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National Transmission, Inc.

About Us

Based in Portage, IN, National Transmission, Inc. is your trusted destination for exceptional transmission services and a comprehensive range of automotive solutions. Serving Portage and the surrounding communities, our skilled team specializes in transmission repairs and excels in various auto services, including brake repair, radiator repair, engine repair, coolant system maintenance, towing, small engine repair, vehicle diagnostics, routine car maintenance, and 4x4 service. Rely on National Transmission, Inc. for outstanding service and dependable solutions for all your vehicle needs.

Areas Served

Portage, IN | Valparaiso, IN | Hobart, IN | Merrillville, IN | Chesterton, IN | Crown Point, IN

What We Offer

Our Services include:

Our Products include:

Testimonials

On 8/31/2026 jboy680 had this to say:
If you ever need anything transmission wise done don't even think of going anywhere else. Lou , His son and his crew do stellar work ! They have done multiple jobs for me over the years and always went above and beyond what they had to do ! I would rate them 10 stars out of 10 !!

On 4/5/2026 Shellie Barron had this to say:
They were highly recommended to me by the owner, Sonny of USA Muffler in Valparaiso. These people showed respect, honesty & value! They rebuilt my complete transmission in a short period of time. The shop crew & well as the front desk treated me & my vehicle extremely well!! A Fantastic team They have there! They do more than just transmissions.

On 4/3/2026 Jimmie Piper had this to say:
Excellent people and service je went above and beyond what was expected and worked with me I recommend these guys respectful and honest thank you guys

On 9/28/2025 Kathleen Hochberg had this to say:
Professional friendly and cost efficient Testimonial written by Kathleen Hochberg on this site.

On 9/16/2025 Mick Gut had this to say:
My family and Ivalways come here..great bunch of guys and always great service at a great cost.

Contact Us

National Transmission, Inc.
5475 US Hwy 6 Portage, IN 46368
Phone: (219) 762-2228
Fax: (219) 763-2029
Email: tranzman23@frontier.com

Where To Find Us

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Our Hours

Holiday Hours May Vary. Please Call For Details.

Monday: 8:00 AM - 5:00 PM
Tuesday: 8:00 AM - 5:00 PM
Wednesday: 8:00 AM - 5:00 PM
Thursday: 8:00 AM - 5:00 PM
Friday: 8:00 AM - 5:00 PM
Saturday: 8:00 AM - 12:00 PM

News

🚗 Don't Ignore the Warning Signs! ⚠️

Strange noises when shifting? Delayed acceleration? Leaking fluid? Your vehicle could be telling you it's time for professional service.

At National Transmission, Inc., we're more than just transmission experts. From transmission repairs and rebuilds to brake service, engine diagnostics, radiator repair, routine maintenance, and more, our experienced team is here to keep your vehicle running safely and reliably. Serving Portage and the surrounding communities, National Transmission provides dependable automotive solutions for both foreign and domestic vehicles.

✅ Transmission Repair & Rebuilds
✅ Brake & Engine Repair
✅ Vehicle Diagnostics
✅ Routine Maintenance
✅ 4x4 Service & More

Don't wait for a small problem to become a major repair. Let our trusted technicians get you back on the road with confidence.

📞 Call today to schedule your service appointment!

When your car needs reliable care, National Transmission Inc. is your trusted local team in Portage, IN. From expert transmission repair and rebuilds to full auto repair, brake service, diagnostics, and routine maintenance, their experienced technicians handle both foreign and domestic vehicles with precision.
Locally owned and operated, National Transmission provides prompt service backed by a 100% parts and labor nationwide warranty, giving you peace of mind every mile you drive. Whether you need engine diagnostics, an oil change, or transmission service, they’re committed to keeping your vehicle running safely and efficiently.
👉 Visit NationalTransmissionPortage.com to schedule your appointment today!

FAQ

What are the signs that my transmission needs repair?
Common signs include slipping gears, delayed shifting, fluid leaks, burning smells, and unusual noises while driving. If you notice any of these symptoms, bring your vehicle in for a full transmission diagnostic.
Do you offer complete auto repair services in addition to transmission work?
Yes! In addition to expert transmission service, we provide a full range of auto repair services including brake repair, engine repair, AC repair, radiator repair, oil changes, and more.
Can I get a diagnostic test if my check engine light is on?
Can I get a diagnostic test if my check engine light is on?
Do you offer towing services if my vehicle breaks down?
Yes, we provide reliable towing services. Whether your vehicle has a transmission issue or another mechanical problem, we can get it to our shop for expert repair.
How often should I schedule regular maintenance like tune-ups or coolant system checks?
Regular car maintenance is key to preventing major repairs. We recommend oil changes every 3,000–5,000 miles, coolant checks annually, and full tune-ups every 30,000 miles, depending on your vehicle and driving habits.

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