Propshaft Runout
 

Back on Labor Day weekend I struck something (due to low water levels). The prop suffered pretty major damage and is being sent off to BBlades for rework. With the damage to the prop I assumed there would be prop shaft damage as well. To get through the Labor day weekend, I heated the prop up and beat it back into a usable shape.. much to my surprise, there wasn't much vibration and the boat performed rather well.... The boat hasn't been used since..... I pulled the boat out of storage today and measured the runout on the prop shaft. I measured a total of .010" of runout. While .010" isn't that much, I assume it is too much for a prop shaft....... So my question is, what is an acceptable amount of run out for a Bravo 1 prop shaft?

The lower unit on my boat is an SEI unit and it has a 3 year no questions asked damage warranty so I plan to send it in. However, I don't want to send it in of .010" is within tolerance (I am guessing its not...)

Send it back, that is too much runout. .005 if memory serves is the max permissible.

I have seen new merc prop shafts as bad as .007..i like to see a max of .003 but you take what you get when it come out of a new cylinder..

Quite frankly if the splines were straight and I owned the lower with no warrantee, I'd give it a whack with a dead blow to get it under .005. Been there, done that, worked just fine. It is twist in propshaft splines that make them weak.

Spines are straight. I was at idle when I struck what ever it was. It actually shut the boat off...... If the lower wasn't covered by a no questions asked warranty, I would probably take a shot at straightening it.... But since it is, all I have to do is pay shipping to get it replaced.

whats the harm in trying the hammer trick,if you make it worse,send it in,if you make it better,go boating.

It is freezing cold still here in MI. The lower has a three year warranty that began may, 3years ago... since the season has not started here in MI yet, no sense in not using this time to send the drive in.... The more I think about it, with as much damage as my prop saw, there may be more hidden damage inside the lower..........

You were at idle and did all that damage?

Yup. I am guessing it was a big freaking rock. What probably saved more damage to the drive is the fact that I am running a labbed prop. Had it not been labbed (thinned) I would guess the drive would have suffered more damage. The prop ended up with one blade folded over about 3" in from the tip. Another blade suffered a very large gouge.

I have some pics of the prop damage, I will try and dig them up in the morning.

Its under warranty, send it back. Not sure if they'll repair or replace the unit as a whole. But it'll either give them the opportunity to look at the gears for that small chance of damage during a repair, or they'll be replaced if the unit is just replaced.

You whacked a rock that hard and the skeg is still in one piece?

phone call from warrantee manager : "hello, mr. psi ? we recieved your prop shaft back and it sure looks like somebody beat the sht out of it w/ a hammer ... "

mr psi : " [I]well... my buddies told me you would still warrantee it if i sledgehammered it a few times ..."

warantee manager : " sorry our warrantees don't include monumental willfull stupidity . just give us a credit card number and we'll ship your new one our right away "

That will fix it.....

http://www.unendorsed.co.uk/wp-conte...loved-ones.png

How did you measure this runout, and at what point on the shaft?

This may be a given, but I'm new to measuring boat stuff.

While funny.... SEI will actually still warranty it.... They have a 3 year no questions asked warranty. I called them at the end of the season and told them I struck something and they said, it is covered just email is a picture of the serial number plate from inside the top of the housing.... They told me of I forgot to loft the drive and drug it up a ramp, they will cover that too.....

It was a freak thing I think. I am thinking it was a side impact. It happened as I was swinging the boat around in the marina canal, to put the bow into the wind. No damage, not even a nick to the skeg. But the prop is a mess.

Sorry brother but a true dead blow hammer leaves no marks on something hard like a prop shaft .

I measured it with a dial indicator that was attached to an adjustable arm, that has a set of clamping pliers on the other end. I took the measurement on the smooth part of the shaft directly behind the splined area. Ideally I would have measured the runout at the end of the shaft, but I needed the nut on there in order to have something to turn the shaft with. So given this, .010" runout wear I measured, probably is even more out toward the end of the shaft..

