Isolator Pad

[QCDriver]

How do you replace the teflon pad for the Z spring?

[QCDriver]

In the post "Air Ride broke", just ahead of his finger I need to replace the teflon pad. Mine does not have torx bolts to remove. Someone told me you

have to drill and tap to get pins out. Could I just lift axle, and dump air, and place pad in? It's missing and is loud.

[QCDriver]

No one can help?

[rhasler]

QC, I think this is what you're looking for, it's originally from an old bulletin that was added to the AL and AL II Service Manual. It describes how to install the pads on chassis that did not originally have them. I think on the later suspensions these were held on with roll pins, it seems like there was a service bulletin or something about them but I haven't been able to find it. The part referred to is a slipper pad, your chassis shows that it uses slipper pad part number 4000-56929 and roll pin part number 4000-582871. Those part numbers should change to a newer number, they are Hendrickson numbers. I think all you should need to do is raise the rear of the main support leaf to relieve pressure from the slipper pads, drive the roll pins out, install new slipper pads, and drive in new pins.

Here are the instructions on installing the pads on chassis not originally equipped with them.

To equip a chassis with slipper pads, four slipper pads 55QF41, eight retainer plates 71RU310P103, and sixteen 3/8" hex head self-tapping screws 131AX280 will be required.

The vehicle must be empty of all load when installing slipper pads (i.e., work on an empty vehicle). Before beginning the installation procedure, take the following precautions:

Chock the wheels of all axles.

Support the frame with frame stands.

Support the axles with jackstands.

Release all air from the air springs.

Replace or install the frame hanger slipper pads, using the following steps:

Complete the left and right sides for each axle at the same time. Remove the rebound bolt locknuts, washers, bolts, spacers and rollers. The torque rods can remain in place.

Apply an upward force on the cross-channel section (cross tube) or the lower air spring brackets with a jack or pry bar. This causes the tips of the main support members to drop away from the cam surface of the spring hanger.

Inspect the top sides of the main support members. If wear is uneven (i.e., grooving marks are not parallel), replace both right and left main support members. If grooves are parallel, or if wear is even, and wear on main support members does not exceed 3/8 inch (10 mm) the existing support members can be reused.

Inspect the frame hanger legs for wear. Replace the frame hanger if wear exceeds 1/8 inch (3 mm). If slipper pads were not previously used, or if existing slipper pads have worn through, also inspect the frame hanger cam area. Replace frame hangers if cam wear is uneven or if the cam area is cracked or worn through.

Remove the worn slipper pads (if used) and place new slipper pads on the frame hangers. If pads were not previously installed, use a slipper pad as a guide, and drill four 11/32-inch holes in each frame hanger.Make sure that the slipper pad is seated against the frame hanger cam surface before drilling holes. Improper seating results in poor slipper pad service life.

Position retainer plates over the slipper pads. Apply lubricating oil to 3/8-inch self-tapping screws. Insert and tighten screws to 25 lb-ft (34 N•m).

Release the jack or pry bar on the cross tube or lower the air spring brackets, allowing the main support members to move up to the new slipper pads.

Early production models used two sizes of rebound rollers. On chassis with slipper pads, use the smaller-diameter rebound roller (part No. 10QK269M).

Assemble the rebound rollers, spacers, bolts, washers and locknuts. Torque the locknuts to 50–70 lb-ft (70–95 N•m).

For tandem axle suspensions, repeat this procedure on the other axle.

[rhasler]

By the way does your truck have some kind of weird Rockwell automated transmission in it?

[QCDriver]

Thanks rhasler. I guess I have to drill in hanger or maybe it's just painted over.

No I have a striaght Meritor 10sp.

I did not want to start this project till I had an idea of procedure.

Thanks Agian.

[QCDriver]

I was putting on a air leveling valve today and finally spotted roll pins. No wonder I could not find them, they are the size of a small,

small finishing nail. The slipper pads looked as they would be pretty large (framing nail size).

On a side note, way are these air ride valves failing. 2nd in year and half. Very clean air, no oil or water.?

[MidniteMechanic]

How are they failing?