Pete's Aero 386
Steve Sturgess
Senior Editor
The big news for Peterbilt this year was the reintroduction of an aero model based on the UltraCab/ UniBilt cab/sleeper to supplement the big-cab 387. Designated the 386, the new model substantially fills the old slot vacated by the 377 A/E when the 387 came along.
That's not a change of heart for Peterbilt. And in fact, the 377 never really went away. However, it did become a variant of the 385 series, available only as a daycab.
With the 386, though, Peterbilt has added a second aero sleeper model that offers customers an alternative to the 387. Or rather, a complement to the big-cab model for customers who either want the features of the bolt-together cab/sleeper or simply want both models in a more mixed fleet.
The complementary nature of the new model is obvious from the styling of the Metton hood and side skirts that borrow visual cues from the 387. The 386 is the truck for the driver who likes the Peterbilt qualities, wants an aerodynamic truck, but likes the feeling and ergonomics of the traditional cab and the visibility it offers to the passenger side.
But don't go thinking the 386 is just a rehash of the 377. Far from it. With the exception of the cab and sleeper structure and the sheet metal, there's much that's new about the 386 – and much of that is in preparation for the upcoming 2007 emissions that will force many changes on truck manufacturers over the next few years.
To get a more detailed look at the 386, we took a test run out of the Denton, Texas, plant heading initially a few miles north on I-35 to top off the tanks at the TA. Then, turning around, we headed south on I-35W through Ft. Worth and on to Waco, where we turned for the edge of the Texas Hill Country.
A lunch break at Billy the Kid's hometown of Hico allowed for a quick average speed calculation, though with no on-dash engine display, there was no opportunity for a quick fuel check. However, after returning via a number of state two-lanes, we topped off the tanks after 346 miles to score a remarkable 6.88 mpg, averaging 46 mph overall.
The Truck
Many of the new features for the 386 center around getting a low hood line for clean aerodynamics and good forward visibility. So there's a new front crossmember that lowers the radiator significantly. And part of the front end redesign includes careful attention to steering, giving the new model just about the tightest turning of any of the Class 8 Peterbilts.
Other front end features included Bendix disc brakes and the Sheppard M100 steering gear that is a particular favorite of mine.
At the rear, a lightweight Pete Air Leaf suspension supported a Dana Spicer tandem featuring a 3.55 ratio and drum brakes. Thus, this 386 had a braking setup that many are tipping for the future – front discs, rear drums – much as the disc brakes started their long evolution in passenger cars.
The 386 front axle sits further back than the earlier aero Pete and the longer nose gives the truck a 126-inch BBC. However, the new axle position not only helps with wheel cut and maneuverability, it allows for improved front axle loading. That means shorter wheelbases for further maneuverability enhancements.
Over the redesigned front end is the new hood in the Metton material that is remarkably tough and impact resistant. The hood has an aggressive slope allowing for relatively close sight to the ground and good air penetration. There's an easy tilt and an anti-blow-down latch on the driver's side.
Unique to the 386 is a NASCAR-inspired sunvisor that also aids aerodynamics with a reverse lip that channels air through the visor and up over the roof fairing.
Mirrors are refined, mounted to the cowl and a lowering of the door belt line, further enhancing visibility to the front and sides.
Chassis fairings also keep the air flowing cleanly. These composite pieces are available in several configurations to accommodate fuel tank mountings forward or back.
As well as composites, there's lots of aluminum in a Peterbilt. Obviously the cab and sleeper are crafted in aluminum and feature bulkhead-type doors, lapped seams and huck fasteners so the cab is tight and rattle free.
But frame crossmembers are aluminum as well, and there were aluminum hubs on the test truck. Wheels were obligatory polished aluminum. The engine also featured an aluminum flywheel housing.
Power for this test 386 was a Caterpillar C15 ACERT 475, rated 475 hp at 2100 and peaking 490 hp at 1,600 rpm. Torque peaks at 1,200 rpm with 1,650 lbs.-ft.
The ACERT engines will run out to the full rated speed, but drivers best beware: For good fuel economy, they need to be kept way down the scale, ideally between 1,100 and 1,400 rpm, so the peak power point of 1,600 rpm is in the driver's favor.
The 3.55 gearing of this truck, with the nine-speed's 0.73 overdrive top gear, gave it a nice, relaxed 1,310 rpm (or 1,314 calculated) at 60 mph with the 22.5-inch Bridgestone rubber. This means 65 mph at the 1,400 rpm limit that Cat would recommend. However, with only nine forward gears, the steps are too big to keep the engine always in the recommended speed range of 1,100 to 1,400 – something that can impact fuel economy. The second owner of this 386 likely will do better because this is the upgradable nine-speed, which is easily converted to a 13-speed for resale value.
