I just acquired a 1990 GMC 1500 4x4 extended cab long box a week or so
ago. The previous owner said it had a VERY violent shake in the front
end that would start at 45mph and stop at 65mph. His mechanic looked
at the front end and couldnt find anything wrong... He was unable to
try to balance the tires as he didnt have a balancer big enough for
the 16 inch rims... but gave him a set of rims and used tires to try
on the front.

He didnt get a chance to swap them before he got a new truck and
parked this one. Before i drove the truck i swapped the fronts. I
didnt have the shudder on the way home. I had the old fronts balanced
and put them back on. I drove it for a few days with no problems
other than a slight vibration from the rear(havnent balanced those
yet, will do in a day or so).

Yesterday I drove at highways speed for about 20 minutes, I
decelerated off the off ramp and then back up to highway, i hit 45 and
there it went BANG BANG BANG BANG... darn near shook the doors off.

I parked, went to the place i was going, got in and drove off. Same
road, same speed. No issue.

It seems to be somewhat intermittant. I'm thinking it could be the
stearing box as the stearing is loose. The ball joints, etc look
good. I just redid the brakes, oil, transmission fluid, plugs,
etc...

The only other thing i can think of is a belt slipping or blister in
the tires.

Any ideas?

Thanks
JOsh

Its neat to watch from the outside too

What size tires?
Do you have a steering stabilizer?

Cheers

<mr.joshq (AT) gmail (DOT) com> wrote

On 18 May 2007 09:15:05 -0700, mr.joshq (AT) gmail (DOT) com wrote:


You kinda have the signs of a caster death wooble. This happens when
the combo of caster, toe-in and camber creates a dynmically unstable
front end that given the chance it can shake REALLY bad. Loose front
end components can agrevate it. Is this truck lift anf have oversized
tires or is it 100% stock?
-----------------
TheSnoMan.com

I had a problem like that on my 95 suburban. turns out that the control arm
bushings needed to be replaced.

<mr.joshq (AT) gmail (DOT) com> wrote