2017 Ford Super Duty 6.7 3.73 Gear Swap UPDATED

2017 Ford Super Duty 6.7 3.73 Gear Swap

Originally published in September 2010 and Updated in Oct 2021.

Ofttimes overlooked, optional gear ratios play a central role in pickup truck performance. If the axle ratio is too tall, the truck may seem to lack power, especially when climbing hills. This may be corrected with a numerically higher axle ratio, often at the expense of unladen highway fuel economic system.

Consider that with a 3.31 beam ratio, the driveshaft turns 3 1/3rd times for every revolution of the rear wheel. With a 4.30 ratio, it turns 4 1/3rd times for every revolution of the rear bicycle. The numerically higher gear ratio (in this case, 4.30) increases wheel torque and improves acceleration from low speeds. Merely the engine does have to run faster to achieve a given speed.

Video: How a Differential Works

Selecting the best gear ratio tin can be tricky as the entire powertrain works every bit a system. Every engine includes a sweet spot in its power curve between peak power and peak torque. Y'all want the manual gearing and axle gear ratio to stay in this sweet spot while hauling the payload at the desired speed.

Also consider that the beam ratio is only a portion of the overall pickup gearing. Manufacturers spend a lot of attempt on powertrain matching. According to Ford Motor Visitor, powertrain matching is really a systems arroyo. Information technology is the engine, transmission, axles and tires working together. It is the effective ratio of engine power transmitted all the way through the drive arrangement to the ground.

The March Toward More Gears

Relying on past history to select an axle ratio may not be the best approach as technology continues to alter. There has been a major development in pickup truck transmission offerings equally manufacturers pack an increasing number of gears into the transmission housing. Many years ago, the four-speed automatic transmission was mainstream. Then it evolved into five speeds and eventually 6 speeds. The terrain, the weight of your loads, the shape of your loads and how oftentimes y'all tow will all influence the right axle ratio. Ram Trucks

In 2012, Ram Trucks introduced an eight-speed transmission for its 2013 1500 models. This evolution of pickup truck transmissions accelerated in 2017 with the introduction of 10-speed transmissions. This was the outcome of a collaboration between Ford and General Motors, and first appeared as an option on the 2017 F-150 pickups. Chevrolet Silverado 2019 pickup truck models followed. For 2020, Ford and Full general Motors both introduced new ten-speed transmissions on their heavy-duty pickups.

Previously mainstream six-speed automated transmissions are currently being replaced by 8- and x-speed transmissions, which are able to provide closer ratios between the gears. "Closer ratios allow for the correct gear at the correct time and can reduce gear hunting on grades and assist take reward of the engine torque curve," says Rod Romain, main engineer, Ram Heavy Duty.

The ultimate goal of a transmission is to continue the engine working in its about efficient speed range, or at the highest torque point when performance is needed. The transmission's computer does whatever it takes to detect the gear that keeps the engine in its well-nigh efficient or best-performing speed range. By having more gear ratios, information technology is possible to keep an engine most its ideal operating speed virtually of the fourth dimension. The transmission's wider overall ratio enables a lower numerical tiptop gear ratio, an aspect that reduces engine speed on the highway.

"Simply, closer ratios may not support a lower numeric beam; it's a system with the engine," says Romain. "If the ratio option works with the engine, sometimes a lower numeric beam ratio can be used and actually improve the overall towing experience. It's a organization with the engine and vehicle. They need to work together for the task at hand and, depending upon the manual ratios, a higher numerical ratio in a higher gear may exist the same as a lower numerical axle in a lower gear."

The way people spec rear axle ratios has changed as the powertrains accept evolved over the past few years. "Years ago, 4.56 and 4.10 were the but gears to have when towing heavy," notes Romain. "With the improved engine functioning nosotros take today, the same loads and even higher can exist pulled with much lower numerical ratios."

Co-ordinate to Ford Motor Visitor, at that place are interconnected reasons to choose optional beam ratios — if you are hauling heavy loads with large trailers in hilly terrain and you do a high frequency of towing. Consider a PowerStroke 6.7-liter diesel fuel that offers a option of a 3.31, 3.55, 3.73 or 4.30 axle ratio. The 3.31 might be capable of towing the trailer. Just if you lot are towing the majority of the fourth dimension, you probably want the 3.55 because it will tow meliorate and provide better fuel economy loaded.

Fuel Economy vs. Towing Efficiency

Starting time with the full combined weight of the vehicle, and so consider the environment. If you bulldoze the vehicle on flat ground in Iowa throughout its life, beam ratio is not as disquisitional as pulling the same load up the hills in Denver. The axle ratio really starts to show when you get into grades. Higher numerical beam ratios can increase performance when towing heavy loads.

Note that pickup tow and booty ratings are listed by beam ratio. The vehicle's tow rating vs. what yous plan on towing is the best way to determine which gear ratio you should select.

The consumer tin can tailor the vehicle'due south driveline to meet their detail needs, according to Toyota Motor Vehicles. If you will never take more than 1,000 lbs. in the back of the truck, you would want the highest ratio (3.73 instead of 4.30) for improved fuel economy because you will not need the torque. All the same, if you lot are towing a ix,000-lb. trailer, you will need that extra torque to go the trailer moving, especially up steep grades (four.30 instead of a three.73).

