Transmission Shop in Denver, CO: 5 Common Signs of Failure

AC Transmission Center
Mechanics performing car maintenance at a professional transmission shop.

If you’re driving along I-70 or tackling the steep climbs of the Rocky Mountains, your transmission is working overtime to keep your vehicle performing smoothly. At AC Transmission Center, the leading transmission shop in Denver, CO, we understand how important it is to catch transmission issues early. If you notice anything unusual, don’t hesitate to call us today at (303) 428-6566 for expert help.


In this blog, we’ll break down the five most common signs of transmission failure. If you notice any of these issues, don’t wait—bring your vehicle to our expert technicians and get back on the road with confidence.

1. Slipping Gears or Hesitating When Shifting

Have you noticed your vehicle slipping between gears or hesitating when shifting? These are two of the most obvious and serious red flags. If your transmission can’t stay in gear or takes too long to switch between them, it could mean the internal clutch packs or bands are wearing out—or you may be low on transmission fluid.



At our transmission shop in Denver, CO, we diagnose and repair slipping transmissions quickly, restoring your vehicle’s performance and safety. Diesel vehicle owners, take note: if you’ve had performance issues while towing or hauling heavy loads, it may be time for a diesel transmission upgrade in Denver, CO.

2. Strange Noises or Grinding Sounds

When your transmission starts making grinding, humming, or whining noises, it's time to act. These sounds often indicate mechanical wear, loose components, or internal damage. For manual transmissions, grinding gears could mean worn-out synchronizers or a failing clutch.



In Denver’s stop-and-go traffic, a stressed transmission can degrade quickly. If you're hearing noises, AC Transmission Center is the transmission shop in Denver, CO with the experience and equipment to pinpoint the problem and fix it right the first time.

3. Leaking Transmission Fluid

Spotting bright red fluid under your vehicle? Transmission fluid leaks are more than a cosmetic issue—they’re a sign your transmission is at risk of overheating and internal damage.



Transmission fluid is essential for lubricating and cooling the vital components inside your vehicle’s transmission. Without proper fluid levels, your transmission risks catastrophic failure. At AC Transmission Center, your reliable transmission shop in Denver, CO, we don’t just detect and repair leaks—we also provide comprehensive transmission fluid flushes and thorough inspections as part of our routine maintenance services to keep your vehicle running smoothly.


For diesel drivers pulling weight across mountain terrain, maintaining transmission fluid levels is essential. A diesel transmission upgrade in Denver, CO may also help extend the lifespan of your vehicle and improve its towing performance.

4. Burning Smell Coming from Your Engine Bay

A burning odor could mean your transmission is overheating. Old or insufficient transmission fluid can cause excess friction, heat, and wear on internal parts. Over time, this can lead to total failure.



If you notice a burning smell while driving or after parking, don’t ignore it. Come see us at our transmission shop in Denver, CO for a full inspection. We’ll determine whether your transmission is overheating and recommend a course of action to prevent long-term damage.

5. Warning Lights or Transmission Error Codes

Most modern vehicles are equipped with advanced diagnostic systems that monitor your transmission. If your check engine light is on—or worse, a specific transmission warning light appears—don’t delay.



At AC Transmission Center, we use the latest diagnostic tools to read transmission codes and identify any underlying issues. Whether it’s a faulty sensor, solenoid issue, or a more serious internal failure, we’ve got the expertise to solve it. For diesel vehicle owners, our diesel transmission upgrade in Denver, CO services are tailored for performance and reliability, even under heavy-duty use.

Why Choose AC Transmission Center?

We’re not just another transmission shop in Denver, CO—we’re your local experts with decades of experience. Here’s why drivers across the Front Range trust us:


  • ASE-certified technicians.
  • Specialization in both gas and diesel transmissions.
  • Honest diagnostics and fair pricing.
  • Customized diesel transmission upgrades in Denver, CO.
  • Local, family-owned business serving Denver since day one.


At our transmission shop in Denver, CO, we understand the unique challenges Colorado roads present. From extreme temperature fluctuations to high-altitude driving, these conditions can take a toll on your transmission. That’s why we offer customized solutions tailored specifically for local drivers, ensuring your vehicle performs reliably no matter the conditions.

