Torsion bars or springs it does not matter. When the truck is jacked into the
air by the frame the lower control arm is forced down by the spring/torsion
bar. The downward motion is contained by the droop bump stop which acts on the
upper control arm. Under these conditions the ball joints are being loaded by
the spring/torsion bar which can be several hundred pounds. When you jack up
the truck by the lower control arm the upper control arm is off the bump stop,
all the load being applied by the spring/torsion bar is being supported by the
jack and the ball joints are only loaded by the weight of suspension parts
above the lower control arm. This is when you can load and unload the tire and
feel for loosness in the ball joints most accurately.
The only time you would let the supension hang by jacking on the frame is in
those designs that the spring acts on the upper control arm and in McPherson
strut designs.
Dave Clement
99 SLT+ CC 4x4
In article <06f701c3c40d$f9d1c8c0$1a00a8c0@Wayne2000>, wallewelt@mai-aec.com
("Wayne Allewelt") writes:
>
>
> IMO, I believe that Josh is right, and this being my third truck with
> torsion bars I have to side with Josh.
>
> The only time that the torsions bars are putting a load on the front
> suspension is when the lower control arm is being pushed up from below, as
> in sitting on the ground or ramps. When you jack up the truck and let the
> suspension hang clear of the ground you do not have any tension load on the
> ball joints except the gravity load put on them by the hub, brakes and
> tire/rim, and you are actually putting a load back onto the torsion bars.
> The idea behind jack up the truck and letting the suspension hang is to take
> the bigger load off of the ball joints, that way they are easier to
> move/check. You do not have to jack up the truck to check the upper ball
> joint. If it is bad it will move with or without a load on it, but jacking
> up the truck does make it easier. I hope this helps.
>
> Wayne
> 01 QC Sport 4x4 V8
>
>
> ----- Original Message -----
> From: <david.clement@verizon.net>
> > In article <brnapu$k2q$1@bent.twistedbits.net>, jbattles@bankfinancial.com
> > ("Josh Battles") writes:
> > >
> > >
> > > "Phillip Batson" <pbatson68@yahoo.com> wrote in message
> > > >
> > > > Hmm. Ok, silly question: How would I know if they are
> > > > going out?
> > >
> > > Okay, this is what you do...
> > >
> > > jack vehicle and support by frame with front wheels about 4 - 5 inches
> off
> > > the ground. take a LONG pry bar (i use a 4 footer) and move the
> suspension
> > > (wheel) up and down (loading/unloading) while having someone look at the
> > > joints. If any sort of extraneous movement is observed, then it's time
> for
> > > new ones.
> >
> > Actually you would want to jack the truck up by the lower control arm so
> that
> > the spring/torsion bar is not loading the suspension.
> >
> > Dave Clement
> > 99 SLT+ CC 4x4
>
This archive was generated by hypermail 2b29 : Fri Feb 06 2004 - 11:47:12 EST