The BSA A7-A10 Forum

Technical => Clutch, Primary, Gearbox => Topic started by: Marqs1979 on 01.03. 2016 20:25

Title: The drive wheel is spinning despite neutral
Post by: Marqs1979 on 01.03. 2016 20:25
I was working on the electrical system and the engine ran , suddenly the rear wheel began to drive foreward despite gearbox was in neutral :( Guess any chaft is being cut ? Or is this something that can happen when the clutch gets hot ?
I guess I have to disassemble and inspect .
Title: Re: The drive wheel is spinning despite neutral
Post by: Greybeard on 01.03. 2016 20:28
Clutch drag I guess.
Title: Re: The drive wheel is spinning despite neutral
Post by: Greybeard on 01.03. 2016 20:30
Could thick, (cold) gearbox oil be causing gear drag?
Title: Re: The drive wheel is spinning despite neutral
Post by: morris on 01.03. 2016 21:03
Worth to have a look to see if the final gear bush is not to tight on the mainshaft.
Otherwise it's just a case of "They All Do That Sir"...
Both mine do it (though it's more of a creep than a spin)
Title: Re: The drive wheel is spinning despite neutral
Post by: Marqs1979 on 01.03. 2016 21:22
Hehe :) I will investigate. But I 'm relieved to hear that I am not alone :)
Title: Re: The drive wheel is spinning despite neutral
Post by: Triton Thrasher on 01.03. 2016 21:33
Unless you were holding the clutch lever in, this has nothing at all to do with the clutch.

And it's normal and not a problem, unless stopping the rotation with the brake makes the engine stall or strain.
Title: Re: The drive wheel is spinning despite neutral
Post by: Clive54bsa on 02.03. 2016 02:23
Marqs, are you able to stop the spinning wheel by applying pressure to the side of the tyre with your foot, shoe on of course?
Clive
Title: Re: The drive wheel is spinning despite neutral
Post by: Marqs1979 on 02.03. 2016 06:45
Unfortunately, I do not think I can stop the wheel with my foot : / I'll look into it but I not have time before Friday :(
Title: Re: The drive wheel is spinning despite neutral
Post by: cyclobutch on 02.03. 2016 12:57
Tend to agree that they all do that. But if it seems more seriously driven then I wouldn't be putting my foot on/in there. What happens when the rear brake is applied?
Title: Re: The drive wheel is spinning despite neutral
Post by: Triton Thrasher on 02.03. 2016 17:50
Can you spin the wheel, when the engine is stopped?
Title: Re: The drive wheel is spinning despite neutral
Post by: Clive54bsa on 03.03. 2016 00:18
Yeah, you're probably right about the foot thing, I suppose the brake application would be more safe. Both my A10's rear wheel spin when the bikes are running on the mainstand, but a bit of friction from my foot stops them from spinning. If that's the case, I'd say you don't have a problem, but after applying the rear brake, the motor stalls or almost stalls, I'd say the sleeve gear on the output shaft of the gearbox was overtightened. A mechanic I know uses an impact wrench to tighten them, I'd not recommend him.
Clive
Title: Re: The drive wheel is spinning despite neutral
Post by: Marqs1979 on 03.03. 2016 06:18
I have not yet had time to try something more but I think I have a problem, because the motorcycle was stretched on my motorcycle lift and began to go foreward :(
Title: Re: The drive wheel is spinning despite neutral
Post by: Marqs1979 on 03.03. 2016 08:17
I might add that the engine and gearbox are refurbished by me and it's not impossible that I have tightened something too hard ?? Or that some bushing is too tight ?
Title: Re: The drive wheel is spinning despite neutral
Post by: bsa-bill on 03.03. 2016 09:20
Quote
not impossible that I have tightened something too hard ??

My guess would be that neutral is not where it should be,
put the bike in neutral.
remove the outer g/bx cover and check that the red dots on the selector mechanism line up.
If they don't then correct them.
If they do then move the selector one tooth out (which way I can't tell you, it's suck it and see)

This is not uncommon on these box's, I've done it myself
Title: Re: The drive wheel is spinning despite neutral
Post by: chaterlea25 on 03.03. 2016 17:34
Hi Marqs,
When you rebuilt the transmission did you fit a new sleeve gear bush?
If so how much clearance did you give it?
Did you drill the 3 oil holes?
With a one piece bush its necessary to make a recess half way in the bush, the originals were 2 piece steel backed, the bronze was machined away where the 2 halves meet
Did you fit a nut with an oil seal? (SRM) the older version of these had a smaller diamater seal that was tight on the mainshaft
It is possible to make the end of the high speed gear contract by overtightening the sprocket nut  *eek*
This happened to me when using an air impact gun

John
Title: Re: The drive wheel is spinning despite neutral
Post by: Viking on 03.03. 2016 20:49
They all do that...

MY two A10 as Well..

If it is like this one:
https://m.youtube.com/watch?v=umEYCFwR16A

It is ok,
Except the all Black tank.  *eek*.  Eeek.
Title: Re: The drive wheel is spinning despite neutral
Post by: Marqs1979 on 04.03. 2016 08:03
Today , I hope to have time with the bike :) All bushings in the engine and gearbox have been replaced ! And bushings looks just like the bushes I replaced with grooves and holes for oil.The exact clearance I do not remember because it's over a year since I did the job , but no shaft or gear was tough to spin. I tested the gears by turning the gearbox by hand.
I have not been driving the motorcycle at all and the engine has been running less than an hour after the renovation . Have not noticed any of these problems before the final minutes .
Title: Re: The drive wheel is spinning despite neutral
Post by: duTch on 04.03. 2016 09:04

 It doesn't sound like a problem at this stage, especially if you can hold the wheel by hand or foot (or hook or by crook)from rotating.

 Conversely, if you can turn the wheel by hand in neutral, or in gear with the clutch hand-lever pulled in and without the engine running, I'd say everything is normal. (thus far)
  In the latter case, there will likely be a bit more resistance than in the former case, which I say is still normal.
 Do those checks and then concentrate on something else.
Title: Re: The drive wheel is spinning despite neutral
Post by: Marqs1979 on 04.03. 2016 10:57
Has tested a bit now. Some problems from the start but I started the engine and drove with the wheel in the air through all the gears , thinking that the gearbox would get some exercise and get oil on all conceivable places.
Now the wheels are still on the neutral gear even when it's in the air. *smiley4*

Thank you all for your interest and help, but maybe I never had any problem :) The future will show
Title: Re: The drive wheel is spinning despite neutral
Post by: BSA_54A10 on 05.03. 2016 11:06
While the clutch is engaged, the clutch drum will be rotating the main shaft.
And this is regardless of weather you are in a gear or not,
The gearbox is full of oil and oil can transmit power which is exactly what is happening inside your box.
The viscoius friction of the oil is causing the sleeve gear to turn which is rotating the back wheel.
When it stops doing this your oil is too thin or the level is way too low.
Title: Re: The drive wheel is spinning despite neutral
Post by: Greybeard on 05.03. 2016 18:03
Well, I said the same only in not so many words! ;)
Title: Re: The drive wheel is spinning despite neutral
Post by: Marqs1979 on 05.03. 2016 18:06
Well, I said the same only in not so many words! ;)

Hehe :)