posted 07-27-2007 12:18 AM ET (US)        

The Installation Guide that came with the hub kit says that Flor-Torq III and IV propellers have fore and aft propeller movement of .76-3.18 mm. I installed the hub kit and propeller today and torqued it down. There was no fore and aft movement in the prop on the shaft but there was a left-right wobble torward the rear of the prop that was very noticeable. How is this wobble going to reduce rattle?

The hub kit package says: Part no. 835257k 9 Flo-Torq III Hub kit for use with Mercury/ Mariner 40-60 hp Big Foot and 90 to 115-HP four-stroke; for stainless and aluminum propellers.

Now I have a 2005 90-HP two-stroke. The package indicates that this kit is not for my motor but the dealer said it was.

Is this the wrong hub kit for my motor?

The drive sleeve is a two -piece part with pins connecting the two pieces. Out of the box there was a space between the two pieces (about 1/16 to 3/32-inch) so that the pins can be seen. Tightening the prop nut to the specified torque did not close that space. Should I tap the two pieces together so that the space will closed and the two pieces touch?

posted 07-27-2007 10:00 AM ET (US)            

You have the correct hub kit. The packaging indicates those four stroke models because they were the ones customers had been complaining about prop rattle with. The Flo-Torq III was designed to help alleviate this prop rattle but they can be used with any other mid-range outboard as well (excepting the OMC/BRP motors).

No, you do not want to press the two halves of the drive sleeve together. They are supposed to be separated by that distance.

You have me wondering about the installation of the Flo-Torq III and IV kits now. I had not noticed any mention of the fore and aft movement. I will have to investigate.

posted 07-27-2007 12:56 PM ET (US)            

I am pretty sure I installed the drive sleeve in the correct direction. The sleeve has a slight taper. Also one portion of the sleeve has four grooves for the adapter splines but the other portion has essentially no grooves. I installed the drive sleeve so that the four grooves and the narrow end of the taper face aft in the propeller.

The wobble or side to side play is noticeable at the forward end of the prop or the end closest to the bow [I called the rear of the prop the end of the prop closest to the bow, I consider the front of the prop to be the aft end where the prop nut is (there is no movement there)].

I just inserted the aft adapter into the drive sleeve and noticed there is side to side movement of the adapter against the drive sleeve at the rear (that is the end that would normally face toward the bow of the boat) of the assembly.

posted 07-27-2007 07:34 PM ET (US)            

I have been thinking about the side to side movement in the prop. As I see it, if I installed the hub kit and prop correctly, and if the prop shaft and bearings are good, then there are two possibilities.

First, it just happens that the Flo-torq III hub kit which I bought has a defect (perhaps the drive sleeve or adapter not being up to required size specs). Or,

Second, my Laser II prop has a defect (maybe that is why I am getting sounds and vibration that do not seem quite right).

posted 07-27-2007 09:08 PM ET (US)            

This is interesting. I just mounted a prop on my own Mercury 90 using a Flo-Torq III hub kit that I have. My results are the same as yours. Lots of wobble and slop.

At first I tried to mount my 20" Laser II but the aft adapter would NOT fit fully into the hub of the prop. The hole in the prop was too small. That surprised me very much. This was the first of dozens of Mercury props that I have ever seen this problem on.

I then fitted a 20" QuickSilver Lightspeed (Quicksilver branded version of the Laser II) and it fit fine, but for the slop.

I am now rather confused about the Flo-Torq III and IV kits and I will explain why:

I believe the intent of the Flo-Torq III and IV designers is the have the aft adapter actually come into contact with the thrust washer and allow the prop nut to form a compression fit between the aft adapter and the thrust washer bypassing the propeller casting itself thus allowing it to float free radially so that the spring action of the hub kit can work.

Unfortunately, this means the tightness of fit of the propeller is dependent upon both the fit of the drive sleeve within the propeller casting (it is usually very tight) and the fit between the aft adapter and the drive sleeve (usually some slop there.)

With a Flo-Torq II kit, the aft adapter is about half the length of the propeller hub. It acts as a washer on the back of the propeller. The prop nut compresses the prop forward onto the thrust washer. Thus a compressed and solid sandwich is formed between the thrust washer, propeller, aft adapter and propeller nut. This is also why 60 ft./lbs. is specified for these hub kits; you want the whole assembly on there good and solid so as to avoid any slop and imbalance.

I now realize that if you did this with the Flo-Torq III or IV, the propeller would be fixed radially vis-a-vis the propeller shaft via the aft adapter. But what you want to have happen if for half of the drive sleeve to fixed vis-a-vis the prop and the other half of the drive sleeve fixed vis-a-vis the propeller shaft. The radial connection is the springing titanium rods within the two part drive sleeve.

Hmmm. This leads me to be a bit chagrined and I will have to wait until later to tell you as I need to go now...

posted 07-27-2007 10:02 PM ET (US)            

Well I knew I didn't install it improperly. I will be waiting in suspense for your final verdict. But your analysis logically leads to another possibility which is that:

Flo-torq III hub kits simply will not work
with Laser II propellers.

My inclination now is to try to get my money back for the kit and just stick to the Flo-torq II kits.