Flo-Torq IV Hub Decreases Loud Clunk, But Has Wobble

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Author Topic:   Flo-Torq IV Hub Decreases Loud Clunk, But Has Wobble

bill705 posted 10-24-2007 02:19 PM ET (US)
Just returned to Tennessee from Jesuit Bend, Louisiana where one of our sons lives. He has a Dauntless 18 with a Mercury 150 Saltwater, and it really had a loud clunk when shifting. Some of the problem was in the idle setting so we did a link and sync and set the idle to 700-RPM.
[Next the unidentified existing propeller was removed and the author] installed the Flo-Torq IV with an Enertia 17p and torqued it to roughly 62-lb-ft (instructions say 55) to get the locking tabs to align. There was no fore and aft movement or wobble.
Ran around in some of the bayous and bays fishing for four or five hours and [the reduction in the idle speed setting and change to the Enertia 17p propeller with Flo-Torq IV hub] really did help [eliminate] the shift clunk. The engine has the non-ratcheting lower unit with the square teeth on the clutch and [with the new propeller and hub] there was a noticeable chatter of some kind during deceleration but no noise or vibration when accelerating or running. [Performance was reported at] 5,300-RPM 42-MPH
Re-torqued the prop after returning and it didn't seem to have changed much if any but the prop now had 1.0-mm fore-and-aft movement (specification says roughly 0.75 to 3-mm) with a good bit of wobble both front and rear unless it was pushed up tight against the thrust washer.
I can see where it would have to have some fore and aft movement in order to work, but does anyone know what Mercury has to say about all the wobble? From what I gather everyone who has installed one has had the wobble. Or does anyone know if it's a problem when installed on the non-ratcheting lower units?
Thanks:
Bill
sosmerc posted 10-25-2007 12:50 AM ET (US)
I don't know what Mercury has to say about this, but I have had to trim about 1/4 inch off the end of the brass insert on some of the Flo-Torq III hubs that I have installed and I wonder if this might help with the Flor-Torq IV hubs as well? I do not think there should be any slop between the propeller and the propeller shaft. Yes, the propeller shaft itself will have some fore and aft play, but the propeller itself should be firm on the shaft. Just my opinion.
L H G posted 10-25-2007 12:00 PM ET (US)
Bill--Are you saying that you get the "loud CLunk" BECAUSE of the Flo-Torque IV hub, and with a light weight Enertia prop? I find that hard to believe.
I use Flo-Torque IV's on my heavy Revolution 4 props with large vent plugs, and get NO clunk at all on the 200 EFI's.
The hub is designed to have all the play you are describing.
bill705 posted 10-25-2007 01:36 PM ET (US)
LHG--[The change in the engine idle setting and the Enertia propeller and Flo-Torq IV hub] did eliminate the clunk when shifting. My only concern was how loose the prop is on the drive sleeve and the noise when decelerating. The square toothed clutch in the lower unit doesn't allow it to ratchet when slowing. #52-859340T(clutch P/N)
The fore and aft movement is within the specs given in the instructions but the only other movement mentioned is the 10° that I took to mean left to right not wobble.
Bill
jimh posted 10-25-2007 09:15 PM ET (US)
[I have tried to incorporate some of the details presented later into the initial narrative in order to make the events more clear. It seems as if at least one reader was confused by the account, however I think that any ambiguity has been removed now.--jimh]
jimh posted 10-25-2007 11:56 PM ET (US)
Bill--Does the wobble you describe happen when the propeller is turning? Or just when it is static and you push on it?
The reason I ask: you mention 3-mm or about 1/8-inch wobble. On my boat that is about all the clearance there is between the propeller blade tip and the anti-ventilation plate. If the propeller had that much wobble it would be close to striking the anti-ventilation plate.
sosmerc posted 10-26-2007 12:44 AM ET (US)
"The hub is designed to have all the play you are describing."
LHG...can you elaborate on this? Are you saying that the IV is designed to allow the prop to be loose on the propshaft? I am not arguing...just asking the question.
