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#815179 07/05/20 9:12 pm
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My 72 engine was overhauled by me 5 or 6 years ago. I had trouble with gear selection then, but resolved it. Now if you go hard in third, 20/25% of the time it changes up into fourth by itself. No crunches or grinding, it's very smooth, and oddly enough at just the right time, presumably at maximum torque. Any ideas please?


1971 BSA A65 Lightning "Bitsa"
1966 BSA A65 "Beezuki" with GT550 two-stroke engine
1974 Triumph T150 830cc
1975 Suzuki GT550
1975 Laverda 1000 3C
1986 Yamaha SRX 600 X 2
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Those engines have the eccentrically mounted, adjustable spring in the outer case. Have you tried messing with that? Can be very aggravating.

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IT SOUNDS LIKE A GREAT UPGRADE. WHAT'S THE PROBLEM. LEAVE IT ALONE.


I APOLOGIZE FOR THE USE OF CAPS. I CAN ONLY TYPE WITH MY RIGHT HAND SO USING THE SHIFT KEY IS BEYOND MY CAPABILITES.

The Devil is in the details.

1957 BSA A10 Spitfire Scrambler (numbers matching, very correct, very nice condition)
1965 BSA A65 Lightning Rocket "Clubman" (restored)
1966 BSA A65 Spitfire MK-II (restored)
1967 BSA A65 West Coast Hornet (under restoration)
1975 Norton Commando Roadster (2100 miles)
2001 Kawasaki W650
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I had a similar problem in my *other* A65, which was caused by worn shift fork tracks in the camplate, but the aberrant shift was from 3rd to neutral (between 2nd and 3rd). Replacing the camplate fixed it. Sloppy shift fork bushings can cause the same problem, but in my case those were ok. Note in this case the shift forks move without the camplate rotating. For the camplate to move by itself, i.e., without being pushed by the shift détente, the notches in the edge of the camplate would have to be all but gone, or the plunger spring weak or broken, and the latter would tend to affect other gear changes.

I'm hard put to picture the shift lever operating on its own, even with a broken or misadjusted return spring, since an up-shift is against gravity.


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'65(lower)/'66(upper, wheels, front end, controls)/'67(seat, exhaust, fuel tank, headlamp)/'70(frame) A65 Bitsa.
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I've never had a problem quite like that, either. And I been messing with a bunch of those gearboxes. But when we come to that later spring setup, all bets are off with me. I even made an outer cover with a big hole in it so I can jack around with that spring easily.

Last edited by leon bee; 07/06/20 7:45 pm.
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it is a weird one.
The gap between detents 3rd and 4th is the longest one on the cam plate, for the auto change to happen the cam plate detent groove for 3rd must be ploughed out.
Worn dogs on the sliding gear may be camming it out of 3rd,
See the other recent gearbox thread, the quadrant stop may be allowing 3rd to over select past the detent, then vibration does the rest.
Is the change from 4th to 3rd clean after the auto 3-4 change?

Last edited by gavin eisler; 07/06/20 8:12 pm.

71 Devimead, John Hill, John Holmes A65 750
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Mark,
I didn't say, but the shift is upside down, 1 up 3 down. I did replace the camplate with the correct new one when I re-built the engine, though I did have a bit of a wrestle with the eccentrically mounted return spring leon mentions. I got it set and it's been ok up till now, and I forgot to mention it does very very, occasionally jump out of third. It,s amazing how smooth the change is, just like a good autobox!


1971 BSA A65 Lightning "Bitsa"
1966 BSA A65 "Beezuki" with GT550 two-stroke engine
1974 Triumph T150 830cc
1975 Suzuki GT550
1975 Laverda 1000 3C
1986 Yamaha SRX 600 X 2
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To get most life out of the sliding gears you can swap them, the std box bas the same sliding gear for each shaft,
swapping them over from lay to main shaft presents unworn dog faces.


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It's normally second that gets stuffed first off in these boxes but that sounds like the dogs on third
are stuffed. You need to go through the whole box really as it can be a combination of things.

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Originally Posted by Peter Gascoigne
Mark,
I didn't say, but the shift is upside down, 1 up 3 down. I did replace the camplate with the correct new one when I re-built the engine, though I did have a bit of a wrestle with the eccentrically mounted return spring leon mentions. I got it set and it's been ok up till now, and I forgot to mention it does very very, occasionally jump out of third. It,s amazing how smooth the change is, just like a good autobox!

Ok, the 1 up / 3 down shifting introduces the factor of gravity to the equation. And you've replaced the camplate, so that can probably be ruled out. I'm not familiar with the newer type of shifter return spring, so I can't comment on that.

