Author Topic: Vibration-causes?  (Read 4994 times)

Offline BSA500

  • Resident Legend
  • *****
  • Join Date: Dec 2007
  • Posts: 705
  • Karma: 4
  • Tonbridge,Kent,UK
Vibration-causes?
« on: 06.11. 2012 19:44 »
I have recently been posting about worn sleeve bushes and horrible vibration. Well no surprise the bushes have been replaced but the vibration remains. To describe the shakes is a little difficult and of course subjective but I will try. Lots of vibration through the drive side footrest mainly, with the timing side joining in and the seat. I gave the crank a tug and tried up and down but no perceptible play I will check the sump gasket for bits of shim but i did that each time I have had issues this year with no bits present,but paranoid me will check again. it does not knock when pushed up hills etc so hopefully not the big ends but it does feel like them. The one thing that occurred to me as I shook my 13 miles home,was I had noticed the splines on the crank were visibly worn last time I dismantled the shock absorber. Can this cause such nasty vibration. Is there anything I have missed oh I have tightened all the engine mounts. *sad2*  

Offline wilko

  • Resident Legend
  • *****
  • Join Date: Mar 2010
  • Posts: 681
  • Karma: 4
Re: Vibration-causes?
« Reply #1 on: 06.11. 2012 20:28 »
Primary chain dry and too tight.

Offline BSA500

  • Resident Legend
  • *****
  • Join Date: Dec 2007
  • Posts: 705
  • Karma: 4
  • Tonbridge,Kent,UK
Re: Vibration-causes?
« Reply #2 on: 06.11. 2012 21:27 »
Nope chain is fine and lubed (ffnarr)

Offline Goldy

  • Warwickshire, England
  • Resident Legend
  • *****
  • Join Date: Dec 2008
  • Posts: 619
  • Karma: 9
Re: Vibration-causes?
« Reply #3 on: 06.11. 2012 21:56 »
Have you checked the security of the top engine brace to the frame.
56 A10 Golden Flash - Restore, ride, relive.                                          
56 C12 BSA project ongoing

Offline metalflake11

  • Resident Legend
  • *****
  • Join Date: Aug 2012
  • Posts: 579
  • Karma: 9
Re: Vibration-causes?
« Reply #4 on: 06.11. 2012 23:43 »
Check all the engine and gearbox nuts and bolts? Hopefully simple as that.
England N.W
1960 A10
England

Offline BSA500

  • Resident Legend
  • *****
  • Join Date: Dec 2007
  • Posts: 705
  • Karma: 4
  • Tonbridge,Kent,UK
Re: Vibration-causes?
« Reply #5 on: 07.11. 2012 08:29 »
 I shall check them all as I go along. This morning as seems the case with the A7 the vibration was not as bad. Don't get me wrong its still there but it can be bearable one day and terrible the next no reason for it to improve I have not touched anything yet. I will check the sump plate,timing and what else?

Offline Flatboy 1950

  • A's Best Friend
  • ***
  • Join Date: Oct 2010
  • Posts: 110
  • Karma: 1
    • Flat Earth Spares
Re: Vibration-causes?
« Reply #6 on: 07.11. 2012 09:34 »
If your back sprocket is eccentric or not correctly seated you could have a drive chain that has a real tight spot causing vibration & destroying those gearbox bushes. Got to be something seriously out of spec. to zap those bushes over & over.

Flatboy.

Offline shuswapkev

  • A's Best Friend
  • ***
  • Join Date: Jul 2012
  • Posts: 124
  • Karma: 0
Re: Vibration-causes?
« Reply #7 on: 07.11. 2012 10:32 »


loose splines on your cush drive..???....picked up an aftermarket  belt drive for my harley..very interesting as the hub fits to a splined shaft..and is a good tight fit...

 but the install instructions... they insist that the splines be covered in loctite on final assmbly... what a great idea...

 i will now use that on all splines in my old bikes...might just get another century out of these thing yet

i had an a65 that vibrated so bad that after 80mph...evereything went blurry...the trouble was just the front wheel...about 8 inches of solder and i could look in the mirrors and read the licence plates behind me

Online Topdad

  • bob hebdon
  • Wise & Enlightened
  • *
  • Join Date: May 2011
  • Posts: 2235
  • Karma: 32
  • l
Re: Vibration-causes?
« Reply #8 on: 07.11. 2012 12:39 »
If all mounting bolts tight ,primary chain etc adjusted ok and rear chain and sprockets serviceable and no probs as per tight spots then I'd say have a go at the splines on the engine shock absorber ,is the nut really tight? I'm sure someone posted on here about worn splines and associated vibes ,they certainly can be fixed but could be expensive ,re how bad it would make the bike I'd suggest a phone call to SRM who are always helpful or any firm recommended by the guys here ,best of luck BobH.
" rules are made for the guidance of wise men and the blind obediance of fools"
United Kingdom

