Watch this guy trash his U-joints!

[Blue Crabber]

Re: Watch this guy trash his U-joints!

Should I lower it from now on to start it on the muffs?

Short answer, yes! You might get away with it all the way up with out any damage, but why take the chance?

Edit: Looks like Gary was faster than me.

 

[Friscoboater]

Re: Watch this guy trash his U-joints!

I am glad this thread educated a few people and might save some u joints!

 

[Knightgang]

Re: Watch this guy trash his U-joints!

And $$$$$$$$$

 

[SeanT]

Re: Watch this guy trash his U-joints!

I sold my old u-joints with my old boat.

No more u-joints for me! (Well, at least, no lower leg anymore).

 

[anon1]

Re: Watch this guy trash his U-joints!

I spent the best $30 ever on my boat by installing a trim/tilt switch out back on the transom for just this reason.

When you want to flush the drive after you get home you can stand right there and lower it and watch it not dig into the ground. When getting ready to go boating you can stand right there and put the drive up before moving, because you also store your drive in the down position, right.

 

[steddy]

Re: Watch this guy trash his U-joints!

Go get your typical 3/8 socket set. Put a socket u-joint between 2 extensions. Now hold one extension level and start turning it while slowly increasing the angle on the other one. You'll feel the u-joint start to bind as the angle increases. The binding increases quickly once you pass a very small angle. You're doing the same thing to your drive when you run it tilted all the way up.

While it's possible to do and you may get away with it for a long time, don't be surprised when one of those u-joints breaks on you.

Then spin it at 5,000 RPM like this guy did.

 

[45Auto]

Re: Watch this guy trash his U-joints!

Upper trim limit is designed to specifically be safe for full power . . . that's the point. Agree, idle only full tilt, but trim? That's how you get your best top speed if your boat and limit are set up right,

If the TRIM limit is set up right, it should be set so that the sides of the outdrive are still supported by the "ears" on the gimbal ring when the TRIM is full up. Going into TRAILERING position raises the outdrive above the "ears" on the gimball ring so there is no side support for the outdrive. All sideloads on the drive when it is above the TRIM limit are transmitted through the outdrive bellhousing (helmet) to the gimbal ring through the pivot bolts. This is the weakest point on the gimbal ring to try to take these side loads and can easily break the gimbal ring.

I don't think I've ever seen a boat that was set up so that it needed full UP TRIM to reach top speed. My experience has been that they'll start porpoising well before the upper TRIM limit.

I would hope that Mercruiser engineered the U-joint angle so that between full down and full up trim they are sized to take maximum engine loads without unusual wear at those drive angles. Up above the TRIM limit (in the TRAILER position) I don't imagine they would last as long at high speed with the radical angle.

Mercruiser TRIM warning:

 

[QC]

Re: Watch this guy trash his U-joints!

I don't think I've ever seen a boat that was set up so that it needed full UP TRIM to reach top speed. My experience has been that they'll start porpoising well before the upper TRIM limit.

Welll . . . my experience is close, but I've always set my boats up to just barely porpoise at the highest speeds and trim levels, then control that with tabs, so if it porpoises before full up trim I would shift some weight forward. If she blows out at full up without propoising then I'd shift weight aft. Obviously heavier hulls are different than lighter ones, but if the bow continues to rise without blowout, my experience is that they are faster.

I would hope that Mercruiser engineered the U-joint angle so that between full down and full up trim they are sized to take maximum engine loads

That was ultimately my point, and I am going to have to look, but it would seem full down and full TRIM up should be equal angles and somewhere in the middle is straight . . .

 

[QC]

Re: Watch this guy trash his U-joints!

P.S. What manual did you pull that from? This is from a Carb'd Alpha manual:

Use extreme caution when operating with drive unit raised. Severe damage to the drive unit may result
if unit is raised beyond the gimbal ring support flanges at engine speeds above 1200 rpm.

 

[jt185]

Re: Watch this guy trash his U-joints!

If the TRIM limit is set up right, it should be set so that the sides of the outdrive are still supported by the "ears" on the gimbal ring when the TRIM is full up. Going into TRAILERING position raises the outdrive above the "ears" on the gimball ring so there is no side support for the outdrive. All sideloads on the drive when it is above the TRIM limit are transmitted through the outdrive bellhousing (helmet) to the gimbal ring through the pivot bolts. This is the weakest point on the gimbal ring to try to take these side loads and can easily break the gimbal ring.

I don't think I've ever seen a boat that was set up so that it needed full UP TRIM to reach top speed. My experience has been that they'll start porpoising well before the upper TRIM limit.

I would hope that Mercruiser engineered the U-joint angle so that between full down and full up trim they are sized to take maximum engine loads without unusual wear at those drive angles. Up above the TRIM limit (in the TRAILER position) I don't imagine they would last as long at high speed with the radical angle.

Mercruiser TRIM warning:

Thanks for posting this!!

 

[RICHARD5]

Re: Watch this guy trash his U-joints!

I am glad this thread educated a few people and might save some u joints!

That's what it's all about, right? I've learned a few things here and I've been on the water all my life in all kinds of boats--skiffs to ships.

 

[RICHARD5]

Re: Watch this guy trash his U-joints!

I spent the best $30 ever on my boat by installing a trim/tilt switch out back on the transom for just this reason.

When you want to flush the drive after you get home you can stand right there and lower it and watch it not dig into the ground. When getting ready to go boating you can stand right there and put the drive up before moving, because you also store your drive in the down position, right.

I like this idea. How is it wired? Does it over ride the trim switch at the control console? A schematic would be great.

 

[skargo]

Re: Watch this guy trash his U-joints!

I like this idea. How is it wired? Does it over ride the trim switch at the control console? A schematic would be great.

I think I have my installation manual/schematics for mine, I love it.

You can see my switch, barely, on the upper left.

 

[45Auto]

Re: Watch this guy trash his U-joints!

P.S. What manual did you pull that from?

Hi QC,

That came from #28 , 2000-2005 Bravo Sterndrives.

 

[anon1]

Re: Watch this guy trash his U-joints!

I like this idea. How is it wired? Does it over ride the trim switch at the control console? A schematic would be great.

It is wired in parallel with the existing switch. At your trim pump are green (for down) and blue (for up) wires that go to the pump solenoids. These are the green and blue that runs from the pump up to the control switch at the helm.

The new switch has a green and blue that just t's in with those green and blue and it has a purple to get power (from feed to the pump, battery, or other always on source).

I think you can get Mercruiser one that has a t-plug built in.