One thing I CAN comment on is slippage between the shift lever and shift quadrant shaft. The slippage can be subtle and can require close examination to detect. (I'll never understand why BSA used such tiny splines at that joint.) If no problem there, and no problem with the return spring, you'll want next to inspect the shift detente, making sure the teeth are intact and that they slip in and out easily, before digging into the gearbox.


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I've brought this up again because even though I've tried to adjust things the bloody thing is still doing it! Since I originally posted this, I just left things alone, because well, it was ok, rev up in third, and it changes into fourth at just the right time. Then it started going into neutral occasionally. Its a 73 engine it's got the eccentric adjustment, so I have adjusted it so there is no pressure on either side of the gearchange arm. (Is that the problem there is no pressure?). Out for a test ride.... third to fourth.... just like a good auto box!

I could understand if it jumped out into neutral, but change up seamlessly and noiselessly?


1971 BSA A65 Lightning "Bitsa"
1966 BSA A65 "Beezuki" with GT550 two-stroke engine
1974 Triumph T150 830cc
1975 Suzuki GT550
1975 Laverda 1000 3C
1986 Yamaha SRX 600 X 2
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What's the camplate like?
Indent plunger?
2nd and 3rd dogs?
selector forks?

Take the box out and stick it in a vice on the bench, you can then see how the thing is working.
Gearboxes in these are normally slung together and the gears seldom engage properly as
standard from the factory. Time and patience can make this better.

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have you inspected the sliding gears? have you shimmed the layshaft endfloat?


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Gavin,

No I haven't checked the end float recently. I had the gearbox to bits about 3,000 miles ago, and I checked everything on NickL's list, camplate and return spring were new. I would have checked the end float then (I think!). After buggering around with the spring tension it worked OK for quite a while, and then started auto changing. When I adjusted the spring the other day there is no pressure on either side of the stop plate, if anything a very slight bit of clearance. Is that right?


1971 BSA A65 Lightning "Bitsa"
1966 BSA A65 "Beezuki" with GT550 two-stroke engine
1974 Triumph T150 830cc
1975 Suzuki GT550
1975 Laverda 1000 3C
1986 Yamaha SRX 600 X 2
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So long as the change works without baulking both up and down, then the return spring is doing its job, i still think the auto change is worn dogs on the sliding gears.Excess end float will not help.The index plunger is supposed to hold the cam plate in each gear position, if it jumps out of third its not working properly, you say the cam plate is new, was the plunger new as well,? if so then the dogs on the sliding gear are camming it out and forcing the plunger off the third gear notch, as mentioned earlier the sliding gears can be swapped from shaft to shaft to get the most out of the unworn sides of the dogs.


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Just because parts are new, doesn't mean they are any good.
I have this continual discussion with blokes on these old crates.
How do you know the 'New Old Stock' item you are fitting didn't
come out of the reject bin? or was filched before use on the
line so never checked? A good example of this is the gearchange
quadrant assembly, i've had several instances where 'New' ones
don't work and have required grinding the body section to prevent
it fouling on the cam plate, yet the used item that was on the bike
was fine other than a bent shaft, which is the normal reason for
replacement.
Tons of beezer stuff was pinched and sold to dealers and users.
It could have been destined for the scrapper or re-work or may
have been perfectly good. No-one knows. The same was probably
true of most of the factories back then.

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Very true.
I remember "back in the day" you could go to a certain pub near Meriden on a Thursday night and get a set of Triumph number and letter stamps for a fiver.
Very genuine--as they had been stamping bikes earlier the same day!

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The 'Busy Bee' cafe just off the M1 at Watford was the place for beezer bits
on a Friday night. GP carbs, RRT2 boxes etc etc. Van loads would arrive.
That's for us southerners who never ventured up to Brum.

Of course, i only ever 'heard' about this sort of thing.

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Hi

Yeah Nick, must have been scary for you Southerners getting as far North as the Watford Gap ha ha.

John

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And of course my memory is of things that happened to other people---never me--- at least not too often!

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Originally Posted by JER.Hill
Hi

Yeah Nick, must have been scary for you Southerners getting as far North as the Watford Gap ha ha.

John


Wasn’t that the Gary Puckett boot leg group? (Gary Puckett and the Watford Gap?)

Though Watford Gap services is nowhere near Watford. Never could get my head around that one.


Now let’s all have a beer beerchug

68’ A65 Lightning “clubman”
71’ A65 823 Thunderbolt (now rebuilt)
67’ D10 sportsman (undergoing restoration)
68’ D14 trials (undergoing transformation)

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Originally Posted by Allan G
Though Watford Gap services is nowhere near Watford.

It’s a big gap.


Amateur Loctite enthusiast.
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The 'Bee" was on the Watford bypass, a favourite 'killing ground' for bikes.
Well south of Watford Gap.... in civilised country. (well, nearly....)
Every bit at well frequented as the Ace, though the culinary delights were
just as horrible. The coffee was like engine degreaser.

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