I experienced looseness fore and aft with the III when they were introduced. My local prop shop and I figured this was not intentional...and we trimmed some material off of the brass insert to eliminate the slop. When the prop nut was tightened, it was pulling the brass insert up against the rear thrust washer instead of seating the thrust washer up against the back of the prop. After trimming, the prop was snug on the propshaft, yet still greatly reduced the "clutch chatter"...especially with stainless props. I have not used a IV yet, so I am only guessing that the brass insert is rather long like the III.
bigjohn1 posted 10-26-2007 10:05 AM ET (US)
Perhaps I am stating the obvious; at the risk of that, here goes. We know the insert on both the Flo-Torq III and IV are 2-peice and are held together by the series of small-diameter stainless steel rods vulcanized to them. It would stand to reason (to me anyway) this design will naturally have a bit of play in it, especially with a very heavy ss prop attached to it.
I have the Flo-Torq III installed on a Trophy Plus 4-blade prop and have all the play mentioned by Bill. I consider it normal for this design and the prop works fine. What am I missing?
bill705 posted 10-26-2007 12:08 PM ET (US)
Jimh:
When the prop shaft is held in to take all of the play out of it, there is 1.0mm fore and aft movement of the prop between the aft adapter and the forward thrust washer.
This is well within the specs given in the installation instructions and when the prop is held forward against the thrust washer there is no movement or wobble to it.
It's when the prop is pulled to the rear that all the wobble shows up. Pulling on one blade at a time and rotating the prop didn't cause it to rub on the lower unit housing or strike the trim tab but it does come close.
I didn't think to try pulling the prop back evenly by the exhaust hub against the aft adapter to see if that would hold it steady, since the forward thrust washer holds it nice and tight when it's held up against it.
Maybe the aft adapter needs a rear thrust washer or shim added to it to stabilize it like the forward thrust washer does.
I also didn't think to check how much torque it takes to overcome the springs in the drive sleeve. you can clearly see and feel the springs begin to give and then stop while you torque the prop nut.
Bill

L H G posted 10-26-2007 04:43 PM ET (US)
I believe that the engineers at Merc propeller know what they are doing. As long as the prop is installed and tightened properly according to their recommendations, why question it? My opinion is that is the way the hub was DESIGNED to work. SOS, I do not think I would have altered the III hub design.
In my case, the Flo Torq IV hub is a completely different animal than the regular II is. Who cares if it appears to have play in it. I think that is why it works! The inner sleeve is full length, as mentioned, but the titanium wire inserts are larger.
Henry posted 10-26-2007 07:03 PM ET (US)
I used a Flo-torq III kit with a Laser II (22 pitch prop). Immediately upon installing it and torquing the prop nut I found that there was no fore and aft movement (which the installation instructions say there should be). But there was a definite and noticeable side to side movement (which I called "wobble"). I removed the prop without running the motor and returned the kit.
I posted a description of this and the resident prop expert on this site said he got the same wobble when he installed his Laser II with a Flo torq III on his Mercury motor. He reached no conclusions.
My conclusion: The Laser II prop simply won't work with a Flo torq III prop kit.
I'd like to hear what Mercury has to say about this issue.
WT posted 10-26-2007 07:16 PM ET (US)
"My conclusion: The Laser II prop simply won't work with a Flo torq III prop kit."
Wonderful! :-( I have a Laser II 20 pitch prop and Flo-Torq III hub kit which it have not installed on my outboard yet.
Warren
L H G posted 10-26-2007 07:31 PM ET (US)
I have run Laser II props on my twin Merc 115 in-line sixes, with the standard II hub kit. Shift smooth, no clunk at all, no need for III's. Great props for a mid-range engine. But I think the III's are designed for the 4-strokes, not 2-strokes or Opti's?
Yours will work, Warren. Sounds like Henry didn't give it a chance. The "play" is normal.
sosmerc posted 10-26-2007 11:29 PM ET (US)
When the flo-torq III was introduced it was for 40-60hp Bigfoot and 90-115 Fourstrokes. It worked so well that I decided to try it on other engines...and it really worked.
I now use it on almost every prop that is built for flo-torq hubs. But as I have said before, trimming a bit of material off of the end of the brass insert will eliminate any looseness or fore and aft slop.
I just went out to my boat and grabbed ahold of my prop. There is no fore/aft slop or side to side slop after running all summer. I do not experience any clutch chatter. My prop is a 17 pitch Enertia with flo-torq III hub on a '98 135 Optimax.
