| [GMCnet] Pulling the Front Clip [message #334263] |
Sat, 30 June 2018 15:04  |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma:
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Senior Member |
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As mentioned in an earlier posting, on Tuesday I helped friends remove the
front clip from a burned GMC. They called me Monday evening asking advice
on how to remove the engine. During the discussion, it became clear that
the coach had a good, undamaged, front frame which had recently been
rebuilt, using Lenzi parts. That led to the conclusion that removing the
whole front clip would be a good idea. Since I'd done that before, I
volunteered to come help, bringing my modified A-frame tow bar to attach
the clip to a pickup truck.
When I arrived at the job site, the 3 guys already there had disconnected
most things and, since the front of the coach was mostly burned away,
cleared most obstacles to the clip rolling out the front. They'd forgotten
a few hidden things and had not dared to remove the 6 bolts holding the
clip to the side rails on each side.
Among the forgotten items was the torsion bars. They, and I, had also
forgotten the need for a torsion bar tool to remove those, so I hadn't
brought mine. To make a long story short, we tried 'most everything:
Jacked the front end up so the A-arms were all the way down; removed the
top shock absorber bolts to allow the A-arms a few more degrees of downward
movement; Forced the adjusting screws out; Removed the bolts from the pork
chop's crossmember and used a hammer to drive it off the pork chops.
Nothing moved a torsion bar AT ALL.
With only removal of the lower ball joint nuts left as an option, we
decided to go ahead and try removing the clip.
I'd been unable to locate the A-frame tow bar I modified years ago by
drilling the coach end holes to 9/16" to fit the bumper bracket bolts. So
I brought along a borrowed one with which we'd just have to use 1/2"
bolts. Aside from having to kludge up a way to spread the legs far enough
to reach the bumper mounting points, that went well.
After replacing the shoring under the rear bogies to ensure the coach
wouldn't fall off, we installed front tires and connected a 4-wheel drive
pickup to the tow bar and began to pull, gently. No luck. Lots of
penetrating oil and some vigorous hammering at the clip-to-side-rail joint,
then pull again. 1/2" movement. Disconnect some still missed hoses,
wires, and tubes. Still 1/2". We'd already tried several heights of the
coach front to try to get the alignment correct, but nothing helped. Those
torsion bars were just TOO tight in the pork chops and/or the A-arm sockets.
Finally, in one last desperate attempt, we had the pickup driver "hit it
hard" -- and the whole clip moved out a foot!
Before going any further, we checked to see where the torsion bars had
released from: They HADN'T! Yep, we pulled the crossmember, torsion bars,
and front clip out "en bloc"! I'd never really given it any thought
before, but the fact is that the torsion bars react each other through that
cross member. The rubber isolators at each end of it really bear no load;
they just "isolate". They can provide some longitudinal restraint for the
drivetrain, but most of that probably comes from the front body mounts.
With a tag axle under the cross member and the steering column back on, an
acrobat could drive the thing! :-)
So, the front clip's out. The tale of how we got the
engine+transmission+final drive out of the frame with a too-small engine
hoist is another horror tale with which I won't burden y'all. We're still
facing the adventure of disassembling the 3 units and loading them on
trailers for their various destinations -- working on dirt with no overhead
beam.
Ain't GMCs fun!?
Ken H.
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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