10 replies to this topic

[KTS]

anyone know the part number for the ACL 20thou/.50 A+ mains bearings ?

 

the .25 bearings I got last time were marked as 3M2205-.25, but the catalogue doesn't list a .50 option (..even though plenty of suppliers list it as an option)

 

for context, i'm trying to find the min/max shaft diameters specs so the machine shop have something to aim for...

[gav]

It's 3M2205-0.50    

[KTS]

It's 3M2205-0.50    

 

thanks - that makes sense !

 

...wouldn't happen to know or have a link to the bearing specs. would you ?

[gav]

 

It's 3M2205-0.50    

 

thanks - that makes sense !

 

...wouldn't happen to know or have a link to the bearing specs. would you ?

 

 

Will try and find out ;)

[gav]

This is all they list unfortunately. Apparently use the standard figures and add 0.5mm.....

Attached Files

•  3M2205.jpg   71.93K   4 downloads

[KTS]

..the full monty as it were !!

 

thanks Gav

[Spider]

The nominal Mains size for the A+ is 2.0011 to 2.0017".

 

Going to 0.020" undersize, the target range would be 1.9811 to 1.9817.

[KTS]

The nominal Mains size for the A+ is 2.0011 to 2.0017".

 

Going to 0.020" undersize, the target range would be 1.9811 to 1.9817.

 

..as the under (over?) sizes are shown as metric for those particular bearings (and none of the others.) I was thinking i should probably work off the metric numbers

 

0.50mm off the STD numbers gives min/max shaft diameters of 50.331 to 50.343 which comes out as 1.9816" to 1.9820", which is a fair bit different...

 

a genuine question: am I overthinking this ?  

[Spider]

In saying 'undersize' I'm referring to the Crank Main Bearing Journal itself. We remove materiel from that so it ends up smaller in size. Sorry for the way I've phased this, I just want to be clear. The ACL Bearings I've been buying are all imperial and these are an imperial engine, so I prefer to stick with that.

If ACL have metricated their bearing shells (which I somehow doubt) then it needs to be checked with them if it's a true 0.5mm oversized (shell) or a nominal 0.5 mm with the true oversize being 0.020".

Checking the Metro Parts Fiche, it shows the undersize (their words !) bearings as being in imperial sizes (sorry, this has had a lot of use);-

 

This is the A+ Crank sizings - in Metric and Imperial

 

and from the ACL Catalogue in Imperial and Metric !

 

I'll try and remember tomorrow to snap off a pic of the ACL Bearing Sets I have, All the Over sizes on those are in imperial sizings.

Edited by Spider, 01 May 2024 - 09:38 AM.

[KTS]

not sure why i hadn't checked before, but the shells are stamped with the metric figure as per the catalogue entry

 

i can't think of any reason why they'd mark them that way if it wasn't what they were...

 

 

i'll go with the metric figure and see what the plastigauge tells me after - if it's too tight I can always get a little more polished off the journals

 

on a related note, and illustrated in the details above:  if the standard big end journals are 1.7497/1.7504 why do a lot of the bearing suppliers provide STD sized conrod bearings sized at 1.7504/1.7509  ?

[Spider]

Yes, they do look to have metricated these shells !