Engine/pump vibration

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Tazza

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I almost have my latest 743 finished but i have a concern with a vibration it has. I have replaced the U-joints but when i put them in they were a bit tight, they would flex in one axis easily but the other they were quite tight. I spoke to the guy i bought them off and he doesn't believe this would be an issue (he works in the bearing business). I thought the same but i still asked him about it all. I'm not too sure where it starts but i would suspect 1500-2000 RPM but if you go a bit higher it goes away and under its not there either. The machine still works great but its something i know isn't quite rite......
Has anyone had an issue like this before? all i can think is the pump/motor aren't in perfect alignment and the stiff U-joints are causing vibrations. That or there was some dirt under the fly wheel and U-joints when i assembled them but i did wire buff it before assembly so it shouldn't be the problem.
I think i will pull the motor on the w/end and check it all and maybe take a small skim off the U-joints to make them fit the housing properly as they were tight to install and i think thats what has caused them to get so tight. The part numbers were correct so the joints aren't wrong, its as if they are slightly over size where they mount up.
Any ideas peeps? The mountings aren't in a1 condition but i'm still happy with their condition, the pump and motor do not have any play.
 

skidsteer.ca

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Tazza
Is there any way to get a dial indicator in there to verify the shaft assemble does not have any run out.
Also the spline that adjust the lenght of the shaft is in good condition and both joints have their cups aligned looking down the lenght of the shaft. I know being out just one spline on the slider allows one joint to travel "ahead" of the other and will cause vibration, noise and eventually failure.
Ken
 
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Tazza

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Tazza
Is there any way to get a dial indicator in there to verify the shaft assemble does not have any run out.
Also the spline that adjust the lenght of the shaft is in good condition and both joints have their cups aligned looking down the lenght of the shaft. I know being out just one spline on the slider allows one joint to travel "ahead" of the other and will cause vibration, noise and eventually failure.
Ken
There is no way for me to check the alignment... I don't have the gear for one and access is really not possible....
The way the u-joints attach to their plates is they have a groove cut in the plate with a recess for the cups to fit in. There is no way the U-joints are out of alignment but they are tight due to being pulled into the recess which i believe is the cause of the tightness. I guess one could be sitting slightly proud too. The spline looked good as well, so i can't see that being it....
I think it will just have to come out so i can check it all. Being so close to the center line i didn't think it would be the cause but i guess you never know.
Its not a small vibration either, you can feel it through the whole machine. Hard to describe but its there.
 

skidsteer.ca

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There is no way for me to check the alignment... I don't have the gear for one and access is really not possible....
The way the u-joints attach to their plates is they have a groove cut in the plate with a recess for the cups to fit in. There is no way the U-joints are out of alignment but they are tight due to being pulled into the recess which i believe is the cause of the tightness. I guess one could be sitting slightly proud too. The spline looked good as well, so i can't see that being it....
I think it will just have to come out so i can check it all. Being so close to the center line i didn't think it would be the cause but i guess you never know.
Its not a small vibration either, you can feel it through the whole machine. Hard to describe but its there.
Could it be a balance problem in the engine. Was it ok before you changed the joints. or it was'nt running?
If I pulled the engine to check I'd run the engine with the pumps unhooked to see how it was then. We call that style of ujoint a "mechanix" they are a excellent design and can't hardly be installed wrong.
Ken
 
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Tazza

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Could it be a balance problem in the engine. Was it ok before you changed the joints. or it was'nt running?
If I pulled the engine to check I'd run the engine with the pumps unhooked to see how it was then. We call that style of ujoint a "mechanix" they are a excellent design and can't hardly be installed wrong.
Ken
Well i don't remember the vibration before, but i didn't run the machine a great deal to test for that...
I was thinking of running it without the jount just to be sure it was still balanced. The engine does run smooth so i reall doubt it is a balance issue but who knows.
I will probably pull the starter and check that the fly wheel is running true just in case there was a bit of dirt under it but i doubt it. I did wire buff all parts before they were re-assembled.
 
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Tazza

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Well i don't remember the vibration before, but i didn't run the machine a great deal to test for that...
I was thinking of running it without the jount just to be sure it was still balanced. The engine does run smooth so i reall doubt it is a balance issue but who knows.
I will probably pull the starter and check that the fly wheel is running true just in case there was a bit of dirt under it but i doubt it. I did wire buff all parts before they were re-assembled.
FIXED
Pulled the engine and tinkered with the uin-joints, threw the bolts in the lathe and took a bit off the heads as i think they were pushing it in for some reason. Either way they now moved MUCH easier than before and the vibration is now gone. I really shouldn't have installed it how it was, it was REALLY tight.
Took me around 2 hrs to remove the engine, fiddle with the uni-joints and replace the engine, it was so smooth reinstalling it too, its scary... Everything lined up really well and just slid into place. I just know next time it will drive me mad trying to get it rite.
 

TriHonu

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Apr 15, 2007
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FIXED
Pulled the engine and tinkered with the uin-joints, threw the bolts in the lathe and took a bit off the heads as i think they were pushing it in for some reason. Either way they now moved MUCH easier than before and the vibration is now gone. I really shouldn't have installed it how it was, it was REALLY tight.
Took me around 2 hrs to remove the engine, fiddle with the uni-joints and replace the engine, it was so smooth reinstalling it too, its scary... Everything lined up really well and just slid into place. I just know next time it will drive me mad trying to get it rite.
Glad to hear you got it sorted out.
It never ceases to amaze me the variety of symptoms you get when a power train joint starts to seize or gets some play in it. Vibration transfers through a machine a long way, and may be noticed first a a good distance away from the actual problem.
 
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