Question About Measuring Crank Runout

Discussion in 'Touring Models' started by Rod Stewart, Feb 17, 2016.

  1. Rod Stewart

    Rod Stewart Active Member

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    I looked at the post in the extreme mods section regarding crank runout, and watched the video.
    This may be a silly question, but could you not measure it from the left side?
    Seems to me removing the primary chain cover is a lot easier than removing half the exhaust system, pulling apart the top end, and pulling the cam cover as well as the cam plate, cams, chains, oil pump, etc to do it from the cam side. Not only that but you can use a socket on the left side to turn the engine over, which you aren't supposed to do from the right side as I understand.
    Thanks.
     
  2. Jack Klarich

    Jack Klarich Expert Member

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    The way the cases support the crank and the heavier pressed in bearings on the left side would not give the readings you are looking for IMO
     
  3. dolt

    dolt Senior Member Contributor

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    Yes, you could measure runout on the left side but what would that tell you? Since the crank is pressed, runout may not be the same on the left side as the right. Runout is measured from the right side because that's where major damage can result from excessive runout. Major runout on the left side may cause some vibration but excessive runout on the right side can cause oil pump failure, instant loss of oil pressure and possible major engine damage, depending on the circumstances.

    I don't know what video you watched. While it is necessary, in most cases anyway, to remove the right side exhaust to get to the cam chest, it is not necessary to pull apart the top end or remove the cam plate. The chain and sprockets must come off but not the cam plate. There is some debate about measuring runout with the cam plate in place vis installed but, having measured both ways, if runout is excessive, the brass bushing on the pinion shaft will not stabilize a tweaked crank. Even if you had to remove the cam plate, plate, pump and cams will all come out as a unit; it takes about five minutes. Rotating the crank is easy; plugs should be removed, trans in 5th/6th gear and rotate the wheel by hand.

    Trust me on this. If you want to measure runout, do it from the right side; measuring from the left side is a waste of time and the data meaningless. If you were to measure from the left side and register runout, you would immediately move over to the right side to check runout there.;)

    I have attached a photo of my home made runout checker. Note that the pinion bushing has been removed for a more accurate reading.
     

    Attached Files:

  4. Rod Stewart

    Rod Stewart Active Member

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    OK I'll buy into the idea that checking the runout on the cam side is the best.
    I thought that in order to check the runout you need to pull the cams, pumps, cam plate etc; so that the right side spindle is able to turn freely with nothing constraining it's actual runout.
    I also thought that unless you have quick fit pushrods you need to pull the top end apart to relieve the valve spring pressure on the pushrods so that they can be removed and free up the lifters? Of course to do this requires the fuel tank to be removed as well. Then the lifters need to be hung in their bores so that they don't drop into the case when the cams are removed? This is what I had to do on mine to change the cams as part of the 103" stage II kit. No big deal in that case since the whole top end and cylinders were changed out anyway.
    But before I would pay a shop $100 an hour now to pull the top end apart so as to check crank runout, I would pay the $185 to change the stock pushrods to quick fit. Then you never have to pull the top end apart again to service cams or anything else in the cam case.
    Please help me understand what you mean.
    Thanks
     
  5. tourbox

    tourbox Senior Member

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    Dolt has you pretty much covered on the correct side to measure the run out.
    99-02 the oem bearing on the left side was a dual timken bearing set up just like the old Shovels & Evos. To me more stable than a pinion shaft bearing
    In 03 they went to the same bearing on the left as the right, same P//N, what is called the pinon shaft bearing.
    tourbox

    You are correct on the Rocker Box removal if you don't have Adj. push rods. I think Dolt was referring to those.
    And yes the nose cone/cam chest has to be empty to take your measurement. I usually use a magnet or 90 deg. pic to remove the lifters out of there bore once the push rods are out of my way.
    I will label them for FI(front intake) or FE(front exhst.) when removing.
    tourbox
     
    Last edited by a moderator: Feb 18, 2016
  6. dolt

    dolt Senior Member Contributor

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    All I am saying is that one can measure crank runout without removing the cam plate for a spot check. The brass pinion bushing in the cam plate will wear rapidly if crank runout is excessive. If crank runout measures .0005" with the cam plate on, it will not measure .012" when removed if the motor has been running in that condition for a while. While there will be a difference in runout measurement with the cam plate on and off, the pinion bushing cannot correct excessive runout. So, all I am saying is the a "spot check" with the cam plate on would be the first thing I would do before going to the trouble to remove the cam plate, etc. for a more accurate reading. If that reading didn't register a big number, I might start looking elsewhere for the vibration.

    I did assume, incorrectly so, that adjustable pushrods would be part of a 96"-103" upgrade; pretty standard in most cases. I that case all that is required is collapsing the pushrod tubes, removing the pushrods and using the magnet holders or magnet to remove the lifters, to pull the cam plate, pump cams, etc. However, even with OEM pushrods, all that is required is removal of the rocker box cover, loosen the rocker supports and pull the pushrods from the top,. collapse the tubes, etc. not that big a deal. Even if I had to remove the tank, with the quick disconnect cross over, that's a five minute operation. I also have to remove the carb and backing plate for full access to the pushrod tubes. On my old FL, the seat does have to come off but not the tank. I do have to raise the tail end of the tank to get to a couple of rocker box cover fasteners.

    Runout will have to be .010" or more to cause abnormal vibration.
     
  7. Rod Stewart

    Rod Stewart Active Member

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    dolt; thanks for clarifying. What you are saying makes perfect sense now.
    I am leaning towards doing the quickie spot check with only the outer chain and sprockets and the outer pinion support plate removed. this frees up the oil pump to move with the pinion shaft if necessary and should provide a reasonable indication if there is a problem.
    If further investigation is warranted then I would use a bolt cutter to collapse the pushrods, hang the lifters, remove the cams and cam plate, and recheck the runout. On reassembly I would go with the quick fit pushrod setup.
    BTW I really like your modified pinion bushing plate for the quickie spot check. ;) Wish I had a spare one I could afford to modify!
     
  8. dolt

    dolt Senior Member Contributor

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    Here's another easy way to check.
    Before I modified the cam plate to check runout, I used a piece of aluminum flat bar that bolted to the face of the cam chest with a piece of 1"x1" aluminum angle attached (with a screw and epoxy) over the pinion shaft to mount the dial indicator. Took about 30 minutes to fab it up. I don't have a picture but I think you can visualize. Your plan to measure will work and I don't believe you will need a second measurement to know if the crank is the problem. Let us know what you see; got me curious now.;)
     

    Attached Files:

  9. Jack Klarich

    Jack Klarich Expert Member

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  10. Rod Stewart

    Rod Stewart Active Member

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    dolt; yes I am real curious as well! :rolleyes:
    It will be a few days before I get a chance to do this; we are in the middle of re-locating to Peoria for a few weeks.
    Jack; thanks for that link. Darkhorse looks like a good resource for bottom end rebuilding, if needs be.

    Just for clarification, am I correct in thinking that with the sprockets removed (but the cams, cam plate, lifters, pushrods etc in place) there is adequate clearance between any partially open valves, such that the pistons will not contact them as I turn the engine over by hand to check the runout??
    The pistons are standard 103" flattop and the cams are SE 255 with .556" lift. No head milling and standard head gaskets.
    Thanks!
     
    Last edited by a moderator: Mar 9, 2016