stiff crank, 1098

[BaritoneUke]

Got my short engine back from a local machine shop (they have done quite a lot with series A's especially minis) and intended to start dressing it but the crank seems quite stiff.
I can turn it with 2 hands but it doesn't turn as easily as I expected. I was tempted to knock down the lock washers and re-torque the mains (i've got a good wrench...norbar) but once you start doing this, why go to a machine shop for the work?
Is this something to be concerned about?

[paul 300358]

If it's been rebored and had new pistons and rings it will be tight.

[BaritoneUke]

If it's been rebored and had new pistons and rings it will be tight.

Good point...probably only turns easily and smoothly before the other bits are fitted. I won't try and take it apart!
Cheers for that, glad I asked now

[philthehill]

No mention of the thrust washers!!
If the thrust washers do not have the correct clearance the crank can be stiff to turn.
The fore and aft movement of the crankshaft should be 0.004" so giving the correct clearance.
I have experienced the thrust washer clearance problem several times in the past and have had to correct the thrust washer clearances to get the correct end float.

[BaritoneUke]

No mention of the thrust washers!!
If the thrust washers do not have the correct clearance the crank can be stiff to turn.
The fore and aft movement of the crankshaft should be 0.004" so giving the correct clearance.
I have experienced the thrust washer clearance problem several times in the past and have had to correct the thrust washer clearances to get the correct end float.

Well...he's changed them I assume because the old ones came back with it. So yes, do need to check them. Got a dial gauge so i'll try with that.
Cheers for that.

[philthehill]

Check the size of the old thrust washers against the new thrust washers as that will give you an indication as to whether the crankshaft thrust faces have been re-ground or not.
In some instances to get the correct clearance I have had to rub down the white metal face of the thrust on a surface plate using a WD40 oiled fine wet & dry paper in a figure of eight formation.

Crankshaft thrust bearing 1.jpg (32.32 KiB) Viewed 1155 times

If the old thrust washers are still good you may find that the clearance is acceptable when they are fitted. New is not always the best.

[BaritoneUke]

UPDATE
A bit of levering on the crank with a big screwdriver showed generally a bit over 0.003 and a bit under 0.004 (measured in several places) so I'm fairly happy that the stiffness is piston ring friction, particularly as it's been rebored and honed. I'll store that tip regarding taking a bit off the thrust washers in my build notebook for future reference