The BSA A7-A10 Forum

Technical => Clutch, Primary, Gearbox => Topic started by: Simon on 23.04. 2017 11:30

Title: A10 gearbox has seized
Post by: Simon on 23.04. 2017 11:30
Guys  I am new to this forum.  I have a Super Rocket which I bought 6 months ago and on which the gearbox seized whilst riding home the other day.

My A10 gearbox has seized and the bushes between the sleeve pinion and the main shaft have disintegrated.  I guess the repair will require regrinds and new size bushes.  Can anyone advise on who could do such work?

May I also please pass on thanks to Beezermacc for a posting 5 years ago about using a bearing puller to remove the clutch centre.  I used a Screw Fix bearing puller which fitted well and worked perfectly on what was appearing an impossible task.
Title: Re: A10 gearbox has seized
Post by: muskrat on 23.04. 2017 11:46
G'day Simon,  *welcome*.
Bugga, that made a mess.
I'm sure someone closer to you could suggest an engineering shop. I'd say SRM.

Now get over to Pictures, Stories and Introductions to give us your story.
Cheers
Title: Re: A10 gearbox has seized
Post by: JulianS on 23.04. 2017 11:59
SRM rebushed my A10 sleeve gear a few years ago, works fine.

You can buy new mainshafts.

Not seen one which got hot like that in over 40 yeays of A10 use. Looks like lack of oil and/or bushes previously replaced with too tight a fit.
Title: Re: A10 gearbox has seized
Post by: beezermacc on 23.04. 2017 12:04
By far the best bloke I know is Richard Clamp. He'll fix it at a sensible price without going daft and replacing everything it doesn't need! His contact details are on the 'Services' page of our website. https://sites.google.com/site/cheshirebsa/services (https://sites.google.com/site/cheshirebsa/services)
Title: Re: A10 gearbox has seized
Post by: Simon on 23.04. 2017 12:25
Smashing, thanks chaps.  I have just spoken to Richard Clamp and it will bubble wrapped this afternoon and in the post tomorrow morning.
Title: Re: A10 gearbox has seized
Post by: Triton Thrasher on 23.04. 2017 15:08
Looks like it's been run out of oil.
Title: Re: A10 gearbox has seized
Post by: Simon on 23.04. 2017 18:19
A good theory, but not the case.  I topped the box up before Christmas, it hardly needed anything, and when  drained it down it was full. 
Title: Re: A10 gearbox has seized
Post by: Triton Thrasher on 23.04. 2017 22:01
Was the primary chain tight?
Title: Re: A10 gearbox has seized
Post by: KiwiGF on 23.04. 2017 22:05
I know you are sending the box away, but this failure happened to me and was easily fixed. I doubt the shaft will be damaged as they seem to be made out of kryptonite! Original One's at least. One of my older posts covers the fix, and use of a brake cylinder hone to hone the new bushes to size.

if heavy grade oil was used in the box  that might be a root cause of the failure *dunno*

as prior post too close a clearance will defininately cause a failure as will bushes spinning in the sleeve gear and/or incorrectly drilled oil holes in the bushes
Title: Re: A10 gearbox has seized
Post by: KiwiGF on 24.04. 2017 08:43
I found a relevant thread, note the reference to early sleeve gear bush failure!

http://www.a7a10.net/forum/index.php?topic=5202.0

Title: Re: A10 gearbox has seized
Post by: Tomcat on 24.04. 2017 09:52
Welcome aboard Simon. A seized gearbox can be a nasty thing, hoping there was no damage to the rider or the motorcycle. If I may offer some advice, grab one of these nuts for the sleeve gear from SRM. I have one on the Super Rocket and it works so well that I have to lube the drive chain! *eek* http://www.shop.srmclassicbikes.com/product/gearbox-sprocket-nut-oil-seal-bsa-pre-unit-swingarm-models
Cheers Peter
Title: Re: A10 gearbox has seized
Post by: Simon on 24.04. 2017 20:30
Gents

Thanks for your comments, advice and past threads.
The primary chain tension was correct but I am unsure of which grade oil was in the box.  Anyway its now on its way to be fixed.
Title: Re: A10 gearbox has seized
Post by: BSA_54A10 on 26.04. 2017 13:33
Originan bushes has a hole in the middle which held oil.
latter bushes are a little shorter so get fitted with a gap between them again to provide an oil reseviour.
The only failures I have seen reciently was where the owner butted up tow bushes without leaving the gap and the bush ran dry.