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Circle D Transmission Now Offers High Horsepower 6L80 and 6L90 Parts

Performance TransmissionCircle D Transmission is excited to announce that we are now offering High Horsepower 6L80 (6L80e) and 6L90 (6L90e) Performance Transmission Rebuild Kits and Parts. We offer FREE UPS Domestic Ground Shipping. Most orders ship the same day if ordered by 12pm, Central Standard Time, Monday through Friday.

Click here for more information about kits and parts

CDT’s Kits are available in multiple horsepower levels:

  • 6L80 (6L80e) Level 2 Rebuild Kit rated up to 550 RWHP

  • 6L80 (6L80e) Level 3 Rebuild Kit rated up to 750 RWHP

  • 6L80 (6L80e) Level 4 Rebuild Kit rated up to 1000 RWHP

  • 6L90 (6L90e) Level 2 Rebuild Kit rated up to 600 RWHP

  • 6L90 (6L90e) Level 3 Rebuild Kit rated up to 750 RWHP

  • 6L90 (6L90e) Level 4 Rebuild Kit rated up to 1100 RWHP

CDT began the journey of taking the factory GM transmission and transforming it so that it could handle the horsepower revolution present today when we purchased a Gen 5 Camaro for R&D. Along the way, there were many requests from fellow horsepower junkies to purchase CDT’s revolutionary Performance Rebuild Kits for the 6L80 (6L80e) & 6L90 (6L90e.)

These Rebuild Kits have the necessary components to dial in your transmission rebuild correctly - from hydraulics to clutch clearances to transmission end-play. Included in each Kit is valuable information pertaining to transmission assembly tips and detailed CDT rebuild instructions. These kits pick up where GM left off in terms of strengthening the OE transmission to handle the ever-increasing horsepower levels of today’s vehicles.

Besides offering the complete rebuild kits for the 6L80 (6L80e) and 6L90 (6L90e) we also offer individual components. One of our more popular parts is the 4140 H.T.S.R. (Heat Treated and Stress Relieved) Billet Reinforced Output Carrier – also known as the Billet Planetary. It includes a 4140 billet steel drive to strengthen the spline area. The drive plate is milled and contoured to the planetary housing to eliminate any possible separation under a load. This is a drop-in part for vehicles producing over 750 RWHP and also for Nitrous and/or Heavy Vehicles including trucks, SUV’s and CTS-V’s.

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Another popular option is the Billet Shaft, Hub and 4-5-6 Clutch Kit for both the 6L80 (6L80e) and the 6L90 (6L90e.) The billet intermediate shaft is made to our specifications to address the weak stock shaft issue, is precision machined from 300M alloy steel and is heat-treated to add strength and durability. The 4-5-6 Clutch Hub is also manufactured to address the weakness in the stock hub while at the same time it improves lubrication to the 4-5-6 clutch module. It is made from 4140 H.T.S.R. billet steel. Our 4-5-6 clutch modules increase apply area and the G3® friction material is formulated to maximize heat resistance and minimize wear to the clutch module.

Understanding the Process & Cost Behind Transmission Repair

Transmission repair

Do you suspect that your vehicle has a major transmission issue? Are you dreading having to research transmission repair options? And, what about how much money the transmission repair is going to cost? Are you also wondering if your car or truck’s transmission is even worth repairing?

If you’re asking yourself those questions, you are not alone and we understand your possible stress and confusion. After all, transmission repair is a costly investment that you are making into your vehicle. Transmission repair is incredibly complex and requires a proper diagnosis from the get-go or else you could open yourself up to huge levels of frustration.

At Circle D Transmission, we are here to guide you through the transmission repair process so that you can make an informed decision. In the end, with the correct information and knowledge, you’ll be able to understand your options and the associated costs behind transmission repair so that you can make a decision that is best for your situation.

So, let’s break down the different repair options when it comes to transmission repair. There are two main options nowadays if your transmission requires rebuilding. You can have your transmission rebuilt by a local facility or you can replace it with a remanufactured transmission. While either of these options can provide you with a quality transmission, there are pros and cons to each.

Let’s start by mentioning the benefits of each option.

One benefit of rebuilding your transmission is that we are able to upgrade parts that frequently fail with high mileage and/or have aftermarket updates. At Circle D Transmission we have decades of experience rebuilding transmissions and we can ward off future issues by replacing/upgrading parts that are known to fail. A benefit of replacing with a remanufactured transmission is that the turn-around-time is typically much faster than rebuilding since the transmission that we purchase is already built and waiting on the shelf of one of our suppliers.

