Well, to everyone's relief, especially mine, here's the final report on our
adventure:
Yesterday morning Lou Boone arrived to help me with the re-assembly of the
coach. The final drive had not yet arrived, so we busied ourselves with
installing the replacement right side axle and general cleanup. Then we
pulled the pinion carrier out of the FD. These pictures show what we found:
https://drive.google.com/open?id=0B3XquSIYjDleQXZPNkFKVUNGRnM
My hypothesis that the ring gear lost part of a tooth, causing the lock-up
and breakage of the axles and housing, was apparently wrong. It seems that
one of the pinon teeth let go and caused the damage to the ring gear tooth,
and the jam and breakage. As the photos show, almost the entire tooth
broke off. Why? Dunno.
The coasting noise I reported earlier was unquestionably a warning, but not
a very clear one. When I changed the FD lube after Bean Station, it looked
good, so little damage had been done by that time -- perhaps the gear had
fractured but was holding its position. There was no obvious reason to do
anything other that what I did -- make another trip. By the end of that
200 mile trip, the new lube was thoroughly polluted with ground up metal;
if the old had looked 1/10th that bad when I changed it, I'd have torn into
the FD then.
But, without being able to turn the pinon with the FD installed, I might
not have even seen the single bad tooth on the ring gear. And would
definitely not have seen any flaw on the pinion, which can only be examined
by removing the FD and the 6 bolts holding the pinon carrier into the FD.
I have no words of wisdom for any other potential victim except, "Don't
ignore a sudden increase in FD noise!".
Oh yeah, according to my records, I'd put 85,746 miles on that 3.55 FD from
Applied GMC, most of it supporting a Cad500 engine -- and a reasonably
moderate driver (not a JimK). I don't think this failure reflects
unfavorable at all on Jim's product. It was not a wear problem but more
what I'd call a "concealed defect", which can never be fully prevented.
After lunch we stopped by the friend's shop where the drive was to be drop
shipped. About 15 minutes after we left there I got a call to come back
and pick it up -- it was there on our first visit.
Offloading the old drive from the engine hoist and mounting the replacement
went smoothly: I was able to bolt on the mounting jig with the new drive
still in the box. An overhead chain hoist that I keep in place lifted the
FD & jig into a perfect position to bolt the jig to the engine hoist.
Installation of the FD went reasonably well despite some difficulty getting
it past my Cad 500 engine mount. It took us until time to clean up for
supper to get the FD bolted in place, but we ended the day feeling very
good about the day's progress.
This morning Lou bolted up and torqued the axles while I installed the
final drive cover he'd cleaned and painted yesterday (we used my old one
because of its temperature sensor and drain plug). Because I'd had to
drain ATF when I removed the FD, we had to pull the vacuum modulator from
the transmission and add fluid 'til it ran out (I didn't want to trust the
dipstick). I pulled the VM while Lou poured ATF from above. When we
thought we had it full, we cleaned up for a test drive. When I shifted
into Reverse, everything operated OK, but when I stopped a few feet later
and shifted into Drive, nothing happened -- nor in S, L, or R! Trying
again, I got D, so moved back onto the rack.
After several VM out, ATF in, VM in, engine run & shift gears, we finally
got reliable shifting. I don't know why we had so much trouble getting a
full fill, but we did. The dipstick read correctly when all was done.
I'm not going to tell you about the one time I tried to HOLD the modulator
in during the engine run & shifting. Nor about the blast of ATF all over
me, the chassis, exhaust pipe, the rack floor... Nope, ain't never gonna
mention that nor the pile of oil absorb I've got to clean up tomorrow.
Once we were cleaned up again, we took the coach for a trouble-free 25 mile
ride. It shifts properly and the FD seems nearly silent -- neither Lou nor
I hears well enough to say "absolutely quiet".
All in all, it's been a frustrating, but educational experience. I hope
this long thread will result in others having less difficulties!
I'll be leaving on Thursday for GMCDL Noccalula Falls, AL. I'm confident
of a trouble-free trip.
Most of all, thanks to all those who offered to, and did, help: The
Richardsons for receiving us and helping with the initial "repairs". Manny
for having the premonition, or something, to send me the two spare axles 18
months before I needed them. Special thanks to Jim K for expediting a
replacement drive to me, and to Craig Lechowicz for getting it built up and
to me promptly. And most of all, to Lou Boone for being here with me
through the critical reassembly and all the times when 4 hands were 10
times as good as 2. Thank all of you and those I didn't mention by name.
Only in "GMC Land".
Over & Out,
Ken H.
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