Author Topic: A10 crankcase question  (Read 603 times)

Offline 900triple

  • A's Good Friend
  • ***
  • Join Date: Oct 2008
  • Posts: 131
  • Karma: 1
A10 crankcase question
« on: 19.03. 2026 09:47 »
Hi,
Im starting to build an A10 from spares I have. I've got the drive side case for a 1959 Road Rocket CA10 R, and the opportunity to obtain a timing side case with casting number NO 717410.
Will the timing case be okay use, and will it take a big bearing crankshaft?
Thanks in advance, Alan

Online rocker21

  • Valued Contributor
  • ****
  • Join Date: Jun 2011
  • Posts: 264
  • Karma: 2
    • Brill Bike Parts
Re: A10 crankcase question
« Reply #1 on: 19.03. 2026 10:23 »
crankcases are in machined pairs, mixing 2 halves could be a big problem, as the timing side bush and the camshaft bearings  are line bored, the crankcases will have a no stamped on them and the 2 halves should have the same no on them. i tried that many years ago and the camshaft locked up .
1960 A7SS motoguzzi Monza 500, motoguzzi V7III special, new triumph speed 400, Ariel Sq4 MKII
www.brillbikeparts.co.uk

Offline 900triple

  • A's Good Friend
  • ***
  • Join Date: Oct 2008
  • Posts: 131
  • Karma: 1
Re: A10 crankcase question
« Reply #2 on: 19.03. 2026 13:41 »
Unfortunately having a matched pair of cases is a non starter.
As an engineer, I'm relatively confident that I can do what is necessary to line up the various assembly parts.
What i really need to know is if the 717140 cast timing side crankcase can be used with the other RR case from 1959.

Offline chaterlea25

  • Wise & Enlightened
  • *
  • Join Date: Jun 2009
  • Posts: 4439
  • Karma: 56
Re: A10 crankcase question
« Reply #3 on: 19.03. 2026 22:45 »
900,
Quote
Unfortunately having a matched pair of cases is a non starter
  *????* *????* *????*

Matching pairs of crankcases are relatively plentyful, why draw work on yourself?
Down the line if our bikes have any value left, one with non matching case halves will have less

John



1961 Super Rocket
1963 RGS (ongoing)

Offline spanersc

  • A's Good Friend
  • ***
  • Join Date: Dec 2008
  • Posts: 196
  • Karma: 1
  • Cambridgeshire. UK
Re: A10 crankcase question
« Reply #4 on: 20.03. 2026 10:55 »
Hi Alan. I have a pair of 'CA10R' cases that have had a primary side B/E let go and have been welded but the timing side is unharmed. I also have a selection of 'CA10' or 'CA10R' cases as matched pairs if you wanted an easier solution. I live in France but will be coming over to the UK briefly at the end of the month. Let me know. Cheers  Pete.
Peter C    Cambridgeshire. UK   1935 Blue Star. 1936 M23 Empire-Star, 1938 B24 Empire-Star. 1939 M23 Silver-Star. 1950 A7 Rigid.  1952 A7ST.   1953 A10 Super Flash.  1954 A7ST.  1955 A7SS. 1956 A10RR.  1962 RGS.  1962 DBD34

Offline spanersc

  • A's Good Friend
  • ***
  • Join Date: Dec 2008
  • Posts: 196
  • Karma: 1
  • Cambridgeshire. UK
Re: A10 crankcase question
« Reply #5 on: 20.03. 2026 11:25 »
I've also found another that has has a repaired hole through the primary side.
Peter C    Cambridgeshire. UK   1935 Blue Star. 1936 M23 Empire-Star, 1938 B24 Empire-Star. 1939 M23 Silver-Star. 1950 A7 Rigid.  1952 A7ST.   1953 A10 Super Flash.  1954 A7ST.  1955 A7SS. 1956 A10RR.  1962 RGS.  1962 DBD34

Offline 900triple

  • A's Good Friend
  • ***
  • Join Date: Oct 2008
  • Posts: 131
  • Karma: 1
Re: A10 crankcase question
« Reply #6 on: 20.03. 2026 11:38 »
Hi Pete, I'm interested in your offers...could you email me so we can discuss?
[email protected]