If you place a block of wood between a prop blade and the cavitation plate while you attempt to tighten the prop nut, you will notice the as you get tight that the propshaft appears to have some "give" to it. This is the result of the split sleeve design and this "give" is where the clutch chatter gets absorbed. And yes, the instructions that come with the flo-torq do allow for .060-.100" of give fore and aft. My experience is this give is not necessary for the prop to perform correctly and chatter-free...I would rather have the prop near solid on the shaft.....Just my Opinion.
I look forward to getting a flo-torq IV to see if there are any significant differences to the III. My guess is the metal rods between the split hub are larger or stiffer to handle higher horsepower application.
L H G posted 10-26-2007 11:48 PM ET (US)
SOS, on the V-6 gearcase, like the Verado I4's, the IV hub is SUPPOSED to be used, not the III, which is only for mid range engines. On the III, I don't think the wires are large enough diameter to handle the torque and power. Try the IV, unaltered. It does have the "give & wobble" you describe, which is the secret of it's operation, I believe. I thought it was strange too, but it works well on my 200 EFI's. It handled their power easily, with no clunk and little gear rattle, and I am running the king of heavy weight props, the Rev 4's with large vent plugs. I understand with a Verado I4, you MUST install the IV hub as standard equipment, any SS prop.
http://smg.photobucket.com/albums/v429/lgoltz/Outrage%2025/?action=view& current=DSCN1463.jpg
sosmerc posted 10-27-2007 12:37 PM ET (US)
I'll get my hands on a IV and check it out. But if there is any looseness of the prop on the shaft, you can bet I'll be fixing that. :)
Henry posted 10-27-2007 10:43 PM ET (US)
Sosmerc:
Do you think that the side-to-side wobble or "play" is normal on a Laser II prop with a FLo-torq III kit?
sosmerc posted 10-28-2007 11:53 AM ET (US)
I certainly don't think it is, but obviously others here do. Just my opinion, but I would trim that long brass insert back at the thrust washer end just enough so that the prop has NO fore and aft play on the propshaft. This will insure that the rear thrust washer is sitting firmly inside the prop cavity and will eliminate the side to side motion.
bill705 posted 10-29-2007 03:09 PM ET (US)
To All:
Sent an e-mail to Mercury that was basically the same as my original post and here's their reply.
The amount of "play" in the prop sounds normal, however, it would be best to consult a Mercury dealer for a visual inspection.
Mercury Outboard Customer Assistance
Ref.# 2007-224594
No mention as to what might be causing the chattering noise I had inquired about.
Bill
Tom W Clark posted 10-31-2007 09:59 AM ET (US)
The design of the Flo-Torq III and Flo-Torq IV hub kits has confounded me for a while. They are excellent at reducing both shift clunk and prop rattle on my motors. But the wobble they allow does not sit well with me.
I found that when mounting an out-of-the-box Flo-Torq III or IV kit on my motors, there is a fore and aft movement along the propeller shaft (or along the hub insert itself) that means the propeller is not really fixed relative to the propeller shaft as we would normally want a propeller to be.
Indeed, the mounting of a conventional propeller or Flo-Torq II equipped prop calls for a propeller nut torque to be 55 foot/pounds or even 100 foot/pounds in the case of some Flo-Torq II kits. The reason why it is so important the nut be tight is to be sure the propeller is seated tightly on the thrust washer and the prop is centered on the propeller shaft. Propeller experts will emphasize the importance of tightening the prop nut to the specified value or above.
In the case of the Flo-Torq III and IV kits, tightening the prop nut compresses the aft adapter (the bronze splined part) against the thrust washer, not the propeller itself. This is contrary to all advice given before, yet that is how it is supposed to be, indeed needs to be, and here is why:
The Flo-Torq III and IV hub kits have a two piece hub insert, (one half fixed vis-a-vis the prop, one half fixed vis-a-vis the propeller shaft) that is connected via titanium rod that act as springs. This allows some limited amount of torsional movement between the propeller and the propeller shaft and acts as a cushion when shifting into gear and as a damper at slow speed when the power pulses from the cylinders may tend to get out of sync with the rotation of the heavy propeller.
In order for there to be movement between the propeller shaft and the propeller, the propeller must not be bearing tightly against the thrust washer. If it is torqued down against the thrust washer, it will be fixed relative to it and the propeller shaft.
It took me a while to figure this out. This summer when I put Flo-Torq IV kits on both of my 150s, I noticed the wobble in the props. I concluded that something was not right and found the length of the aft adapter did not allow the prop nut to tighten the prop the way I expected it to be. There was a distinct side-to-side wobble which I did not like.
