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fun with thrust washers
212rowboat
Member Posts: 2,591 ✭✭✭✭✭
this is DANG curious to me... I like to think i've a pretty good sense of mechanics, but then something like this happens..
i swapped props... from a ron hill marine pleasure five 14.25x19p to a stiletto 14.5x21p, both stainless... I've owned them both a long time but have never ran the stiletto- still haven't... about to, though. The only 'real' reason i pulled the RH is because a buddy of mine wants to try it before he seeks out to get his own... no problem... i pulled it, and handed it over with mounting hardware and all (less the thrust washer)... i've got multiples of multiples thrust washers and adapters, castle nuts and nylon lock nuts, tab locks and retainer washers, ect...
i slid the stiletto on the shaft and... there is play, and the ends of the splines peek out from the hub's end.. no bueno. so, i've a choice here- either i can use a lock-washer (split variety) or a flat washer between the nylon nut and the prop to absorb the gap and cover the exposed splines, or, i can see what's going on with that thrust washer...
i briefly considered stacking thrust washers... i changed my mind. i've heard too many stories about bad things happening when folks stack them, though i hear a different reason every time- none of which stand the acid test of scrutiny... but... the common factor to broken shafts was always stacking thrust washers.....
apparently the thrust washer i had on it is too thin... it's OE merc... I understand Sierra makes one for the alpha and bravo that is a full 1/8th inch thicker- which is how much spline i've got peeking out, so... i go to rummage through the box to find one...
i don't have one any thicker than another, so... i'm thinking i need to order one... and then? this happens:
i pulled the thrust washer that was on there and has been on there a long time to simply compare it to the others i have which are all the same... guess what? all the same... instead of re-installing that one, though, i installed a brand new one- brass merc OE... same precise dimensions... I slapped the prop on and expect it to be the same as before and.... there are no splines poking out..... huh? i think to myself "i must have put that thing on backwards" and as I'm taking the nut off again i remember the hole on the thrust washer, when properly installed, has a taper nearer the drive side- meaning: the washer itself won't seat unless you have it on correctly... i pulled the prop off because i was already 'there', and.... the thrust washer is properly installed and seated... i pulled it off and compared again just to be sure- and the washers dimensions match for every one i have.
i slipped the 'old' one on and there are splines poking out... i slip the 'new' one on and there aren't. the 'new' one is on there and the prop nut is re-installed. i'll be taking it off again to use a new prop nut because the nylon lock is a little loose for my tastes, but i don't think i'll be pulling the prop back off unless it just flat out doesn't perform.
confused. help? what is going on with that thrust washer and hub?
by the way- BOTH (and 'all' for that matter) of the props (and all the props i have) are pressed in splined hubs... they are no different... i considered THAT is what was going on, but no... same prop- different but matching thrust washers- one 'fits' properly and one doesn't...
has anyone seen that before and what the @*&*! was it?
i swapped props... from a ron hill marine pleasure five 14.25x19p to a stiletto 14.5x21p, both stainless... I've owned them both a long time but have never ran the stiletto- still haven't... about to, though. The only 'real' reason i pulled the RH is because a buddy of mine wants to try it before he seeks out to get his own... no problem... i pulled it, and handed it over with mounting hardware and all (less the thrust washer)... i've got multiples of multiples thrust washers and adapters, castle nuts and nylon lock nuts, tab locks and retainer washers, ect...
i slid the stiletto on the shaft and... there is play, and the ends of the splines peek out from the hub's end.. no bueno. so, i've a choice here- either i can use a lock-washer (split variety) or a flat washer between the nylon nut and the prop to absorb the gap and cover the exposed splines, or, i can see what's going on with that thrust washer...
i briefly considered stacking thrust washers... i changed my mind. i've heard too many stories about bad things happening when folks stack them, though i hear a different reason every time- none of which stand the acid test of scrutiny... but... the common factor to broken shafts was always stacking thrust washers.....
apparently the thrust washer i had on it is too thin... it's OE merc... I understand Sierra makes one for the alpha and bravo that is a full 1/8th inch thicker- which is how much spline i've got peeking out, so... i go to rummage through the box to find one...
i don't have one any thicker than another, so... i'm thinking i need to order one... and then? this happens:
i pulled the thrust washer that was on there and has been on there a long time to simply compare it to the others i have which are all the same... guess what? all the same... instead of re-installing that one, though, i installed a brand new one- brass merc OE... same precise dimensions... I slapped the prop on and expect it to be the same as before and.... there are no splines poking out..... huh? i think to myself "i must have put that thing on backwards" and as I'm taking the nut off again i remember the hole on the thrust washer, when properly installed, has a taper nearer the drive side- meaning: the washer itself won't seat unless you have it on correctly... i pulled the prop off because i was already 'there', and.... the thrust washer is properly installed and seated... i pulled it off and compared again just to be sure- and the washers dimensions match for every one i have.
i slipped the 'old' one on and there are splines poking out... i slip the 'new' one on and there aren't. the 'new' one is on there and the prop nut is re-installed. i'll be taking it off again to use a new prop nut because the nylon lock is a little loose for my tastes, but i don't think i'll be pulling the prop back off unless it just flat out doesn't perform.
confused. help? what is going on with that thrust washer and hub?
by the way- BOTH (and 'all' for that matter) of the props (and all the props i have) are pressed in splined hubs... they are no different... i considered THAT is what was going on, but no... same prop- different but matching thrust washers- one 'fits' properly and one doesn't...
has anyone seen that before and what the @*&*! was it?
Comments
two things i learned during this-
- while brass thrust washers won't gall (weld) to the dissimilar metal of the shaft and ruin the shaft, it will wear a lot more than you'd expect, causing/allowing ever so slight slippage up and down the shaft which accelerates the wear?
- the brass wearing like that when i wouldn't have expected it to just caused the torque on the prop nut to be added to my checklist before launching.
we're not talking a little difference- we're talking the difference between the splines extending beyond the hub about an 1/8th", or sitting roughly flush with the hub...whodathunkit? I would never have imagined a flippin' thrust washer would 'go bad'!!! heheheheheeee- at least they're no where nearing a boat unit to replace.