The rebirth of the Baby 8

Nov. 1, 2011
Call it the Goldilocks Solution: a truck that's not too big, yet not too small; not too powerful, yet definitely not weak; not too heavy, yet not too light; all with a price tag that fits a fleet's wallet just right. That, then, is the space into which more lightweight Class 8 truck models, often called Baby 8s in industry parlance, are being introduced by OEMs these days. These trucks attempt to

Call it the Goldilocks Solution: a truck that's not too big, yet not too small; not too powerful, yet definitely not weak; not too heavy, yet not too light; all with a price tag that fits a fleet's wallet just right. That, then, is the space into which more lightweight Class 8 truck models, often called “Baby 8s” in industry parlance, are being introduced by OEMs these days.

These trucks attempt to meld together specific characteristics from both the medium- and heavy-duty worlds into a single, cost-conscious package aimed at several distinct markets, such as LTL, regional, municipal, and construction. Simultaneously, the basic definition of a Baby 8 is changing, too, says Landon Sproull, chief engineer for Peterbilt Motors Co.

“In the old days, the term Baby 8 basically meant a ‘low-powered’ Class 8 truck” equipped with a 9L engine, he explains. Now, the term means something totally different, even though it's a truck that still sports a 9L or 10L engine.

“Today's 9L engines have far more power and low-end torque than anything in the past,” Sproull says. “While it would be a struggle for a Baby 8 to pull 80,000 lbs., that 9L will do just fine hauling 50,000 to 70,000 lbs. By comparison with the past, these new Baby 8s are much stronger trucks.”

As an example, he points to Peterbilt's Model 382 and Model 384 as tractors that fit the mold of the modern-day Baby 8: lightweight, single rear-axle daycab configurations shorn of the expensive interior packages commonly found on long-haul, on-highway tractors.

“The customer for these kinds of trucks is coming from two different perspectives,” Sproull notes. “On the one hand, you've got a medium-duty customer looking to step up into a truck with a chassis built for durability and longevity, yet not a vehicle that operates very differently from what they currently use.”

On the other, he says, you've got traditional Class 8 customers — say municipal dump truck fleets or TL operators moving into shorter-haul regional, dedicated, and/or pickup and delivery routes — that simply need a less expensive tractor that still delivers on fuel economy and long-term hardiness.

“That's why the Baby 8 is getting more attention,” Sproull explains. First and foremost, it's got true Class 8 “bones,” which in many cases translates into long life of 10 to 20 years, he notes.

“Second, it's light and lightly powered, so it delivers great fuel economy,” Sproull continues. “Finally, since these trucks typically stay close to home, fleets don't put a lot of money into the interiors, so it comes in at a much lower cost than the traditional long-haul Class 8, which requires all the extras because drivers truly live in those trucks for long stretches.”

T.J. Reed, director of product marketing for Freightliner Trucks, however, sees demand for Baby 8s largely coming from the vocational segment of the market. “Yes, there's demand for Baby 8s as regional-haul tractors from the LTL perspective, but today we're really seeing it more from vocational customers; for example, in dump-truck applications where the need to plow snow is a yearly requirement.”


A 9L and even 11L engine provides a lighter front end, Reed says, allowing for the additional weight of a snow plow while providing shorter bumper-to-back-of-cab (BBC) measurements of 107 to 114 in. versus the 120 in. found with traditional Class 8 configurations.

“These guys are trying to get the same durable chassis and cab of a Class 8 with shorter dimensions and lighter weight so these vehicles can maneuver better, haul more, and get better fuel economy where possible,” he explains.

In Freightliner's case, the Baby 8 translates into an M2 112 tractor or 114 SD (for “severe duty”) vocational chassis. It is typically equipped with a Cummins ISL 9L or ISB 10L engine mated to either an automated or fully automatic transmission.