My conclusion was the aft adapter was too long and that if I shortened it a bit that would allow the prop to synch up tight. So I cut about 1/8" off the aft adapters and reinstalled. Now the props were tight with no wobble.
The result? My propellers shifted with the same amount of clunk, not the soft shifting I had experienced with my first trial of the Flo-Torq IV kit. I had defeated the design of the Flo-Torq IV kit with my modification, the same modification sosmerc describes above.
Yes, in theory you could shorten the aft adapter exactly the right amount to allow the aft adapter to synch up tight at precisely the point where all slop is removed from the propeller-to-shaft fit, but this is not realistic.
I also caution you that not all propellers, not even all Mercury Flo-Torq props have the same hub length. Adjust one aft adapter to fit perfectly on one Mercury propeller and it is NOT going to fit the next one the same way. This is why there is range in the specification for fore and aft movement in the Flo-Torq III and IV kit instructions.
Tom W Clark posted 10-31-2007 10:07 AM ET (US)
Reading through this thread again, I want to clear up some misconceptions.
The Flo-Torq III kit will fit the small tube Laser II just as well as any other Flo-Torq prop, no better, no worse.
The Flo-Torq III is nominally designed for the 60 HP Bigfoot, 90 and 115 four strokes but can be used on many other motors as well, including the small V-6s. I have talked with more than one certified Mercury mechanic/dealer that tells me they perform just fine on the 135 and 150s.
This is analogous to the fact that the Flo-Torq IVs is nominally designed for the 135, 150 and 175 Verados only, yet they seem to work well on larger motors too as evidenced by Larry's experience with them on his (super powerful) Mercury 200s.
Henry posted 10-31-2007 01:47 PM ET (US)

Tom W. Clark:
We have discussed this issue before when I installed a Flo torq III kit on my Laser II and discovered the wobble. You responded that you found the same wobble but were busy at the time and the issue was not pursued. I did not like the wobble so I just returned the F-T III kit and went back to the FT II.
Are you now saying that a Laser II prop can be run with a F-T III kit and the associated wobble without detriment to the motor, the kit, or the prop but still eliminate the clunk and maintain the superior peformance of a stainless steel prop?
Tom W Clark posted 10-31-2007 09:41 PM ET (US)
Henry,
That is a good question. The answer is (apparently) yes. This is how Mercury intends the Flo-Torq III and IV kits to work (for now.)
I am not entirely comfortable with the slop. I suppose that when the boat is in motion, the propeller will bear on the thrust washer and self-center, but if this is always the case, why then is there such importance placed on torquing a prop nut at all?
Let me be clear: with the Flo-Torq II and IV hub kits, the prop nut is NOT bearing directly or indirectly on the propeller when the boat is in forward motion. The prop will bear on the thrust washer by its own propulsion; the only thing the prop nut does is hold the aft adapter in securely in place.
I suspect we will see some improvement upon this design at some point. The Mercury Flo-Torq design is a good one. I have come to appreciate the benefits to us, the boating population, of this field-replaceable design, but we should also understand the the entire Flo-Torq family of kits has evolved over time.
There have been many, many refinements of the Flo-Torq components over the last decade. There have also been some poorly manufactured components that required modification to work properly. Yes, even Mercury makes mistakes sometimes. I have no doubt we will see the Flo-Torq II and IV kits improve over time.
WT posted 10-31-2007 10:47 PM ET (US)
Henry:
When I ordered my Laser II it came with a Flo-Torq II. I called Mercuery and they told me that if I'm runnibg a 90 hp Mercury 4-stroke, I should use a Flo-Torq III.
I just had the new Laser II and Flo-Torq III installed today. Haven't checked it out yet.
Call Mercury if you have any questions.
Warren
Henry posted 11-01-2007 01:15 AM ET (US)
Tom W.Clark and WT:
Thanks for the responses. I am not comfortable with the slop either that is why I have decided not to use the FT-III kit (for now).
I have a Mercury 90 hp two stroke. Maybe I will call Mercury and ask what kit they recommend with th 90 two stroke and the Laser II.
Tom W Clark posted 11-01-2007 08:04 AM ET (US)
Henry,
You can always use the Flo-Torq II kit unless your Mercury 90 two stroke is an older one like my 1993 model. In that case Mercury recommends the use of a Flo-Torq I (rubber hub) kit.

