Replacement Axle Housings
Cracks may develop in the rear axle housings on certain Mack model chassis equipped with AL rear suspensions and Mack rear axles. These cracks would be noticed on the top or bottom corners of the housing in the area behind the axle seats, as shown in Figure 1.
Affected chassis were manufactured May 2004 or later and are equipped with housing Part No. 19QF5318P7 or 19QF5318P8.
If you notice axle housing cracks, replace the existing housing with the new housing. Part No.19QF5318P11 replaces Part No. 19QF5318P7 in rear axle housings without anti-lock brakes and 14 mm housing material thickness. Part No. 19QF5318P12 replaces Part No. 9QF5318P8 in rear axle housings with anti-lock brakes and 14 mm housing material thickness.
Before replacing both housings, verify the axle housing part numbers by checking the warranty history to see if the housings were previously replaced. If the housings were replaced previously, and the chassis is equipped with the 19QF5318P11 or 19QF5318P12 housings, replace only the housing that has cracked and do not replace both housings in these cases.
If the housings were not previously replaced and the chassis is equipped with housing Part No. 19QF5318P7 or 19QF5318P8 (11 mm housing material thickness), replace both housings with the housings having 14 mm material thickness.
An alternative method of verifying the axle housing part numbers is by checking the axle identification tag (see Figure 2). The housing will be identified by ID No. A 3121 E 2865 or A 3121 E 2866. The last four digits of the identification number identify the housings as follows:
If one axle housing is cracked, and the ID number on both housings ends in 2865, replace both housings. If one axle housing is cracked, and the ID number on both housings ends in 2866, replace only the cracked housing.
