5 Speed Bonnie gearbox help

[L.A.B.]

Hello Paul,

I expect you have read through the messages above and there could be some info that will help?



The four-speed info given in the Haynes book isn't any help here whatsoever for the five speed box (or the late four-speed box either!)?

You said "the manual and Haynes" so do you mean you have a factory manual and a Haynes manual? If so then at least you should have the correct gearbox assembly instructions (build in neutral then select first etc.) then the inner cover should be offered up and the best way to set the quadrant position is to let it drop fully under its own weight, then as the inner cover is slid into position the *inner* end of the quadrant should be lifted -but by only a small amount (just enough to engage the first camplate tooth, that is apparently the best way to set the quadrant.
If that doesn't fix the selection problem then the fault could be in the selector mechanism somewhere?
But one thing at a time eh?

And maybe Andy_G could possibly offer some observations as he has had rather more recent experience of sorting this problem at first hand!
  

[paulrb]

Hi

Yes I have a workshop manual too and which has more detail. I built the gearbox in neutral and I seem to have all gears moving the camplate and rotating the wheel. but when I assemble the cover with first gear seleted and with the quadrant on the second tooth, I only get three gears. I have also tried various positions around the second tooth.
I bought the bike in bits and the last part to finish is the gearbox. I got my MOT last week with only three gears. (good job the gearbox does not need to work for the MOT and I only had to go a short distance). I thought I had all the gears before I took the bike for a test ride..

I have also changed all the springs in the plunger too. I think maybe I have got it right at some point but maybe I am waiting for a completly slick change box whilst it is oil free!

Thanks for the advice, I will give it another go. Its been a bit of a challenge.

Cheers

Paul

[L.A.B.]

You say you are only getting three gears?

Do you know which three gears?

Are you sure you are moving the camplate to the *first* gear position (rotate camplate clockwise as viewed from the rear of the motorcycle)?

[paulrb]

Hi

I think I got fourth with some force on the gear lever. Yes I believe I have engaged first rotating clockwise. First and second seem very smooth. maybe it is something to do with the selector for 4th and 5th. I have a recon gearbox. but the selectors are old.

[L.A.B.]

You said that you could select all the gears by rotating the cam plate. So the fault would seem to be with the selector mechanism (somewhere?)

[Charlie]

Hi, I recently had exactly the same symptoms when I rebuilt my Jubilee T140 5 speed gearbox - it was caused by misalignment of the quadrant.  Here are some tips that I worked out after much trial and error.

a) Make sure you've got a way of turning the engine over; remove the index plunger and spring so you can easily move the cam plate to change gear; install all the gears. (Use lots of thick grease to hold bits in place if necessary).
b) Rotate the cam plate as far as it will go so that first gear is engaged. Make sure the cogs closest to the open side of the box are fully meshed together. Turn the engine over a few times to make sure the cogs are all aligned OK and that first gear is working.
c) Dont yet put the gastket or any goo in place.
d) Gently push the gearbox inner cover into place, with the quadrant hanging down under gravity. Just before the cover goes home rotate the quadrant so the inside part rises just a few millimeters - you should be able to feel the quadrant mesh as you push the cover home.
e) Do up the 3 retaining bolts/screws lightly.
f) Slip the clutch push rod into place and leave it so it sticks out about half an inch.
g) Replace the index plunger.
h) Using a long tyre lever or similar you can GENTLY lever the quadrant against the clutch push rod so it changes gear. You'll need to turn the engine over as you are doing this - preferably by rotating the rear wheel. Make sure all 5 gears plus neutral engage.
j) Once you're sure you've got the hang of it, remove the gearbox inner cover and refit in the same way only this time use a gasket!

I found the Haynes and Triumph manuals fairly unhelpful on this topic, but once I stopped trying to understand them and used the technique above it all fits together easily. (And works!).

[paulrb]

Thanks

I will give it a go tonight. I think the camplate is in the right position with all the gears, just timing the quadrant. As I have never had this bike running before (bought as a non runner), I have changed so many parts such as the clutch, it is hard to isolate the problem.
Cheers

Paul

[L.A.B.]

And if you get the quadrant timing correct then you should be able to check the selection of all gears without the quadrant coming into contact with the either end of the slot?

When testing the gear selection I'm sure that I could move the quadrant just using hand pressure (whilst rotating the mainshaft etc. with the other hand) , with a piece of rag between my hand and the quadrant.  

[paulrb]

I can find all the gears with a tyre lever but it is stiff, it is not exactly a gemtly levering to move the quadrant.  I cannot move the quadrant with my hand. The quadrant does not touch either side of the slot. But when I install the outer cover the LH gear change is easy for 1st, 2nd, 3rd but difficult to find the other gears even whilst rotating the wheel and pulling on the lever. I am starting to wonder if I need to look at the selectors again. Maybe the 4th 5th selector is worn, or something is not lining up, maybe shafts?
I am getting somewhere as I have all the gears moving the quadrant. Wish it was RH change instead..

[Andy_G]

Dismantle the box and check the selectors to make sure they are not bent. This shouldn't be as bad as it sounds as the gears come out in their clusters. Seems like you have had some really good advice and I cannot offer any better. Seems like my problem was slightly different. Good luck and thanks for the compliments on your email.

[paulrb]

Hi

I have looked at the selectors, they do not look bent but the lug which insert into the camplate looks chipped and worn on two of them (layshaft selector, not the main shaft 4th). The other thing that concerns me is I fitted a new clutch and belt drive and I may not of driven home the clutch hub as the main shaft to the gearbox has a lot of play pullng forward and tends to drift upward thus I have to push the shaft down to engage through the bearings of the gearbox cover. I seem to have good gear selction without the gearbox cover or quadrant engaged. Its a bit baffling. I will have another play with it.

 

[paulrb]

I may of found the issue, I have worn lay sahft selectors (lobs that insert into camplate), however the camplate has heavy corrosion on the fourth gear indent. I have read before on forums that you can use a dremel to repair corroded camplates. Also on top of this I found small pieces of needle roller bearing from the rear part of the layshaft, probaby difficult to replace? At least the gears are new..
I have my work cut out to repair this.. summer is rolling on too.
I am starting to think it would of been easier to put the engine on the bench to work on or aquire a bike lift.
Thanks for all the advice
Paul

[Andy_G]

You are most welcome although, I doubt I was much help to you. Come back if you have any more difficulties and of course, let us know if it works ok.

[paulrb]

Hi

I have changed the layshaft selector forks and cleaned the camplate but still find it hard to get the high gears, even by turning the camplate without the plunger or quadrant attached. I may need to replace the camplate which is a bigger job than I anticipated. At least I got the needle rollers back in..
I may look at the clutch first as the springs maybe too tight, not sure if this would casue it but you never know.

It certainly has me thinking...

Paul

[L.A.B.]

I may look at the clutch first as the springs maybe too tight, not sure if this would casue it but you never know.

I don't see how the clutch spring pressure could affect the gear selection (when the engine isn't running) but it must be remembered that the gears and shafts do need to be rotated either by turning the main shaft or the sleeve gear as the camplate is moved so that the gear dogs can engage.