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Author	Topic: Flo-Torq IV Hub Decreases Loud Clunk, But Has Wobble
bill705	posted 10-24-2007 02:19 PM ET (US) Just returned to Tennessee from Jesuit Bend, Louisiana where one of our sons lives. He has a Dauntless 18 with a Mercury 150 Saltwater, and it really had a loud clunk when shifting. Some of the problem was in the idle setting so we did a link and sync and set the idle to 700-RPM. [Next the unidentified existing propeller was removed and the author] installed the Flo-Torq IV with an Enertia 17p and torqued it to roughly 62-lb-ft (instructions say 55) to get the locking tabs to align. There was no fore and aft movement or wobble. Ran around in some of the bayous and bays fishing for four or five hours and [the reduction in the idle speed setting and change to the Enertia 17p propeller with Flo-Torq IV hub] really did help [eliminate] the shift clunk. The engine has the non-ratcheting lower unit with the square teeth on the clutch and [with the new propeller and hub] there was a noticeable chatter of some kind during deceleration but no noise or vibration when accelerating or running. [Performance was reported at] 5,300-RPM 42-MPH Re-torqued the prop after returning and it didn't seem to have changed much if any but the prop now had 1.0-mm fore-and-aft movement (specification says roughly 0.75 to 3-mm) with a good bit of wobble both front and rear unless it was pushed up tight against the thrust washer. I can see where it would have to have some fore and aft movement in order to work, but does anyone know what Mercury has to say about all the wobble? From what I gather everyone who has installed one has had the wobble. Or does anyone know if it's a problem when installed on the non-ratcheting lower units? Thanks: Bill
sosmerc	posted 10-25-2007 12:50 AM ET (US) I don't know what Mercury has to say about this, but I have had to trim about 1/4 inch off the end of the brass insert on some of the Flo-Torq III hubs that I have installed and I wonder if this might help with the Flor-Torq IV hubs as well? I do not think there should be any slop between the propeller and the propeller shaft. Yes, the propeller shaft itself will have some fore and aft play, but the propeller itself should be firm on the shaft. Just my opinion.
L H G	posted 10-25-2007 12:00 PM ET (US) Bill--Are you saying that you get the "loud CLunk" BECAUSE of the Flo-Torque IV hub, and with a light weight Enertia prop? I find that hard to believe. I use Flo-Torque IV's on my heavy Revolution 4 props with large vent plugs, and get NO clunk at all on the 200 EFI's. The hub is designed to have all the play you are describing.
bill705	posted 10-25-2007 01:36 PM ET (US) LHG--[The change in the engine idle setting and the Enertia propeller and Flo-Torq IV hub] did eliminate the clunk when shifting. My only concern was how loose the prop is on the drive sleeve and the noise when decelerating. The square toothed clutch in the lower unit doesn't allow it to ratchet when slowing. #52-859340T(clutch P/N) The fore and aft movement is within the specs given in the instructions but the only other movement mentioned is the 10° that I took to mean left to right not wobble. Bill
jimh	posted 10-25-2007 09:15 PM ET (US) [I have tried to incorporate some of the details presented later into the initial narrative in order to make the events more clear. It seems as if at least one reader was confused by the account, however I think that any ambiguity has been removed now.--jimh]
jimh	posted 10-25-2007 11:56 PM ET (US) Bill--Does the wobble you describe happen when the propeller is turning? Or just when it is static and you push on it? The reason I ask: you mention 3-mm or about 1/8-inch wobble. On my boat that is about all the clearance there is between the propeller blade tip and the anti-ventilation plate. If the propeller had that much wobble it would be close to striking the anti-ventilation plate.
sosmerc	posted 10-26-2007 12:44 AM ET (US) "The hub is designed to have all the play you are describing." LHG...can you elaborate on this? Are you saying that the IV is designed to allow the prop to be loose on the propshaft? I am not arguing...just asking the question. I experienced looseness fore and aft with the III when they were introduced. My local prop shop and I figured this was not intentional...and we trimmed some material off of the brass insert to eliminate the slop. When the prop nut was tightened, it was pulling the brass insert up against the rear thrust washer instead of seating the thrust washer up against the back of the prop. After trimming, the prop was snug on the propshaft, yet still greatly reduced the "clutch chatter"...especially with stainless props. I have not used a IV yet, so I am only guessing that the brass insert is rather long like the III.
