possible coupler problems.....vibration.

[oops!]

hi guys....im running an older rebuilt 350 (possibly a 78) with an alpha 1 gen 2 roughly a 1996.

i am experincing a vibration between 3k and 4k.
at 4 it flattens out. i would describe the vibration as mid to severe at 3k. ( carb problems did not allow me to monitor between 2-and 3k on the tach).

the coupler i have is a triangular style off my v6 4.3. the type that bolts to the outside edge of the flywheel.
i think the number is 18-2323. (the pics are black and white in the book and it is difficult to see for sure)

i have 3 main questions.....

1. when the coupler is insetred onto the shaft.....there seems to be some slop. not much....but some.....i compaired this with a different coupler and there was no slop at all.
is the slop normal? and is the coupler shot?

2. the drive shaft inserts allmost all the way into the coupler....i measured approx 3 1/2 inches ...it seems it can go in deeper....is the 3 1/2 inches enough?

3. if the 3 1/2 inches is not good enough....do i use the type of coupler that bolts to the center of the flywheel.....(number 18-2172) this will give me an extra 1/2 inch depth into the coupler.

these questions are aimed at finding the cause for the vibration.

btw.......one of the spring washers between the transom plate and the flywheel housing (in the phonelic washer) was partially broken this will be replaced.....i dont know if that will have anything to do with the vibration i dont think so.....but i want to give you as much info as possible.

thanks guys.....
oops

 

[Gary H NC]

Re: possible coupler problems.....vibration.

I have a feeling the slop or play in the coupler is the vibration.
How did the splines look?

Good question for Don on what couplers will work.

 

[oops!]

Re: possible coupler problems.....vibration.

the splines looked ok inside the coupler.....just a small partially shiny area inside the coupler (at the deepest point of insertion) that i could tell the distance of insertion......the was confirmed by measurements off the transom plate with the drive bolted on.

the toatal time under load was approx 1 hr.

 

[JustJason]

Re: possible coupler problems.....vibration.

any runout in the coupler? Is there any way with an engine on a stand to set up a dial indicator and have the tip hit the inner rim of the coupler to get a measurement?

 

[oops!]

Re: possible coupler problems.....vibration.

without running it up on a dyno......i have no idea how to do a dry land run up....

i could run it on its mounts and feed the cooling system with a garden hose...... inner but the transom plate would make findings difficult, as there isnt much room.

 

[oops!]

Re: possible coupler problems.....vibration.

by the way jason....i am unframillar with the term "runout" in the coupler.....can you please explain?

thanks guys

 

[starsnstripers]

Re: possible coupler problems.....vibration.

I'm thinking maybe, you said one spring washer was broken? That may cause the engine to drop a bit on one side therefore though it out of alignment. I'm not sure if thats enough drop to cause a vibration at various rpms but i suppose it's possible. I know on the older 165 MC-1 they had a revision to cut those spring washers (both) to get a better alignment so it must change to some extent, with that one broken.

 

[oops!]

Re: possible coupler problems.....vibration.

the alignment was bang on before the water test.

unfortunately....i unbolted the rears and the top of the fromt mounts.....THEN took an alignment reading. it was reading good all the way round except for a small 1/4 inch space on the bar that was not connecting the splines...

however the bar went in good and was easy to insert and pull.

 

[Bondo]

Re: possible coupler problems.....vibration.

i am unframillar with the term "runout" in the coupler.....can you please explain?

Hi Oops,... How ya doin' Buddy,...
The best way to check run out is by checking the alignment at 1/4 turns of the motor...
Run out is deviation from true center, by turning the motor, it should be even at all points...

Did you use the flywheel cover/ rear motor mount from the Gen.II, or the motor(older),..??

I can't feature there should be slop with the shaft engaged in the coupler...
Is there Any twist type slop, or just shake the shaft slop,..??

The mixin' 'n matchin' you're doing gets alittle odd sometimes,... But it Should work...
The fractured washer is of concern,+ the slop in the splines needs further investigation...

I'll check in later to see where ya gettin'....

 

[Don S]

Re: possible coupler problems.....vibration.

Did you re-check the alignment like I explained in your restoration novel, errrr post?

 

[oops!]

Re: possible coupler problems.....vibration.

wow....thanks guys.

yes don .....i did.

however i had allready pulled the bolts from the back and loosened the front mounts. so the readings were ambigous at best.

the alignment tool was great except for a small 1/4 inch spot of no contact.

this moved with the motor rotation.

the tool slid in and out with ease to full insertion

 

[oops!]

Re: possible coupler problems.....vibration.

Hi Oops,... How ya doin' Buddy,...
...

Did you use the flywheel cover/ rear motor mount from the Gen.II, or the motor(older),..??

I can't feature there should be slop with the shaft engaged in the coupler...
Is there Any twist type slop, or just shake the shaft slop,..??

....

the transom asembly and the flywheel cover is from the alpha 1 gen 2 set up...(v6) so the total back end ....except the block and flywheel are a configuration that worked earlier.

the slop is a very slight twist......and a shaft shake slop...possibly as much as 1.8th inch

 

[Don S]

Re: possible coupler problems.....vibration.

You didn't put some unknown flywheel on it did you? And replace that broken spring washer under the motor mount.

 

[oops!]

Re: possible coupler problems.....vibration.

the flywheel i had used first was a bbc .( it was sold to me as the correct one) it was used for 15 minit run up......then pulled

that was exchanged to an engine re manufacture supplied zero balance flywheel......the triangular coupler bolted right on......the rubbers fit perfectly in the circular inset in the wheel.

this current configuration is the one with the vibration

 

[Don S]

Re: possible coupler problems.....vibration.

Is it the same flywheel that has always been on that engine, that is what I am trying to determine.

 

[oops!]

Re: possible coupler problems.....vibration.

no it is not.

the engine previously was form a specially built for me cube van with an automatic transmission.......it had a flex plate.

the well known company that built the engine, supplied me with the new zero balance flywheel. and assured me that it was the correct one for the new application

 

[Don S]

Re: possible coupler problems.....vibration.

Have you tried a different prop?

 

[oops!]

Re: possible coupler problems.....vibration.

i tested the brand new rebuilt 19 inch prop on my bayliner at 4200 rpm and found no vibration from it....

i also at the same time.....took the big boat and ran it up on the muffs with out the prop...

no vibration......but also.....it was not under load.

the prop shaft looked very stable at approx 2000 rpm in gear....i did not have a potentiometer.

 

[Don S]

Re: possible coupler problems.....vibration.

i tested the brand new rebuilt 19 inch prop on my bayliner at 4200 rpm and found no vibration from it....

Not sure what that means, Is that the prop that was being used on the boat that vibrates?

 

[oops!]

Re: possible coupler problems.....vibration.

also.....at this exact second......i have acess to another coupler.

i beleive it is a "crank mount" (for lack of better terminoligy)....and not the "triangular" type...it was off an sbc alpha application.....

would there be harm in using this.....?

my understanding is that they were for older motors that had a different setback for shaft/block positions. (i hope im explaining that right without going into great detail.)

this would allow for deeper insertions into the coupler and at least i can see if the slop goes away