Portable Press

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The following is a description of a method for removing and installing OEM style suspension bushings in Pantera a-arms. This method uses a 3/8 inch electric drill, three hole saws, three pressing adapters, and a purpose built portable hydraulic press.

Figure 1 shows an OEM style suspension bushing. The bushing consists of a central metal tube bonded to rubber. The rubber is bonded, in turn, to an outer metal sleeve which has a flange at one end. The central metal tube is swaged to washers at each end.

Figure 2 shows bushings installed in a Pantera a-arm. The bushings are a slight interference fit in the a-arm. When the a-arm is installed in the suspension mounting brackets in the chassis, the a-arm mounting bolt clamps the washers at the ends of the bushing in the mounting bracket and the bushing does not rotate on the mounting bolt. The movement of the suspension a-arm twists the rubber which is bonded between the central metal tube and the outer metal sleeve. Because the rubber is twisted when the a-arm moves, the a-arm should be installed in the chassis mounting brackets at the normal ride height position before the a-arm mounting bolts are tightened. This will prevent over stressing the bushing rubber when the suspension moves.

Figure 2 also shows labels to establish the location of the a-arm “inside” and “outside” with respect to bushing mounting surfaces.

Figure 3 shows the details of an installed a-arm bushing. Note that the installed bushing extends farther on the “outside” (to the right in the picture) of the a-arm than it does to the “inside” (to the left in the picture). The bushings must be installed in this orientation or the a-arms will not fit the suspension mounting brackets on the chassis.

To remove the bushing from the a-arm, the right hand most washer in Figure 3 must be separated from the central metal tube, the flange on the bushing outer sleeve (the metal part adjacent to the a-arm) must be removed, and the rubber bonded between the central metal tube and the outer metal sleeve must be removed. The outer metal sleeve can then be pressed out of the a-arm.

Figure 4 shows the three hole saws used to remove all but the outer sleeve of the bushing. The pilot shaft for each ole saw is sized to fit the central tube of bushing. No lubrication of the pilot shaft is required.

Figure 5 shows an a-arm mounted in a vise and Hole Saw #1 in position to saw the outside metal washer where it is swaged to the central metal tube. Hole Saw #1 is a 5/8 inch (16mm) saw with a custom pilot that fits the central metal tube.

Figure 7 shows Hole Saw #2 in position with a sawn off a small rubber donut and ready to saw off the metal flange which is part of the bushing outer sleeve. Hole saw #2 is a 1 ¼ inch (32mm) saw with a custom pilot which fits the central metal tube. The flange must be sawn off to gain a surface for pressing the bushing out of the a-arm.

Figure 8 shows Hole Saw #2 having sawn off the metal flange of the outer sleeve. The #2 hole saws in the two picture are the same size but are of different colors.

Figure 9 shows Hole Saw #3 in position to cut away the rubber bonded between the central metal tube and the outer metal sleeve. Hole Saw #3 is a 15/16 inch (24mm) saw with a custom pilot which fits the central metal tube.

When using Hole Saws #1, #2, and #3 it will be best to use the same saw on all the bushings to be replaced before changing to the next saw. This will minimize the number of times you will need to install and remove the hole saws in the drill motor.

After using the three hole saws, the outer sleeve will be the only part of the old bushing which remains in the a-arm. The saws are only used from the “outside” of the a-arm. The inside surface of the bushing outer sleeve will be unblemished, flat, and normal to the bushing centerline. This surface will be used for pressing the outer sleeve from the a-arm.

Figure 10 shows the portable hydraulic press. The frame is made of ½ inch by 2 inch steel welded and all joints reinforced. A 4 ton hydraulic bottle jack provides the pressing force. So as to keep the press as compact as possible, the vertical axis of the bottle jack is mounted slightly to the left of center in the press.

Figure 11 shows the portable press mounted in a vise. The press is mounted offset to the left to afford easy access for a-arms, bushings, and bushing adapters.

Figure 12 shows the three press adapters used in pressing out old bushings and pressing in new bushings.

Figure 13 shows an a-arm mounted in the press ready to press out an old bushing. The Removal Adapter on the bottom is piloted in the outer sleeve of the old bushing and the Large Ring Adapter on the top is piloted on the surface of the a-arm. The adapter on the bottom is solid and is slightly smaller in diameter than the hole in the a-arm and is slightly longer than bushing. This allows the Removal Adapter on the bottom to fully press the outer sleeve of a bushing out of the a-arm. The Large Ring Adapter on the top is hollow and allows the bushing to be pushed clear of the a-arm.

When pressing the bushings, position the a-arm and adapters under the center of the hydraulic bottle jack.

Figure 15 shows an a-arm with an old bushing outer sleeve pressed half way out.

After fully pressing the old bushing outer sleeve out of the a-arm, the a-arm opening should be lightly sanded with fine sandpaper, checked to be free of burrs, cleaned, and lightly coated with oil. The new bushing is a slight interference fit in the a-arm. If the bushing can not be fully seated because of rust, dirt, burrs, etc there is no way to remove the bushing without destroying it.

NOTE: Even with a 4 ton press, you may find a bushing which will not move. If this happens, insert a hacksaw thru the center of the outer bushing sleeve and cut a groove completely thru the outer bushing sleeve. Do not cut into the a-arm. This groove will release the interference fit pressure on the bushing and the bushing may now be pressed out.

After fully pressing the bushing out, a new bushing can be pressed in. The new bushing must be pressed in using the flange which is part of the outer sleeve. The outer sleeve flange must be used for pressing the bushing in to protect the rubber bonding. Figure 16 shows the relationship between an OEM style bushing and the Small Ring Adapter used to press the bushing into the a-arm. The Small Ring Adapter bears on the outer sleeve flange but prevents the pressing force from bearing on the outer washer or central metal tube.

Figure 17 shows a new OEM bushing and the adapters used to press the bushing into the a-arm. The Small Ring Adapter at the top is mounted on a new bushing and applies the pressing force to the flange of the new bushing outer sleeve. The Large Ring Adapter on the bottom supports the a-arm and provides space for the inside end of the bushing to clear the a-arm. The bushing is fully seated when the outer sleeve flange if tight against the a-arm.

Bushings must be installed with the bushing flange on the “outside” of the a-arm. The front bushing is pressed in from the front most side (“outside”) of the a-arm and the aft bushing is pressed in from the aft most side (“outside”) of the a-arm. If the bushings are installed with the bushing flange on the center part of the a-arm or with one bushing flange on the outside of the a-arm and the other bushing flange toward the center of the a-arm, the a-arm will not fit the mounting flanges on the chassis. When the bushings have been installed, they cannot be removed without destroying them.

When using the portable press, the orientation of the a-arm, whether pressing old bushings out or new bushings in, is always with the inner edge of the a-arm bushing opening toward the bottom of portable press. Old bushings are pressed out in the upward direction and new bushings are pressed in the downward direction.

Bushings require considerable force to press out and in. An OEM bushing which has never been replaced has not moved in over 30 years and has grown very fond of the intimate relationship it enjoys with the a-arm.

Figure 19 shows the details of the adapters used to press the bushings in and out. The adapters are made from 1 1/2 inch bar stock and 1.5 in OD 0.090 wall thickness tubing.

The 0.375 deep small spacer has the ID opened to 1.375 inches to fit the OEM bushing.

The positioning tab on the deep adapter is made from a section of 1.5 OD tubing with radius opened as required to fit. This positioning tab is not absolutely required, but it makes the pressing setup easier and more secure.