Offline BSA500

  • Resident Legend
  • *****
  • Join Date: Dec 2007
  • Posts: 705
  • Karma: 4
  • Tonbridge,Kent,UK
Re: Vibration-causes?
« Reply #9 on: 07.11. 2012 15:23 »
The nut is tight and I had a look at the SRM site and they charge £97 to repair but it would need the engine stripped and sent to Wales from Kent(not cheap). Also I don't know how quick it would be turned around as I use the machine every day for transport to work. I could email SRM just for info. I swear I had read about a guy with the same issue and he"glued" bits of shim to the crank and then slid over the collar  *smiley4*

Offline wilko

  • Resident Legend
  • *****
  • Join Date: Mar 2010
  • Posts: 681
  • Karma: 4
Re: Vibration-causes?
« Reply #10 on: 07.11. 2012 20:39 »
Can't see how a worn driveside spline could cause vibration??? Clutching at straws, fellows.

Offline BSA500

  • Resident Legend
  • *****
  • Join Date: Dec 2007
  • Posts: 705
  • Karma: 4
  • Tonbridge,Kent,UK
Re: Vibration-causes?
« Reply #11 on: 08.11. 2012 08:30 »
What symptons do you notice for worn splines?. Some have described them as noisy??. The old girl was vibrating very badly this morning and I am sure there is a new noise when you drop the throttle and are slowing down. Problem with these machines is that there are many noises that are 'normal' but would scare the living s*** of a modern bike owner which are the bad ones??.
I will drop the sump plate off tonight to see if there is a collection of metal.
Andy

Offline BSA_54A10

  • Wise & Enlightened
  • *
  • Join Date: May 2008
  • Posts: 2008
  • Karma: 32
    • BSA National
Re: Vibration-causes?
« Reply #12 on: 08.11. 2012 09:47 »
Fun part.
Try to work out if it is engine or transmission related.
Find a nice flat piece of road and run the bike right out through each gear.
If the vibes come in at the same engine speed in each gear then you are looking at something wrong from the clutch basket to the push rods.
If it comes in at roughly the same speeds then you are looking at gearbox , frame & wheels.
It could even be something as simple as an unbalanced tyre.
you might have to go up & down the road a few times.
Let us know how you go because without this basic info we are just chasing shadows
Bike Beesa
Trevor

Offline JulianM

  • A's Best Friend
  • ***
  • Join Date: Jun 2012
  • Posts: 233
  • Karma: 14
  • www.historiccompetitionservices.be
    • Historic Competition Services
Re: Vibration-causes?
« Reply #13 on: 08.11. 2012 10:03 »
Just re read the OP,

When my bike destroyed itself, the first sign of anything was feeling a severe knock like Big ends but not just under load but any time the throttle was used.  Another trip up the yard just to listen again and yep, I reckoned it was the ends and getting worse!   Looked further and the barrel flange was broken!
HOWEVER  what I discovered inside was that the liner had also slipped down and round slightly and had been hitting the connecting rod!
My advice would be, If it sounds "Endy" and "Feels Endy"  whip the barrel off and have a look!  It's a lot less painful than the catastrophe that I found!     I am fairly sure that my barrel flange cracked, liner slipped and then flange broke big time. However a liner can easily slip on their own although they really shouldn't.  You may be feeling the rod being slowly chewed away!   Check and be safe!  It's only a days work!

Regards,
Julian  
55 Ariel HS mk1,
58 BSA Super Rocket Scrambler special,
60 BSA Gold Star, Jim hunter desert racer,
64 Norton N15CS,
65 Triumph TR6 SS,
66 Triumph Bonneville,
71 AJS Stormer,
71 BSA Rocket 3,
71 Laverda 750SF,
71 Laverda/Egli 750SF, Race bike,
73 Norton Commando 850,
74 Moto Morini 3-1/2 Sport,
74 Bultaco Sherpa 350,
76 Beta Cross 50,
77 Moto Guzzi Le Mans Mk1,
80 Ducati 900 MHR,

Offline BSA500

  • Resident Legend
  • *****
  • Join Date: Dec 2007
  • Posts: 705
  • Karma: 4
  • Tonbridge,Kent,UK
Re: Vibration-causes?
« Reply #14 on: 08.11. 2012 10:06 »
Christ it vibrates all the bloody time and covers the whole range of all know vibrations from shakes to tingles. Doesn't sound good when you put it like that *sad2*. Most happy at 45-50 miles per hour even then there is vibration. Oh god looking more like an engine split coming-again :! :!.
I can get the engine down into big parts in under two hours-go me.
Andy