Author Topic: Big end nuts  (Read 1249 times)

Online muskrat

  • Global Moderator
  • Wise & Enlightened
  • **
  • Join Date: Jul 2009
  • Posts: 8165
  • Karma: 106
  • Lake Conjola NSW Oz
    • Shoalhaven Classic Motorcycle Club Inc
Big end nuts
« on: 15.07. 2009 15:00 »
G'day Blokes,
                 heres a curly one. Just fitted a lge journal crank in. Went to wind it round and got to 4o'clock and clunk. Wound it back to 8o'clock clunk. I counted all my spanners, none missing. Split cases, look for marks. The big end nuts hit the cases. I always use new nuts but had none so I put spring washers under the nuts. I removed the said washers and reassembled. Spins fine. A bit close don't you think ? Once I get up in revs and with a bit of crank flex will it take itself out to lunch ?
Cheers
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
Australia
Muskys Plunger A7

Online RichardL

  • Outside Chicago, IL
  • Wise & Enlightened
  • *
  • Join Date: Nov 2007
  • Posts: 4997
  • Karma: 48
Re: Big end nuts
« Reply #1 on: 15.07. 2009 15:10 »
Others will fill in the missing details, but there is an issue of two or three different styles of nuts sitting on landings of various machined depths.

Richard L.
Plan on signing up for the world-wide 2017 DISTINGUISHED GENTLEMAN'S RIDE on September 30, 2018. Watch website at https://www.gentlemansride.com for details.

Online chaterlea25

  • Wise & Enlightened
  • *
  • Join Date: Jun 2009
  • Posts: 3178
  • Karma: 45
Re: Big end nuts
« Reply #2 on: 15.07. 2009 15:37 »
Hi Muskrat,
I wonder if the rods hitting the casings has anything to do with your offset gudgeon pin pistons?
the off set will alter the angle of the rod, maybe making the nuts stick out farther than before????
Just a thought!!
Regards
John O R
1961 Super Rocket
1963 RGS (ongoing)

Online bsa-bill

  • Wise & Enlightened
  • *
  • Join Date: Mar 2006
  • Posts: 5413
  • Karma: 61
Re: Big end nuts
« Reply #3 on: 15.07. 2009 17:22 »
long nuts need the botom corners ground off so far up

All the best - Bill
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

Online muskrat

  • Global Moderator
  • Wise & Enlightened
  • **
  • Join Date: Jul 2009
  • Posts: 8165
  • Karma: 106
  • Lake Conjola NSW Oz
    • Shoalhaven Classic Motorcycle Club Inc
Re: Big end nuts
« Reply #4 on: 15.07. 2009 22:16 »
Thanks fella's. Richard, would the correct nuts be listed in the parts cat for lge journal rods? John, would you agree that with the offset they would hit one way and not the other? Bill, Would Bastard Stopped Again ground the nuts for clearance at the factory ? Bill, are you "THE" BSA BILL from WA ?
Cheers
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
Australia
Muskys Plunger A7

Offline beezalex

  • North Carolina, USA
  • Valued Contributor
  • ****
  • Join Date: Jan 2008
  • Posts: 374
  • Karma: 4
Re: Big end nuts
« Reply #5 on: 15.07. 2009 22:40 »
I would feel safer clearancing the cases or barrels (whichever it's hitting) as opposed to altering the rods or bolts.  And yes, I'd give myself at least 1 mm of clearance to allow for flex.  Clay works well for showing clearances.  Good luck.
Alex

Too many BSA's


Online chaterlea25

  • Wise & Enlightened
  • *
  • Join Date: Jun 2009
  • Posts: 3178
  • Karma: 45
Re: Big end nuts
« Reply #6 on: 16.07. 2009 00:09 »
Hi Muskrat,
You are probably right, about them hitting one way and not the other!!
Another question, are you now fitting a large journal crank and rods to a small journal cases?
I have seen some cases with relief's ground into the casing, always thought it had happened when a bigend was failing?????
I am not in favour of taking any metal off the bigend nuts
Regards
John O R
1961 Super Rocket
1963 RGS (ongoing)

Online muskrat

  • Global Moderator
  • Wise & Enlightened
  • **
  • Join Date: Jul 2009
  • Posts: 8165
  • Karma: 106
  • Lake Conjola NSW Oz
    • Shoalhaven Classic Motorcycle Club Inc
Re: Big end nuts
« Reply #7 on: 16.07. 2009 09:31 »
No john the cases are DA10 17*** and grinding the nuts would be the last resort. I will split cases againto check clearance. I would be happy with 1/16".
Cheers,
          Jim
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
Australia
Muskys Plunger A7

Online bsa-bill

  • Wise & Enlightened
  • *
  • Join Date: Mar 2006
  • Posts: 5413
  • Karma: 61
Re: Big end nuts
« Reply #8 on: 16.07. 2009 12:01 »
Bill, are you "THE" BSA BILL from WA ?

Sorry I'm in UK

All the best - Bill
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

Online muskrat

  • Global Moderator
  • Wise & Enlightened
  • **
  • Join Date: Jul 2009
  • Posts: 8165
  • Karma: 106
  • Lake Conjola NSW Oz
    • Shoalhaven Classic Motorcycle Club Inc
Re: Big end nuts
« Reply #9 on: 16.07. 2009 12:42 »
This is the BeezaBill I was thinking of. http://www.geocities.com/beezabill/ check out his workings. must be the long distances down here, gotta get there quicker, whatever you ride.
Cheers
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
Australia
Muskys Plunger A7