Lister 8/1 connecting rob bearing shim

[Chris]

Does anyone have the dimensions for this? I need to make one and I am wondering is I just trace the outline of the bottom bearing holder, would that work? or do I have to add a bit for the flange of the bearing shells to stop them from shifting (Rotating). I just replaced the crankshaft on my old VA, (aircooled 8/1) and now I need a shim otherwise the crank siezes up when tightening the connection rod bolts.
Thanks
Chris

[admin]

don't fit them so that they would be between the shells, as to stop rotation.

they only fit the cap to rod interface

bob g

[Chris]

Bob g thanks.
Chris

[mbryner]

Didn't someone mention once to just cut up an aluminum can for the con rod bearing shims?

And the dipper is what holds the shells from rotating, or is it different on a VA?

Marcus

[Derb]

Hi Fellas. Forgive me if I have this wrong. It is accepted practice to place a shim between the con rod and the bearing cap to adjust the clearance between the bearing and the crankshaft ? This on an engine with plain split shell bearings ? I am trying to get this in perspective from a mechanics point of view. In the shop I would be looking to (1) get a set of correct dimension shells assuming that the conrod and crank are  machined correctly or (2) have the conrod machined to correct size or (3) grind the crank to accept the undersize shells you have. By packing out the rod are you not producing an oval hole ? I have seen in my time some animals file the conrod mating surfaces to take up loose bearings and I pity the poor bugger who comes along further down the track and has to repair the engine properly. But maybe I have this all wrong - I am happy to be corrected. Cheers, Derb.

[flywheel]

Placing a shim or shims of the proper thickness between the rod and rod cap is how the bearing clearance is adjusted.  Without shims a new set of rod bearings will probably be to tight. 

You may need shims on each side of the rod and cap to obtain the proper clearance.   Use plastigage to check clearance - from auto parts stores like NAPA.

There must be clearance between the bearing and crankshaft for proper oiling of the bearings.  If there none your bearings probably won't last 15 minutes before your engine locks up.
                                                                                                                          flywheel

[admin]

Derb

the practice of shims is a hold over from babbit days, and was used when shell type came into use so that you could not only set up
the right clearance but also take up slack later as they wore out, however

it is still to be seen whether or not the new brgs have enough white metal to actually take up any slack do to wear, the older brgs were
relatively thickly laid with white metal allowing for quite a bit of take up.

if the new brgs are built like modern brgs with very thin white metal any take up would be very small if at all in my opinion.

bob g

[Derb]

Hey Bob. That I could understand - white metal bearings that is. I have done a few myself, but never heard of anyone scraping a shell bearing as the bearing material is so damn thin. Wouldnt do me though. Cheers.