Author Topic: Timing side main bearing  (Read 4902 times)

Offline Goldy

  • Warwickshire, England
  • Resident Legend
  • *****
  • Join Date: Dec 2008
  • Posts: 619
  • Karma: 9
Re: Timing side main bearing
« Reply #15 on: 25.10. 2010 15:54 »
Sorry manosound I did not answer your question. The noise was a knock/rattle mostly heard on light load.
56 A10 Golden Flash - Restore, ride, relive.                                          
56 C12 BSA project ongoing

Offline chaterlea25

  • Wise & Enlightened
  • *
  • Join Date: Jun 2009
  • Posts: 3253
  • Karma: 47
Re: Timing side main bearing
« Reply #16 on: 25.10. 2010 22:28 »
HI Goldy,
If thats the case make sure you have the pressure release valve checked *ex* *ex* *ex*
The first items to suffer wear when the oil pressure drops are the cam and followers, Unless the PRV is passing the oil at too low a pressure *eek* *eek*

HTH
John O R
1961 Super Rocket
1963 RGS (ongoing)

Offline Goldy

  • Warwickshire, England
  • Resident Legend
  • *****
  • Join Date: Dec 2008
  • Posts: 619
  • Karma: 9
Re: Timing side main bearing
« Reply #17 on: 26.10. 2010 09:46 »
Thanks for the advice guys all very usefull. I will let you know how it goes.
56 A10 Golden Flash - Restore, ride, relive.                                          
56 C12 BSA project ongoing

Offline Goldy

  • Warwickshire, England
  • Resident Legend
  • *****
  • Join Date: Dec 2008
  • Posts: 619
  • Karma: 9
Re: Timing side main bearing
« Reply #18 on: 30.10. 2010 15:21 »
Does anyone know the tolerances for boring out the timing side bearing (standard diameter).
56 A10 Golden Flash - Restore, ride, relive.                                          
56 C12 BSA project ongoing

Offline MG

  • Resident Legend
  • *****
  • Join Date: Dec 2009
  • Posts: 949
  • Karma: 23
Re: Timing side main bearing
« Reply #19 on: 30.10. 2010 18:45 »
I machine them to a radial play of 1.5-1.7 thou.

But make sure the timing side journal is okay, they tend to wear out of round and/or conical. If so, it has to be cleaned up and the bush machined afterwards accordingly!

HTH, Markus
1955 A7 Shooting Star
1956 A10 Golden Flash
1961 Matchless G12 CSR

www.histo-tech.at - Restoration, Repairs, Racing

Austria

Offline Goldy

  • Warwickshire, England
  • Resident Legend
  • *****
  • Join Date: Dec 2008
  • Posts: 619
  • Karma: 9
Re: Timing side main bearing
« Reply #20 on: 01.11. 2010 12:09 »
I did not realise the dimensions are on the BSA sheets and are 1.5 to 0.5 thou. I don,t like the 0.5 that sounds a bit tight to me so I think that 1.5 to 1.7 sounds good. I have taken out the old bush and it,s a two piece bush. Has a steel casing with and bronze liner. I talked to C and D Autos this morning and they say they don,t like those as the bronze centre has been known to turn and block the oil holes. I had not thought of that.
56 A10 Golden Flash - Restore, ride, relive.                                          
56 C12 BSA project ongoing

Offline A10Boy

  • Wise & Enlightened
  • *
  • Join Date: Jun 2008
  • Posts: 1075
  • Karma: 11
  • Solihull, Near Birmingham England.
Re: Timing side main bearing
« Reply #21 on: 01.11. 2010 12:58 »
I have heard of that happening, thats why I use the solid lead bronze ones from Mike [mentioned above]. BTW T&L will line bore to half a thou.
Regards

Andy

1958 Super Rocket
Plus
1974 Kawasaki Z1a
Yam XJR 1300

Offline A10Boy

  • Wise & Enlightened
  • *
  • Join Date: Jun 2008
  • Posts: 1075
  • Karma: 11
  • Solihull, Near Birmingham England.
Regards

Andy

1958 Super Rocket
Plus
1974 Kawasaki Z1a
Yam XJR 1300

Offline Rocket Racer

  • Wise & Enlightened
  • *
  • Join Date: Jun 2009
  • Posts: 1431
  • Karma: 16
  • A kiwi with a racing A10 rig and too many projects
    • NZ Classic Sidecar Racing
Re: Timing side main bearing
« Reply #23 on: 02.11. 2010 03:24 »
I did not realise the dimensions are on the BSA sheets and are 1.5 to 0.5 thou. I don,t like the 0.5 that sounds a bit tight to me so I think that 1.5 to 1.7 sounds good. I have taken out the old bush and it,s a two piece bush. Has a steel casing with and bronze liner. I talked to C and D Autos this morning and they say they don,t like those as the bronze centre has been known to turn and block the oil holes. I had not thought of that.

I'm running a white metalled bush, which had less than a thou and was hand scraped.
after a 10 minute run on castor oil, it hit the track and we had over 7k on it after a few laps, hasnt failed yet *whistle*
mind you also on methanol, so doesnt get hot!
A good rider periodically checks all nuts and bolts with a spanner to see that they are tight - Instruction Manual for BSA B series, p46, para 2.
New Zealand

G/F DAVE

  • Guest
Re: Timing side main bearing
« Reply #24 on: 02.11. 2010 09:19 »
Beware of the solid type timing side bushes these wear out your timing side journal instead of the bush  also in the event of oil starvation they can lock up the crank and wreck the crankcase. Ive never had any problem with the steel lined white metal bushes just make sure they are fitted with a locking screw to retain inner sleeve.I now run a ALPHA steel lined bush on my Flash 20.000 miles later still nice and smooth with no concernable vibrations.The first time I rebuilt this motor I used a SRM solid bush this locked up within 50 miles of running I would never use one again.The original BSA bush was steel lined I still have a few old ones of these that can have a new liner fitted . Your choice I suppose if you dont ride much then its no problem *smile*. Dave.


 NOTE SHOULD READ 500 MILES NOT 50. & YES A10 BOY IT WAS ASSSEMBLED CORRECTLY

Online bsa-bill

  • Wise & Enlightened
  • *
  • Join Date: Mar 2006
  • Posts: 5454
  • Karma: 62
Re: Timing side main bearing
« Reply #25 on: 02.11. 2010 09:41 »
Quote
in the event of oil starvation they can lock up the crank

And the bi metal ones do not ?
Something very wrong if the bush locked up within fifty miles
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Offline A10Boy

  • Wise & Enlightened
  • *
  • Join Date: Jun 2008
  • Posts: 1075
  • Karma: 11
  • Solihull, Near Birmingham England.
Re: Timing side main bearing
« Reply #26 on: 02.11. 2010 10:53 »
I thought the SRM one was Phosphor Bronze not Lead Bronze? Lead bronze is better on the crank, whatever, any meterial will "lap" the crank if the oil isnt clean.

In any case if it went chest up after 50 miles it was obviously assembled wrong.
Regards

Andy

1958 Super Rocket
Plus
1974 Kawasaki Z1a
Yam XJR 1300