“With today's new technology, such engines generate more horsepower and torque with a smaller displacement, allowing these fleets to hit the ‘sweet spot’ in terms of performance and fuel economy,” Reed notes. “At the same time, a more robust chassis and cab positions them to achieve more vehicle longevity. As we all know, fleets of all stripes are extending equipment ownership cycles today.”

Yet Jim Hebe, Navistar senior vice president-North American sales operations, stresses that the case for Baby 8s in today's market isn't a completely cut-and-dried scenario — particularly on the tractor side of the equation.

“By the time you take a 9L engine up to where it needs to be, in many ways it resembles an 11L engine but without the ability to haul 80,000 lbs. up and down the road for 100,000 mi. or more per year,” he says. “It's really all about the torque and duty cycle a fleet requires, and the weight savings a Baby 8 offers might not result in the right fit for certain applications.”

That being said, the Baby 8 will only grow as a bread-and-butter style of fleet truck in the vocational space, Hebe contends. “Municipal fleets especially like it because its light front end and front axle allow for the weight of snow plows and PTO [power take off] additions. It's also attractive to refuse companies as well.”


Reducing both weight and cost for vocational Class 8 customers is what drove Mack Trucks to introduce a Baby 8 version of its Granite vocational straight truck earlier this year. Dubbed a “medium heavy-duty” or “MHD” model by the company, this configuration is intended for municipal and other fleets with what Mack calls “cost-sensitive applications.”

The new Granite MHD is being offered in both set-forward and set-back axle configurations, with power supplied by a Cummins ISL 9L diesel engine, which can be mated with either an Allison automatic or Eaton manual transmission.

“In the current economic environment, companies are taking an even harder look at how much truck they truly need,” said Curtis Dorwart, Mack's vocational products marketing manager. “Our new Granite MHD delivers just the right amount of … strength, durability and reliability, along with valuable weight and cost savings.”

Back on the tractor side of the ledger, though, price considerations will continue to make the Baby 8 a player for a range of on-highway needs, says Frank Bio, product manager-trucks for Volvo Trucks North America.

“A lot of time today fleets are focused on price as the availability of capital is only becoming a bigger driver in [vehicle acquisition] strategies,” he says. “They are also now looking for longer extended life and since first owners now want to keep their equipment for longer ownership periods, they need durability and longevity at a price point that fits their budget.”

From Volvo's perspective, those considerations are encapsulated in its VNM tractor — a 4×2 daycab tractor configured with an 11L engine and 10-spd. manual, automated, or automatic transmission.


This type of truck addresses several different customer needs, Bio explains. For some medium-duty customers, a Baby 8 might provide many of the same features they've come to love from a beefier Class 7 truck, a so-called “Super 7.”

“When these types of customers move up, they want to keep the advantages of that smaller medium-duty footprint while gaining the durability and longevity the Class 8 offers,” Bio says.

Yet for traditional Class 8 customers, the Baby 8 is now in some ways becoming an application-specific product designed from the start to fit a specific operational niche, he points out.

“In the past, a fleet might take older long-haul tractors and shift them into regional or urban pickup-and-delivery operations,” Bio notes. “Now they would rather optimize the operation from the start, getting a truck that will last for a long time, 15 years or more, that also offers better maneuverability and fuel economy and thus more profitability over time.”


Fleets are no longer rigidly segmented by operation anymore, with TL carriers focused on just long-haul freight and LTL operators running hub and spoke, pickup-and-delivery routes.

“Today, fleets operate in a wide mix of markets,” Bio says. “A traditional TL carrier might now have an LTL division, a dedicated operation, even local delivery activity. So now they need a wider mix of vehicles than they did before, and that's why the Baby 8 is seen by them as a good fit.”

“Depending on commodity hauled, I would say, yes, fleets are trying to develop lighter-weight Class 8 specs,” adds Alan Fennimore, vocational marketing manager for Kenworth Truck Co.

