Crank Run-out.....

Discussion in 'Harley Davidson Extreme Modification' started by Bartman420, Sep 28, 2014.

  1. Bartman420

    Bartman420 Member

    What are you looking at and how do you check it?
  2. HDDon

    HDDon Experienced Member Contributor Retired Moderators


    BUBBIE Well-Known Member

    Don has you covered with the Vid...

    The 2.5 to 3 thous. is Good... .0025.... .003..

    When the cam-plate is put on and checked, It usually shows MUCH Less than the first crank check because the cam-plate crank bushing Holds the crank from the Little Wobble it has without the plate. UNLESS the cam-plate Bushing is worn and it Will over time.

    IF some Cranks are out like .006 or more, A Tight bushing will hold the wobble to some degree Until the bushing Wears... Then you will see More at the crank with the cam-plate on... VIBRATION will show up when wear is there...

    One owner said When the bike was new, IT never Vibrated and after 12,000 miles, now it SHAKES... The Crank was probably Out and the wobble was held to a minimum then Wear and the Wobble got worse and Worse...

    Harley Raised their specks to a higher number so that they didn't have to replace the Mass of out of Speck cranks... ? on where they are now... Asking the HD service techs may get you an abundance of answers:newsmile100:

    At or Under 3 thous. at the crank on the cam side with cam-plat off is good.

    More than 4 to 5 :bigsmiley15: in my book.

    :D mine was .0015 the 5 tents was because I could see the needle Barely move a tad on the .001.

    Somebody made a slip with the hammer pounding the cranks together on MY bike:newsmile100:

  4. dolt

    dolt Senior Member

    The video shows how to check run out. .003" is the criteria generally used for the "go/no go" decision to run gear drive cams as the video indicates. I would disagree with the comment in the video that one should pull the crank and have it trued, balanced and welded if run out is .005" or more. Not recommending it but I know some that are running gear drive cams with run out between .004"-.005" with no issues. There are larger/smaller gear sets that one can use to accommodate such situations and the gear sets will be set up on the "loose" side and will make more noise than if lash was within the specified clearances. IMHO, even with acceptable run out, gear driven cams provide no performance advantage over chain driven cams but do eliminate the possibility of tensioner failure. However, the early tensioners had a history of failure that is not shared by the later hydraulic tensioners or the new CYCO tensioner. Gear drive cams are a personal choice and using the .003" criteria as the "go/no go" criteria is wise.

    Run out greater than .006" will start to exhibit with motor movement a bit more than normal and when run out exceeds .008", it will be obvious that something is wrong. Unusual vibration/shaking to the point that the ride is not fun, fairing brackets will fail, etc. Then it's time to true up and balance the crank or trade the bike. JMHO :D