Custom Semi-Truck Transmissions
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Pure Power.
Relentless Control.

Built to hook up and stay hooked up.

Sled pulling asks a transmission to hold maximum torque under sustained, escalating load without letting go. We build custom Eaton Fuller based pulling transmissions with ratios, clutch engagement, and components matched to your sled, your class, and your track.

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Built For Sustained Load

Components chosen to handle escalating pulling resistance.

Crower Slipper Clutch

Engagement tuned to control power delivery without shock-loading.

Pulling-Specific Ratios

Gearing built around torque delivery, not top-end speed.

Race-Proven Builds

Trusted by pulling competitors who demand relentless control.

A Different Kind Of Fight Than The Track

Sled pulling doesn’t ask for a quick burst of power — it asks for sustained, maximum torque against a load that gets heavier with every foot of travel. The weight transfer system on the sled means resistance climbs throughout the pull, right up until the truck can’t move it any further.

That’s a fundamentally different demand than drag racing or hill climbing, and it changes how we approach ratio selection, clutch engagement, and component selection from the ground up.

  • Sustained maximum torque, not a short burst of power
  • Load increases progressively throughout the pull
  • Built specifically around pulling competition, not adapted from racing

Built To Handle Stress The Road Never Sees

Every component in a pulling drivetrain is subjected to loads far beyond typical highway or even race-track use. Gears, shafts, and bearings are all working near their limits for the length of the pull — which is why we build pulling transmissions with CNC-machined internals and heavy-duty components selected for this specific kind of abuse.

We inspect and evaluate every component with high-load sled-pulling stress in mind, not general-purpose durability.

  • Components selected for sustained, near-maximum load
  • CNC-machined gears and shafts for strength under stress
  • Built with the goal of supporting reliability pull after pull

Gearing Built Around Torque, Not Top Speed

Pulling ratios are chosen with a completely different goal than a race transmission — the aim is to keep the engine making maximum usable torque against a constantly increasing load, not to maximize speed or RPM. That usually means lower, closer-spaced gearing than you’d run on the track.

We factor your engine’s power curve, sled weight class, and typical pull length into ratio selection, so the setup is built around how your specific combination performs under load.

Ideal ratio selection depends on your engine, class rules, sled type, and pull length. Recommendations are built around your specific combination — results vary by track and conditions.

Clutch Engagement & Ground-Speed Considerations

Getting power to the ground without breaking traction is just as important as the power itself. Here’s how we approach it.

Clutch Engagement & Power Control

A Crower slipper clutch is designed to allow controlled, progressive engagement under heavy load — helping put power down smoothly instead of shock-loading the drivetrain or breaking traction at the hit.

Depends on setup & track surface

Traction & Ground-Speed Considerations

As the sled's resistance increases, wheel speed and traction demands shift throughout the pull. We consider ground-speed behavior and traction conditions when planning ratios and clutch engagement together as one system.

Results vary by track prep & weather

Custom Eaton Fuller-Based Builds

Every pulling transmission starts with an Eaton Fuller based platform, rebuilt with CNC-machined internals and set up specifically for your class, sled weight, and pulling style.

Built around your class & sled

Crower Slipper Clutch Rebuilding & Setup

Incorrect clutch setup is one of the most common reasons pulling transmissions fail or underperform. We specialize in rebuilding and properly setting up Crower 12.5″ slipper clutches for the specific demands of sled-pulling competition.

A correctly set up slipper clutch is designed to help reduce drivetrain shock, control engagement through the pull, and protect the rest of your driveline investment.

  • Crower 12.5" slipper clutch rebuilds for pulling applications
  • Engagement setup tailored to your class and sled weight
  • Tested and verified before it goes back on your truck
See Slipper Clutch Rebuilding

Run Your Pulling Numbers Before You Build

Use our Gear Analyzer to calculate tire size, differential ratio, and gear spacing for your pulling combination — then compare setups before you commit to a build.

Launch Calculator

How We Build Your Sled-Pulling Package

01

Consultation

We learn your class, sled type, weight, and pulling goals.

02

Ratio Analysis

We use real data and the Gear Analyzer to dial in gearing for your combination.

03

Clutch Setup

Crower slipper clutch rebuilt and set up for controlled, progressive engagement.

04

Build

CNC-machined components, precision assembly, built as a complete pulling package.

05

Test & Verify

Checked for correct engagement, strength, and accuracy before it leaves the shop.

06

Delivered Ready To Hook

Shipped or picked up, ready for the pit and the pull.

THE RIGHT BUILD STARTS WITH DETAILS THE RIGHT

Every custom transmission begins with understanding your truck, racing application, and performance goals. Send us your current transmission, rear gear ratio, tire diameter, loaded or bobtail configuration, and the result you want to achieve. We’ll review your combination and contact you to discuss the right direction for your build.

Frequently Asked Questions

What transmission is best for sled pulling?
There’s no single “best” transmission — it depends on your class, sled weight, and engine combination. Most of our sled-pulling builds start from an Eaton Fuller based 13- or 18-speed platform, rebuilt with CNC-machined internals and custom gear ratios matched to your specific pulling setup. Talk to us about your class and truck, and we’ll recommend the platform that fits.
Do you rebuild Crower slipper clutches?
Yes. We specialize in rebuilding and properly setting up Crower 12.5″ slipper clutches for sled-pulling applications, with engagement tuned to your class and sled weight to help support controlled power delivery.
How is pulling gearing different from race gearing?
Pulling gearing is built around sustained, maximum torque against a constantly increasing load — not top speed. That generally means lower, closer-spaced ratios than you’d run on a quarter-mile or hill-climb setup, where the goal is RPM and speed instead of sustained pulling force.
Can you help me choose the right ratios for my class?
Yes. We’ll walk through your engine’s power curve, sled weight class, pull length, and typical track conditions to plan ratios around your specific combination. You can also model different setups yourself using our Gear Analyzer before committing to a build.
How long does a sled-pulling build take?
Timelines vary based on the scope of work and current shop workload. Once we’ve reviewed your truck and confirmed the build plan, we’ll give you a realistic estimated timeline — reach out for a current turnaround estimate.
What clutch setup works best for hooking up hard?
A Crower slipper clutch, properly rebuilt and set up for your class, is designed to allow controlled, progressive engagement — helping put power down without shock-loading the drivetrain or breaking traction at the hit. The right setup depends on your truck, sled weight, and typical track surface, so it’s worth talking through your specifics with us.
Do you ship completed transmissions?
Yes, we ship completed transmissions across the U.S. and Canada. Contact us before shipping anything so we can confirm logistics, documentation, and timing on both ends.
What information do you need to quote a pulling build?
Truck make/model/year, pulling class and sled weight, engine and approximate horsepower, current transmission and rear gear ratio, current clutch type/brand, and your typical track conditions and pull length. The more detail you give us, the more accurate the quote.

Your win starts here.

Let’s build a transmission that’s built for your track, your power, and your goals.
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