bigjohn1	posted 10-26-2007 10:05 AM ET (US) Perhaps I am stating the obvious; at the risk of that, here goes. We know the insert on both the Flo-Torq III and IV are 2-peice and are held together by the series of small-diameter stainless steel rods vulcanized to them. It would stand to reason (to me anyway) this design will naturally have a bit of play in it, especially with a very heavy ss prop attached to it. I have the Flo-Torq III installed on a Trophy Plus 4-blade prop and have all the play mentioned by Bill. I consider it normal for this design and the prop works fine. What am I missing?
bill705	posted 10-26-2007 12:08 PM ET (US) Jimh: When the prop shaft is held in to take all of the play out of it, there is 1.0mm fore and aft movement of the prop between the aft adapter and the forward thrust washer. This is well within the specs given in the installation instructions and when the prop is held forward against the thrust washer there is no movement or wobble to it. It's when the prop is pulled to the rear that all the wobble shows up. Pulling on one blade at a time and rotating the prop didn't cause it to rub on the lower unit housing or strike the trim tab but it does come close. I didn't think to try pulling the prop back evenly by the exhaust hub against the aft adapter to see if that would hold it steady, since the forward thrust washer holds it nice and tight when it's held up against it. Maybe the aft adapter needs a rear thrust washer or shim added to it to stabilize it like the forward thrust washer does. I also didn't think to check how much torque it takes to overcome the springs in the drive sleeve. you can clearly see and feel the springs begin to give and then stop while you torque the prop nut. Bill
L H G	posted 10-26-2007 04:43 PM ET (US) I believe that the engineers at Merc propeller know what they are doing. As long as the prop is installed and tightened properly according to their recommendations, why question it? My opinion is that is the way the hub was DESIGNED to work. SOS, I do not think I would have altered the III hub design. In my case, the Flo Torq IV hub is a completely different animal than the regular II is. Who cares if it appears to have play in it. I think that is why it works! The inner sleeve is full length, as mentioned, but the titanium wire inserts are larger.
Henry	posted 10-26-2007 07:03 PM ET (US) I used a Flo-torq III kit with a Laser II (22 pitch prop). Immediately upon installing it and torquing the prop nut I found that there was no fore and aft movement (which the installation instructions say there should be). But there was a definite and noticeable side to side movement (which I called "wobble"). I removed the prop without running the motor and returned the kit. I posted a description of this and the resident prop expert on this site said he got the same wobble when he installed his Laser II with a Flo torq III on his Mercury motor. He reached no conclusions. My conclusion: The Laser II prop simply won't work with a Flo torq III prop kit. I'd like to hear what Mercury has to say about this issue.
WT	posted 10-26-2007 07:16 PM ET (US) "My conclusion: The Laser II prop simply won't work with a Flo torq III prop kit." Wonderful! :-( I have a Laser II 20 pitch prop and Flo-Torq III hub kit which it have not installed on my outboard yet. Warren
L H G	posted 10-26-2007 07:31 PM ET (US) I have run Laser II props on my twin Merc 115 in-line sixes, with the standard II hub kit. Shift smooth, no clunk at all, no need for III's. Great props for a mid-range engine. But I think the III's are designed for the 4-strokes, not 2-strokes or Opti's? Yours will work, Warren. Sounds like Henry didn't give it a chance. The "play" is normal.
sosmerc	posted 10-26-2007 11:29 PM ET (US) When the flo-torq III was introduced it was for 40-60hp Bigfoot and 90-115 Fourstrokes. It worked so well that I decided to try it on other engines...and it really worked. I now use it on almost every prop that is built for flo-torq hubs. But as I have said before, trimming a bit of material off of the end of the brass insert will eliminate any looseness or fore and aft slop. I just went out to my boat and grabbed ahold of my prop. There is no fore/aft slop or side to side slop after running all summer. I do not experience any clutch chatter. My prop is a 17 pitch Enertia with flo-torq III hub on a '98 135 Optimax. If you place a block of wood between a prop blade and the cavitation plate while you attempt to tighten the prop nut, you will notice the as you get tight that the propshaft appears to have some "give" to it. This is the result of the split sleeve design and this "give" is where the clutch chatter gets absorbed. And yes, the instructions that come with the flo-torq do allow for .060-.100" of give fore and aft. My experience is this give is not necessary for the prop to perform correctly and chatter-free...I would rather have the prop near solid on the shaft.....Just my Opinion. I look forward to getting a flo-torq IV to see if there are any significant differences to the III. My guess is the metal rods between the split hub are larger or stiffer to handle higher horsepower application.
