New Richmond’s Destination for Diesel Performance & Custom Transmission Repair

Family-Owned Excellence in Every Repair

At Harmon Performance Transmission & Diesel Repair, we are a family-owned and operated shop dedicated to providing elite care for your daily driver or your high-performance specialty vehicle. Our team of ASE-Certified Technicians brings specialized expertise to every job, ensuring your vehicle receives the precise attention it needs to stay on the road. From domestic cars to foreign SUVs and heavy-duty trucks, we offer a welcoming, dog-friendly, and handicap-accessible environment designed to make your repair experience as stress-free as possible.

What We Do

Precision Transmission & Diesel Services

At Harmon Performance Transmission & Diesel Repair, we specialize in delivering thorough, accurate transmission repairs and diagnostics for all types of vehicles—from domestic and foreign cars to heavy-duty trucks and specialty performance builds. Our experienced technicians are equipped to service both automatic and manual transmissions, along with 4WD systems, clutches, and critical driveline components like U-joints and driveshafts.

In addition to our deep expertise in transmissions, we proudly offer comprehensive diesel service and repair. With highly skilled diesel technicians on our team, we’re equipped to handle everything from diagnostics and routine maintenance to complex engine and performance repairs—helping diesel owners get the reliability and power they depend on.

Whether you’re dealing with shifting issues, need fluid service, require driveline repair, or are facing a major transmission or diesel repair, our commitment to precision and quality ensures your vehicle gets the expert care it deserves.

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Who We Are

About Harmon Performance: Certified Expertise You Can Trust

Choosing the right shop means choosing peace of mind. As a family-owned business, we treat every vehicle as if it were our own. We back our work with industry-leading credentials, including ASE Certification, TransGo Tech Certification, and active membership in the ATSG (Automatic Transmission Service Group). To make your service more convenient, we offer 24-hour drop-off and a local shuttle service, ensuring your day doesn’t stop just because your vehicle is in the shop.

Our Mission

Quality, Service, and Community

Our mission at Harmon Performance Transmission & Diesel Repair is to deliver exceptional repair and diagnostic services with unwavering integrity. We strive to exceed expectations through expert craftsmanship and a deep commitment to the New Richmond community.

Uncompromising Quality

We utilize only high-quality parts and state-of-the-art equipment to ensure long-lasting reliability.

Customer-Focused Service

From our accessible shop to our personalized communication, your convenience is our priority.

Community Commitment

We aren’t just a shop; we are your neighbors, invested in keeping our local drivers safe and satisfied.

Flexible Financing

for Unexpected Repairs

Unexpected transmission issues—especially for high-torque diesel trucks and performance builds—don’t have to stall your life. At Harmon Performance Transmission & Diesel Repair, we offer flexible financing options to help you get back on the road, or the track, without the upfront stress. Whether you are facing a heavy-duty diesel overhaul or a custom performance build, our financing solutions ensure your vehicle receives the elite care it deserves today.

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Quick & Easy:

Apply in minutes and receive an instant decision.

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Budget-Friendly:

Choose a payment plan that fits your monthly budget.

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Get Service Today:

Don’t wait—get the repairs or performance upgrades you need now and pay over time.

Apply for Financing

What Our Customers Say

See Why Our Customers Love Us

    
 
 
          Mark Jackson 
 
 
 
 Trustindex verifies that the original source of the review is Google. I bought a 2018 GMC Denali and noticed it had a shudder. I researched the issue and found out it was a common problem with the transmission. I went to Harmon and inquired about solutions. They gave me options And explained the fix. I chose a transmission rebuild. They kept me informed through the process and  finished it in good time. I picked up my truck last week and am totally impressed with how the truck now shifts and runs.
  
 
         Gerald Kruse 
 
 
 
 Trustindex verifies that the original source of the review is Google. Seems like a great place. Very clean and organized shop. Wish my transmission would have been repairable
  
 
         michael 
 
 
 
 Trustindex verifies that the original source of the review is Google. I recently had a service done on my transmission (fluid and filter change) and I couldn't be happier with the entire experience! From the moment I walked in the staff was very professional, honest and upfront about everything that would be done including the price! Jason took the time to explain everything that they found and recommended I should fix or keep an eye on outside of service they were doing and never once pushed me to have them fix everything else right then and there.
The quality of their work is top notch and my vehicle shifts smoother then ever. They finished the job on time as expected and kept me updated throughout the whole process. Its rare to find a place with this kind of customer service now days and one you can trust. So all of this is why they earned a 5 star from me and highly recommend them for any vehicle/transmission concerns you may have! Thank you guys for a great experience!
  
 
         Leslie Dickinson 
 
 
 
 Trustindex verifies that the original source of the review is Google. Jason has looked at 2 of my vehicles now to see if the transmissions were bad. He's very good and honest. I highly recommend them. I'd give 10 stars if I could. Thank you for the great service.
  
 
         Jason Adams 
 
 
 
 Trustindex verifies that the original source of the review is Google. The guys there are very up front about what you need and don't need. Plus they are very good at their job. This place really knows their stuff
  
 
         Nick Lauber 
 
 
 
 Trustindex verifies that the original source of the review is Google. These guys are awesome, highly recommend
  
 
         Dillon Proulx 
 
 
 
 Trustindex verifies that the original source of the review is Google. This shop is awesome. My wife and I brought our jeep in for a transmission replacement. They had honored our word and were extremely patient while we were sourcing funds for the unexpected repair. I would recommend this shop to anyone. Thanks again!
  
 
         Stuart Buehler 
 
 
 
 Trustindex verifies that the original source of the review is Google. I can't say enough good things about this shop. I have been looking for a great trustworthy local mechanic and found them now. I had taken my vehicle to another auto shop for all fluid changes and services. I was told my vehicle needed a new transmission out of the blue. I decided to take it for a second opinion and brought it to Harmons. They did all of the proper testing and determined I infact do not need a transmission. They serviced everything, found a few areas that needed attention and got me taken care of. Extremely happy I decided to bring it in. I will take all of my vehicles here now.
  
 
  
 
  
 
   Google rating score: 4.9 of 5, based on 51 reviews