Need Help With Prop Shaft

[fndv8]

Wondering if anybody could help me out I've gone thru 3 prop shafts in the last 3 yrs the last one being fit by a marine mechanic who knew of my problem and lined the v-drive up and told it its all lined up and is all ture
boat ran great for 6 mths just the other day it started the old vibration between 1,200 - 1,400 rpm after an Inspection Ive found one of the Coupler
bolts broken in half.....(this is where the last 3 shafts have snapped right in the middle where the coupler joins the shafts)

could my problem be the the v-drive ?? eg. not turning the output shaft straight ???

Or could it be the coupler itself out of line ????

Or is my v-drive out of line again ?????

doesn't look like the mounts have moved or anything like that
it all looks the same

please help its driving me crazy !!!!!!! :mad:


Boat is a ski boat w/ 350 chev
casale v-drive

[058]

Could be that the v-drive is moving around. Post a pic of the v-drive and its mounting.

[fndv8]

I'll get some pics up after work
the v-drive does vibrate when the boats going nothing huge you can just feel it working also very slight back and forward motion is this normal ?

[Moneypit]

I'll get some pics up after work
the v-drive does vibrate when the boats going nothing huge you can just feel it working also very slight back and forward motion is this normal ?

NO.........

[RiverRacer]

I'll get some pics up after work
the v-drive does vibrate when the boats going nothing huge you can just feel it working also very slight back and forward motion is this normal ?

Is the v-drive moving back and forth or just the output shaft???, if the v-drive is moving you need to line it up and tighten it up!.. You need to fix this before using it again!..

[tunnelrunner]

Could this be caused by an out-of-whack driveshaft or an incorrectly aligned strut?

[fndv8]

when i say the v-drive moves I only mean flexing when its working in gear
the v-drive box isn't moving between its mounts the v-drive housing is strong and cant be moved by hand you can only feel vibrations when its in gear when your hand is sitting on top hopefully this is a better way to describe it

[058]

when i say the v-drive moves I only mean flexing when its working in gear
the v-drive box isn't moving between its mounts the v-drive housing is strong and cant be moved by hand you can only feel vibrations when its in gear when your hand is sitting on top hopefully this is a better way to describe it There should be no movement at all. Pics will help.

[FC-Pilot]

Could there be a slight bend of the output shaft of the v-drive?

Paul

[RiverRacer]

when i say the v-drive moves I only mean flexing when its working in gear
the v-drive box isn't moving between its mounts the v-drive housing is strong and cant be moved by hand you can only feel vibrations when its in gear when your hand is sitting on top hopefully this is a better way to describe it

It ain't supposed to be moving/flexing at all, your mounts must be too small. But if it's vibrating that bad you better check to see if you have a bent prop shaft and bad strut bushing and an unbalanced prop, does the prop shaft line up to the v-drive?, the coupler should slide on real easy with a new strut bushing!... If you can post some pics of your setup, that would help!..

[fndv8]

heres the pics

[fndv8]

heres more

[058]

Your V-drive has no struts. The prop shaft is pushing the gearbox forward causing a mis-alignment. Add struts and re-align the box. Art, can you post some pics of a properly mounted V-drive? Edit to add: The way your center plate has been cut down for, I assume seat or floorboard clearance further reduced the strength of the mounting plate.

[RiverRacer]

WOW, I can see why that would be moving around, and that hole in the plate don't help either!. If it was mine I'd be trashing that plate and brackets and start over!. But you could fabricate braces as close to the v-drive as possible going back to the stringers!. I don't have a pic with braces handy, but here's one I made for a K boat last year, 3/8" plate with 3/8" angle on both sides of of the plate, also used bolts with the shoulder going thru all three pieces, no threads otherwise the threads will eventually chew up the brackets and plate and you end up with slop in the bolt holes and that will cause the v-drive to move around!...

http://img132.imageshack.us/img132/923/vdriveplatebs5.jpg

[shooter2]

You sure do nice work Art. I was surpirised how normal the hardware was in the Gambler that Ray brown built for Norm Woods. Same old same old for many years. I have to try to get pics of my stuff to post.

Brian

[RiverRacer]

You sure do nice work Art. I was surpirised how normal the hardware was in the Gambler that Ray brown built for Norm Woods. Same old same old for many years. I have to try to get pics of my stuff to post.

Brian

Thanks Brian,

This stuff has been done like this for 30 years and it works, you know the saying "if it works don't fix it"....:D

[shooter2]

Thanks Brian,

This stuff has been done like this for 30 years and it works, you know the saying "if it works don't fix it"....:D

Ya but there is always room for change and innovation.

[RiverRacer]

Ya but there is always room for change and innovation.

True, but that costs $$$$$$$$$$ and probably end up with the same results!..:D

[fndv8]

update:

Took the boat out over the weekend went fine apart from breaking a coupler bolt on the output shaft of the v drive

just wondering if the hole on the coupler didn't line up eg not tapped right could cause the vibrations and snapped bolt ??

see pics

to me it really looks like that snapped bolt was never straight and on an angle

[RiverRacer]

Damn, that thing is a POS you need a new one, bolt was probably bad or over tightened or both!.. Looks like you need a new shaft log seal too, and where is the safety collar???..:eek:

[fndv8]

yeah going to get a new coupler this week.
no room for a safety collar unless you can have them on the outside of the boat eg just before the rudder so the shaft cant slide and hit the prop

[RiverRacer]

yeah going to get a new coupler this week.
no room for a safety collar unless you can have them on the outside of the boat eg just before the rudder so the shaft cant slide and hit the prop

There's some room now if you move the coupler up closer to the v-drive(only need 1/16" clearance)you might have room, maybe shorten the hose a tad also!.. You mean in front of the strut, yeah you can put one there, I don't like it there because it blocks the flow of water to the strut bushings!..

