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Drive shaft knocking question?

vee-driven

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Took the rayson out last weekend and heard a knocking in the drive shaft area. My Question is if there is not any degree of angle in the drive shaft U joints will that cause a knocking noise?
 

AzGeo

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Did they knock in the past ? Have you ever GREASED them ? Did any of the 'balance pieces' fall off the driveshaft ? (check the bilge) All the 'internet experts' suggest multiple degrees on each end without knowing any of the dynamics involved. The faster it spins, the more it wants to STRAIGHTEN OUT, not fold into stupid angles ! The straighter the better and only when you LUBE all the joints will you control the harmonics. The angles will NEVER be perfect (most hulls move around in rough waters), but keeping everything lubed and all the mounting bolts TIGHT will prevent failures in most cases.
 

BamBam

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Did they knock in the past ? Have you ever GREASED them ? Did any of the 'balance pieces' fall off the driveshaft ? (check the bilge) All the 'internet experts' suggest multiple degrees on each end without knowing any of the dynamics involved. The faster it spins, the more it wants to STRAIGHTEN OUT, not fold into stupid angles ! The straighter the better and only when you LUBE all the joints will you control the harmonics. The angles will NEVER be perfect (most hulls move around in rough waters), but keeping everything lubed and all the mounting bolts TIGHT will prevent failures in most cases.

I was taught when I built boats that you need a few degrees of "deflection" to keep the needle bearings moving. If you build the shaft completely straight the u-joints will eventually lock up. The transmission output shaft and the v-drive input shaft need to be parallel so the load on both the front and rear u-joint are equal.

Knock in the drive line could be from worn strut bearings or issues in the v-drive too. the sound travels through the system so check all of the pieces.
 

AzGeo

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IMHO no matter how hard you try the driveline is never 'perfectly straight' and the boat 'moves around' at speeds, so I don't feel the 'needle bearings' (if properly greased) should have any problems. (I have not had problems with them) IMHO less angle creates 'less heat, less harmonics, less wear, and less drag' on the entire driveline. This is not a car driveshaft but it does 'move around' in the boat as the twists and bounces (deflecting the hull shape) across the water. IMHO a well designed and balanced drive line wants to run in a straight line, not at angles, the faster the RPMs the more it wants to be straight. (balanced mass in motion) I would never intentionally do a drive line install with 'built in angles' just to move the needle bearings, the angles always create 'unknown side loading and harmonics' of which I feel are much worse than 'stuck needle bearings'. Also, I've worked on a number of boats that had parallel gearboxes and you really need to know how 'drive lines' and 'U joints' operate when you work on those. SURE the noise could be from anywhere and I just gave my responce to his question about 'U joint angles'.
 

vee-driven

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Thanks guys, im gonna pull the drive shaft and take it to my local drive shaft guy. The v-drive is brand new, new propshaft, seal and collar, i replaced the strut bushings last year and there is probably less than an hour on the whole drive. i even checked my engine oil, it looks great, oil pressure is good and i cut the filter apart and not even a spec in it so engine is good.
 

djunkie

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Thanks guys, im gonna pull the drive shaft and take it to my local drive shaft guy. The v-drive is brand new, new propshaft, seal and collar, i replaced the strut bushings last year and there is probably less than an hour on the whole drive. i even checked my engine oil, it looks great, oil pressure is good and i cut the filter apart and not even a spec in it so engine is good.

I had Drive Shaft masters in Harbor City do the one in my Schiada. It's smooth as can be.


Sent from my iPhone paid for with Union money. :D
 

vee-driven

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He does all my drive shafts, im gonna have him recheck this one.
 

djunkie

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He does all my drive shafts, im gonna have him recheck this one.

Same here. Never had a single issue with him. Other than worrying about getting killed by his dogs. LOL. My Schiada drive shaft was way outta balance.


