spline washer and tab washer question

[eli_lilly]

Hello,<br /><br />I am replacing a Mercury prop of unknown pitch (numbers are worn off) with a Michigan Wheel 032043 on the lower unit of a 72 Merc 650. I selected that prop (11 3/4 x 12) as a starting point based on the propping charts in the motor's service manual. <br /><br />The current prop has two "pins" molded into the rubber part of the hub. The tab washer had matching holes. The new prop has no such holes. The service manual shows a completely different configuration involving a spline washer and tab washer. It's not clear to me from the picture what type of hub that might apply to. Is the spline washer/tab washer configuration the one that is appropriate to use for the Michigan Wheel prop?<br /><br />Thanks,<br />E

 

[WillyBWright]

Re: spline washer and tab washer question

How many cylinders does that motor have? You have the wrong prop if it has 4 cylinders. I could be off by a year or two, but I don't think the 3-cylinder models came out until the mid 70s. The one you bought fits a triple. Triples have fiberglass clamshell hoods. 4-cylinder models have the classic metal wrap-around covers.

 

[eli_lilly]

Re: spline washer and tab washer question

It's a 1972 3 cyl 650, of that I am sure. However, the lower unit is not the original, it might be off the 4 cyl 650.<br /><br />Thanks,<br />E

 

[WillyBWright]

Re: spline washer and tab washer question

Original parts in order of assembly:<br />62122A1 Thrust Hub (shouldered)<br />Prop<br />62124A1 Thrust Washer (shouldered)<br />Nut<br /><br />Updated parts in order of assembly:<br />73345A1 Thrust Hub (flat face)<br />Prop<br />14-76281 Locking Tab<br />Nut<br /><br />The nut is the same.<br /><br />The original thrust washer and hub fitted inside the bore of the hub of the prop. They are shouldered.<br /><br />The replacement thrust washer doesn't fit into the bore of the prop hub. The newer props have a flat surface there and the newer thrust hub butts up to that.<br /><br />You can't mix up the hardware or you'll damage the prop and possibly the gearhousing.<br /><br />Michigan wheel made/makes both styles of prop.

 

[eli_lilly]

Re: spline washer and tab washer question

Thanks for the information, it's been a huge help. I see that the prop I removed uses the updated parts. However, on the Michigan Wheel replacement, it looks like it might be a mix of the old and new. The front is flat metal, identical to the previous one, so I assume the flat face thrust hub is proper. However, the rear is "open" - there is the center spline, the rubber (which is inset), and then the inner metal hub. I am thinking that this might use the 62124A1 assembly or maybe just Sierra 18-1191.<br /><br />E