Thanks for saying it.... it needed saying. :stooges:

Is the picture showing up? It shows on my Windows Surface, doesn't show on my iPhone......

Ya, that seems excessive.

Got all of the oil drained, degreased and cleaned it up today. So it is ready to ship back to SEI. Hopefully I can get them to send me a box to ship it back in.....

To properly measure the runout, the propshaft really needs to be taken out of the lower and checked on a bench with precision tools.

wow. thats a great vendor. well... then let me suggest this... i think you send it back or whatever and get a new one but if you want to try to straighten it , take it out and take it to your local heat treating shop. they spend half their lives straightning bent shafts that bend while being heat treated and can usually get them inside of a 1/10 or 2 at a cost so cheap you can't believe it. beating it with a hammer is wrong not only because it is crude and stupid but it is also ineffective. when a shaft bends, the metal both on the compression and tensile side of the bend work harden instantly. when you try to just bend it back , the material on either side of those two spots is softer than the original position so the staft " straightens " by " bending again right next to the original bend... so you end up with the grain structure in an S shape. you will feel it when you run your fingers down it when you are done " fixing" it. if you are on a desert island and need to get home then you take a rock and beat it close to straight and get home. if you have some mechanical sympathy and care about your hardware at all and have any sense of craftsmanship, you either get them to send you a new one or straighten it properly.

with all due respect to the guys with the hammers at the ready, doing something the wrong way like some hack just because you can get away with it, doesn't make it the right way to do something.

Very true ... wacking it with a hammer is not the solution ... it's not very hard nor labor intensive to drop the lower - pull the prop shaft... get it straightened correctly - then replace and reset the bearing load.... may be a good time to take a peak at the pinion anyway....

Sorry guys but were talking about a very minute amount of movement . Holy hell it's not bent in half . Gently finessing that tiny amount out of that shaft will not effect the changes in the steel that you prescribe nor would i consider it butchery . Nor will you bait me into a long drawn out argument as the point is moot anyway .

So true. Its done every day in industry with great success. This isn't rocket science. There is a fine line between a perfectly correct solution and a workable solution. In reality we deal with workable solutions. In theory we deal with perfectly correct solutions. Let the baitng beginning as I won't be biting either.

With .010" runout measured so close to the housing, I'd be more worried about the bearings than the shaft.

I put the dial indicator on it again today, this time at the very end of the shaft (Since the lower is now off the boat I was able to turn rotate the vertical shaft. It measured out at .063". So that is considerable....

Update on getting it repaired. Due to the crappy weather here in Michigan, I was 30 days late pulling the boat out of storage.. Well I checked my paper work and damn it if I didn't wait too freaking long.... As it turns out I bought the drive on 4-2-11. I called them and they won't budge. The guy said, "because we have such an open warranty policy and as for as long as it is (3 years) we simply can't allow for exceptions". Owning my own company and dealing with customers wanting the return policy stretched, I get it.... While bummed out, I am not upset with them. It is my fault not theirs for waiting so long.... The good news is, the day I did the damage I called my insurance company and started a claim. After I contacted SEI (last fall) I decided to "suspend" the insurance claim. I called my insurance company and they reopened the claim...... Since it is an aftermarket SEI lower and not a Mercury Bravo lower it isn't as easy as dropping the boat off at the local shop.... But my adjuster seems very easy to work with so hopefully I will get this all resolved and in the water soon.

I guess I'm missing something, if you bought it on 4-2-11 wouldn't a 3 year warranty carry you until 4-2-14- a little less than a year from now??

IF your insurance company won't cover it I will at no labor charge install a new shaft in it for you and inspect the rest of the lower if you want as I REALLY want to see what SEI is using for lower gears anyways. You would just have to remove the lower from the upper and bring it to me 100 miles north, Smitty

I meant to type I bought it on 4-2-10.... My bad.

Articfriends, insurance may be replacing the entire unit... If so, I will let you know if I end up with the old one as well....