Those Bridgestone drive tires were the latest EL, with 32/32nds of tread.
The Cab
The whole cab interior has received a redesign as well. The multiplex dash is the obvious part, with a lot of technology behind it, providing for enhanced performance and features while removing yards of wire from the rear of the instrument panel. This has allowed for a redesign of the heater and ventilation ducting, also enhancing its performance.
The "A" panel ahead of the driver is common to all traditional Petes with big speedometer and tachometer, flanked by six engine gauges. The "B" panel to the right has the air and chassis temperature gauges and is customizable. In our case, this was the Fleet Gauge package, which included, oddly, a pyrometer in the eight-gauge-and-a-clock setup.
The Prestige trim level includes a woodgrain dash with the new digital climate controls set low on the wing, sharing space with the ConcertClass stereo and the rocker switches. Key and engine start are to the left of the column and the windshield wiper control is a column-mounted stalk occupying automotive-style positioning.
The trim has a very automotive appearance as well, hardly surprising because the designers were going for a BMW/Lexus-like feel with the redesign. It's very elegant and simple, and the marketing people at Pete think the luxurious feel will appeal to drivers – especially newer generation drivers more used to this approach in the cars they drive, even if they may not be the above sporty sedans.
A little at variance with this was the practical rubber mat on the floor. But if you want carpet, there's another trim level above: the Platinum, which brings a wealth of wood trim as well.
Interestingly, in the cab redesign, the classic Peterbilt clutch pedal is retained, much to the delight of the customers, says Pete. Actually it works well and allows for a very simple linkage. And there's now a dead-pedal footrest out to the left side. Just above this is the foot-release clamp for the tilt and telescope steering column.
Storage is fairly well provided with overhead bins, featuring optional doors on the test 386. There's a good sized glovebox and in-door bins and a giant cupholder. We weren't out long enough to assess the lighting, but there would appear to be plenty of lights for both reading and for access.
Also overhead, a one-piece headliner makes the cab feel bigger, as do the doors with the lower beltline. The controls for the central locking and mirror rotation and heat are located up on the side-window "sill" just ahead of the substantial door pull.
The Sleeper
The cab's footwells are uncluttered and the seats are far enough apart to give good access back to the sleeper. Here open cabinets with vinyl closures on this 386 provide the storage, and the fridge sits high on the passenger side where it can be reached by standing or from the optional upper bunk. Also up high were additional storage shelves across the back wall and above the windows.
There's a large window on either side for plenty of daylight and, again, generous night-time lighting. The two baggage compartments were lighted and could be accessed from inside the cab by tilting the 42-inch bunk.
Hidden from view was the thermal insulation package for both cab and sleeper, always a wise option both for the added comfort and the greater noise attenuation.
Colors in the sleeper complement the new trim in the cab – Arctic Grey in the case of our truck.
The sleeper was the 70-inch raised roof for 78 inches of headroom inside and generous floor area. But despite its height, the 386 still needs a rooftop fairing for optimum fuel economy.
On The Road
We were alerted by Jim Park, our colleague on the Canadian HighwayStar Magazine that he had not achieved very good fuel mileage on his test drive. But he had taken the truck before the roof fairing had been fitted. With that fairing, plus some additional schooling in the optimum technique for driving the ACERT Cats, I did better. When we checked the fuel mileage we were astounded to find we had bettered Jim by 2 mpg, returning an overall of 6.88 mpg for our 346-mile round trip.
However, that was achieved by lugging the 475 down to as little as 1,000 rpm at times. And never letting it out beyond 1,600 rpm when running through the gears – and then only in the high side of the transmission. Also, limiting top speed to around 64 mph kept us on the magic 1,400 rpm.
The truck was very comfortable and rode nicely, though not quite as well as the outstanding 379 we last drove with the funky-looking Flex Air suspension. It seemed a little noisy, but putting the sound meter on it confirmed that it ran at much the same level as previous test Petes. Under maximum acceleration it showed a highly creditable 72 dB(A), only a shade more than soft pedaling along at cruise. Idle was a mere 62 dB.
The long-legged gait, cruising at 1,400 rpm, begged for use of the nice Caterpillar cruise control. With its "soft cruise" activated, this felt more natural, rolling off a couple of mph on the short grades then overspeeding by a similar number on the downslopes making the most of the Cat full-range governor.
Out in the wide-open Texas range, the maneuverability and visibility of the Pete were not really tested. But there is no question this 386 turns tightly, only about 10% less tightly than the Euro-inspired Volvo VN. And the changes to the doors, mirrors and hood make forward and side views much less obstructed than previously.
