flywheel end play uneven through rotation

[Crawdad]

I went to set the flywheel end play and found that with the flywheel in one position I have about .001, and if I rotate 180* (keeping my indicator at the same spot, I have about .008, for a difference of .007
I tried a different flywheel and found a difference of about .017 (yes, that's a lot), again measured at two spots in the rotation. To be clear, I am not measuring runout on the flywheel as it rotates, I am saying I get very different end play measurements at different rotations.
Any ideas what could cause this? The motor is fully assembled.

[Bruce.m]

Maybe indicate off the shoulder of the crank (at flywheel end). Press from the pulley end to seat against the bearing and rotate to see if the crank to bearing mating position moves. That is one side of the end float. If that doesn’t explain the situation then it’s the flywheel side. Did you measure with the shims being clean & dry with no oil etc?

[Crawdad]

Good idea, I'll do that. (Yes, the shims were clean and dry). Thanks.

[Ol'fogasaurus]

Just a thought. If you can remove the flywheel and measure the thickness and surface constancy of the back surface of the mounting area where the bolts go through for thickness consistency. The flywheel is machined based on the flywheel's bolting to the unit that spins it so any inconsistency or "warp" showing up could be caused by that.

Back in the day, when light flywheels were all the rage, this was often a problem.

Lee

[Crawdad]

I wasn't able to get an indicator on the snout of the crank, but I repeated my measurements and found that in some positions on the rotation, with a certain shim stack I would have .005 play with free movement (a nice little click upon pressing the flywheel in and out). Pressing harder on the flywheel would not give any further movement. In other positions on the rotation, I would have essentially no play, but if I press hard, I could get the same .005.
So it seems that in some positions, the shim stack is giving me some springiness, and in others it is not. I am going to regard .004-.005 with compression as OK and call it a day.

[Ol'fogasaurus]

Also, as small as the differences area are, the + and - tolerance changes in those local areas would have me a bit concerned also.

Everything, even as small as you have found, does have a tolerance allowance. If you are pushing the engines design (RPMs in this case) Do you know what the tolerance for the flywheel is supposed to be?

I looked this up and there is a lot of information here: what is the flywheel tolerances for a vw a/c engine

Giving it a try as it is might be OK as long... as it is within the engine's tolerance level but be prepared also.

[Crawdad]

I'll just add that I have 6 shims in there, for a total of over 60 thou (that could give me some extra springiness.) That is because the flywheel isn't quite right, a custom job made to mate my Type 1 VW motor to a Subaru 5-speed gearbox. Previously I described the process of designing it, involving a 3-D printed prototype. I may have goofed on some of the measurements, or maybe it was machined wrong:

viewtopic.php?t=150113&start=45

[Ol'fogasaurus]

That first pix of the CSK of the hole in the cover is now not strong ("edge margin") as designed so, assuming there is any movement (such as expansion and contraction, et al) where the plate will be intended to be put, has the potential of being a problem.

The word "extra-springiness" bothers' me and is it one of the reasons for the CSK in the above pix? Even a small difference in thickness also can change the balance of the flywheel especially where the change is.

I would double check the machining of the flywheel and the shims also. Off road driving is different even it is just going to be a "putsy-putsy" driven vehicle... I still think I would have everything checked just to be comfortable.

Again, my opinion.

Lee

[Ol'fogasaurus]

Have you got the problems fixed yet?

Lee

[Phil69]

This is why I tend to steer people away from lightened flywheels if the engine is going into a full weight vehicle.

[Ol'fogasaurus]

I've run a couple of lightened flywheels before. My blue buggy has one and the Flywheel for the V6 for my black buggy is also lightened (and balanced) with a 4-puck clutch assy. I usually don't have an older flywheel use as people "slipping the clutch" can cause the metal in the flywheel to harden or harden in spots and not machine well.

A lightened flywheel isn't really the best of ideas for a daily driver. It has some uses but also some drawbacks.

To keep the speed the same on the road, especially on a long drive, the lightened flywheel can get to be a problem. For around town it can be better but "stop and go" can get tiresome which also can cause fast wear of the disc and pressure plate.

It has it's uses but it also has drawbacks...if this helps so plan ahead.

Lee