driveshaft bushing?

[robert graham]

That rubber driveshaft bushing...is it in constant contact with the driveshaft spinning at up to 5000+RPM's, and how is it lubricated, and what keeps the rubber bushing from overheating/melting, like with a dry water pump impeller?
I understand that a "dab of marine grease" is recommended to keep the bushing running quiet. Anybody know?

[boats.net]

It just runs in the water exiting from engine.

[robert graham]

Water cooled and lubricated!...thanks for the explanation!....That had not occurred to me at all!

[rodbolt17]

and its not rubber, and its actually slightly larger on the ID than the OD of the shaft.
its a sintered bronze type materiel inside a rubber jacket.

[BQUICK]

And, as far as I know was only used on the longer (25 and 30) shaft motors. I ran my 25 in shaft 200 for years w/o one. Just put one back in last year.

[rodbolt17]

its used on most the mid range and up 4 strokes and most all 25 and 30" 2 strokes.

[robert graham]

Sintered bronze inside a rubber jacket...no we know!...is it lubricated with the water or the dab of grease?...

[rodbolt17]

water,grease and its self lubricated.

[kboehme123]

My Yamaha 90hp 4-stroke

And, as far as I know was only used on the longer (25 and 30) shaft motors. I ran my 25 in shaft 200 for years w/o one. Just put one back in last year.

My Yamaha 90hp 4-stroke Drive Shaft Bushing went bad and the midsection is too corroded to replace with a new one. Is it ok to run my engine without this part? What are the odds of my motor breaking down without this part? Please advise, thank you

[robert graham]

My Yamaha 90hp 4-stroke Drive Shaft Bushing went bad and the midsection is too corroded to replace with a new one. Is it ok to run my engine without this part? What are the odds of my motor breaking down without this part? Please advise, thank you

How do you know it "went bad"?..maybe you're already running "without one"?

[kboehme123]

it went bad because we took the lower unit off and the bushing started falling out in pieces. It is now cleaned out and I'm thinking of having a welder apply a new lip so I can insert the new bushing with the circ clip. What do you think?

[robert graham]

If it's operating fine without it, maybe leave it alone?...Welding a lip up in there could be a trick. Wonder if you could find a good used mid-section on line to replace your corroded one?

[kboehme123]

if a new bearing fits kind of tight, I'm going to seat the bearing and then use a 4 minute quick steel epoxy by Versa Chem to fix that bearing in place. I heard it wasn't smart to run the engine without this bearing. Have you heard anything differently about running the engine without this bearing since there is a bearing in the crankshaft and also one on the lower unit jacket? Thanks for your help Robert.

[robert graham]

Like I say, I don't think my 90C has a driveshaft bushing, and I've heard of folks operating without them after they fail....maybe just run it without and see?...worst that might happen could be some vibration?...

[robert graham]

But if you're gonna epoxy the bearing in place, maybe polish your driveshaft where it passes through the bearing and grease it good, so it'll run without binding. Maybe driveshaft flex at 5000RPM's might shake loose that epoxy and bushing slides down the shaft???