One of the features I was most keen to explore was the braking with the air disc front setup. However, while the truck stopped well enough for a fully loaded unit (we scaled at just a shade under 80,000) it took a prodigious shove on the pedal to get the retarding force. Still, the fade performance of air discs gives them a strong performance edge, so even if there appears to be no added braking effort as on this 386, they are still a worthwhile safety plus.
Operational Factors
There was a lot going on here to evaluate. But the big thing was the fuel economy. There are varying reports on the success of the Cat ACERT technology: Some drivers can't get to grips with it, others have resounding success as frequently announced in Cat's testimonials. Did the same thing happen here accounting for the difference between Park's fuel numbers and mine?
Whatever, 6.88 mpg from an engine with under 2,000 miles and running at maximum gross weight is a marvelous tribute to the aerodynamic efficiency of the new 386.
What's more, it combines potential fuel economy with the very traditional values of the 37X models, fine-tuned since their launch back in the mid-1980s.
The addition of the UltraCab just adds to the package, with a wide-open cab/sleeper access and living space. This opening can be closed off with a panel when the sleeper is removed for the truck's second or third life. Thus the lifelong resale value of the 386 is enhanced over integral sleeper trucks that cannot be similarly modified.
Conclusions
It's in the potential operational savings that the attractiveness of the 386 lies. Potential lower fuel bills and the versatility of the UltraCab could very favorably impact the life cycle cost of the new aerodynamic model from Peterbilt.
That's what the company is betting on. And it looks to be a safe bet to me.
Test Vehicle Specs
Tractor Peterbilt Model 386
Frame 10-5/8 with aluminum crossmembers
Engine Caterpillar C15 475; 1,650 @ 1200 rpm
Clutch Eaton Fuller 15.5-in Easy Pedal
Transmission Eaton Fuller RTOC 16909A 9/13 speed
Drive Axles Dana Spicer DSP40 40,000#
Axle Ratio 3.55 to one
Rear Suspension Peterbilt Low Air Leaf 40,000#
Front Axle Dana Spicer E1202W 12,000#
Front Suspension Taper Leaf 12,000#
SteeringSheppard M100
Foundation Brakes
Front Bendix disc
Rear Dana Spicer ES 16.5 x 7 drum with MGM park on rear
Wheels Pilot mount Alcoa aluminum, polished
Tires
Front Bridgestone R280 295/75R22.5
Rear Bridgestone M726EL 29575R22.5
Fifth Wheel Jost Air Slide 6.75-in height
Fuel Tanks 26-in, 135 gallon x 2
Cab Aluminum, 126 in BBC, fiberglass hood
Cab Aero Options Cab-top deflector, side skirts,extenders
Cab Interior Trim Prestige
Seats Peterbilt UltraRide HighBack
Sleeper 70-inch Ultracab, 63-in HiRoof
Paint Dupont two-stage White
Additional Equipment
Peterbilt stainless quarter fenders; deck plate; PHP10 aluminum hubs; CR Scotseal Plus oil seals; Denso 130-amp alternator; Phillips pre-heater; Horton fan clutch; Bendix 15.8 cfm compressor; CAT compression brake; Firewall mount Donaldson air cleaner; vertical exhaust; synthetic lubes; remote lube for clutch; Bendix AD-IS air dryer; common keys; thermal insulation package; second bunk; vinyl closet covers; arm rests; tilt/tele steering column; doors on header cabinets; power windows; sunvisor; ConcertClass audio; Fleet Spec instrument package.
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Dimensions
Length 345.5
Width 96
Height 156.5
Wheelbase 282
Step Heights 16/34/49
Floor height 49
Baggage liftover 49
Frame ht @ Fifth Wheel 40
Turning circle
Left 79.5
Right 77.5
Closest sight to ground 8
Noise at idle 62 dB(A)
Cruise 72
max accel 72
RPM 1310
In Cab
Shoulder width 66
Height at standup point 63
Seat to ceiling min 43 in, max 49 in
Legroom
(driver) min 24, max 30
(passenger) min 11, max 19
Footwell width driver & passenger 26
Sleeper
Walkthrough seats 12
Width 89
Height at bunk 78
Bunk to ceiling (lower) 57
Bunk width lower 42, upper 32
Length 73
Peterbilt 386 On Road
Total on-road time 7hrs 28 mins
Fuel used (tank-to-tank) 50.263 gal
Distance 346 mi
Average speed to break 56.31 mph
Second leg 38.13 mph
Overall 46.34 mph
Fuel economy overall 6.88 mpg
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