Prop hits the trim tab....

[Rocky_Road]

I went to move my Quicksilver Stilleto prop from my old Alpha unit, to my newer Alpha Gen II lower unit...and the prop will not clear the Gen II anode trim tab.

The trim tab on the 1985 circa Alpha is considerably smaller...should I (and can I) simply swap them?

 

[cpubud]

Re: Prop hits the trim tab....

yes or just replace with a shorter or new flat one if needed

 

[ziggy]

Re: Prop hits the trim tab....

you can grind off the tab a little bit like this...

or ya can try swapping them too. some of the newer drives i've seen don't even have a fin. just the anode disc....

 

[Bondo]

Re: Prop hits the trim tab....

Ayuh,....

The Torque Tabs come in various flavors,... Just pick whatever 1 works...

 

[Rocky_Road]

Re: Prop hits the trim tab....

Thanks, guys!

I also have seen the latest drives with just a flat plate...always wondered why?

I think that I will swap the tabs for now, and pick up one of the flat versions to try out.

No way I am going to let the Stilleto 'sit' on the shelf...!

 

[QC]

Re: Prop hits the trim tab....

always wondered why?

Just not a big deal with power steering . . .

 

[Rocky_Road]

Re: Prop hits the trim tab....

Just not a big deal with power steering . . .

That makes a world of sense...although I have rack and pinion steering.

I have returned from Boater's World...and I had to make a decision, that I was not prepared to make. Turns out that the flat plate that they carried was aluminum, and the package warned that "aluminum, and zinc, cannot be mixed on the outdrive". Inasmuch as I had no idea as to what my OEM trim tab was made of, I walked out with a zinc, and an aluminum, version of the flat plate. My gut told me that Mercury would have used zinc....

Removed my OEM, and judging from the sheer weight, it was actually aluminum...so much for 'gut impressions'!

Just a note to the readers of this post...you have to know which material is currently on your outdrive...and make sure that you don't introduce the opposite choice.

 

[jerryjerry05]

Re: Prop hits the trim tab....

Just use the skinny one if you have rack and pinion.Jerry

 

[Rocky_Road]

Re: Prop hits the trim tab....

Just use the skinny one if you have rack and pinion.Jerry

You read my mind, Jerry.

I am going to find out if I can get the 'skinny' one...in aluminum.

This could be a real 'chore'...my local Mercruiser parts department is parts information challenged!

Maybe someone here can give me the Mercruiser part number that I need...?

 

[Don S]

Re: Prop hits the trim tab....

My gut told me that Mercury would have used zinc....

Merc doesn even sell Zink anodes anymore, since 91. (See link to service bulletin), only aluminum and magnesium.
Service Bulletin 91-19

Merc does have the trim anode for the outboards that have the fin moved aft for prop clearance. You may find that without that trim anode, you will have some torque steer problems.

Here's what they look like,

Here is their part number etc.

http://www.iboats.com/Quicksilver_Anode_Trim_Kit/dm/keywords.brand_392_Mercury--view_id.166968

 

[Rocky_Road]

Re: Prop hits the trim tab....

Merc doesn even sell Zink anodes anymore, since 91. (See link to service bulletin), only aluminum and magnesium.
Service Bulletin 91-19

Merc does have the trim anode for the outboards that have the fin moved aft for prop clearance. You may find that without that trim anode, you will have some torque steer problems.

Here's what they look like,

Here is their part number etc.

http://www.iboats.com/Quicksilver_Anode_Trim_Kit/dm/keywords.brand_392_Mercury--view_id.166968

You approach the mountain...humble yourself...and hope that the prophet will listen to your pitiful request.

Thank you, Don....

I placed my order with iboats.com (invoice #519225).

Anyone need a new, flat, aluminum Mercruiser sacrificial tab...? Real cheap...?

 

[ziggy]

Re: Prop hits the trim tab....

glad yer getting her fixed like ya want....
fwiw.... the grind off the tab method is mercruiser approved. service bulletin 82-11 covers this in service manual #4...

the jist of what it says is that if all else fails to gain clearance.

"If none of the preceding are the cause for interference, the trim tab MUST BE modified to provide sufficient clearance. Remove stock from the trim tab with a file or grinder, at location shown in Figure 1. Do not remove any more stock than absolutely necessary" the pic in the service bulletin looks similar to the cut out i added to my tab..

 

[Rocky_Road]

Re: Prop hits the trim tab....

glad yer getting her fixed like ya want....
fwiw.... the grind off the tab method is mercruiser approved. service bulletin 82-11 covers this in service manual #4...

the jist of what it says is that if all else fails to gain clearance.

"If none of the preceding are the cause for interference, the trim tab MUST BE modified to provide sufficient clearance. Remove stock from the trim tab with a file or grinder, at location shown in Figure 1. Do not remove any more stock than absolutely necessary" the pic in the service bulletin looks similar to the cut out i added to my tab..

I already decided to cut my OEM...based upon your picture. Knowing that a stainless steel prop has very little 'flex' under stress, I figure that I can get the clearance pretty darn tight, and still get the maximum tab for any 'torque steer' issue. I have no problem with extra parts lying around....

I assume that the leading edge of the 'cut' area was chamfered to a sharp point...or will that really matter?

 

[ziggy]

Re: Prop hits the trim tab....

Knowing that a stainless steel prop has very little 'flex' under stress

yep..... i'm running aluminum so gave myself a little extra clearance to allow for the flex...

I assume that the leading edge of the 'cut' area was chamfered to a sharp point

yep.. though i didn't get to carried away with the sharp point. more of dull rounded point. ground it off with a grinder and smoothed it with a flat file. i don't think it matters too much. but i wouldn't think that just ground off flat would be the greatest. surely some taper should be in order...

 

[Rocky_Road]

Re: Prop hits the trim tab....

yep..... i'm running aluminum so gave myself a little extra clearance to allow for the flex...
yep.. though i didn't get to carried away with the sharp point. more of dull rounded point. ground it off with a grinder and smoothed it with a flat file. i don't think it matters too much. but i wouldn't think that just ground off flat would be the greatest. surely some taper should be in order...

Perfect...!

I'll have the modifications done long before the iboat part arrives. I might run a straight cut down to the bottom leading edge...just for the aesthetics. Can't hurt...since I just installed a tab, that is really 'non-existent'!

Then, I will try both out to see if there is any real difference.

Happy boating...and Merry Christmas!