Mac Crank Numbers - ID crank

[Rod Hytonen]

I have a crank sealed in original Mc bag, marked "58128, for MC 20-30-45"

The PTO journal is the larger size, for those motors listed (as well as the

MC40) and the crank comes with a nut and is LH threads, no keyway.

Thus it's a legit 58128 -

It even has the instruction sheet, and the bag has not been opened far

enough to get the crank itself out.

The instructions list the alternate numbers :

50756A
58128
60313A
63440
69346
87699

But the crank itself (I can see through the bag)

is marked 90868.

and yes, I'm reading it right.

Anyone ever see one with that number?

(They must have made an upgrade? Or perhaps shot peened or something?)

Thanks,

Rod

[Scott Kneisel]

Hi Rod,
After production for the Mc45 was over, there was a lot of demand for the 58128 cranks so McCulloch corp came out with a replacement crank for the Mc20-45 series which was originally the 58128. The replacement is identical in every respect except for the PTO which has no key slot and Left Hand threads. I have one of those in my Mc45 and it is really a preferable crank. I am not sure of the part number but I'll bet it is 90868. Check the PTO for a key slot.
That is my take.....anyone else?
Scott

[Phil Parkinson]

I have just picked up a Mac 40 and the crank fitted to it has numbers 58196, was this a replacement crank? as I cannot find it in any of my IPLs.
Thanks
Phil

[vince hughes]

Phil, you're looking at the forging number, the part # should be stamped on the counter weight on flywheel side.

Somewhere in '75, Mac went LH with all there cranks, saws included. Replacement LH cranks were packaged with the original part number on the bag, but a LH number on the part. (mostly in the 90xxx for karts) Engines produced after the big switch, came with LH cranks installed, and probably had the correct number in the later IPLs.
The cranks you have listed are from completely different engines, first one is 49er, second is 20-30-45, 69346 is RH 101B

[Phil Parkinson]

Thanks Vince, Its a bit hard to see any numbers on this crank as there is a fair amount of welding to add weights, don't know if that is a good or bad thing. The crank is still fitted to the motor as is the flywheel which has a small 5 stamped on it, does that mean it's a 5degree, I've never seen one before.

[vince hughes]

Phil,
That number is imposible to see unless you have the crank in your hand, sometimes the bearing even gets in the way. The '5' on the flywheel is for 5 degree, which should have started with the Mc9,Mc45, and Mc75 engines in 1965. Who knows whats been swapped around after all this time?

Update on crank numbers. The 60313A is a saw of 5.3 CI. Service replacement crank is p/n 90892 which is LH version. This is basically Mc6 crank with dual (small) ball bearings.

[steveohara]

The OEM Mc 45 crank should not have any welding. The welded on plates only came from McCulloch on the 1.835" stroke cranks.
Did McCulloch offer a 'hop up" crank with more counterweight at some point?
Steve O'Hara