Now, let’s move on to discuss warranties. When we rebuild your transmission here at Circle D Transmission, the typical warranty that we offer is 2 years or 24,000 miles, whichever comes first. Warranty issues must be brought back to us at our location in Houston, Texas. If you replace it with a remanufactured unit, the warranty can go up to 3 years or 100,000 miles, whichever comes first. Remanufactured transmissions typically offer a nationwide warranty. Both warranties typically cover parts and labor. So, if you are planning to keep your vehicle for many years and/or travel out of the greater Houston area often, you may want to consider a remanufactured transmission for greater peace of mind.

You also need to consider if your vehicle’s transmission is worth fixing. When clients bring this valid question up to us, we urge them to assess the rest of the vehicle. If the rest of the vehicle is in good working order then it probably makes sense to invest in the transmission and have it rebuilt or replaced. If you go to trade in a vehicle with a malfunctioning transmission, you’re going to take a fairly substantial hit in the value of the vehicle -- one that is likely equal to the cost of repairing the transmission. Other costs associated with purchasing a new vehicle are:

  • Depreciation of the new vehicle

  • Unless you pay cash, you will have a monthly payment with finance charges

  • Taxes and fees paid to purchase the new vehicle

  • Additional insurance costs on the new vehicle

Are you thinking about buying a used vehicle instead, so that you don’t have to take out as large of a loan and can factor in less loss due to depreciation? Think again... you could possibly be buying someone else’s problems... including a malfunctioning transmission in the near future. By keeping your current vehicle, you know the service history, so you’re less likely to have a surprise.

If you allow Circle D Transmission the opportunity to earn your trust, we assure you that we will provide you with ample information upfront so that you can make a decision that makes sense for you now and years down the road!

So how much does it cost to repair or replace a transmission? The average cost to rebuild or replace with a remanufactured unit is $3,000 - $5,000.

For an estimate, call 713-895-7019 or click here to schedule an appointment.

True Transmission Experts at Circle D Transmission

Do you know what it means to be a true transmission expert? To us it means specializing in one area and working every day to remain as an expert. At Circle D Transmission we specialize in transmission repair - we don't repair brakes, engines, air conditioners, or any maintenance services other than transmissions. What that means to YOU is that we are experts in our field. Our highly trained transmission technicians are able to hone in and become transmission experts with today's sophisticated transmission units. So, if you suspect that your transmission is giving you an issue, go see a transmission specialist - one that is an expert and has the experience to diagnose your transmission properly. Call us at 713-895-7019 or send us an email to:

Frequent Transmission Issues

On a daily basis we get phone calls from clients describing the issues noted below. If your vehcicle is experiencing any of these issues your best bet is to bring it to Circle D Transmission so that we can complete an initial evaluation and address any potential transmission issues. 

1 - I am pressing the gas, but the RPMS are going up and my vehicle is not moving like normal - my transmission seems to be slipping


2 - I hear a strange noise that seems to be coming from my transmission - especially when it changes gears

3 - I notice a leak where I park my car 

4 - My check engine light is on and my car seems to be stuck in one gear

If you're experiencing any of the issues above please call Circle D Transmission at 713-895-7019 or email us at:



Rebuild my Transmission or replace with a Remanufactured Transmission?

At Circle D Transmission, we pride ourselves in the proper diagnosis of your transmission problem. If we determine that your transmission requires rebuilding or replacing, you have more options these days. There are times that it makes more sense to replace your transmission with a remanufactured unit instead of us rebuilding it. For instance, severe hard part damage, a lack of available parts, or a longer / nation-wide warranty, are all things to consider when making the decision to replace your transmission. At Circle D Transmission, we approach every vehicle on an individual basis and look for the best solution for you and your situation. If you suspect that you're having transmission issues, the first step is to bring it to us for a professional diagnosis. Call us at 713-895-7019 or email us at: 

Circle D Transmission - Houston's Top Choice for Professional Diagnosis and Repairs
Circle D Transmission, located in Houston, Texas has been helping people just like you since 1976 with their transmission repair needs. We are still owned and operated by the same family for over 4 decades. So, when you begin noticing a problem with the transmission in your vehicle, we know what you’re thinking...How much is this going to cost me and how long will I be without my vehicle? We know that bringing your vehicle to a transmission repair shop is...