L H G	posted 10-26-2007 11:48 PM ET (US) SOS, on the V-6 gearcase, like the Verado I4's, the IV hub is SUPPOSED to be used, not the III, which is only for mid range engines. On the III, I don't think the wires are large enough diameter to handle the torque and power. Try the IV, unaltered. It does have the "give & wobble" you describe, which is the secret of it's operation, I believe. I thought it was strange too, but it works well on my 200 EFI's. It handled their power easily, with no clunk and little gear rattle, and I am running the king of heavy weight props, the Rev 4's with large vent plugs. I understand with a Verado I4, you MUST install the IV hub as standard equipment, any SS prop. http://smg.photobucket.com/albums/v429/lgoltz/Outrage%2025/?action=view& current=DSCN1463.jpg
sosmerc	posted 10-27-2007 12:37 PM ET (US) I'll get my hands on a IV and check it out. But if there is any looseness of the prop on the shaft, you can bet I'll be fixing that. :)
Henry	posted 10-27-2007 10:43 PM ET (US) Sosmerc: Do you think that the side-to-side wobble or "play" is normal on a Laser II prop with a FLo-torq III kit?
sosmerc	posted 10-28-2007 11:53 AM ET (US) I certainly don't think it is, but obviously others here do. Just my opinion, but I would trim that long brass insert back at the thrust washer end just enough so that the prop has NO fore and aft play on the propshaft. This will insure that the rear thrust washer is sitting firmly inside the prop cavity and will eliminate the side to side motion.
bill705	posted 10-29-2007 03:09 PM ET (US) To All: Sent an e-mail to Mercury that was basically the same as my original post and here's their reply. The amount of "play" in the prop sounds normal, however, it would be best to consult a Mercury dealer for a visual inspection. Mercury Outboard Customer Assistance Ref.# 2007-224594 No mention as to what might be causing the chattering noise I had inquired about. Bill
Tom W Clark	posted 10-31-2007 09:59 AM ET (US) The design of the Flo-Torq III and Flo-Torq IV hub kits has confounded me for a while. They are excellent at reducing both shift clunk and prop rattle on my motors. But the wobble they allow does not sit well with me. I found that when mounting an out-of-the-box Flo-Torq III or IV kit on my motors, there is a fore and aft movement along the propeller shaft (or along the hub insert itself) that means the propeller is not really fixed relative to the propeller shaft as we would normally want a propeller to be. Indeed, the mounting of a conventional propeller or Flo-Torq II equipped prop calls for a propeller nut torque to be 55 foot/pounds or even 100 foot/pounds in the case of some Flo-Torq II kits. The reason why it is so important the nut be tight is to be sure the propeller is seated tightly on the thrust washer and the prop is centered on the propeller shaft. Propeller experts will emphasize the importance of tightening the prop nut to the specified value or above. In the case of the Flo-Torq III and IV kits, tightening the prop nut compresses the aft adapter (the bronze splined part) against the thrust washer, not the propeller itself. This is contrary to all advice given before, yet that is how it is supposed to be, indeed needs to be, and here is why: The Flo-Torq III and IV hub kits have a two piece hub insert, (one half fixed vis-a-vis the prop, one half fixed vis-a-vis the propeller shaft) that is connected via titanium rod that act as springs. This allows some limited amount of torsional movement between the propeller and the propeller shaft and acts as a cushion when shifting into gear and as a damper at slow speed when the power pulses from the cylinders may tend to get out of sync with the rotation of the heavy propeller. In order for there to be movement between the propeller shaft and the propeller, the propeller must not be bearing tightly against the thrust washer. If it is torqued down against the thrust washer, it will be fixed relative to it and the propeller shaft. It took me a while to figure this out. This summer when I put Flo-Torq IV kits on both of my 150s, I noticed the wobble in the props. I concluded that something was not right and found the length of the aft adapter did not allow the prop nut to tighten the prop the way I expected it to be. There was a distinct side-to-side wobble which I did not like. My conclusion was the aft adapter was too long and that if I shortened it a bit that would allow the prop to synch up tight. So I cut about 1/8" off the aft adapters and reinstalled. Now the props were tight with no wobble. The result? My propellers shifted with the same amount of clunk, not the soft shifting I had experienced with my first trial of the Flo-Torq IV kit. I had defeated the design of the Flo-Torq IV kit with my modification, the same modification sosmerc describes above. Yes, in theory you could shorten the aft adapter exactly the right amount to allow the aft adapter to synch up tight at precisely the point where all slop is removed from the propeller-to-shaft fit, but this is not realistic. I also caution you that not all propellers, not even all Mercury Flo-Torq props have the same hub length. Adjust one aft adapter to fit perfectly on one Mercury propeller and it is NOT going to fit the next one the same way. This is why there is range in the specification for fore and aft movement in the Flo-Torq III and IV kit instructions.
