Simmons Diesel Performance, LLC

Simmons Diesel Performance, LLC Specializing in light duty diesel pickups, all repairs minor to major. We also carry our own line of upgraded transmissions.

We offer complete diagnostics, fuel system repairs & upgrades, engine repairs, electrical, HVAC, driveline, steering, and suspension service, and upgraded transmissions. Located in Barnesville, Georgia we at Simmons Diesel Performance, LLC specialize in all Ford, Dodge/Ram, and Chevrolet diesel trucks up to a 5500 series. all built in house for any of your needs. We take pride in our customer serv

ice as well as the quality and precision of our work. We are very meticulous, we work on just a couple of vehicles at a time so that the job is never rushed, this way we are able to guarantee every job is done accurately and even the tiniest bit of detail is paid attention too and never overlooked. We design and build all specialty components in house and do the work ourselves from start to finish. All items that we construct are designed with Solid Works CAD program to assure the most precise fitment and assembly. The machining, engine &, transmission builds, fabrication and certified welding is also completed in our shop to guarantee our work is done in the most accurate way. Due to the detail and time we spend on our jobs we are not always able to answer the phone. Please call 470-592-2268 If no answer leave us a detailed message with your name, contact number, reason for your call, and all of your vehicle information such as: make, model, year. You can also email us [email protected]. We thank you for your patience and will be in touch with you as soon as possible!

Wrapping up a leaking 6.7 Powerstroke upper oil pan.
05/29/2026

Wrapping up a leaking 6.7 Powerstroke upper oil pan.

05/28/2026
At Simmons Diesel, we don’t just build new transmissions—we bring your existing one back to life too. 🔧Whether you’re lo...
05/01/2026

At Simmons Diesel, we don’t just build new transmissions—we bring your existing one back to life too. 🔧

Whether you’re looking for a fresh build or need your current transmission repaired and running stronger than ever, we’ve got you covered. Quality work, real performance, and reliability you can count on.

Don’t replace it if you don’t have to—let Simmons Diesel rebuild it right.

Dropping in a Stage 1 6R140 into this F250 and making sure it stays cool with a transmission cooler, because power mean...
04/29/2026

Dropping in a Stage 1 6R140 into this F250 and making sure it stays cool with a transmission cooler, because power means nothing without reliability!

04/27/2026

Part 2 of our strange vp44 diagnostic. Gotta love the lack of information given from the beginning.
It was stated that "the problem started when the injectors were installed".... turns out its also when an ECM was installed.... as well as a complete engine build!

Allison Transmission and transfer case service on this L5P.
04/24/2026

Allison Transmission and transfer case service on this L5P.

Just doing a quick oil change… you know, the kind where the whole engine accidentally falls apart.
04/23/2026

Just doing a quick oil change… you know, the kind where the whole engine accidentally falls apart.

Now this one is a first. I've never seen a shaft splinter like this!
04/23/2026

Now this one is a first. I've never seen a shaft splinter like this!

04/22/2026

Part 1 of our strange vp44 diagnostic. Like and follow for part 2!

This is exactly why we hot flush EVERY transmission cooler that we do any transmission repairs on. Our flush machine may...
04/21/2026

This is exactly why we hot flush EVERY transmission cooler that we do any transmission repairs on. Our flush machine may run for 2 days (or nights) straight on this vehicle, but we've seen them like this before and have never had an issue when the flushes are done properly. Plus it saves our customers the cost of a transmission cooler and radiator.

Address

107 Yatesville Road
Barnesville, GA
30204

Opening Hours

Monday 8am - 11:59am
1pm - 5pm
Tuesday 8am - 11:59am
1pm - 5pm
Wednesday 8am - 11:59am
1pm - 5pm
Thursday 8am - 11:59am
1pm - 5pm
Friday 8am - 11:59am
1pm - 5pm

Telephone

+14705922268

Website

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