Equipment Type

Mack Pinnacle is Solid and Satisfying

Class 8 truck has axle-forward design, and a stronger engine gives Truck Editor Tom Berg a solid ride.

September 01, 2007

New 12.8-liter MP8 dieselin highway type MaxiCruise tuning makes up to 485 horsepower. It's strong and clean-burning. Maxidyne and Econodyne versions have somewhat different operating characteristics.

The black Pinnacle Axle Forward retains the squarish nose and no-nonsense lookof the CH on which it's based. This one has heavy specs including a 14,600-pound-capacity steer axle.

Burlwood-trimmed dash has big gauges and easy-to-use rotary HVAC controls.
 

Yellow Pinnacle Axle Back's nose has smoother styling and a chrome V that used to denote Vision, the model from which it was derived.

Accelerator and brake pedals are the same height from the floor, allowingeasy and safe operation.

Test Set

Truck: Mack Pinnacle Axle Forward (CHU613)conventional daycab 6x4 tractor, BBC 116 inches

Engine: Mack MP8C (MaxiCruise), 485 hp @ 1,600 rpm (465 @ 1,800 rpm) and 1,660 lbs.-ft.@ 1,500 rpm (1,600 @ 1,100 rpm), w/back-of-cabdiesel particulate filter

Clutch: Eaton Solo 15.5-in. 2-plate ceramic, 9-spring

Transmission: Eaton Fuller RTLO-16913A, 13-speed overdrive

Front axle: 14,600-lb. Mack (by Meritor) FXL,on taperleafs

Rear axles: 44,000-lb. Mack (by Meritor) S440,on Mack (by Hendrickson) AL461 air-ride

Wheelbase: 196 inches

Brakes: Meritor Q+ S-cam drum w/Bendix ABS and Roll Stability control Tires & wheels: Bridgestone 11R24.5, M843 front, M711 rear, on Alcoa Dura-Bright polished aluminum discs

Fuel tanks: Twin 93-gal. polished aluminum

Trailer: 48-foot aluminum-steel flatbed

Can a new name make a big difference? Back in January 2006 we reported on a CH Rawhide, a fancied up version of a tough and reliable tractor Mack's been making for years. I scanned that article and was reminded that I liked the Rawhide's copious chrome trim and described it as quiet and good riding, while also noting that I had some trouble shifting its Mack 18-speed transmission in low range. I can now confess that I had a lot of trouble shifting it; it was nearly new, and like some Mack gearboxes, it needed to be broken in.

A year and a half later, I found myself in another daycab tractor, the Pinnacle shown here, and found I could go through the gears easily, and even float shift without the clutch much of the time. That to me made the Pinnacle Axle Forward, which is based on the old CH, an altogether different machine, even though the credit goes mainly to the Eaton Fuller 13-speed at the other end of the lever. Fullers are usually easy to shift right off the bat, if the truck builder's linkage allows it, and this one did.

But wait. There was another black Mack Pinnacle at this company-sponsored demonstration at the Las Vegas Speedway in Nevada, and its MaxiTorque 13-speed shifted easily, too. It's the same series as that 18-speed in the CH, so it appears Mack has made some changes for the better. In fact, executives said, the Pinnacle is indeed a changed truck, with more sound-deadening insulation, redesigned controls and instruments, and a stronger and longer cab.

Actually, there are two Pinnacle models, one with the forward-set axle as this pair had, and another with a setback steer axle. Each has weight-distribution or maneuvering advantages, depending on where and how a truck is to be operated. The axle-back version has smoother nose styling and a V at the top of its grill that used to mean Vision, on which it's based.

Changing the chrome V to a P would be difficult, so I'd have eliminated the V and made the grill look like that on the axle-forward model, which has a no-nonsense, straight-across upper bezel. But they didn't ask me.

They did ask me how the trucks drove, and I gave them a thumbs-up. The Pinnacles were such nice performers that I spent an hour more than authorized on the designated loop outside the speedway's grounds. This involved stretches of Interstate 15 and State Route 604, which border the grounds to the north and south. Our hosts instructed us to run clockwise, but I reversed it because northbound 604 has a stiff uphill stretch from just past the speedway to within a mile of the I-15 interchange. This provided a nice workout for another of the Pinnacle's new features, the 12.8-liter MP8 diesel.

The "8" joined the previously available 10.8-liter MP7 in January. Both, of course, are equipped to meet the government's new exhaust emissions limits, and both are smokeless and odorless. They exhale through oxidation catalysts and particulate filters, and you'd think those things would choke performance but they don't. The engines — Mack's and everyone else's — are gutsy and responsive, and drivers will like them when they begin appearing, even if the big Pre-Buy of '06-powered trucks has choked off sales for the time being.

MP means Mack Power, and the "8" has more of it — up to 485 horsepower and 1,660 pounds-feet of torque in MaxiCruise tune, versus 395/1,560 tops with the "7." The 7 is adequate, but the 8 is more satisfying to drive. Of course, higher horsepower in any engine series makes a big difference in acceleration and hill climbing. The MP8-485 handled the 6-percent grade on SR604 in 7th-direct (10th of 13 ratios), while the MP8-445 in the other Pinnacle Axle Forward required going to 6th-direct or overdrive (8th and 9th ratios) and topped the hill about 5 mph slower.

Those comparisons are fair, as I pulled the same flatbed trailer with both tractors. The trailer, with its spread tandem, was loaded with palletized concrete blocks, and I guessed the combination weight to be about 78,000 pounds. The tractor I'm focusing on in this article (numbered 5 for the demo) weighed a little more, as it had heavy specs, including a 14,600-pound steer axle, making it suitable to pull lowboys, equipment trailers, and other construction-oriented jobs. The other Pinnacle (number 3) had a 12,000-poundsteer axle.

Quietness is a principal improvement in the new Pinnacles, and this was apparent as soon as I had either rig up to highway speeds. There was little wind or road noise — the same thing I said about the CH Rawhide in that previous article — but it seems even more true of the Pinnacles. Mack engineers spent a lot of time fitting new noise-deadening insulation to the new trucks, and they probably knocked off several decibels. Most folks who drive Macks for a living will probably notice this on the new models.

Also nicer are the instruments — big white-on-black gauges with snappy bright-metal bezels and easy to use rocker switches. The rotary knobs for heating and air conditioning are simpler and easier to understand. To turn on the A/C, you push a reasonably sized button marked with a snowflake instead of hitting the tiny Max A/C button as on the old CH. The accelerator and brake pedals are the same height off the floor, making them easy and safe to operate.

The steel cab is about 4 inches longer than the CH cab, providing more leg and belly room for big guys and gals, and providing room behind the seats to stow stuff. This was an option last year, but now it's standard on both Pinnacles and the vocationally oriented Granites. Also, the reinforced Granite cab — claimed to be the strongest cab Mack has ever built — is now used on the Pinnacle.

All in all, the new Pinnacle, particularly this Axle Forward model with its MP8 diesel, has a strong, solid feel that made it more than worthy to be included in the demonstration. The demo was the first in a series that comprises the Mack Performance Tour, and customers (actual and hoped-for) are being invited to participate at venues across the country.Attend if you get an invite (or ask your local Mack dealer for one), because you'll be impressed.

 
 

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