The Pantera Place
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Replacing A-Arm Bushings - Using A Vise
By Bill Taylor
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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, four pressing adapters, and a stout bench vise capable of opening 3 ½ inches between the jaws.
Figure 1 is a picture of 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 is a picture of a bushing installed in a Pantera suspension a-arm. The bushing is 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.
Note that the installed bushing extends farther on the “outside” (to the right in the Figure 2) of the a-arm than it does to the “inside” (to the left in Figure 2). 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 2 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 3 shows an a-arm mounted in a vise and Hole Saw #1 in position to saw the outer metal washer from it’s swage 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 4 shows the outer washer separated from the central metal tube.
Figure 5 shows Hole Saw #2 in position to saw off a small rubber donut and then saw off the 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 so the bushing can be pressed out of the a-arm. Figure 6 show Hole Saw #2 having sawn off the flange of the outer sleeve. The saws in Figure 5 and 6 are the same size but different colors.
Figure 7 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 is the only part of the bushing which now remains in the a-arm. The saws are used from the “outside” of the a-arm. In order to press against a flat surface normal to the bushing centerline, the pressing adapter on the left in Figure 8 is placed on the “outside” of the a-arm and the adapter on right is placed on the “inside” of the a-arm. The adapter on the right will bear against an unblemished surface of the inner sleeve.
Figure 8 shows the a-arm with the outer sleeve still installed mounted in a vise with two adapters. The adapter on the right is piloted in the outer sleeve and the adapter on the left is piloted on the surface of the a-arm. The adapter on the right is solid and is slightly smaller in diameter than the hole in the a-arm and is slightly wider than a-arm. This allows the adapter on the right to fully press a bushing out of the a-arm. The adapter on the left is hollow and allows the bushing to be pushed about half way out. This adapter design is used to minimize the opening size of required of the vice and make the adapter more rigid for the initial press of the bushing.
When pressing the bushing, position the a-arm and adapters as near the center of the vise as possible to minimize stress on the vise and direct the pressing pressure along the axis of the bushing.
Figure 9 shows the bushing outer sleeve pressed half way out. When this position is reached, the adapter on the left must be changed for one with greater depth to allow the bushing to be pressed fully out.
Figure 10 shows an a-arm with the bushing outer sleeve pressed half way out. At this point, the left adapter must be changed to an adapter with greater depth.
Figure 11 shows the second adapter on the left. This adapter pilots on the part of the bushing that has been pressed out. This adapter is deep enough to allow the bushing to be fully pressed 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 stout vise and long lever arm, you may find a bushing which will not move. If this happens, insert a hacksaw thru the center of the outer sleeve and cut a groove completely thru the outer sleeve. Do not cut into the a-arm. This groove will release the interference fit pressure on the sleeve and the bushing sleeve 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 12 shows the relationship between an OEM style bushing and the adapter used to press the bushing into the a-arm. The adapter bears on the outer sleeve flange but has a relief so the adapter does not bear on the outer washer or central metal tube. Figure 13 shows the adapter mated to the bushing.
Figure 14 shows a new OEM bushing and the adapters used to press the bushing into the a-arm. The adapter on the left is the same adapter used when pressing the inner sleeve half way out. The adapter on the left provides space for the left end of the bushing to stand clear of the a-arm when the bushing is fully seated. The adapter on the right is the adapter which bears on the flange of the bushing outer sleeve. 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 goes on the front most side of the a-arm and the aft bushing goes on the aft most side 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.
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.
I used a 4 inch Wilton engineer’s vise to test these adapters and it worked very well. But, it certainly was not easy work for the vice. Figure 15 shows the piece of tubing used to increase the leverage on the vise handle.
Figure 16 shows the saws, adapters, and the vise punishing piece of tubing used for pressing the bushings. The red saw is saw #1, the yellow saw is saw #2, the white saw is saw #3. The solid adapter with the stepped diameter is used to push bushings out. The longer of the two pieces of short tubing is the adapter used when pressing the bushing fully out. The shorter of the two pieces of short tubing is used when pressing the bushing half way out and also used when pressing bushings in.
The disc shaped adapter with the recessed area is used to bear on the outer sleeve flange when pressing bushings in.
Figure 17 shows the adapters used to press the bushings in and out. The adapters are made from 1.5 inch and 2 inch bar stock and 1.5 inch OD 0.090 wall thickness tubing.
The positioning tabs are made from sections of 1.5 inch OD tubing with the radius opened as required to fit. The positioning tabs on the small and large press adapters are not absolutely required but they aid in positioning the adapters and made the setup more secure. The 2 inch diameter adapter could be replaced with a ring made from 1.5 inch OD tubing with the ID opened to 1.375 inches to fit the OEM bushings.