The case bolts are like thick rubber bands that stretch a long way when tightened. The object is to stretch them just into their working range when torquing them up. Once torqued they hold that clamping power for a few months, then they relax just a hint. So to find a bolt that is still at full torque a year or a half a year later is almost impossible.

 

You discover that the bolts seem to be very tight if you attempt to add torque. Not the case (pun). The torque load has stuck the bolt at the head contact surface and the thread contact area. There is a word for this factor, but I forgot it. So the proper procedure is to unscrew the bolt a full turn. The idea that the torque is to be done with "Dry" threads is a bit hopeful. Some lubrication was there from running, less than perfect cleaning or just touching the threaded end with your hands. So the torque on each bolt is actually different to start with.

 

So, if you want to see what the torque was approximately, mark a corner of the bolt head with a dot. Mark the case next to that dot. Unscrew the bolt a full turn with a breaker bar. Not a torque wrench.

 

Set the (Clicker style) torque wrench to the torque you expect to find.

Mark the socket right over the corner of the case bolt with the dot.

 

In one smooth motion with no stops, crank the mark on the socket around until the mark on the iron lines up. You may find the click before that so just stop at the click. Or, you may not find a click so you just keep turning until the click. You may find that all of the bolts need to turn a bit further to pull the same torque. Or all of them stop before the marks line up.

 

I use Nickel anti seize on the threads and under the heads and torque to the smaller of the torque range numbers. I torque the case bolts 6 times on the day of the build, then again the next day. I always find a few unhappy bolts the next day. You may loose a bolt now and then doing it my way, so keep a few spares on hand.

 

If you are turning a bolt and it is not gaining torque, stop turning it a discard it.   

 

Whatever method you use, do the torque pattern 6 times. You will be surprised how many bolts keep turning as the stack settles down to dead flat.

 

The irons are just not all that stiff. If it is holding torque the stack will keep a warped iron flat enough to run. So the engine may finish the race with all the irons junk and warped to junk status. So a leak from a warped iron is less likely.

 

Will retorquing the stack stop the leak? Maybe....................

 

Lynn E. Hanover

 

 

 

message dated 8/17/2012 11:41:22 A.M. Eastern Daylight Time, echristley@att.net writes:

I have a very slow oil leak, and I think I've traced it to originating at the joint between the rear rotor housing and
rear side plate.  I'd rather not open the engine up to apply sealant, but it is half a day's work to disassemble
everything down to the point I can get a torque wrench on the case bolts.  I'm conflicted on if I should go ahead and
break the case open if I'm down that far already.

How likely is that the seeping oil can be solved by re-torquing the case bolts?  If the torque is correct, is it likely
that the end plate is warped?

Would a good plan be to check the torque, and only continue disassembly if there is no movement?  That is assume that if
it is torque properly it must be a warped plate or missing sealant, but if the torque is low bringing it up to spec will
solve the leak.


--
Homepage:  http://www.flyrotary.com/
Archive and UnSub:   http://mail.lancaironline.net:81/lists/flyrotary/List.html