Auto transmission parts on the floor awaiting inspection at a local transmission shop.

Let’s Keep Your Transmission Running Strong

Your transmission is one of the most complex systems in your vehicle. When it fails, it can leave you stranded—and stuck with a hefty bill. Don’t let it get that far.



If you’ve noticed any of the five warning signs discussed above, it’s time to schedule an inspection at AC Transmission Center, the leading transmission shop in Denver, CO. Whether you need a minor repair or a full diesel transmission upgrade in Denver, CO, we’re here to help with fast, reliable service.


Call us today at (303) 428-6566 or visit our contact us page to book your appointment. Trust us to keep your transmission—and your vehicle—running at peak performance.

Let’s get your gears shifting smoothly again.

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Unleashing Performance: The 6L80 Transmission's Valve Body Zip Kits and the Power of PR Valve Updates

By AC Transmission • January 10, 2024
As automotive technology advances, the quest for optimal performance and efficiency drives continuous improvements in vehicle components. In the realm of automatic transmissions, the 6L80 transmission has garnered praise for its reliability and smooth operation. However, enthusiasts and professionals alike recognize the transformative impact of specific upgrades, particularly those involving valve body zip kits and PR valve updates. In this blog, we delve into these enhancements and their profound effects on the 6L80 transmission. Understanding Valve Body Zip Kits: Valve body zip kits have become a game-changer for those seeking to unlock the true potential of their 6L80 transmission. These kits consist of carefully selected components, including upgraded valves, springs, and other precision parts, designed to enhance fluid flow and optimize shift performance. By addressing inherent design limitations and refining hydraulic control, valve body zip kits contribute significantly to the overall efficiency and responsiveness of the transmission. Benefits of Valve Body Zip Kits: Improved Shift Quality: Valve body zip kits are engineered to refine the hydraulic control within the transmission, resulting in smoother and more precise shifts. The upgraded components reduce friction and enhance fluid flow, mitigating the potential for harsh or delayed gear changes. Drivers experience a more seamless and enjoyable driving experience, particularly during acceleration and deceleration. Enhanced Durability: Upgrading the valve body with zip kits often involves the incorporation of more robust materials and improved designs. This leads to enhanced durability, reducing wear and tear on critical components. The result is a transmission that can withstand higher stress levels, making it an ideal choice for those who demand both reliability and performance from their vehicles. Adaptability to Performance Modifications: Enthusiasts who are keen on modifying their vehicles for increased power and torque find valve body zip kits to be a valuable asset. These upgrades ensure that the transmission can effectively manage the added stress associated with performance modifications. Whether it's a turbocharger, supercharger, or other aftermarket enhancements, a properly upgraded valve body can accommodate these changes seamlessly. The Power of PR Valve Updates: Parallelly, the Pressure Regulator (PR) valve plays a pivotal role in the performance of the 6L80 transmission. Updating the PR valve involves refining the pressure regulation within the transmission, leading to several advantages: Redesigned: The GM OEM PR valve had manufacturing defects that has led to common transmission failures due to excessive wear from fluid flow. The newly designed PR valve along with a newly drilled port hole into the pump allows fluid flow to be more uniform when actuating the valve. This correction in design has improved the longevity of the transmission. Optimized Line Pressure: A precisely tuned PR valve ensures that the transmission maintains the correct line pressure under various driving conditions. This optimization contributes to improved shift quality, fuel efficiency, and overall transmission performance. Reduced Heat Buildup: Efficient pressure regulation minimizes the risk of excessive heat buildup within the transmission. This is particularly crucial for those who use their vehicles for towing or other high-stress applications. By keeping temperatures in check, the updated PR valve promotes longevity and reliability. Conclusion: In the dynamic world of automatic transmissions, valve body zip kits and PR valve updates emerge as transformative enhancements for the 6L80 transmission. These upgrades go beyond routine maintenance, offering enthusiasts and professionals alike an opportunity to unleash the full potential of their vehicles. From improved shift quality to enhanced durability and adaptability to performance modifications, these updates empower drivers to experience a new level of driving satisfaction with their 6L80-equipped vehicles. nt source.