Home / Equipment / Isuzu Trooper front suspension Part I / Part II

The 1998-2002 Trooper offers good front suspension travel for an independent front suspension ( IFS ) vehicle. in 1998+ Isuzu used longer control arms to allow for improved travel in stock form. The most common method of increasing the static ride height ( lift ) of the Trooper is to "crank", or add additional pre-load to the torsion bars. This method will allow about 1" of lift without using manual hubs, or the CV boots will fail quickly. More importantly though is the loss of droop, or more accurately called suspension extension travel. Increased extension allows the vehicles tires to follow the contour of the terrain ( articulation ) and provide better traction.

On an Isuzu Trooper, and most IFS vehicles, you want a minimum of 60 mm (2.36") of extension travel. The Trooper in stock form has nearly 80 mm of extension travel. Without any modifications, for every millimeter of lift you gain by cranking the torsion bars, you loose the same amount of extension travel.

Suspension Camber: There are no complete suspension lifts on the market for the Isuzu Trooper that address all of the changes in suspension dynamics (such as a drop kit). One of the effects of only adding torsion bar preload is the change in Camber. In the case of adding lift there is an increase in negative camber (while looking at the front of the vehicle the top of the tire will be closer to the centerline of the vehicle than the bottom) Negative camber is great for rear engine race cars that want to limit understeer, but it does not make for a neutral handling SUV. You normally want a centered or slightly positive camber. This allows the vehicle to understeer slightly, instead of oversteer (when the rear end of the vehicle begins to slide). An SUV that understeer's is much more predictable and is safer.

So how do you get better extension travel? It is actually quite easy with the proper tools, and not expensive.

I performed these modifications to increase the extension travel of my 1998 Trooper, and to correct the suspension camber.

1. Ball Joint flip
2. Low profile bump stop ( snubber )
3. Shock spacer

Beginning measurements with a 30 mm ( 1.18" ) torsion bar lift:
Distance from fender flare to wheel hub: 520 mm at static ride height
Distance from fender flare to wheel hub: 559 mm at full extension
Total extension travel 39 mm ( 1.54" )

Ending measurements with a 30 mm ( 1.18" ) torsion bar lift: :
Distance from fender flare to wheel hub: 520 mm at static ride height
Distance from fender flare to wheel hub: 582 mm at full extension
Total extension travel after modifications 62 mm ( 2.44" )

That is an improvement of 23 mm (.90") of extension travel
See part II for complete measurements of wheel travel

Many of these modifications can be performed on older Trooper II's, and Rodeo and Amigo products

Note: These modifications require mechanical skill and understanding of vehicle suspension systems. Perform these modifications at your own risk!

Ball Joint Flip

Step 1:

Vehicle in park (1 st gear with manual), parking brake engaged. Place jack stand under lower control arm cross member. Jack up vehicle and remove the front tire for the side you are currently working on.

Step 2:

After removing the wheel, you need to remove the cotter pin from the 22mm castle nut located below the upper control arm. After the cotter pin is removed, you need to remove the 22mm castle nut from the knuckle assembly. This nut is very tight and may require a cheater bar, or long wrench. In order to completely remove the nut, you may need to bend the brake line bracket down slightly.

Step 3:

You need to separate the spindle knuckle from the ball joint. The knuckle and ball joint are connected via a ~19mm tapered shaft. After the castle nut is removed the ball joint is still attached due to the pressure in the tapered shaft (similar to a tie rod end). It is not difficult to separate the two, but it does require the right tool. I used a three pound sledge. After hitting the knuckle squarely on the top and sides several times, the ball joint and knuckle separated. Make sure the jack is under the lower control arm , to prevent the assembly from dropping and putting pressure on the brake lines, CV's etc. The knuckle drops about 1.5", and the upper control arm will spring upwards. Use caution.

Step 4:

Remove the ball joint. 1998-2002 Troopers have three 12mm bolts attaching the ball joint to the upper control arm, 1997 and older have four 12mm bolts. The 1998 and newer ball joints are not serviceable, and should be changed if you vehicle is high mileage.

Step 5:

Install the ball joint below the upper control arm. By moving the ball joint from above to below the control arm you realize the total of the thickness of the ball joint mounting flange (8.3mm) and the thickness of the control arm at the mounting point (4.2mm), for a total of 12.5 mm or .49".

Step 6:

Now you need to reinstall the castle nut and cotter pin (use a new one). Consult your shop guide of proper torque settings. You will need to jack up the lower control arm, and push down on the upper control arm to reinstall the castle nut. It requires more coordination than strength

At this point you have made an improvement of 14mm. The factory upper control arm extension bump stop and shock is now the limiting factor.

Low Profile Bump Stop

Step 1:

Remove the old upper control arm bump stop ( snubber ). I used a set of channel locks to pull the rubber to the side and cut it below the step. It is very easy.

Step 2:

Install a low profile bump stop. I used a prothane # 19-1319 Ultra thin butn. It is 10.2 mm thin. The factory bump stop is 16.2 mm thin. At this point you have gained only an additional 4mm of extension travel. The shocks are the limiting factor, not the bump stop.

Additional Shock Travel
Since there is only an additional 6mm of travel available before the new bump stop is the limiting factor, it is not worth installing new shock towers, etc. to gain additional shock length. I used a 6 mm spacer to give me the extra extension travel I needed. Now the suspension extension stops at the low profile bump stop, as it should.
This picture shows the suspension at full extension. The vehicle needs to be realigned, as the changes will affect the vehicle toe in.
Driving Impression

I immediately noticed the difference in ride quality at higher speeds off highway. The suspension will not come to an abrupt stop as it cycles through the available travel as it did before. IFS has limited travel to begin with, every little bit helps.

Go to Part II for trail photos and complete measurements