Flywheel Runout?

[Jhoppy]

I have a 71 mercury 1350 and I see a little wobble in the flywheel while running and am wondering how much run out is normal to see on the flywheel. And yes I have disturbed the bolts on the hub (I know bad), I had a very hard time removing the flywheel. After several attempts with a steering wheel puller and broken bolts (I know bad) I bought the right puller and removed the hub with my breaker bar in one had and 18? crescent wrench in the other pulling for all I was worth. When I got it off I found the on the tapered section of the shaft had seized to the hub and had torn metal off the hub when I removed it. So I carefully ground the transferred metal off the taper and kept checking to make sure I got all the ruff sections ground down to flush or a little below. Then I used some spray paint as bluing and checked to be sure I had good contact in the undamaged sections of the tapers and repeated until I was happy with the contact. So with all that I have done I am not sure if I need to take things back apart and look for anything that might be causing my wobble or if the little bit that I have is normal.

Thank you to anyone that can tell me how much wobble in the flywheel is normal. I know that none would be ideal but that?s not what I have.

Hoppy

 

[sschefer]

Re: Flywheel Runout?

I have a 71 mercury 1350 and I see a little wobble in the flywheel while running and am wondering how much run out is normal to see on the flywheel. And yes I have disturbed the bolts on the hub (I know bad), I had a very hard time removing the flywheel. After several attempts with a steering wheel puller and broken bolts (I know bad) I bought the right puller and removed the hub with my breaker bar in one had and 18? crescent wrench in the other pulling for all I was worth. When I got it off I found the on the tapered section of the shaft had seized to the hub and had torn metal off the hub when I removed it. So I carefully ground the transferred metal off the taper and kept checking to make sure I got all the ruff sections ground down to flush or a little below. Then I used some spray paint as bluing and checked to be sure I had good contact in the undamaged sections of the tapers and repeated until I was happy with the contact. So with all that I have done I am not sure if I need to take things back apart and look for anything that might be causing my wobble or if the little bit that I have is normal.

Thank you to anyone that can tell me how much wobble in the flywheel is normal. I know that none would be ideal but that?s not what I have.

Hoppy

Your at risk of damaging the crank and bearings. The engine is percentage balanced at the flywheel. If you look at the flywheel, you'll see balancing points. It's a production run balance job meaning that all of the cranks are considered equal so only the flywheels are balanced. Each flywheel will have different balance points but once balanced they will interchange with other like engines.

If you've gotten it of center enough to visually see a woble you should either continue to try to correct it or replace it. Sorry to be the bearer of sad news but I would just replace it since the resultant damage will be much more expensive.

 

[saumon]

Re: Flywheel Runout?

You said that you grind to remove metal. Did you grind the inner hub of the flywheel or the crankshaft end?

 

[sschefer]

Re: Flywheel Runout?

You said that you grind to remove metal. Did you grind the inner hub of the flywheel or the crankshaft end?

Cross your fingers..

 

[Jhoppy]

Re: Flywheel Runout?

You said that you grind to remove metal. Did you grind the inner hub of the flywheel or the crankshaft end?

I had to grind some on both but mostly the crank. Im not talking alot of wobble just a little. I measured it a month ago when i put it together and now have just got it runing it was only about .016 of an inch or so with i dile indicator on top just inside the pull start ring. i will remeasure latter on today.

hoppy

 

[saumon]

Re: Flywheel Runout?

This is not a good news. A used flywheel is easy to find and change, but a crankshaft is a whole different story (had to split the crankcase apart).

What i'm worried about is that this wobble can cause the premature failure of the crankshaft bearings and upper seal...

 

[sschefer]

Re: Flywheel Runout?

I had to grind some on both but mostly the crank. Im not talking alot of wobble just a little. I measured it a month ago when i put it together and now have just got it runing it was only about .016 of an inch or so with i dile indicator on top just inside the pull start ring. i will remeasure latter on today.

hoppy

.006 is max.

 

[Jhoppy]

Re: Flywheel Runout?

Ok I have re-measured it and it is .012 measuring it on top of the flywheel just inside the pull start ring. It is .018 measuring it on the top of the ring gear and .003 measuring it on top of the flywheel just outside of the crank hub. Also the high and low spots were almost all in line meaning that the run out probably is because of the taper. Replacing the crank and flywheel is not and option, I would be better off replacing the power head for that amount of work and cost. I spent a lot of time grinding on the tapers and got it as close to perfect as possible and I do not think I can make it any better than it is. So I will probably run it as is like I said It is not a lot of wobble .018 is equal to about 5 sheets of paper and that?s the worst measurement I had.

sschefer I am interested to find out where you got the max of .006 spec and where and how it is measured.

Thanks

Hoppy

 

[saumon]

Re: Flywheel Runout?

?Check Crankshaft Runout

Runout is a measure of how straight your crank is. You measure it with a dial gauge on a magnetic base. Drop the front and rear main bearing halves into the block. Put a couple drops of oil on the bearings and then lay the crank in them. Attach the dial indicator to the block with it's magnetic base and place the tip on the middle main journal. Rotate the crank and measure how much the dial indicator moves.?

So the measure is at the middle of the crankshaft. It's hard to tell how much does it mean at the end. Anyway, runout is more the measure of a ?bend?. Yours could be perfectly straight for now but with some material missing at the end, the weight of the unbalanced flywheel turning at high speed wil distort it in no time...

And here's wehre the 0.006 come from:

 

[sschefer]

Re: Flywheel Runout?

Ok I have re-measured it and it is .012 measuring it on top of the flywheel just inside the pull start ring. It is .018 measuring it on the top of the ring gear and .003 measuring it on top of the flywheel just outside of the crank hub. Also the high and low spots were almost all in line meaning that the run out probably is because of the taper. Replacing the crank and flywheel is not and option, I would be better off replacing the power head for that amount of work and cost. I spent a lot of time grinding on the tapers and got it as close to perfect as possible and I do not think I can make it any better than it is. So I will probably run it as is like I said It is not a lot of wobble .018 is equal to about 5 sheets of paper and that?s the worst measurement I had.

sschefer I am interested to find out where you got the max of .006 spec and where and how it is measured.

Thanks

Hoppy

Hoppy, that is measured at the crank on the top bearing surface.

The spec is out of the Merc Service Manual.

 

[saumon]

Re: Flywheel Runout?

As they don't specify the procedure in the manual, i do the opposite i.e. i place it on the block resting on the upper and lower bearings and measure the runout at the center. It could possibly give similar result.

Thoses specs are related to the crankshaft length. For smaller engine up to 60hp it's 0.002. Over that it's 0.006.

 

[Faztbullet]

Re: Flywheel Runout?

I dont think Merc gave spec's for this on the old inline due toa) the crank is shimmed and will rise and fall with rpm (end play is .004-.012) and (B) belt drive engine which slighty drags/preloads crank to front and side. Also do not measures the from the outter flywheel as it could not be centered true due to worn flex plate