Fuel economy (college rpms interpret to increased fuel use), the weight to be towed or hauled (you lot want the engine to stay at an efficient speed on hills), roads traveled (steep grades vs. flat highway) and expected speed are all factors to consider when choosing the right ratio, advises Ram Trucks. You may choose a ratio that keeps the engine at the lowest rpm for fuel economy. But if y'all are not traveling fast enough on the highway, it volition lug the engine and prove to be less efficient. Yous want to keep the engine at the most efficient rpm for a set up speed, no matter what the load.

Consider the top speed at which you desire to bulldoze, the fuel economy you wish to achieve at that highway speed and the load you intend to tow or haul. For example, if you wish to tow x,000 lbs. at 55 mph on flat highway, a mid gear ratio will continue the engine rpms up enough to maintain power with efficiency. If you want to bulldoze at a high rate of speed, go with a smaller numerical gear ratio to keep the rpms equally low every bit possible.

Towing a heavy load and fuel economy don't go manus in hand, co-ordinate to General Motors. The lower gear ratio volition give you the drivability you lot need to effectively tow the load at the expense of slightly higher engine rpm at higher speeds vs. a vehicle with a higher ratio. Nevertheless, if you employ a last drive ratio that is too high, you will have to rev the engine more and the manual clutches will generate much more than oestrus due to slipping when trying to go the load moving. The stop result is you damage your transmission.

The weight of the load isn't the only consideration. Information technology is the weight of the load as well equally the aero characteristics of the load, notes General Motors. If you pull a large trailer that has a large frontal area, information technology has a very loftier aero touch on going down the highway compared to a flatbed trailer with a Bobcat and lawn servicing equipment. The aero characteristics are quite dissimilar for those ii vehicles, and that has a huge bear upon on towing on the highways.

Performance Relative to Apply

General Motors previously performed extensive testing with its L96 gas engine and both the standard 3.73 and optional 4.ten axle ratios. That 3.73 vs. a 4.x has a huge touch on engine rpm considering you are selecting second gear with a iii.73 to pull the course, but you lot can hit 3rd gear with a 4.10. Your engine speed is nigh 1,000 rpm lower, so temperatures under hood are going to be significantly lower.

Higher numerical ratios often increase fuel consumption. The penalty in fuel economy varies because it depends then much on your use, Ford Motor Company points out. If you drive the vehicle with low loads, you will see a fuel economy decrease with a higher numerical axle ratio, particularly at highway speeds. If you are driving loaded a lot of the time, in that location is a indicate where fuel economic system crosses over and is equivalent or even ameliorate. If you are driving in a city surround at slower speeds, you lot may likewise see a fuel economic system increment with a higher numeric axle ratio.

Many defended commercial trucks do not offer a choice of axle ratios. Ane ratio is used since the trucks are primarily beingness used for a commercial-type awarding where they are all heavily loaded.

Tire Size Changes Ratios

Changing tire size also affects the gear ratio. A larger tire plays the same role as smaller gear ratios. Even so, yous now may be adding rotating mass, which decreases efficiency and also negatively changes the dynamics of the vehicle for which it was designed.

A one-in. decrease in tire diameter has most the same impact of i/3rd of an axle footstep. For example, if a 3.73 beam ratio currently is matched with a 31.2-in.-diameter tire, then the tire is decreased to 30.2 in., the revolutions per mile increase from 650 to roughly 670. That gives you most a 3.85 axle ratio.

Go on in heed that vehicles are designed to be operated with a specific-sized tire. Most manufacturers don't recommend changing tire size, as this will touch treatment and performance of the vehicle.

Touch on on Wear and Tear

A college numerical gear ratio doesn't automatically reduce wear and tear under heavy loads.

Energy must be transferred somewhere, notes Ram Trucks. The vesture and tear will increase in i area and drop in another depending upon what the load is and the drive cycle. Most article of clothing and tear is dependent upon driving habits, east.thou., slipping the clutch, jack-rabbit starts, over- and/or under-revving the engine, etc.

Only a college numerical ratio volition relieve wear on both the engine and manual. Information technology is more of a do good to the transmission because it will have a greater mechanical advantage over the load when trying to get the load moving.

The contempo proliferation of transmissions with more than gears makes the overall gearing more effective. Multiple speeds give multiple options to proceed the engine in the most efficient operating range at a particular speed.

It'south all nigh balance. A manufacturer may choose a 3.73 because it knows the client of a heavy-duty truck is going to tow, just isn't going to tow a 20,000-lb. combined package. So, the manufacturer tries to provide the best performance with a 3.73. Then there is the customer that has the 3500 dually; it has the pocket-sized 17-in. tire and 4.10 axle ratio. This volition give the customer the best performance for the twenty,500-lb. combined packet.

The best advice is to fully understand your awarding. The beam selection also impacts many factors other than fuel economy. That beam ratio is key to thermal performance. If y'all are going to tow a lot of weight, the higher numerical gear ratio volition actually ameliorate the durability of the vehicle.

"Match the tow rating of your vehicle to the task you are request it to practise and you will be fine," says Romain.

DOWNLOAD HERE

2017 Ford Super Duty 6.7 3.73 Gear Swap UPDATED

Posted by: lenorasentort.blogspot.com