The ProductThe torsion bars on Isuzu's pre-'92 Troopers are not terribly firm.
Many trucks sag or wallow under rough driving conditions. Some older Troopers
look like their front ends have been lowered for drag racing! Cranking up the
height control arm bolt returns some the lost height, but it does little for the
inherently weak stock bars. This is particularly evident in rough terrain.
To address this problem, CALMINI offers upgraded bars featuring approximately
25% higher spring rate, with a two millimeter thicker minor (unsplined)
diameter. The CALMINI bars come nicely packaged, with thick vinyl caps
protecting their splined ends. The blue powder coat finish is high quality and
should be long-lived.
The InstallThese are the tools I used for this install:
- 27mm socket
- 1/2" ratchet
- 3' cheater bar
- floor jack (or Hi Lift in this case)
- the factory jack
- sledge hammer
- wood for blocking under jack
- grease gun
- 2 floor jackstands
- Optional Tonka truck
The day/s before your installation, soak the height control arm bolts with
Liquid Wrench or a similar penetrant. Give the underside a good rinse to avoid
getting a clump of dirt in your face when you're under the truck.
Apply the parking brake and block the rear tires to prevent movement, and
loosen the front wheel lug nuts. Be sure to watching for stripped or stubborn
studs or nuts that may need replacing, a common Isuzu woe. Jack up the front end
and remove the wheels. Support the front of the frame (not the suspension) with
Begin loosening the height control arm bolt. Soaked in penetrant, (you
did apply it, didn't you?) the bolt should come out slowly but surely. If
not, the cheater bar or air tools will do the trick. I needed a three foot
cheater, but then I didn't heed my own advice and apply penetrant.
Once the height adjusting bolt is out, remove the height control arm. Easy,
right? If not, try using a jack to lift on the torsion bar just forward of the
height control arm. (Editor's Note: Torsion bars are very strong in their
designed use, which is twisting moment applied only to their ends. The bars are,
however, succeptible to failure if point-loaded along their lengths. The
smallest nick may result in localized stress and subsequent failure. If you do
use the jack here, be sure to pad its jaw with a wood block. I suggest
completely unbolting the torsion bar socket from the rear of the lower A-arm and
just muscling the bar out of both sockets without using the jack.)
For a better angle, tilt the jack by placing a half inch thick piece of wood
under the jack's base closest to the rocker panel, pushing the bar and the arm
up and in toward the middle of the undercarriage. Be careful of clearance in the
tight space under the truck, and rap with a hammer on the height adjusting arm
until it slides back off the torsion bar (you did apply Liquid Wrench,
Once the arm is off, remove the torsion bar. Easy, right? If not, try using
the factory jack to lift the front suspension - only enough to unweight the
torsion bar. This should give you more leeway to wiggle and shake the bar loose.
Wear gloves, because the bar can come loose suddenly, and there are plenty of
sharp corners just waiting to eat your knuckles.
Unused torsion bars are not side-specific, but used torsion bars take a 'set'
and must be installed on the same side, twisting in the same direction, as they
were when previously used.
Remove the vinyl
cap, grease the splines and use a hammer to gently tap the front end of the new
CALMINI torsion bar into place. I left the rear vinyl cap on the torsion bar,
but a chunk of wood might offer better protection from the hammer. If the bar
doesn't slide in easily, consider removing, cleaning, greasing, and reinstalling
the spline socket on the lower control arm.
Lift the torsion bar, just as you did when you removed it. Grease the splines
and carefully line up the height control arm with the splines, then gently tap
it on with a hammer and wooden block.
Reinsert the height control arm bolt, but ONLY after greasing it. I greased
one but not the other and found out just how much difference it made when I
needed three feet (and more!) of the cheater bar to move the bolt. When about
3/4" of bolt was sticking up out of the control arm nut I replaced the wheels,
jacked it back up and removed the jackstands. I cranked up the bolt for more
height, after lifting the weight of the front end, unweighting the torsion bars.
Here again, the cheater bar was a must. I made several trips to town, over
railroad tracks and through rutted alleys to allow the bars to 'settle in'
before I made final ride height adjustments with a tape measure, jack, and
Changing ride height changes wheel alignment, so consider having the truck
Performance ImpressionThe WomBAT weighs a porcine 4800lb, yet one of
the first impressions I had was that the CALMINI torsion bars were much too
stiff, even harsh. Bumps and minor potholes initially produced rough bangs, and
I was dreading my wife's summary of the new ride quality. I lowered tire
pressure in the BFG ATs from 40psi to a more sane 35psi and headed for the DiRTI
(Drainageway Ramp Travel Index) test.
The DiRTi test
simulates a 20 degree ramp, following a marked tire route up an asphalt
embankment. This attempt at the slope left the lead tire on the ramp some 8"
further downhill than the WomBAT's previous high point. The CALMINI torsion
bar's increased spring rate is potentially capable of the same travel as the
stock bar. In this case, on the WomBAT, the bars allowed less effective travel,
despite the 200 plus pounds of front winch and bumper. Fortunately, later
adjustments of the torsion bar revealed that articulation gains could be made by
lowering the front end back into the normal range of travel, preventing
premature maxing out of front suspension's downward travel. As before, the vast
majority of articulation continued to come from the rear leaf springs.
After the DiRTI test, I started the real dirty testing. I was surprised, as
the initial ride harshness seemed to disappear as I bashed over ruts, holes, and
ditches. My impression was that the torsion bars limbered up, and broke in. The
ride no longer suffered the jarring blows I was feeling immediately after
install, nor did the truck bounce and bottom out due to the massive bumper and
winch combo. Instead, the front end just soaked up the roughness, smoothing out
roads I would formerly have taken at far more cautious speeds. This improved
ride was certainly due in part to decreased tire pressure, but the vast
improvements in ride quality are clearly a result of CALMINI's torsion bars.
Since the installation, I have continued to be impressed with a number of
handling characteristics that the torsion bars have improved. The truck bounces,
dives, and wallows far less than it did with the cranked up stock bars, and
rough terrain handling ability is much improved. As a result, my driving off
road is much less tentative, and the approach to ruts and the like is more
likely to be aggressive.
The bars are also an improvement on pavement. Whoop-t-doo pavement changes,
where the stock bars used to allow the front to bottom out, are now easily
handled, and steering response is more precise. The front end also rolls less
because the thicker bars resist cornering compression better in sharp turns. All
of these things are a boon to street driving, especially given the Trooper's
less than Porsche-like handling.
ConclusionIs the CALMINI torsion bar the upgrade that your WomBAT
needs? The answer lies in the two factors: the type of terrain you drive, and
the weight you may add over the front end. Unequivocally, these bars are
required if you have, or plan to have, a winch. Even without a 100 plus pound
bumper, the winch's mass will make you want these firm bars because of their
increased spring rate. This will be doubly true if you thrash the truck in the
kind of places where that winch will be needed.
What if you will never add more weight than say a pair of fog lamps and an
ITOG sticker? Here, in particular, the decision will come down to the terrain
you plan to explore, and or whether you are pleased with your truck's current
ride. For most people, the Trooper's suspension, at both ends, is simply too
soft. It bottoms too easily and leaves the driver flinching at every good sized
dip or hole. Having driven a friends '91 with the same bars but no winch/bumper,
I can say that the control is exceptional. The front end stays flatter in road
turns, and mountain-road ruts no longer faze the suspension. That makes the
CALMINI bars a great option for a lot of Trooper folks out there.
Please mail the Isuzu ORC Staff
if you have questions or comments about this page.
Department Isuzu ORC
Bakersfield, CA 93313 U.S.A.
For more information, email CALMINI.