[fndv8]

Ok, I think i've found the problem my v drive mounting holes in the bearers / stingers have be come larger then they should be with the vibrations going thru the boat what a wanna do is take the v-drive out fill in these holes and start again with new mounting holes

My question is ...whats the best way to do this keeping in mind I dont have a whole heap of cash to use also if i did i'd just replace the timbers

I was thinking epoxy resin to fill the holes then make new ones & would it be strong enuff ?

[058]

The holes got wallowed out because the v-drive mounting plate is moving. Every time you nail the throttle the prop and shaft are pushing the v-drive forward. You need to double up the mounts like Art has done [pictured] or add struts to the box. Allow the box to move and your problems will continue.

[fndv8]

yes, I was planing on doubling up the mounts and adding struts also
just wanted to know the best way of filling the old holes and starting fresh

[shooter2]

WOW, I can see why that would be moving around, and that hole in the plate don't help either!. If it was mine I'd be trashing that plate and brackets and start over!. But you could fabricate braces as close to the v-drive as possible going back to the stringers!. I don't have a pic with braces handy, but here's one I made for a K boat last year, 3/8" plate with 3/8" angle on both sides of of the plate, also used bolts with the shoulder going thru all three pieces, no threads otherwise the threads will eventually chew up the brackets and plate and you end up with slop in the bolt holes and that will cause the v-drive to move around!...

http://img132.imageshack.us/img132/923/vdriveplatebs5.jpg

Hmm, intresting ski racks in that boat, made of balsa, never seen that before, but then again I dont get out much. Have you ever actually checked angle for being square when you get it> Any of the stuff that I bought for my boat was not square enough at all, so I machined it.

Brian

[RiverRacer]

yes, I was planing on doubling up the mounts and adding struts also
just wanted to know the best way of filling the old holes and starting fresh

Drill out the holes to the next size to clean them up, then epoxy some dowels in!..

[RiverRacer]

Hmm, intresting ski racks in that boat, made of balsa, never seen that before, but then again I dont get out much. Have you ever actually checked angle for being square when you get it> Any of the stuff that I bought for my boat was not square enough at all, so I machined it.

Brian

Ok, I'm a dumb $hit I guess but I don't see any ski racks, and there were none there when I rigged it???:confused: Yep, a lot of times the angles are not 90* in that case some sanding is in order but usually it's real close, gotta check for that when you buy the stuff!...

BTW, in case anyone is interested that v-drive was built by Tom Bentley!..

[shooter2]

Ok, I'm a dumb $hit I guess but I don't see any ski racks, and there were none there when I rigged it???:confused: Yep, a lot of times the angles are not 90* in that case some sanding is in order but usually it's real close, gotta check for that when you buy the stuff!...

BTW, in case anyone is interested that v-drive was built by Tom Bentley!..

Dem there thingys on the side with da round holes.

[RiverRacer]

Dem there thingys on the side with da round holes.

Dem there thingys are gunnel supports, original B boat stuff!..:D

[shooter2]

Dem there thingys are gunnel supports, original B boat stuff!..:D

But only ever seen them made of plywood. Looks like balsa in the pic to me.

[RiverRacer]

But only ever seen them made of plywood. Looks like balsa in the pic to me.

They are, just laminated!..:D

[shooter2]

Hey Carteaco: Here is the thread I was talking about.. The pic Art posted was good and on here.

Brian

[gfinishline]

When you do "re-rig" your boat I suggest you FIRST level the trailer and bunks. A bent or twisted trailer can cause many problems. I had a customer back in the late 1980's, with a 5/8's Howard runner that we were setting up for SE class. It was sitting on a Competitive trailer that had never been in an accident. After doing "bottom work" durring reassembly, everything went well. Then the owner took it home, tore it down for polishing and powdercoating. He reassembled it on the trailer. But once in the water the entire boat vibrated at all RPMs. Actually pulled shaft out of coupler in the water, saw the problem and went back to shop. Lifted the boat and put it on a "leveled" shop dolly (looked just like in the water), re-set all mounts. Measured the "original trailer", 3/4" high in the right rear. No wonder the previous owner "had problems" with the boat. Please "set - up" your trailer, BEFORE you move or align your V-drive.

[FC-Pilot]

George, thanks for the insight. Some times we forget about the little things.

Paul

[RiverRacer]

Ya know, 99 1/2% of the people never give any thought about the trailer, and it shows when you see them going down the road, more boats get ruined from a bad trailer especially when it sits over the winter with the motor in it, and even with the bunks set to the boat the weight of the motor along with the boat will still put a sag in the bottom unless you have a cross member under the motor and none do, that's why I always pull the motor if the boat is going to sit for any amount of time!..