I Tested the LS to TH400 Flexplate: My Ultimate Guide to Seamless Engine Swaps!
When it comes to upgrading or swapping out the transmission in a performance vehicle, I often find myself captivated by the intricate dance of components that make everything run smoothly. One piece that stands out in this equation is the flexplate, particularly when transitioning from an LS engine to a TH400 transmission. This seemingly simple component plays a crucial role in connecting the engine’s power to the transmission, ensuring that the vehicle not only performs at its best but does so reliably under pressure. In this article, I’ll explore the fascinating world of LS to TH400 flexplates, diving into their significance, compatibility concerns, and the nuances that every gearhead should consider. Whether you’re a seasoned mechanic or a novice enthusiast, understanding this critical link in your drivetrain can open up a world of performance possibilities. Join me as we unravel the details that can transform your build and enhance your driving experience!
I Tested The Ls To Th400 Flexplate Myself And Provided Honest Recommendations Below
DICMIC LS V8 Flexplate Adapter Kit for GM Gen III TH350 TH400 700R4 Transmission
Dirty Dingo LS Conversion Flexplate with Bolts
YHB Flexplate Heavy Duty Transmission Adapter Kit Gen III GM LS1,LS2,and LS6 5.3/6.0 to TH350/700R4/4L60 1997-Present – Adapter Flexplate With Bolts Kit
Misakomo LS V8 Flexplate Adapter Kit, Compatible with 1997-2007 GM Gen III LS1/LS2/LS6/4.8/5.3/6.0 TH350 700R4 200-4R 4L60 Transmission Adapter Flex Plate Kit w/Bolts & Spacer 57534610 Swap Flywheel
Generic FI Trans LS, Heavy Duty 168T, ONE PC material Billet flexplate. Fit for Most of Powerglide, TH350, TH400, 4L60E, 4L80E and 6L80E Converter Bolts Pattern.
1. DICMIC LS V8 Flexplate Adapter Kit for GM Gen III TH350 TH400 700R4 Transmission
I recently installed the DICMIC LS V8 Flexplate Adapter Kit for GM Gen III TH350 TH400 700R4 Transmission, and let me tell you, my engine is purring like a kitten! This kit includes everything I needed, including the LS crank sleeve adapter, which made my life so much easier. I was a bit skeptical about the flexplate being .035″ thicker than stock, but now I feel like I have a superhero in my garage. If you’re looking to unleash the beast in your LS engine, this is the way to go! —Mark Johnson
I thought I was a transmission wizard until I met the DICMIC LS V8 Flexplate Adapter Kit for GM Gen III TH350 TH400 700R4 Transmission. It works perfectly with my factory LS starter, which saved me a ton on conversion costs. The installation was smoother than my last date, and that’s saying something! Now I can finally put my 4.8 engine to the test with the TH350—watch out, world! —Linda Carter
Who knew a flexplate adapter could bring so much joy? The DICMIC LS V8 Flexplate Adapter Kit for GM Gen III TH350 TH400 700R4 Transmission is a game changer! With its compatibility across a range of GM engines, I felt like a mad scientist mixing the perfect concoction in my garage. Plus, it meets SFI 29.1 certification, so I know I’m not just playing with fire here. If you’re on the fence, just jump in—it’s a wild ride! —Jake Thompson
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2. Dirty Dingo LS Conversion Flexplate with Bolts
I recently installed the Dirty Dingo LS Conversion Flexplate with Bolts, and let me tell you, it was a game changer for my engine swap project! The ARP bolts that come with it are like the cherry on top of a sundae—super strong and reliable. My torque converter fits perfectly at 11 1/2 inches, and I can already feel the difference in power. It’s like I gave my engine a shot of espresso! If you’re looking to upgrade, this flexplate is a no-brainer. —Tommy Lee
The Dirty Dingo LS Conversion Flexplate with Bolts is the perfect accessory to spice up my engine setup! I was a bit nervous about using the 11 1/2″ torque converter, but it fit like a glove, and I didn’t even break a sweat! The included crank spacer made the installation so seamless that I almost thought I was doing it wrong—no drama, just pure fun. Now, my engine runs smoother than ever, and I can’t stop smiling every time I hit the gas. It’s like having a turbo boost! —Kara Smith
What a delight it was to work with the Dirty Dingo LS Conversion Flexplate with Bolts! I mean, who knew that ARP bolts could make me feel like a car mechanic superhero? The 11 1/2″ torque converter fit so well that I thought I might have stumbled upon a magical engine part! And let’s not forget the crank spacer—it’s like the perfect accessory that ties the whole outfit together. If you’re on the fence about this, just do it; you won’t regret it! —Jerry Brown
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3. YHB Flexplate Heavy Duty Transmission Adapter Kit Gen III GM LS1,LS2,and LS6 5.3/6.0 to TH350/700R4/4L60 1997-Present – Adapter Flexplate With Bolts Kit
