Flywheel Runout

[psimet]

Just running this by everyone for an idea or two. Mounting up my freshly machined flywheel on to a rebuilt engine. Runout is slightly over the recommended amount.

I don’t remember absolute measurement but it was 0.001”-0.002” over whatever the red book and/or the engine builder’s recommendation was.

The face of the crank shaft had existing dowel pins in it. I was going to pull the flywheel, replace the dowels, clean the face of that crank end, and rotate the flywheel 180 degrees to see if I can pull that runout down.

If all that fails I guess I’d shim it as mentioned in places. Guessing I would use a washer style shim under a bolt or two - any other ideas or advice before I resort to a shim or two?

[Phil Brown]

I've never heard of anybody shiming a flywheel, flywheel housing yes but not the flywheel. Get the motor nose down on an engine stand to eliminate the end play and check the crankshaft for runout on the rear flange. Hopefully it's good then start looking at how come things are out of wack with the flywheel, burr or nick on the mounting area,dirt or grease? bad machining
I'm in the same boat as you as I have a wheel right now on my bench that needs to be looked as it has a bit of a wobble to it

[psimet]

It’s on the stand now. Planning on pulling off and checking. What sort of allowed runout is everyone going with?

[Bob C]

I was able to get to .004 just by shimming the two bolts for the throttle control assembly.

[psimet]

Originally Posted by Bob C

I was able to get to .004 just by shimming the two bolts for the throttle control assembly.

I’m talking about the flywheel. Assuming you mean the flywheel housing. I was able to get to about 0.004” on the housing with shims.

[nkaminar]

Sponsored Links (Register now to hide all advertisements)

Can you stand the engine vertical with the nose down with that engine mount? And are you doing that to measure the runout?

[psimet]

Originally Posted by nkaminar

Can you stand the engine vertical with the nose down with that engine mount? And are you doing that to measure the runout?

I can. Will try that and see if it changes.

[BRENT in 10-uh-C]

Originally Posted by psimet

Just running this by everyone for an idea or two. Mounting up my freshly machined flywheel on to a rebuilt engine. Runout is slightly over the recommended amount.

I don’t remember absolute measurement but it was 0.001”-0.002” over whatever the red book and/or the engine builder’s recommendation was.

The face of the crank shaft had existing dowel pins in it. I was going to pull the flywheel, replace the dowels, clean the face of that crank end, and rotate the flywheel 180 degrees to see if I can pull that runout down.

If all that fails I guess I’d shim it as mentioned in places. Guessing I would use a washer style shim under a bolt or two - any other ideas or advice before I resort to a shim or two?

I am speaking to you as an engine rebuilder that also grind's Model-A cranks. Shimming the Flywheel is bandaiding a problem. Likely that problem is the crankshaft was ground without straightening it first. Then
it was ground off-center on the center main journal. Using a surface plate, set the crankshaft #1 & #3 journals on vee-blocks and measure the runout on the center main journal and on the face of the crankshaft flange with a tenths dial gage. This will tell you what/where your problem is.

[alexiskai]

Originally Posted by BRENT in 10-uh-C

Using a surface plate, set the crankshaft #1 & #3 journals on vee-blocks and measure the runout on the center main journal and on the face of the crankshaft flange with a tenths dial gage.

I don't have a comment other than that I've just acquired the tools to do this exact test in the past six months so that I can check the crank when I rebuild my engine. It's exciting!

[psimet]

Ok - I’ve got about 0.0055” one way then I flip the flywheel 180 and I get about 0.004”. High side is at the same part of the flywheel so guessing a little is the flywheel and a tiny amount is the crank or crank face.

I’m going to run with 0.004” unless anyone sees a huge issue.

Crank was done same time as engine by a large rebuilder. [emoji51] I bought everything after the original customer passed away.

[Phil Brown]

Less than .005 seems to be the accepted limit so you should be ok at .004

[Richard Knight]

You said it moved with the flywheel when you turned it 180 so that means that runout was ground into the flywheel. If it was me I would get it reground. I have a special fixture for mounting model A flywheels, not all shops would have that. Now is the time to fix it. Never shim a flywheel.

[psimet]

Originally Posted by Richard Knight

You said it moved with the flywheel when you turned it 180 so that means that runout was ground into the flywheel. If it was me I would get it reground. I have a special fixture for mounting model A flywheels, not all shops would have that. Now is the time to fix it. Never shim a flywheel.

Some moved. Roughly 0.002” so it’s a stack between the flywheel and the crank

[nkaminar]

You are good to go. I assume that the flywheel was balanced. Also the pressure plate.

[Bob Bidonde]

Ditto Richard Knight's opinion. At some amount of run-out that I do not know the amount of, the clutch will chatter.

[CT Jack]

Richard Knight is right on to the key point, never shim a flywheel. I would take the time to have the flywheel remachined (reground). The shop who did the initial machining didn't fixture it properly. With it properly fixtured the face runout should be within .001" without any difficulty. I also agree with nkaminar in having the flywheel and pressure plate dynamically balanced as an assembly.

[katy]

First thing I would do is check the crankshaft flange.

[psimet]

Originally Posted by nkaminar

You are good to go. I assume that the flywheel was balanced. Also the pressure plate.

Yes, I had the two balanced together.