off, thanks very much to everyone for great suggestions and such quick help. I'm going to try to answer questions in order.

Robert, putting it together and getting them to settle in was kind of where I was headed. The layshaft is in correctly, I measured it on assembly after reading about that length difference in another thread here before I started assembling. I'm going to go check out the G9/G10 and G9/G7 mating per Greg's suggestion and if all is well there I think I'll reassemble and try running things in a bit. Also thanks for your generous offer of help. I would definitely take you up on that if I can't get it straightened out.

Greg, thanks for that valuable insight. I'm going to be away from the bike for a few days. I will check the gear mating out when I'm back and report what I find. That sounds like a very likely culprit. It would fit with what is happening very well.

Bill, thank you, I've tried it both ways, cover on it's the same result. Then I've pulled it off to switch out cam plates, etc. and ensure that I can get it to move through the gears with a little help. I've swapped pinions on the cam plates as well to be sure they weren't binding due to height differences, etc.. Thanks for the suggestion though and I'm sure you're correct, the plate takes care of shaft alignment and stiffness.

Vibrac, thank you, I believe I've got it right but never hurts to double check..... a few times with me.

Chankly, I will look at that as well.

Thank you all... I will report back mid week after I've had a chance to check things out.

Mark
My friend reported similar problems on a box of his and could not find any fault, until he found out, that
the spring-loaded peg which fixes the cam plate on its outer surface was machined at a wrong angle.
(Supplied by VOCS). Fitting an old original solved all problems. If you still have the old one, why not try?
 

vibrac

Well Known and Active Website User
VOC Member
One strange item in the kit there was a G112 in the kit together with the pin that is riveted at the end of G66AS but the roller G112 was alloy! I already had a new G66AS and I am reluctant to fit another pin and an alloy roller I know these components were not in my 1999 kit
There was also a G59 (the toothed part) and a rivet to make a G59AS this I did use, but back in 1999 I did not as I could see no difference in the tooth forms and everything worked OK (Ben one the championship twice on that box)
It should not be guesswork a simple sheet of notes would suffice
 

oexing

Well Known and Active Website User
VOC Member
Well, I was alerted by tales of " slow" gear changes on the Vincents. So when I found that gear lock detent plunger I was quick to realise I did not like the design: When trying to rotate the camplate the plunger gets a lot of side load from spring action pushing it into the v-slot that prevents the camplate from turning. So the plunger gets high side load when it has to lift a bit and side load in its bore creates quite some friction - that I would not want in gear changes. Also the pointy top of the plunger is not great but essential as there is no fixed orientation for it in the bore. In the end I designed a lever and only a spring is in the old bore for preloading the lever. So I am quite positive about this for getting smooth gear changes. Sure, this will be a bit more agricultural than on smaller bikes when you look at the massive gears inside which I guess would easily handle 200 hp no problems. Now compare this with gears inside some Ducati or the like !!

Vic

P1050797.JPG

P1050798.JPG
 

greg brillus

Well Known and Active Website User
VOC Member
Tim that extra G 112 and the rivet you mention are not for the roller on the end of the G 66 AS. The alloy sleeve slides over the peg section of the G 49 lever stop, this is the peg that the legs of the G70 spring sit around. The other rivet part replaces the same rivet in the G 66 AS lever, near the pivot point again where the same G 70 spring sits around. These parts then limit (reduce) the travel of the lever G 66 AS so the gearbox does not overshift. Well that's my take on it anyway............ Cheers.
 

Glenliman

Well Known and Active Website User
VOC Member
John McDougall played with the cam plate on the standard box.
He copied the general shape of the Norton AMC camplate. The AMC box is well known for slick shifting
This camplate change made the 4 spd Vincent gearbox shift like a Norton.
So it would appear that it's not the heavy gears that slow the shifting, as is sometimes suggested.
He was considering producing small lots of the modified camplate, but never got around to it.
One thing the 4 speed Vincent box has that a 5 speed Quaife doesn't is a 1.19 ratio (3rd) , a single gear that pulls hard from 60mph to up to 100 mph without over revving. It's an excellent ratio for hills, two up. You can run along at 70 or even 80mph two up on an 8 percent grade and have the engine right in the sweet spot , not overly busy with revs but producing lots of grunt.
This is 3800 rpm at 70, 4300 at 80mph.

Glen
 
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