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vee-driven

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just pulled it and its goin in tomorrow. i might jack up the motor at the nose cone and shim the motor mounts to put a little ngle in the drive shaft. what years your little white truck, i see you all over lomita.
 

djunkie

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just pulled it and its goin in tomorrow. i might jack up the motor at the nose cone and shim the motor mounts to put a little ngle in the drive shaft. what years your little white truck, i see you all over lomita.

It's an '87.


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vee-driven

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i sold my 72 shortbed a few months back, miss that thing. i drive the big charcoal gray crewcab long bed chevy diesel with the rayson-craft sticker on the back window.
 

overpriced hallet

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Just a stupid question but do you have internal flaps in your exhaust tips??? as I have seen many of guys hear knocking noise and chased it forever, just to find out I walked up and shuved a stick in the exhaust and hold them open and noise was gone. I learned the same way and it drove me nuts.
 

vee-driven

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no flaps in the exhaust. the sound i would compare to a rope with a clasp on the end wrapping around the propshaft and going knock knock knock on the floor.
 

djunkie

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i sold my 72 shortbed a few months back, miss that thing. i drive the big charcoal gray crewcab long bed chevy diesel with the rayson-craft sticker on the back window.

I think I know that truck. You live off of Cypress right?


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overpriced hallet

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Well sounds like your on the right track, were the u-joints loose or siezed at all? I was gonna ask about your v-drive but I thought you had steve-o do it so you should be fine there.
 

vee-driven

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steve-o did the v drive, no issues there. djunkie, im off pennsylvania.
 

sangermike

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Vee Driven how's the Rayson running besides the driveline noise. you got any pics of it in the water or video of that bad boy running. I should have mine in the water this year.
 

repoman

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does it go away when you rev it up? if so it is gear lash in the v drive. mine does it when it idles in gear a long time. like you i have an enter cooler and when you idle long enough in gear like at blue water the fuel condenses on the enter cooler core and causes a rough idle . the rough idle rattles the gears in the v drive and makes that sound.
 

NicPaus

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Boat is good to go something came loose not sure. He called said ready to hit Parker next weekend.
 

Little D

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If you have a prop shaft cover, make sure its tight and in place.
 

Sold Honda bought Hondo

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IMHO no matter how hard you try the driveline is never 'perfectly straight' and the boat 'moves around' at speeds, so I don't feel the 'needle bearings' (if properly greased) should have any problems. (I have not had problems with them) IMHO less angle creates 'less heat, less harmonics, less wear, and less drag' on the entire driveline. This is not a car driveshaft but it does 'move around' in the boat as the twists and bounces (deflecting the hull shape) across the water. IMHO a well designed and balanced drive line wants to run in a straight line, not at angles, the faster the RPMs the more it wants to be straight. (balanced mass in motion) I would never intentionally do a drive line install with 'built in angles' just to move the needle bearings, the angles always create 'unknown side loading and harmonics' of which I feel are much worse than 'stuck needle bearings'. Also, I've worked on a number of boats that had parallel gearboxes and you really need to know how 'drive lines' and 'U joints' operate when you work on those. SURE the noise could be from anywhere and I just gave my responce to his question about 'U joint angles'.
X2:eek:
Vetts up to 82 run close to zilch for u-joint angle, no grease fittings and make 100k with no issues. .
Maybe installed d/s with u-joints out out of sync?
My d/s is little more than a late 60s chev 4 wd front shaft with vette companion flanges on each end and even running crazy angles in a truck don't seem to have problems....
U-joints are plenty forgiving to a point...But even in automotive application the faster it spins the less angle (under load) the better...been spinning my deal 66-7k past few days
(triple digits
attachment.php
...i'd be surprised if it had more than 1* on either end....As for knocking...under load/rpm or low speed/load? Mine has knock/bang/rattle anything less than 2k...always been like that.
Something i found that works well for chasing noises...ear plugs..been using the twist/lick/stick kind for a while.
Or.....when in doubt...take it all apart and check everything..TWICE, WITH
YOUR GLASSES ON! Them glasses caught the beginnings of a crack in prop shaft key way.
 
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