On this page
- Which transmissions do you work on?
- What are the signs a clutch is going?
- Automated manual problems: software or hardware?
- Rebuild, repair or exchange unit?
- Do you work on driveshafts, axles and differentials?
- Transmissions and drivetrain parts
- Clutch adjustment, clutch replacement, rebuild or exchange unit
- Transmission, clutch and axle jobs
- How does a transmission or clutch job move through the shop?
- Questions
Which transmissions do you work on?
The shop repairs and rebuilds transmissions in-house, on heavy-duty Class 8 tractors, medium-duty trucks such as box trucks, and light-duty diesel pickups, across the common makes: Freightliner, Peterbilt, Kenworth, Volvo, Mack, International and Western Star.
That covers manual, automated manual and automatic transmissions, and an exchange unit is an option when a truck cannot wait for a rebuild.
Manual transmissions still lead among owner-operators. In OOIDA's 2022 member survey, 30% of owner-operator trucks had a 13-speed, 24% an 18-speed and 16% a 10-speed, while 23% ran an automatic or partly automatic transmission.
Fleet trucks are a different mix. Many newer tractors come with an automated manual, a manual gearbox shifted by a computer.
Sources: OOIDA 2022 Owner-Operator Survey
What are the signs a clutch is going?
The usual signs, and what each one points at:
- Slipping: engine rpm climbs but road speed does not, most often pulling a grade loaded
- Chatter: a shudder through the truck when pulling away
- Hard shifts at a stop: grinding into first or reverse can mean the clutch is not fully releasing or the clutch brake is worn
- Noise: a squeal or growl with the pedal down points at the release bearing
- Free play: on a manually adjusted clutch, free play shrinks as the clutch wears
- Smell: a burning smell after a hard launch or a long creep in traffic
Adjusting a manually adjusted clutch on schedule adds life, and checking free play is a routine PM item. Once the adjustment is used up, or the clutch has been slipped hot, replacement is the fix. Self-adjusting clutches need no routine adjustment. See fleet maintenance for PM service.
Clutch replacements are done in-house at the Indian Trail shop, and the flywheel is checked while the transmission is out.
Automated manual problems: software or hardware?
Often it takes checking both, because an automated manual is a manual gearbox run by a computer, and one symptom can come from software, a sensor, the air or electric actuators, or worn parts.
- Software and calibration: a controller that needs an update, or a clutch that has to relearn its engagement point after a repair
- Sensors and wiring: speed and position sensors, the shift selector, or a chafed harness
- Air supply: on air-shifted units, low or wet air can make shifts slow or incomplete
- Hardware: a worn clutch, a failing clutch actuator, worn shift forks or damaged gears
The transmission controller logs its own fault codes, and reading them properly takes software that talks to that transmission. The shop reads them with heavy-duty diagnostic software that covers the major makes.
A software fault can look like a failed part, and a failed part can set codes that look like software. Swapping a transmission on a guess is an expensive way to find out which. How fault codes are read is covered on truck diagnostics.
Rebuild, repair or exchange unit?
It depends on what failed: a leak, a shift problem or one worn part is usually a repair, wear across the gears and bearings calls for a rebuild, and an exchange unit trades the wait for a rebuild for a swap.
- Repair
- Fixes the fault, often with the transmission still in the truck where the part can be reached: seals, the shift housing, air valves and lines, or sensors.
- Rebuild
- The transmission comes out and apart. Worn gears, bearings and seals are replaced, synchronizers too where the design has them, and the unit is reassembled to spec.
- Exchange unit
- A remanufactured transmission, rebuilt ahead of time, goes in, and the old unit usually goes back as a core.
Metal in the oil, or noise that follows the transmission through the gears, usually points past a simple repair.
An engine that comes out for an overhaul exposes the clutch and flywheel as well, so the two jobs are often planned together. See diesel engine repair.
The shop rebuilds transmissions in-house, Eaton Fuller manuals among them, and fits an exchange unit where one makes more sense. Repairs carry a warranty of 1 to 3 years, depending on the part and its maker's warranty.
Do you work on driveshafts, axles and differentials?
Yes. Driveline repair is done in-house, from the transmission back: driveshafts, U-joints and carrier bearings, axle shafts and wheel seals, differentials, and the power divider on a tandem-drive tractor, including differential and inter-axle differential rebuilds.
Customer reviews describe it: one semi was towed in with a broken axle and a power divider actuator leaking air, and left with a new axle, the rear cleaned out and the actuator fixed.
Driveshafts and U-joints
The driveshaft carries power back to the axles. A U-joint at each end lets it change angle as the suspension moves, and on a long wheelbase a carrier bearing holds up the middle.
A vibration that rises with road speed, or a clunk when taking up drive, often means a worn U-joint or carrier bearing. A U-joint left to fail can drop the driveshaft.
Axles and differentials
Each drive axle has a differential, which lets the wheels on each side turn at different speeds in a corner. A whine or howl that changes on and off the throttle often points to its gears or bearings.
A broken axle shaft can leave a truck unable to pull away. When one is replaced, the housing is worth cleaning out so no metal from the break stays in the gear oil.
The power divider
On a tandem-drive tractor, the power divider, also called the inter-axle differential, splits power between the two drive axles. Its lockout, worked by an air actuator, locks the two axles together for poor traction. Engage it only when stopped or moving slowly with no wheel spinning, and switch it off once the road improves.
A leaking actuator can leave the lockout stuck in or out, which is why an air leak there is worth fixing even when the truck still drives.
Oil on an axle housing is worth a look before it becomes a broken part. Oil from a leaking wheel seal can soak the brake linings, which turns it into a truck brake repair job as well.
