Big end bearing sizes for a Type one

Craig Torrens 6 times Australian, 7 times State Hillclimb Class Champion

8,040 posts · joined Jan 2003 · 23 Nov 2011, 9:40 pm

#873885

What is the largest "under sized" big end bearing for a type one crank ?

I've heard they go up to 2mm under sized, but that sounds extreme !!

matberry Moderator Go hard or go home

8,114 posts · joined Mar 2006 · 23 Nov 2011, 9:52 pm

#873888

My 1st thought and 1st check in a suppliers catalog goes to +1.5mm

Matt Berry Motorsports...air cooled advice, repairs and mods Ph 0408 704 662
OFF-ROAD,CIRCUIT,DRAG,STREET,ENDURANCE

Craig Torrens 6 times Australian, 7 times State Hillclimb Class Champion

8,040 posts · joined Jan 2003 · 24 Nov 2011, 2:53 pm

#873969

cheers

psimitar Son of Jim - Creator of Good

2,506 posts · joined Jan 2009 · 3 Dec 2011, 11:01 pm

#875523

the 2mm is only for the thrust bearing. Journals I though only go to 1mm as beyond that there is no casehardening left on the crank.

Yea, just checked and 1mm crank, 2mm crankcase and 2mm thrust.

madness is in the eye of the beholder 👍

matberry Moderator Go hard or go home

8,114 posts · joined Mar 2006 · 4 Dec 2011, 7:37 am

#875547

I think you'll find 1.5 BE bearings. Mains come in up to 2.0mm on the back (case) and .75mm on the crank. Re-nitriding is possible to re-harden the crank. This is done to all modified and some reground cranks if done right as the nitriding is only around .005" deep (iirc).

Matt Berry Motorsports...air cooled advice, repairs and mods Ph 0408 704 662
OFF-ROAD,CIRCUIT,DRAG,STREET,ENDURANCE