JD 401b industrial flywheel removal any one familar?

[bemodoc]

Hi everyone I just got my backhoe running and was going to adjust the clutch and things just didn't feel right.I used a video inspection camera and found a broke clutch release shaft and a broke grade 8 bolt that held the throw out bearing fork to the clutch shaft.Needless to say I had to split the tractor to gain access to the shaft.I also pulled the pressure plate and clutch plate to check these.I found that the flywheel has 15 to 20 stress cracks where the disc contacts the flywheel which one crack is pretty bad.I am probably looking at replacing the flywheel.Here lies the problem.The wheel has 7 holes.6 of which are retaining bolt holes I am assuming and one locating dowel pin.problem#1 JD parts manual shows only 4 bolts are used to retain the wheel,which my wheel only has 4 bolts in it.I thought the worse and put a rod in the two unoccupied holes and it went down in the holes less than 3/8ths of an inch.I then looked in the holes with my video inspection camera and it looks like broken bolts in there.What mystifies me is that these 2 holes are tapped with 1/2 by 13 threads in the casting of the flywheel and I am assuming into the crank shaft flange also which leads me to believe this is why the bolts broke as you can not normally run a bolt into to separate threaded surfaces with out binding,not being able to clamp the two surfaces together.Problem#2 is I have not tried to remove the flywheel yet because I believe there is 2 to 4 threads or more in the threaded flywheel portion depending on the thickness of the wheel.I am needing to know if any one is familiar with this flywheel setup.The JD parts manual at www.jdparts.com only calls for 4 bolts.Did someone feel that the other 2 holes needed bolts thinking they were missing and broke them because of the threaded flywheel holes? I do not know.I am tempted to drill these out and attempt to use an easyout to remove them.I feel that I will have to pry the wheel off and pull the threads out if at all possible out of the threaded flywheel holes depending on how much of the bolts are left in the wheel.The 1/2x13 threads in the flywheel were verified by a tap.I do have an angle drill that I may be able do drill them.All information greatly appreciated.thank you

 

[Barry 1]

The 2 threaded holes are jack holes,used to remove the flywheel.Remove the 4 bolts,and screw 2 bolts into the threaded holes,tighten evenly to push the flywheel off the crank.

 

[bemodoc]

Barry1-- thank you so much for your answer.This is a life saver it will save me a lot of grief.This is why I posted my question as my mind kept thinking why is the flywheel threaded there has to be a reason and it was not for the flywheel bolts.I am fairly new to the backhoe/tractor game,I have run heavy equipment all my life but never had to work on much of it as you can tell.I have always told everyone that would listen that everyone has something to learn from someone else young or old and I am old 68 yrs and still learning.Again Barry1 Thank You