5 Speed Quaife

[Brian Thompson]

Hello ,
When fitting the 5 speed to cases that are apart ( twin), do I need to fit the G53 bevel stop. I had been told otherwise, but thought that the bevel stop would be there when someone was retro fitting the 5 speed from the 4 speed.
The G53 isn't there at present.
Thank you
brt650

 

[greg brillus]

The problem is that the 5 speed camplate needs more rotational travel. On mine it seems by about another 9/16 of an inch. What i would do is still run the G53 bevel stop, but on the G39 AS bevel gear, i would grind some extra travel to equal sides of the cut out area on the bevel gear to give you the extra travel, say around 2 mm per side, and try it out. Ideally it would be nice if the G39 AS bevel gear had two more teeth on it, because when the 5 speed is used, this gear is more or less at its extremes.....that is that in either 1st or 5th gears, the bevel gear is only engaged by about one tooth, although i don't think this presents any issues. Do a dummy fit up of the gearbox and rotate the G40 shaft through its total travel making sure it engages all gears and neutral...then double check it is fully engaging 1st and 5th gears by selecting either one at a time and unscrew the G37 cap nut, remove the plunger/ spring assembly, and check that you can visually see the detent in the cam plate for that gear, and is fully lined up with the center of the hole. This check is to confirm that these gears are in fact fully engaged and that the detent plunger is holding it in gear.....this is why you need more travel with the bevel gear.......Hope this helps......Greg.

 

[vibrac]

never gave me any trouble with the bevel
If its a second hand box there were some issues with position of some shims in early batch

 

[Brian Thompson]

Thank you Greg,
The 5 speed is new. I have the first of two engines to start to assemble and the third to dismantle. I want to get the G39AS right before I put the cases together. I was told that I can leave out the G53. What is it's function really with the little spring attached to it?Is it's function merely to help with assembly or to take some of the weight of the gearshift indicator arm? I have bought 3 new G40's and G39's to go into these engines as they have the modified spigot arrangement to give each other support.
Thanks
brt650
P.S I have joined the VOC and I'm waiting to go blue.

 

[Brian Thompson]

Also,
Thank you to whom ever it was that shifted my posting to the correct section.
Much appreciated.
brt650

 

[vibrac]

spring is an assembly aid I always leave it out and hang something on the other end to keep it in position when assembling

 

[BigEd]

You are welcome.

Also,
Thank you to whom ever it was that shifted my posting to the correct section.
Much appreciated.
brt650

 

[greg brillus]

I think you will find that the G53 is there to aid in assembly, given that you usually insert the gearset, shafts, selector forks and camplate all together in one go. So if the G53 was missing then the bevel could rotate to whatever possition it liked. So by providing a "STOP" If you like....then when you offer up the internals and push them fully home in the case, with the G40 shaft rotated anti clockwise looking from the kick start cover side first.....it aligns the two bevel gears to get the "Timing" of the gears meshed correctly. But now with the 5 speed you need extra travel of the upper bevel gear. As Vibrac has pionted out earlier that this gave him no problems on his....my first check would be to align the 5 speed camplate with an original 4 speed one, and check if it needs the extra travel that i'm talking about, perhaps not all 5 speeds need the extra travel, as there have been different ones made over the years..........Greg.

 

[Brian Thompson]

Thanks Vibrac and Greg,
I have another engine to do first tomorrow. Strip apart a DBD34 BSA engine. Same owner. This stuff has been sitting since 1964.
Once that's done I'll check the cam plate's and let you know.
Cheers
brt650

 

[clevtrev]

The problem is that the 5 speed camplate needs more rotational travel. On mine it seems by about another 9/16 of an inch. What i would do is still run the G53 bevel stop, but on the G39 AS bevel gear, i would grind some extra travel to equal sides of the cut out area on the bevel gear to give you the extra travel, say around 2 mm per side, and try it out. Ideally it would be nice if the G39 AS bevel gear had two more teeth on it, because when the 5 speed is used, this gear is more or less at its extremes.....that is that in either 1st or 5th gears, the bevel gear is only engaged by about one tooth, although i don't think this presents any issues. Do a dummy fit up of the gearbox and rotate the G40 shaft through its total travel making sure it engages all gears and neutral...then double check it is fully engaging 1st and 5th gears by selecting either one at a time and unscrew the G37 cap nut, remove the plunger/ spring assembly, and check that you can visually see the detent in the cam plate for that gear, and is fully lined up with the center of the hole. This check is to confirm that these gears are in fact fully engaged and that the detent plunger is holding it in gear.....this is why you need more travel with the bevel gear.......Hope this helps......Greg.

Not so, that the 5 speed needs more travel. The angle between first and
fifth, is exactly the same as the angle between first and fourth on the
standard box. Near enough 148 degrees.
With a bevel gear there is only one tooth engaged.
As for the job of the pin, it`s not only for the spring, but it is the limit stop, to prevent the bevel gears from disengaging.
I and others have found quite a few Twin gearboxes that have never been in either first or top, since they left the works. Invariably this has been the result of the bevel gear in the camplate featuring a machining fault. The relationship of the engaging tooth, being out of sync with the location in the plate, or it could be the hole in the plate.