- The problem
- A deficiency exists in the welds securing the rear spring insulator bracket to the axle housing. This is due to improper positioning of the weld, in relationship to the bracket and axle housing. Failure of the welds would cause separation of the spring insulator bracket and the axle housing, resulting in improper alignment of the affected axle.
- The fix
- Dealer will reweld the insulator spring bracket at no cost to owner.
Vehicle safety record
1977 Mack HMM Problems, complaints & recalls
No owner complaints about the 1977 Mack HMM have been filed with NHTSA. It is covered by 4 recalls, the latest in November 1977 for the hanger / bracket.
NHTSA data checked
DMore problems than a typical HMM year, for its age
- Complaints
- 0
- Recalls
- 4
- Crashes
- 0
- Fires
- 0
- Injuries
- 0
- Deaths
- 0
1977 Mack HMM recalls 4
Recall repairs are free. Your dealer fixes them whether or not you bought the car there - check your VIN at nhtsa.gov/recalls to see if yours is done. What to do
- The problem
- The involved vehicles do not conform to federal motor vehicle safety standard nos. 207, "Seating systems", and 210, "seat belt assembly anchorages". Vehicles equipped with viking t-bar seats have the seat belt anchorage located under the seat. The tether belt ruptured when subjected to the forces required in the safety test.
- The fix
- Dealer will relocate the tether belt floor anchorage to correct the problem, without charge to owner.
- The problem
- The involved vehicles do not conform to federal motor vehicle safety standard no. 209, "Seatbelt assemblies". Although the seatbelts in question performed marginally with respect to the 5000 lb. Load requirement, additional testing confirmed that the anchor could fail, allowing either the anchor to slip over the hold-down nut or the anchor to separate into two pieces.
- The fix
- Dealer will inspect and, if necessary, replace seat belt assemblies without charge to owner.
- The problem
- The flex blade fans on the involved vehicles may develop cracks in the laminated stiffener as a result of fatigue during operation. If such a condition exists and the cracks go undetected, continued operation could cause pieces of the stiffener to break off.
- The fix
- Dealer will replace the original fan with a steel fixed blade fan, free of charge.
What owners say
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No complaints about the 1977 Mack HMM yet
No owner has filed a complaint about this vehicle with NHTSA. If yours has a problem, share it here and report it to NHTSA.
Mack HMM: every year compared
All HMM yearsQuestions about the 1977 Mack HMM
Does the 1977 Mack HMM have any recalls?
Yes - NHTSA lists 4 recalls for the 1977 Mack HMM: hanger / bracket (November 1977); anchorage (November 1977); anchorage (October 1977); fan (October 1977). Recall repairs are free at any authorized dealer. Enter your VIN at nhtsa.gov/recalls to see whether yours has been fixed.
How many complaints has the 1977 Mack HMM had?
None have been filed with NHTSA so far.
Is the 1977 Mack HMM a reliable vehicle?
Its Safety Index is 26 out of 100 (grade D: more problems than a typical Mack HMM year, for its age). The index weighs complaints, crashes, fires, injuries, deaths and recalls against how long the vehicle has been on the road, compared with the same model's other years. It is not a measure of every repair - read the complaints and owner experiences, and have any used vehicle inspected before you buy.
What should I do if my 1977 Mack HMM has a problem?
If it is a safety problem, stop driving it if it is unsafe and contact your dealer. Report it to NHTSA at nhtsa.gov/report-a-safety-problem - enough reports start investigations and recalls - and share your experience here so other owners know what to look for.
Source: U.S. National Highway Traffic Safety Administration (NHTSA) complaints and recalls, checked . Complaints are owners' own reports and are not verified. How we use the data