454 coupler splines gone
06-30-2014, 07:06 AM
#11
When the drive is turned all the way port or starboard the action of the u joints pulls the shaft in and out of the coupler with every rotation. This is only a very small amount, but will wear them without grease, so it is more than just for assembly/dis-assembly.
06-30-2014, 10:16 AM
#13
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iTrader: (1)
The Merc spline/coupler grease is different from the rest of the greases you use on other parts of the boat.
According to Merc it has a 'special' heat transfer compound. They say if you don't use it you are f*d. So I have always used it - I store it in a seperate grease gun that I labeled.
Just as an FYI.
According to Merc it has a 'special' heat transfer compound. They say if you don't use it you are f*d. So I have always used it - I store it in a seperate grease gun that I labeled.
Just as an FYI.
06-30-2014, 03:40 PM
#14
Registered
The Merc spline/coupler grease is different from the rest of the greases you use on other parts of the boat.
According to Merc it has a 'special' heat transfer compound. They say if you don't use it you are f*d. So I have always used it - I store it in a seperate grease gun that I labeled.
Just as an FYI.
According to Merc it has a 'special' heat transfer compound. They say if you don't use it you are f*d. So I have always used it - I store it in a seperate grease gun that I labeled.
Just as an FYI.
Just went out today and purchased a tube of this magic elixir-- and yes a separate grease gun will be enshrined!
3pointstar
07-01-2014, 12:19 AM
#15
Banned
iTrader: (9)
As some said - bad transom can wipe out a coupler in a short time, A bad gimbal bearing that has worn bearings in it causing slop movement of the input shaft going into the coupler,
Weak motor mounts / blocks / stringers which ever the motor mounts mount to as it drops down the engine alignment,
improper engine alignment.
Never greasing the coupler over time will cause it as well.
Also prop impact or dragging the prop on the lake bottom, we see this a lot with the bravo III as it wipes out the couplers right then and there. Sometimes not even a bent blade or spot on the prop as the coupler gave way first in which saved the prop & drive.
Wrong coupler for your app
Defective coupler to begin with, as it could have been not set perfectly dead middle or for whatever reason,
Whoever installed the coupler warped it externally because they did not follow the proper torque pattern and proper torque for installation.. IMO wrong grease did not cause this.
Weak motor mounts / blocks / stringers which ever the motor mounts mount to as it drops down the engine alignment,
improper engine alignment.
Never greasing the coupler over time will cause it as well.
Also prop impact or dragging the prop on the lake bottom, we see this a lot with the bravo III as it wipes out the couplers right then and there. Sometimes not even a bent blade or spot on the prop as the coupler gave way first in which saved the prop & drive.
Wrong coupler for your app
Defective coupler to begin with, as it could have been not set perfectly dead middle or for whatever reason,
Whoever installed the coupler warped it externally because they did not follow the proper torque pattern and proper torque for installation.. IMO wrong grease did not cause this.
Last edited by BUP; 07-01-2014 at 12:28 AM.
07-01-2014, 09:19 AM
#16
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Bup;
All reasons coupler could fail, although I think mis- alignment for whatever reason, would be a major cause. Forcing a constant side load on the splines, would rotate the shaft egg shape pattern, under extreme torque. The gimbal bearing is trying to hold it on center, but the coupler center a foot or so away, is running out. The rubber donut has some give, or it would fail, or bind right away. The shaft must be harder, as it wiped out the splines, and still looks ok. A strong hole shot, all the horsepower at once, can't plane the boat right away, so it's pushing say, 500 HP, against a wall of water the boat can't overcome until the stern gets on top of it. All of it is on the coupler splines. When I want to go, I push the throttle way up, then back off at the speed I want, usually around 40 or so. Since I don't like pulling engines in the summer, I will treat it with a little more respect.
All reasons coupler could fail, although I think mis- alignment for whatever reason, would be a major cause. Forcing a constant side load on the splines, would rotate the shaft egg shape pattern, under extreme torque. The gimbal bearing is trying to hold it on center, but the coupler center a foot or so away, is running out. The rubber donut has some give, or it would fail, or bind right away. The shaft must be harder, as it wiped out the splines, and still looks ok. A strong hole shot, all the horsepower at once, can't plane the boat right away, so it's pushing say, 500 HP, against a wall of water the boat can't overcome until the stern gets on top of it. All of it is on the coupler splines. When I want to go, I push the throttle way up, then back off at the speed I want, usually around 40 or so. Since I don't like pulling engines in the summer, I will treat it with a little more respect.
07-01-2014, 09:49 AM
#17
Banned
iTrader: (9)
As I said also possible wrong coupler for your app. Your pushing 500 hp and problably over 550 torque as I thought you had a stock engine. Back then 454 black engines were 330 hp max and less torque #'s than your motor currently. Also agree how you drive the boat as we all know can be very hard on the outdrives especially if you drive like you stole it. A lot of people forget about the couplers as it in the mix as well when your hard driving. Just my 2 cents.
