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Please please help. Getting conflicting answers. Which 4 blade for 97 zt280

S

Stb103

New member
I've been having issues. Boat revs and slips under full throttle. More so weighted down. Was told it was a coupler, installed new one same issue. Then was told was prop and To switch to 4 blade. Currently have 25 pitch mirage now, runs 100 rpm under redline now . I'm being told bravo one 4 blade is the way to go, but have been told 23 and 24 pitch. Please someone help me. Can't get a straight answer. So I'm here hoping checkmate owners can help. Has stock 502 mpi
 
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Calm thyself. You've come to the right place. I suspect that you may have been talking to the wrong people. What 'coupler' are we speaking of? It does sound as if a prop change has helped with the 'slippage' issue as you are now running at maximum rated RPM?. But at what speed? Are you able to trim the outdrive up for maximum speed?
 
Initially I ran 68 with the mirage 25 , it started to drop to mid 60s. Run 4900 rpm at wot. Started slipping, checked to see if prop hun was blown, to find out there isn't one on this boat like my last boat. Was told the coupler would cause that. Paid to have it replaced, they pulled the motor and put new coupler in. Same issue. Another friend said he had a similirar issue and was his prop, I was planning on getting a 4 blade anyway because I usually have 5 people on the boat to help get on plane. I just ordered a bravo 1 4 blade 24 pitch after reading on here that's the preference. I hope it fixes it and it's not the drive.
 
Well, off the top of my head, If we're talking about a 1.5 gear Bravo being spun at 4900, with a 25 pitch I think we're in the 12% slip arena at 68 mph. That seems good in the scheme of things. I'm guessing that you didn't get to see the engine coupler when it was replaced.
 
No I bought it from my local marina , my friend replaced it. He used a backhoe to pull the motor. Now I used to run high 60s, it slowly dropped to mid 60s sometimes low when I could even get there. Most times it just revved up and didn't go so I have to back off as it revved past the limiter.
 
Is the prop a Mirage Plus which will have a flo-torq hub or an old Mirage with a pressed in rubber hub? If it is the later then it sounds like a spin hub. Which is a much easier fix than a new coupler (which seemed unlikely).

Dumb question? You don't have the drive overtrimmed do you?

Mirage Plus is probably the right prop for the rig. I doubt you need a 4 blade which will likely slow you down.
 
I'm not too savvy yet so I'll answer the way it was examined to me....he checked to see if the hub spun and said it's a solid hub as opposed to his boat with has a plastic hub that spins to protect the drive. That's why we did the coupler but found out it wasn't the coupler after pulling the motor and replacing it.
 
The plastic hub he has is a flo-torq and doesn't spin but breaks free. There is such a thing as a solid hub but that is doubtful on a Mirage. You likely have a pressed in rubber hub that actually can spin. And if it does, the hub is toast and must be replaced. Any prop shop can do it.
I don't think your friend knows as much about boats as he thinks. I would now be concerned if he aligned the drive when he replaced the motor. That 'is' how you ruin a coupler and/or a gimbal bearing. You need alignment tool and you usually cannot find one in the glove box of a backhoe.
 
One could place alignment marks on the prop and securing nut, and operate vessel for a quick trip. As soon as 'slipping' occurs, check alignment marks. ANY change would indicate problem, or would that be prop lem.
 
A alignment tool was used , and he said it's a no hub setup, no breakaway or pressed. He said a spline with metal teeth. Hope this helps.
 
Mark said:
The plastic hub he has is a flo-torq and doesn't spin but breaks free. There is such a thing as a solid hub but that is doubtful on a Mirage. You likely have a pressed in rubber hub that actually can spin. And if it does, the hub is toast and must be replaced. Any prop shop can do it.
I don't think your friend knows as much about boats as he thinks. I would now be concerned if he aligned the drive when he replaced the motor. That 'is' how you ruin a coupler and/or a gimbal bearing. You need alignment tool and you usually cannot find one in the glove box of a backhoe.
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They made the old school Mirage in solid hub. That's what ndaniels 29p Mirage is that he runs. My dad also has a 21p and a 27p Mirage in solid hub. Now the new Mirage Plus props are almost all Flo-Torq hub props.


As far as the 4 blade props go, I can't say what a ZT likes, but most Convincors love a Bravo 1 prop. From past experience, if you can spin a 25p 3-Blade to redline, you might want to go up to a 26p in a Bravo.
 
Close to redline. Isn't rule of thumb from going to a 3 to a 4 blade to drop a pitch? That's what I've been reading online. I ordered the 24p bravo one.
 
Stb103 said:
Close to redline. Isn't rule of thumb from going to a 3 to a 4 blade to drop a pitch? That's what I've been reading online. I ordered the 24p bravo one.
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My boat will spin a 23p Mirage Plus and a 24p Bravo 1 to about the same RPM. However, it hates the 3-blade prop. Handles like crap and blows out all the time. But again, this is a different hull than yours.
 
corey331 said:
They made the old school Mirage in solid hub. That's what ndaniels 29p Mirage is that he runs. My dad also has a 21p and a 27p Mirage in solid hub. Now the new Mirage Plus props are almost all Flo-Torq hub props.


I stand corrected.
If it is a solid hub and the coupler is good then there is nothing else to slip except that the prop is not biting. It would be worth trying any borrowed prop in same pitch and see what happens. I use a 25P Mirage on my 23' and it has great grip. Maybe your big motor is just overpowering the 3 blade.

And if he used an alignment tool then he sounds like the real deal. Sorry to have questioned your friend. Guys make this mistake all the time and mess things up.
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I did lots pf prop testing on 251, 253's found the mirage plus a tad faster, but not a good all around prop for these boats, bravo 1 4 blade best all around and still good top end, you boat should not be much different, would start with a 24 and see where you are RPM wise there.
 
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