Cheers. Alan

Offline bikerboy

  • Valued Contributor
  • ****
  • Join Date: Dec 2011
  • Posts: 486
  • Karma: 4
Re: A10 crankcase question
« Reply #7 on: 20.03. 2026 16:45 »
Its noot only the crank needing to be line bored the same occurs with the cam bushes so I would not advise using unmatched cases personally


BSA A10 x 4
BSA A65 Lightning
Triumph T150v
Tribsa (A10 frame 750 Bonnie motor)

Offline spanersc

  • A's Good Friend
  • ***
  • Join Date: Dec 2008
  • Posts: 196
  • Karma: 1
  • Cambridgeshire. UK
Re: A10 crankcase question
« Reply #8 on: 22.03. 2026 07:03 »
Hi Alan.  I have sent you an email. Cheers Pete
Peter C    Cambridgeshire. UK   1935 Blue Star. 1936 M23 Empire-Star, 1938 B24 Empire-Star. 1939 M23 Silver-Star. 1950 A7 Rigid.  1952 A7ST.   1953 A10 Super Flash.  1954 A7ST.  1955 A7SS. 1956 A10RR.  1962 RGS.  1962 DBD34

Online Rex

  • Wise & Enlightened
  • *
  • Join Date: Apr 2017
  • Posts: 2041
  • Karma: 10
Re: A10 crankcase question
« Reply #9 on: 22.03. 2026 09:45 »
Its noot only the crank needing to be line bored the same occurs with the cam bushes so I would not advise using unmatched cases personally

There can be issues with mis-matched deck heights too, but it's all solvable with time, skill and/or money.

Offline 900triple

  • A's Good Friend
  • ***
  • Join Date: Oct 2008
  • Posts: 131
  • Karma: 1
Re: A10 crankcase question
« Reply #10 on: 22.03. 2026 20:14 »
Thanks everyone for your input, much appreciated.

Pete, you're email didn't arrive.

Cheers, Alan

Offline spanersc

  • A's Good Friend
  • ***
  • Join Date: Dec 2008
  • Posts: 196
  • Karma: 1
  • Cambridgeshire. UK
Re: A10 crankcase question
« Reply #11 on: 24.03. 2026 10:27 »
I'll give it another go. Pete
Peter C    Cambridgeshire. UK   1935 Blue Star. 1936 M23 Empire-Star, 1938 B24 Empire-Star. 1939 M23 Silver-Star. 1950 A7 Rigid.  1952 A7ST.   1953 A10 Super Flash.  1954 A7ST.  1955 A7SS. 1956 A10RR.  1962 RGS.  1962 DBD34

Offline spanersc

  • A's Good Friend
  • ***
  • Join Date: Dec 2008
  • Posts: 196
  • Karma: 1
  • Cambridgeshire. UK
Re: A10 crankcase question
« Reply #12 on: 24.03. 2026 10:31 »
Hi Alan. I've forwarded it again but all seems correct with your email address. Have a look and let me know. Cheers Pete.
Peter C    Cambridgeshire. UK   1935 Blue Star. 1936 M23 Empire-Star, 1938 B24 Empire-Star. 1939 M23 Silver-Star. 1950 A7 Rigid.  1952 A7ST.   1953 A10 Super Flash.  1954 A7ST.  1955 A7SS. 1956 A10RR.  1962 RGS.  1962 DBD34

Offline fffcycles

  • A's Good Friend
  • ***
  • Join Date: Feb 2021
  • Posts: 201
  • Karma: 2
Re: A10 crankcase question
« Reply #13 on: 24.03. 2026 14:53 »
Don’t forget to check your junk I lose a lot to what some 12 year old in Bangladeshi thinks should be blocked as “unknown or spam” .
Frank P Kamloops BC
1948 A7 Long Stroke, a collection of BSA D1/B44/B50/A65 from the 50's thru 70's, Ariels/Nortons/Triumphs and a smattering of Japanese

Offline 900triple

  • A's Good Friend
  • ***
  • Join Date: Oct 2008
  • Posts: 131
  • Karma: 1
Re: A10 crankcase question
« Reply #14 on: 25.03. 2026 08:54 »
Hi Pete, no sign of your email. Could you try this one?
[email protected]

Cheers, Alan