Spec’ing a new pinnacle. Looking for insight from those who have run Mack rears.

[Notch358]

Building a new truck with 46k rears and can’t find any information or testimonials of Mack rears on the internet. Only what Mack advertises. Personally like the idea of straight across driveshafts to avoid driveline vibrations but has anyone here run them and do the carriers hold up? The truck will be a 27’ Pi64t. 14,600 FA, 505c, MDrive 12 speed, 46k Mack rears with a 3.58 gear and a neway suspension. 

Edited October 7 by Notch358

[mrsmackpaul]

So these axles have top mounted centers ?

Or is this the Volvo equivalent ?

Certainly wont find many people that have anything bad to say about a Mack rear end 

Camel back springs are rough and tough but I'm pretty sure Mack stopped these a few years ago 

A photo of the axles may help get some better answers, I have never heard of a 46,000 lb Mack backend 

 

Paul

[Notch358]

It is the Mack top loader rears yes. Supposedly they’re assembled by meritor now but all Mack parts still but I could possibly be wrong. Just what I’ve found. Haven’t seen many out where I am in the Massachusetts and Rhode Island area. The normal spec out here for Mack seems to be meritor rears

[67RModel]

15 hours ago, Notch358 said:

Haven’t seen many out where I am in the Massachusetts and Rhode Island area.

What have you been looking at? 😁. Your in New England. Just about any vocational Mack older than 2007 (maybe newer) will have those axles under it. There has to be a litany of of those trucks still running around up there. You asking about an axle and carrier design with at least an 80 year legacy and have been essentially unchanged over that timeframe. Of course there are pros and cons when comparing them to other axles, however, generally speaking they are probably some of the most robust axles available without getting into specialty stuff. Of course this is a Mack forum so the information may be biased but I have never known anyone to dislike that setup for heavy duty work.....

[Notch358]

You would think that but everyone up here has meritor rears on tractors. I’m betting the trash industry, mixers and tri-axles are prevalent with them but I’m just a gas hauler that only hits the road when the sun goes down. Idk how these guys work days and sit in traffic all day.

[The Heinz]

I think Mack still sells the camelback, which they better. I haven't met anyone that actually likes the mRide (vRide with the stupidly expensive v-rods that break all the time), and there's obviously applications where air ride is not suitable. 

As for Mack rear ends, I really haven't seen any problems outside of age or abuse. I have seen more Meritors fail than Macks, but those probably weren't Meritor's fault. 

[Lmackattack]

If you are staying local with your truck and you have a mack dealer near you, you will be fine with mack rears. If you are over the road you might consider eaton or Meritor simply for parts availability when out on the road. Also If your truck has a dump bed or other body mounted to the frame know that mack rears have to come out from above where others can slide out from under the truck. that can make a big diffrence in servicablity reasons.

 

If you do go with mack rears I strongly suggest to avoid going with Macks automatic powerdivider.  Get a manual power divider and manual full locking main diff so that the truck has good traction with the air ride. 

 

Mack rears are good but I kinda lean towards off breed just for parts cost reasons. Mack seams to be the highest price for parts out of all the truck mfg out there. then the parts shortages that seam to come with Mack. not sure if other mfg have the same issues but I know Pete never had issues getting me parts where Mack often did.

 

Im in chicagoland so We have just about every dealer ship around here plus parts warehouses

[Geoff Weeks]

Mack rears have a smaller "bowl" that sticks below the axle housing (being a double reduction rear) which can be a real advantage when working off road in rough work sites. 

For fuel hauling,on road, there is no advantage to the design, more bearings and likely more heat when run down the road.

I worked on some Macks, but I had IHC, Eaton and Rockwell (Meritor) and found that all were good, and all had something that could have been improved. The Rockwell's were the only ones that outright failed on me, but they were put though a lot, before they failed, sometimes hauling 168K GVW on 40 K rears.

All will work and if cared for give good service, but I think single reduction for on highway service would be the best.

If the interaxle driveshaft is designed properly it doesn't cause problems or vibrate, despite being at angles, that is what U joints are designed to do. You have to get the pinion angles correct, so the joint angles are correct. 

Edited Sunday at 12:20 AM by Geoff Weeks

[Notch358]

Thanks for the info guys. Made some good points.