Transmissions and drivetrain parts
The shop works on the manual, automated manual and automatic transmission families below, the ones common in heavy and medium-duty trucks as of 2026, and on the driveline behind them.
Manual
The number is the count of forward gears.
Automated manual
The International T14 pairs with the S13 engine.
Automatic
Common in medium-duty and vocational trucks.
Drivetrain work in reviews
Named as work customers describe.
Clutch parts explained on this page
Replaced or checked together on a clutch job.
Driveline, repaired in-house
The power divider is another name for the inter-axle differential.
The shop behind the work
- Technicians
- About 20
- Service trucks for road calls
- 4
- Trucks we run ourselves
- 55
- Warranty, depending on the part
- 1 to 3 years
Clutch adjustment, clutch replacement, rebuild or exchange unit
Four fixes for a drivetrain that is slipping, grinding or making noise, from a routine adjustment to a different transmission.
| Option | When it applies | What it involves | Downtime |
|---|---|---|---|
| Clutch adjustment | A manually adjusted clutch whose pedal free play has closed up, before it starts to slip | Setting release bearing travel and clutch brake squeeze back to spec, often during PM | Shortest of the four, and often done during PM |
| Clutch replacement | Slipping, chatter, an adjustment that is used up, a failed release bearing, or a clutch damaged by heat | Removing the transmission to replace the clutch, release bearing and clutch brake, and checking or resurfacing the flywheel | Longer: the transmission comes out |
| Transmission rebuild | Internal wear or damage, such as metal in the oil or noise through the gears, with a case that can be reused | Removing and stripping the transmission, replacing worn gears, bearings and seals, and reassembling to spec | Longest: the transmission comes out and apart, and waiting on parts can add time |
| Exchange unit | Damage too extensive to rebuild, a case that cannot be reused, or a truck that cannot wait for a rebuild | Fitting a remanufactured transmission and returning the old unit as a core | Depends on when the unit arrives |
All four are done in-house at the Indian Trail shop.
Transmission, clutch and axle jobs
A transmission acting up the day before a booked load
- What failed
- The truck's transmission started acting up, with a load already booked for the next day, so the customer needed service as soon as possible.
- What we did
- The mechanic checked it, found the problem and fixed it, and the truck got moving in time for its next pickup.
A new clutch put into a customer's truck
- What failed
- The truck needed a new clutch.
- What we did
- A new clutch went in, and the customer wrote about going back to get more work done.
A broken axle and a leaking power divider actuator
- What failed
- The truck had a broken axle, and the power divider actuator was leaking air.
- What we did
- The shop towed the truck in, put in a new axle, cleaned out the rear and fixed the actuator. When the driver came to collect it, the truck and trailer were hooked up and ready to roll.
- Time in the shop
- Towed in on a Saturday afternoon and back on the road pretty quickly
How does a transmission or clutch job move through the shop?
A transmission or clutch job usually runs like this.
Drop-off or road call
Call (980) 313-6059, answered 24 hours a day, and say what the truck is doing. A truck that will not go into gear can be towed in: say which gear it stuck in and what the dash shows.
Road test and inspection
Where the truck can be driven, the complaint is confirmed on a drive, and the clutch, linkage, air supply and oil are checked.
Codes and data
On automated manuals and automatics, the transmission's codes and live data are read with heavy-duty diagnostic software that covers the major makes.
Estimate and approval
Diagnosis is a flat diagnostic fee, quoted when you call. The repair, rebuild or exchange is priced, and the estimate approved, before work starts.
Repair
The repair, rebuild or exchange is done in-house. When the transmission comes out, the clutch and flywheel are checked as well.
Relearn and road test
Automated manuals usually need a clutch relearn after clutch or actuator work, and the truck is road tested before it is released.
Invoice and payment
The invoice lists the parts and labor, and repairs carry a warranty of 1 to 3 years, depending on the part and its maker's warranty. Payment is by check, card, cash, Zelle, Apple Pay or Cash App.
Questions
Do you rebuild Eaton Fuller transmissions at the Indian Trail shop?
Yes. Transmission rebuilds are done in-house at the Indian Trail shop, Eaton Fuller manuals included, and an exchange unit is an option when a rebuild would keep the truck down too long. Manuals are still the most common transmission among owner-operators, and the comparison above sets a rebuild against an exchange unit.
Can a Charlotte owner-operator keep driving on a slipping clutch?
Not for long. A clutch that slips only on a hard pull may get the truck to a shop, but slipping makes heat quickly, and heat can crack the flywheel and finish off the clutch. Drive gently, avoid pulling a loaded grade, and call before setting out.
The phone is answered 24 hours a day, and a mechanic can come out day or night, weekends included. A clutch that slips on flat ground is safer towed in than driven. Call (980) 313-6059.
Do you work on automated manual transmissions for Union County fleets?
Yes. Transmission work is done in-house on every common make fleets run, from Freightliner and International to Volvo and Mack. That includes the Eaton Cummins Endurant, Detroit DT12, Volvo I-Shift and PACCAR TX-12, read with heavy-duty diagnostic software that covers the major makes.
Many automated manual faults are traced with the transmission's own software before any part comes out, so the software matters as much as the tools. Fleet accounts get net 30 to 45 terms: see fleet maintenance.
What does a power divider repair involve at the Indian Trail shop?
It depends on what failed. A leaking lockout actuator, an air line or a switch is a smaller job than a worn inter-axle differential. Both are done in-house, including inter-axle differential rebuilds.
What should a Matthews driver note before bringing in a transmission problem?
When it happens: cold or warm, loaded or empty, and in which gears. Any grinding, whining or clunking, any fault code or warning light, and whether the clutch pedal feels different. On an automated manual, write down what the gear display shows. Earlier repair invoices for the transmission or clutch help too.