Performance Improvement Ideas

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"How to improve on and off road handling and eliminate Death Wobble on a Jeep Cherokee using poly control arm bushings."

October 16, 2009 by Mike Strawbridge

Installing Poly Control arm bushings:

 Scott's XJ Wagoneer was showing the beginnings of the classic Jeep Cherokee death wobble.

After checking all the normal problems, we noticed that the drivers side control arm bushings were very mushy due to oil leaking from the air filter box (Classic Blow by problem as well) down onto the control arm had softened the rubber control arm bushings.

Having noticed the handling improvement that the poly bushing made to my 91 Jeep Cherokee Laredo, we decided to install them on his XJ as well.  The poly bushing can limit flex on an off road rig but, we have not seen much limitation on my 91 we decided to use them on the Wagoneer.  

We started by removing the lower control arms.  These can be removed one at a time with the Jeep sitting on the ground.

We used a hole saw to cut out the old rubber bushing .

Once the old bushing was removed, we used a wire brush to clean the inside of the control arm bushing shell.

The inside bore has to be cleaned and polished to allow the polyurethane bushing to press in easily.

We used a vise to press in the new bushing.  If aligned properly it slides in easily.

In order to completely seat the bushing, there has to be space to receive the part of the bushing that extends beyond the control arm.  We found a Ford axle nut socket was exactly the right size. A C Clamp was used as a press.

The lower control arm with the Poly bushings installed.

The poly bushiong are a tight fit into the mounting points.  we used a floor jack to press them into place.

An alignment pin was used to line up the bolt holes.

Torque the mounting bolts to the correct specs.  We replaced the stock Torx head fasteners with new grade 8 bolts.

The upper control arms are a bit harder to get to.  We removed the lower shock bolts to let the axle droop to the point the lower control arms limit the movement and supported the body on jack stands.

This gave just enough room to get wrenches on the upper control arm mounting bolts.

Again a hole saw was used to remove the old bushing material.  The axle end has to be done on the truck rather than on the drill press.

We fabricated a press out of a piece of pipe some large washers and some threaded rod.  The bushing pressed in easily once correctly aligned.

The body end upper bushing is installed just like the lowers using the drill press to polish and the vise to press in the bushings.

We had a little trouble getting the last bolt holes to line up as the axle had rotated slightly while the control arm was out.  We put a pry bar under the spring perch and used a floor jack to lift the bar and rotate the axle back to the correct alignment for the bolt.

The performance on the road was immediately noticeable.  Turn in is now much crisper and the high speed wander is now completely gone.  But best of all no more scary death wobble shaking!

More traditional Death wobble cures are listed below:

Front tires out of balance
Front alignment out of spec
Loose track bar
Worn track bar bushings
Worn track bar end
Need adjustable track bar
Bad bushings/joints in control arms
Worn/damaged steering stabilizer
Worn/damaged shocks
Worn/damaged tie rod end
Bad U Joint
Bad ball joint
Loose frame mount
Steering box looseness
Need drop pitman arm
Drive shaft(s) not balanced
Bad front hub assembly
Wrong size wheel studs in hub

See My Blog for more Death wobble cures and other Jeep Cherokee XJ Maintenance tips

Mike Strawbridge October 16, 2009

Are you absolutely thrilled with the car you are now driving?  Would you like to make it better express who you are?  Or do you just want to improve your Jeep's handling either on or off road? Mike Strawbridge's Car-coaching.com is here for you.

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