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

Phil Arundel

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VOC Member
If you can't find anything with the camplate, I would put it together and almost unscrew the pivot pin,
By making the pivot more loose it might make it more free ?.
That would tell you if that was the trouble.
Greg said about grinding a Nats off the pivot pin ?, To take the gear out of mesh a bit.
Cheers Bill.
Hi Bill - yes, sorry, should have mentioned the the crankcases are new! I did have to have them machined with a milling fly cutter to prevent the flywheels catching the inside of the cases - I had about a couple of mm taken off. Problem solved.
I am fairly confident that it is the camplate - it runs 2mm out of true when spun on the spindle. I have sent it to Maughans to be sorted. Happy days!!! Still enjoying the challenge though.
It was interesting that you used to race Vincent’s. I used to mechanic for a guy called Wally Dawson from Hull when I was 17/18 (1970’s !!) before I went to uni. He raced an AJS 7R Seeley. Also, of the same period, knew Dave Boxall who raced a Vincent - he kept it in his front room when he retired from the circuit - and Tony Myersa great time for British motorcycle racing.
Cheers
Phil
 

Bill Thomas

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VOC Member
I had a time in the 80s, When I had a bike in the front room !, And a Lathe, Now the Wife don't even want Me in the house !.
The 70 s and 80 s were good times to race, Don't know how they can afford it now.
Shame you could not fix your problem yourself, It would have given you a big Boost.
Good Luck, Bill.
 

Phil Arundel

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VOC Member
They sure were. Try buying her some flowers & comb your hair & she may let you back in!!!
Yes I really wanted to solve the problem myself but have no safe means of pressing the Bevel gear in or out without fear of damaging the camplate.
I’ll report back when sorted if you are not fed up of hearing from me!
Cheers
Phil
 

Bill Thomas

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VOC Member
Sorry, I should not have said that, We must all know out limitations, I have to farm stuff out sometimes,
I hate it.
I got such a Buzz, When we did a Comet and they gave us a Mag which went the wrong way, I was at my Brothers, 3 hours from my place, A phone call from an Expert told us what to do, He was worried we would not be up for it !, Grind a new slot in the points cam at just the right spot, I told him, Between us, Ron and me have over a 100 years of welding ,Grinding and messing with stuff.
It's the best when you can make something out of a disaster.
As for the Wife, I give up !.
Don't worry, I love to chat about these problems. Cheers Bill.
 

Phil Arundel

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VOC Member
Hi Bill - j have received the camplate back from Maughans & hope to get the gearbox together today. The camplate now runs true so fingers crossed all gears can be selected.
Cheers
Phil
 

Bill Thomas

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VOC Member
Hello Steve, So you think it was a faulty new Camplate ?, That's strange, I know they are hardened, Because I wanted to lighten one for racing, But did not bother in the end. Good Luck, Bill.
 

Phil Arundel

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VOC Member
Afternoon Bill.
Finally I have success ?
I called Maughans again and spoke with Steve.
He suggested checking the clearance between the camplate bevel gear/pinion G33 and the roof of the crankcase (with a feeler gauge). If there is no clearance pressures can be placed on the selector forks thus making gear change very difficult. To solve this problem an amount has to be ground off the face of G33 to create some clearance - this I did on a linisher.
Also (as suggested) I honed the hole through each of the selector forks - sometimes, when the selector forks pin is pushed into its housing, distortion of the hole through the selector fork can cause friction on the selector fork bar G30.
At long last I can select all four gears!! ??
Thank you Bill (and all) for the advice and encouragmet you have given - must admit I was getting to the end of my tether!
Great these Vincents aren’t they!
Cheers
Phil
 

Bill Thomas

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VOC Member
Well done Phil, With Vincents, It never stops !, I went out on my ex L/ning yesterday and now I have a bad misfire on the rear cylinder, Rita ignition, I think/hope its a rear coil, But we shall see, Maybe the Mk2 Amals I have just fitted and hand cut the slides, She has been a good bike for years, But these things happen !.
Cheers Bill.
 

Garth Robinson

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VOC Member
Well done Phil, With Vincents, It never stops !, I went out on my ex L/ning yesterday and now I have a bad misfire on the rear cylinder, Rita ignition, I think/hope its a rear coil, But we shall see, Maybe the Mk2 Amals I have just fitted and hand cut the slides, She has been a good bike for years, But these things happen !.
Cheers Bill.
I have been following this thread closely,as I have been having similar problems with a motor I am building up at the moment.They are series B cases that I purchased "for spares" in 1973.Being out of use for that time,they weren't too bad.They had the camplate boss repaired by welding,a neat looking job.I fitted new bearings,spindles and oil pump and all went well.Came time to assemble the gearbox and the wheels fell off the cart.Unknown to me,the cases had not been used after the camplate spindle repair.A small blob of weld was restricting the movement of the quadrant gear in the roof of the gearbox.Heads and barrels were on,I hoped not to pull it all apart so soon.I got to work with a Dremel,a mechanics' mirror and a portable QI light,and in 3 hours it was done.
I was using a set of original gears,shafts and selector forks I had accumulated over time,but,on assembly I found the movement of the gear change much heavier than i am used to, with the change into third so heavy that I worried about breaking something.Nothing seemed obviously tight,so I removed the contents of the box.I dremeled the slots in the camplate with a green stone,but on re assembly nothing was different.
I then proceeded to substitute each gear,one at a time ,hoping to find an improvement,but no luck.Substituting selector forks and their bar was also no use.I was at my wits end now,and I recalled Bill mentioning the need for accuracy when repairing the spindle boss.As a last resort,I had a complete new set of gears I purchased on E Bay 6 or 7 years ago.I started by using the E Bay double gear,surprisingly, a perfect gear change.
On removing the cluster again,I measured the width of the double gears I had been using,and I found the 2 original gears I had tried measured 2.623 and 2.625 inches.The new gear which solved the problem measured 2.596 inches.I used a set of digital verniers for this,but close enough to show the difference.
I have always tried to avoid mixing up new and used bits,where ever possible,but it's the one time it paid off for me.I wonder if any other members purchased those gear sets,and if they had any luck with them.
Finally,when tightening the cover plate screws fully,the gearbox tightened up on the last half turn of the screws.Apart again.The layshaft bearings were Timken,and new.Compared to the old one I had taken out,the small radius on the inner race where the layshaft fits was slightly smaller on the new ones .Out with the Dremel again,to remove a poofteenth of metal from the shoulder on each end of the layshaft.Success.
As Bill said,they are all different.Now it's time to go to the timing chest.
 

Bill Thomas

Well Known and Active Forum User
VOC Member
Morning Garth, Maybe after the cases were welded, The joints were ground flat ?, Mine are bad and have to use silicone on the top joint of the cases, I like a bit of end float on the mainshaft, So the oil can get to the bush that the chain sprocket goes on, In fact I grind two notches in the inner end of the sleve.
Good Luck, Bill.
 
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