Tom W Clark	posted 10-31-2007 10:07 AM ET (US) Reading through this thread again, I want to clear up some misconceptions. The Flo-Torq III kit will fit the small tube Laser II just as well as any other Flo-Torq prop, no better, no worse. The Flo-Torq III is nominally designed for the 60 HP Bigfoot, 90 and 115 four strokes but can be used on many other motors as well, including the small V-6s. I have talked with more than one certified Mercury mechanic/dealer that tells me they perform just fine on the 135 and 150s. This is analogous to the fact that the Flo-Torq IVs is nominally designed for the 135, 150 and 175 Verados only, yet they seem to work well on larger motors too as evidenced by Larry's experience with them on his (super powerful) Mercury 200s.
Henry	posted 10-31-2007 01:47 PM ET (US) Tom W. Clark: We have discussed this issue before when I installed a Flo torq III kit on my Laser II and discovered the wobble. You responded that you found the same wobble but were busy at the time and the issue was not pursued. I did not like the wobble so I just returned the F-T III kit and went back to the FT II. Are you now saying that a Laser II prop can be run with a F-T III kit and the associated wobble without detriment to the motor, the kit, or the prop but still eliminate the clunk and maintain the superior peformance of a stainless steel prop?
Tom W Clark	posted 10-31-2007 09:41 PM ET (US) Henry, That is a good question. The answer is (apparently) yes. This is how Mercury intends the Flo-Torq III and IV kits to work (for now.) I am not entirely comfortable with the slop. I suppose that when the boat is in motion, the propeller will bear on the thrust washer and self-center, but if this is always the case, why then is there such importance placed on torquing a prop nut at all? Let me be clear: with the Flo-Torq II and IV hub kits, the prop nut is NOT bearing directly or indirectly on the propeller when the boat is in forward motion. The prop will bear on the thrust washer by its own propulsion; the only thing the prop nut does is hold the aft adapter in securely in place. I suspect we will see some improvement upon this design at some point. The Mercury Flo-Torq design is a good one. I have come to appreciate the benefits to us, the boating population, of this field-replaceable design, but we should also understand the the entire Flo-Torq family of kits has evolved over time. There have been many, many refinements of the Flo-Torq components over the last decade. There have also been some poorly manufactured components that required modification to work properly. Yes, even Mercury makes mistakes sometimes. I have no doubt we will see the Flo-Torq II and IV kits improve over time.
WT	posted 10-31-2007 10:47 PM ET (US) Henry: When I ordered my Laser II it came with a Flo-Torq II. I called Mercuery and they told me that if I'm runnibg a 90 hp Mercury 4-stroke, I should use a Flo-Torq III. I just had the new Laser II and Flo-Torq III installed today. Haven't checked it out yet. Call Mercury if you have any questions. Warren
Henry	posted 11-01-2007 01:15 AM ET (US) Tom W.Clark and WT: Thanks for the responses. I am not comfortable with the slop either that is why I have decided not to use the FT-III kit (for now). I have a Mercury 90 hp two stroke. Maybe I will call Mercury and ask what kit they recommend with th 90 two stroke and the Laser II.
Tom W Clark	posted 11-01-2007 08:04 AM ET (US) Henry, You can always use the Flo-Torq II kit unless your Mercury 90 two stroke is an older one like my 1993 model. In that case Mercury recommends the use of a Flo-Torq I (rubber hub) kit.