Ron,
I sent a differential crown gear bolt thru the non-distructive testing
laboratory at an unnamed major aircraft manufacturing company, once based
here in Seattle. The bolts are fine.
Rootes did not follow their own blueprints and they used mild steel
fender-washers under the bolt heads. With every shift, these washers ever so
slowly get thinner and thinner, causing a loss of torque on the bolts. As
they loosen, they become more susceptible to shock and eventually they snap.
I have removed many broken bolts from differential carriers where the
bolt heads are visually intact, but they have snapped: I have removed many,
many more that are in situ with little or no torque.
About ten years ago I assembled a kit to replace the original (now
stressed) bolts and the incorrect soft steel washers. I used a special
aircraft graded cap screw with a long shoulder to keep the side thrust on the
shoulder and not on the threaded portion as Rootes did. Not one differential
that has my kit installed has failed from loose bolts over the same ten-plus
years.
If you are interested, I may be able to find two tech-tips that were
written at the time by Dick Sanders and myself. I had to discontinue
supplying the kit due to lack of interest: it did not make sense to have
several hundred dollars of special parts collecting dust.
Jim Leach Pacific Tiger Club Seattle
|