“Fuel economy is the predominant driver of the lighter weight spec for linehaul and pickup and delivery. Even vocational fleets, including fuel haulers, are looking for the additional payload a lighter truck provides,” he says. “A Class 8 chassis with all or some of these changes — less option content, lower horsepower or a smaller engine, such as 8L or 9L power — will typically yield a lighter and less expensive truck or tractor.”

Fennimore agrees that the Baby 8 is a great chassis for niche market segments, noting that Kenworth has seen success with its T440 and T470 models in pickup-and-delivery, vocational and municipal markets, with what he terms “a pretty common T440 tractor spec” for Baby 8 customers today consisting of a 12,000-lb. front and 23,000-lb. rear axle capacity with a Paccar PX-8 engine.

“Right now, vocational seems to be a little higher user for the Baby 8 chassis at this point,” he points out. “I would say that Kenworth's T440 and T470 models are [sold as] mostly daycabs and extended daycabs [in the Baby 8 configuration] with about 10% sleepers.”

Yet Fennimore believes that time will tell as to whether the sales arc for the Baby 8 continues to strengthen or instead dips down.

“The eventual return to a more normal truck market and fuel prices will dictate the demand for future growth in this special class of chassis,” he says.

Less shifty

One of the major characteristics of the renewed interest in the Baby 8 configuration is that a good proportion of these trucks are increasingly being spec'd with automated and fully automatic transmissions, although there's wide disagreement among OEMs as to the overall market penetration of those two transmission types versus their all-manual brethren.

According to Jim Hebe, Navistar's senior vice president-North American sales operations, some 75% of the company's Baby 8 orders are spec'd with a fully automatic Allison gearbox, with the remaining 25% largely equipped with Eaton's UltraShift automated manual transmission (AMT).

“As Eaton develops more versions of its UltraShift package to fit more vocational niches, however, we envision more of them being ordered,” Hebe stresses. “Both of these transmission types [fully automatic and AMT] are gaining in popularity very fast.”

Alan Fennimore, vocational marketing manager for Kenworth Truck Co., agrees, noting that AMT and fully automatic gearboxes make up over 40% of the transmissions spec'd for his company's Baby 8 trucks.

“The typical driver for a Baby 8 is less experienced, thus the higher usage for an AMT [or fully automatic model] over the normal Class 8 configuration,” he says.

Landon Sproull, chief engineer for Peterbilt Motors Co., also believes AMTs and fully automatic gearboxes “make perfect sense” for the Baby 8 operating style, but it's not being reflected in the specs being ordered today.

“We still haven't completely figured out why, because we can't be too far away from a shift to AMT and fully automatic transmission simply because of the growing shortage of experienced drivers,” he explains.

“There's just a lot more stop and go in the space where Baby 8s operate, so we definitely think [AMTs and automatics] are where the trend will go,” Sproull notes. “But as of right now, we're still at just 10%.”

About the Author

Sean Kilcarr | Editor in Chief

Sean previously reported and commented on trends affecting the many different strata of the trucking industry. Also be sure to visit Sean's blog Trucks at Work where he offers analysis on a variety of different topics inside the trucking industry.

Voice your opinion!

To join the conversation, and become an exclusive member of FleetOwner, create an account today!

Sponsored Recommendations

Report: The 2024 State of Heavy-Duty Repair

From capitalizing on the latest revenue trends to implementing strategic financial planning—this report serves as a roadmap for navigating the challenges and opportunities of ...

Fleet Industry Benchmarks: How does your fleet stack up?

Discover how your fleet compares to industry benchmarks and gain insights from a 2024 Benchmarking Report on maintenance spend, turnaround time, and more. Join us to identify ...

Build a Tolling Program to Manage Toll Fees and Risks

Fleets looking to effectively manage their operational costs should consider their tolling costs. Download the PrePass whitepaper, “Build a Tolling Program to Manage Toll Fees...

Reducing CSA Violations & Increasing Safety With Advanced Trailer Telematics

Keep the roads safer with advanced trailer telematics. In this whitepaper, see how you can gain insights that lead to increased safety and reduced roadside incidents—keeping drivers...