Prop Fitment

[colbythekid]

Hello

I have an old 1970 Fiberform with a Mercury 165 inline 6. I am not sure what model the outdrive is.

I purchased the boat last year and am looking to replace the prop as the prop that it came with is a little chewed up.

I was able to track down a prop with the same diameter and pitch as the one that the boat came with. There is one issue. The center part of the prop (the hub?) on the new prop sits higher up on the spline shaft then the old prop. So the washer with the splines on the inside of it can't catch the splines on the shaft. I am assuming this is an issue with retaining the nut and prop on the outdrive during use?

When purchasing a new prop is there a way to select how high / low the hub sits inside the prop?

Or is there a work around for the new prop that I purchased?

Thank you in advance for all your help.

Colby

 

[ThomW]

If the prop you purchased is the same pitch and diameter as the old one, you may just have the wrong hub kit in the prop for the motor. They sell various hub kits (the part that inserts into the prop).

 

[Scott06]

Thats an mc 1 drive. A prop for mc1, R,MR, and alpha drives will fit it.

I believe The thrust washer need to be changed out to work with your current prop.

it doesnt look like your new prop has a removable hub , its pressed in right?

 

[colbythekid]

Thats an mc 1 drive. A prop for mc1, R,MR, and alpha drives will fit it.

I believe The thrust washer need to be changed out to work with your current prop.

it doesnt look like your new prop has a removable hub , its pressed in right?

If the prop you purchased is the same pitch and diameter as the old one, you may just have the wrong hub kit in the prop for the motor. They sell various hub kits (the part that inserts into the prop).

Thank you both for the quick reply!

The prop that I just took off is 1.5" from the front (the part facing away from the outdrive) and to the metal housing where the hub would sit. While the new prop that I have that same distance is only 1.25".

That 0.25" is the difference between getting the thrust washer and nut on and not.

Is there a way to order a prop with a lower set internal hub?

Hopefully that all makes sense.

Thank you!

 

[jimmbo]

In the late 70s Mercury made some changes to the Prop Hubs and different Thrust Washers were required. Fast Forward 40+ Years, and throw in a few more Brands of Props and it can get complicated/confusing very quickly

 

[Bondo]

Ayuh,.... Welcome Aboard,...... The problem is on the other end of the prop,.....
Pull it off, 'n post a picture of the front of the prop, 'n the drive where it goes,....

 

[jimmbo]

What brand is the New Prop? The Manufacturer should be able to provide the correct Thrust Washer

 

[colbythekid]

Ayuh,.... Welcome Aboard,...... The problem is on the other end of the prop,.....
Pull it off, 'n post a picture of the front of the prop, 'n the drive where it goes,....

What brand is the New Prop? The Manufacturer should be able to provide the correct Thrust Washer

WOW! So it turns out I'm an idiot. I should have Googled the definition of the different parts.

I pulled the OLD Thrust Washer off the outdrive and put the NEW Thrust Washer that came with the prop and everything fits as it should.

One last quick question. Is there a toque specification for the nut?

THANK YOU all for helping me out with this!

 

[Scott06]

WOW! So it turns out I'm an idiot. I should have Googled the definition of the different parts.

I pulled the OLD Thrust Washer off the outdrive and put the NEW Thrust Washer that came with the prop and everything fits as it should.

One last quick question. Is there a toque specification for the nut?

THANK YOU all for helping me out with this!

Good and tight… theorteically i think its 35 or 45 ft lbs but just get it good and tight with a calibrated elbow on the wrench…

 

[jimmbo]

WOW! So it turns out I'm an idiot. I should have Googled the definition of the different parts.

I pulled the OLD Thrust Washer off the outdrive and put the NEW Thrust Washer that came with the prop and everything fits as it should.

One last quick question. Is there a toque specification for the nut?

THANK YOU all for helping me out with this!

Well, you are acting like a Spoiled Child, are you going to hold your Breath till you turn Blue...
Do you want a Pom-pom on that toque?

 

[colbythekid]

Good and tight… theorteically i think its 35 or 45 ft lbs but just get it good and tight with a calibrated elbow on the wrench…

I'd like to think I have a well calibrated elbow. Thank you so much for the help!

 

[colbythekid]

Well, you are acting like a Spoiled Child, are you going to hold your Breath till you turn Blue...
Do you want a Pom-pom on that toque?

I'm not sure how I am acting like a spoiled child, but still do appreciate your help with this.

 

[jimmbo]

To Quote you

"WOW! So it turns out I'm an idiot. I should have Googled the definition of the different parts."...

 

[Scott06]

 

[Texasmark]

Good and tight… theorteically i think its 35 or 45 ft lbs but just get it good and tight with a calibrated elbow on the wrench…

Service manual for 75-125 hp outboards says 55 ft-lbs....for a number. As stated, good and tight.