Truck Transmission Repair in Glasgow, MT
Shift Smooth, Drive Strong Expert Transmission Service for Diesel and Heavy Duty Trucks
Your truck’s transmission is one of its most complex and critical systems. When something goes wrong with shifting, power delivery, or drive performance, you need an experienced shop that understands the demands of commercial and diesel trucks. At Thompson & Sons Inc. in Glasgow, MT, we offer complete transmission diagnostics, repairs, rebuilds, and service for heavy-duty and diesel trucks.

Whether you’re dealing with hard shifts, fluid leaks, gear slippage, or full system failure, our technicians have the tools and training to get your truck back to peak performance quickly and reliably.
Full Service Transmission Repair for Commercial Trucks
We specialize in medium- and heavy-duty truck transmissions, including both automatic and manual systems. Our facility is equipped to handle everything from minor component repairs to full transmission rebuilds and replacements.

Our transmission services include:
Transmission diagnostics
Fluid and filter replacement
Clutch adjustments and replacements
Gear and synchro repair
Valve body service
Torque converter replacement
Transmission cooler line repair
Seals and gasket replacement
Rebuilds and reman installations
We work on Eaton, Allison, Fuller, Spicer, ZF, and all major OEM transmission systems found in commercial vehicles, diesel pickups, and Class 8 trucks.
Signs Your Transmission Needs Service
Transmission problems often start subtly and worsen over time. Knowing the early signs can save you thousands in repairs and prevent roadside breakdowns.
Common warning signs include:

- Delayed or rough shifting
- Slipping gears while driving
- Fluid leaks under the truck
- Grinding or whining noises
- Check transmission light or error codes
- Loss of power to wheels
- Difficulty engaging drive or reverse
- Burning smell from undercarriage
If you’re experiencing any of these issues, don’t wait. Early diagnostics can often prevent a full rebuild and extend the life of your transmission.
Clutch Repair and Replacement
For manual transmissions, clutch wear is inevitable — especially under heavy hauling and frequent shifting. We inspect, adjust, and replace clutch systems for diesel and commercial trucks of all sizes.

Clutch services include:
Clutch disc and pressure plate replacement
Hydraulic system checks
Slave and master cylinder replacement
Flywheel resurfacing or replacement
Pilot and throw-out bearing service
If you notice slipping, shuddering, or difficulty shifting, your clutch may need attention. Our team can diagnose the issue and provide fast, cost-effective service to get you back in gear.
Transmission Rebuilds and Replacements
In cases of major failure, a full rebuild or transmission replacement may be the best solution. Thompson & Sons Inc. offers in-house rebuilds for many transmission types, as well as access to remanufactured OEM units.

Benefits of a rebuild or reman unit:
- Restores original performance
- Addresses internal wear and damage
- Includes updated components and gaskets
- Backed by warranty options
- Cost-effective vs. total truck replacement
We’ll walk you through your options and provide transparent pricing based on your truck’s make, model, mileage, and usage.
Fleet Transmission Service
Fleet operators rely on consistent powertrain performance to meet delivery timelines and safety standards. We work with local companies and contractors across northeast Montana to provide preventive transmission maintenance and timely repairs for fleet vehicles.

Fleet services include:
- Scheduled fluid service and filter changes
- On-site diagnostics and inspections
- Priority turnaround for urgent repairs
- Detailed service history tracking
- Discounted labor rates for fleet clients
Avoid costly downtime and transmission failure by keeping your fleet serviced by our experienced heavy-duty technicians.
Mobile Transmission Diagnostics
Transmission problems don’t always happen in the shop — that’s why our mobile repair team can come to you. Our mobile units are equipped to provide basic transmission diagnostics and support wherever your truck breaks down.

On-site transmission services include:
Visual inspections for leaks or component failure
Fluid checks and top-offs
Shift linkage adjustments
Electronic diagnostics for error codes
Referrals for towing or rebuilds when needed
If mobile repair isn’t enough, we’ll help coordinate transport to our facility for full service.
Why Choose Thompson & Sons Inc.
We know how important it is for your transmission to perform under pressure. At Thompson & Sons Inc., we combine real experience, trusted parts, and honest service to deliver transmission work that lasts.

Here’s what makes us a top choice for truck transmission repair:
Years of diesel and commercial repair experience
In-shop and mobile capabilities
Transparent recommendations — no upsells or guesswork
Competitive pricing and fast turnaround
Locally owned, community-focused service
Support for individuals, fleets, and equipment operators
From minor fixes to full rebuilds, we handle transmission repairs the right way — so you can shift with confidence.
Schedule Transmission Repair Today
Don’t risk a breakdown or unsafe shifting. Call Thompson & Sons Inc. to schedule expert transmission repair, request an inspection, or ask about fleet service.
Phone:
(406) 228-4801
Email:
thompsonmandsons@nemont.net
Location: 53997 Highway 2 West, Glasgow, MT 59230
Hours: Monday to Friday, 8 am – 12 pm and 1 pm – 5 pm
We keep Montana’s trucks moving — one shift at a time.