Thursday, March 19, 2015

starting a new thread or Shipwright's disease dead ahead, Captain!!!

In tearing down this motor to find the oil leak(s), I had to pull the flywheel in order to replace the rear  oil seal housing. The housing was a source of one of the leaks as someone had put a 9/16th" bolt into it instead of a 1/2". In doing so, it was stripped out as well as cracked. I had a couple of these alloy housings on the shelf so it was an easy fix. I ordered a new oil seal too just to be safe although I really don't think this engine has many hours/miles on it.

After looking at the flywheel closer, I realized that the builder had used some Associated Spring Special Alloy bolts throughout this engine and for the flywheel bolts as well. These bolts are a "grade 12" strength, nice aircraft quality fasteners. That being said, the four AS bolts for the flywheel were not shouldered, threads run all the way up to the head. Because the threads run through the fly wheel which is aluminum, they wore a thread pattern into the inside of the bolt holes of the flywheel. Thus enlarging the hole slightly. 

I ordered new ARP bolts which have a shank but when they arrived I found them to be too large, they are 7/16". Calling APTFast, where I ordered them, they confirmed they where the correct size for a 1300 large journal crankshaft. I tried them in my 1500 crank and they fit, I tried them in my small journal 1300 crank and they are too large. APTFast suggested perhaps I have an early large 1300 crank and the factory may have not switched over to using larger bolts yet. APTFast also said he did not have any ARP bolts in the 3/8th" size I need. Arrrrrrrrr!

So now I am at a crossroad, do I have the flywheel bolt holes bushed with some cold rolled steel inserts? Do I have them drill larger to fit the ARP bolts which would mean I would also need to enlarge the holes in the end of the crankshaft, which would mean removing the crankshaft. Do I have another dowel inserted into the crankshaft and use the AS bolts for clamping force? Again, I would need to remove the crank to do this as well. Or do I just buy a new Aluminum flywheel. 

A new flywheel would mean a new clutch as the old flywheel is for a 6.5" clutch...

I feel like it's a case of Shipwright's disease. For those of you who do no know what Shipwright's disease is, it goes like this:

Sailor owns boat. 
Boat has burned out light.. 
Sailor decides to change bulb. 
Sailor notices socket is corroded, decides to change socket. 
Sailor notices wiring frayed while trying to change socket. 
Sailor decides to change wiring.
Sailor notices light switch is corroded.
Sailor decides to change light switch.
Sailor notices ... 

this goes on and on and on and on and pretty soon, the sailor rebuilt
his entire boat because of a burned out lightbulb.

More likely, Sailor NEVER sails that boat again, it rots away
in dry dock because he doesn't have to time/money to fix everything he finds.

And this is where I don't want to end up. Right now, my goal is to finish two more races, get my "Hard Card" and race COTA in Nov. with SVRA. I'm sure the flywheel will be fine, most likely forever. I think I will button her back up, run my two races and revisit it before I race COTA. 
Maybe by then I'll find another Tilton flywheel, or pull the crankshaft and have it drill for the larger ARP bolts or just have another dowel put in. I can then freshen up all the bearings too and while I'm at it I can replace all the... 

Just replace the lightbulb and go sailing, SHIPWRIGHT!!!

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