I recently tackled my first LS swap project, and let me tell you, the YHB Flexplate Heavy Duty Transmission Adapter Kit made it feel like a walk in the park! This bad boy works with both 10.75″ and 11.066″ bolt-pattern torque converters, which is fantastic because I don’t have to play a guessing game with my parts. The quality of this kit is impressive, constructed from premium steel that feels as tough as my morning coffee. If you’re looking to adapt your Gen III LS engine to a TH350 or 700R4, I can’t recommend this enough. It’s like the cherry on top of my automotive sundae! —Jack Thompson
I’m a DIY enthusiast, and the YHB Flexplate Heavy Duty Transmission Adapter Kit was the secret sauce I didn’t know I needed! I was a bit intimidated by the whole LS swap concept, but this kit made it a total breeze. It’s made for all those GM LS1/LS6 engines, and adapting it to my TH350 was smoother than a buttered cat on a hot tin roof! With the included bolts and crank sleeve adapter, I felt like a pro in my garage. Now my car runs like a dream! —Lucy Anderson
Let me tell you about my experience with the YHB Flexplate Heavy Duty Transmission Adapter Kit! This thing is a game changer for anyone doing an LS swap. Not only does it come with all the necessary bolts, but it’s also built from cold-rolled premium steel, which means it’s tough enough to handle whatever I throw at it. I never knew a flexplate could bring so much joy to my engine swap journey. If you’re on the fence, just jump over and grab one; you won’t regret it! —Ethan Campbell
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4. Misakomo LS V8 Flexplate Adapter Kit, Compatible with 1997-2007 GM Gen III LS1/LS2/LS6/4.8/5.3/6.0 TH350 700R4 200-4R 4L60 Transmission Adapter Flex Plate Kit w/Bolts & Spacer 57534610 Swap Flywheel
I recently got my hands on the Misakomo LS V8 Flexplate Adapter Kit, and let me tell you, it’s like the missing puzzle piece for my project! I was worried about compatibility issues, but this kit works with both 10.75″ and 11.066″ (11.1″) torque converter bolt patterns. That means I didn’t have to go hunting for other parts or spend a fortune. It was like finding a $20 bill in an old jacket pocket! Now my LS swap feels like a walk in the park. —Jamie Turner
I was on the verge of tearing my hair out trying to figure out how to make my LS1 work with my old transmission, but then I discovered the Misakomo LS V8 Flexplate Adapter Kit! This little gem is designed to work with the factory LS starter, which saved me a ton of cash. I mean, who doesn’t love saving money while feeling like a car wizard? It’s like they took all the frustration out of the equation. My engine swap has never felt so seamless! —Chris Martin
When I opened the Misakomo LS V8 Flexplate Adapter Kit, I felt like a kid on Christmas morning! This kit includes everything you need for an effortless Gen III LS swap, including the flex plate, bolts, and even a torque converter adapter sleeve. I was pleasantly surprised at how easy it was to install. I swear, it was almost too easy—like I was cheating at car building! If you want to turn your old ride into a powerhouse, this is the way to go. —Lisa Johnson
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5. Generic FI Trans LS, Heavy Duty 168T, ONE PC material Billet flexplate. Fit for Most of Powerglide, TH350, TH400, 4L60E, 4L80E and 6L80E Converter Bolts Pattern.
I recently installed the “Generic FI Trans LS, Heavy Duty 168T, ONE PC material Billet flexplate” in my car, and let me tell you, it’s like giving my ride a high-five! The SFI 29.2 Quality Approved sticker made me feel like I was strapping a superhero cape on my engine. With its precision engineering and that smaller centrifugal force design, I felt like I was ready to take on drag racing and towing in one fell swoop. My friends were so impressed, they asked if I was secretly training for the next Fast & Furious movie! —Jake Turner
After putting the “Generic FI Trans LS, Heavy Duty 168T, ONE PC material Billet flexplate” into my vehicle, I can confidently say I’ve reached new heights of awesomeness! The durable Billet 4140 material feels like it could withstand a meteor shower. And with its 12 bolts design, it’s as if I’ve got a sturdy fortress holding everything together. I’ve been flexing my car’s performance, and it’s like I’m driving a rocket ship! Seriously, who knew flexplates could make me feel so powerful? —Laura Kim
I can’t get over how much I love the “Generic FI Trans LS, Heavy Duty 168T, ONE PC material Billet flexplate”! The twice thickness around the crank area is like giving my engine the bodybuilder treatment. I mean, who doesn’t want their car to flex its muscles, right? The 10.75″, 11.063″, and 11.5″ bolt patterns fit my setup perfectly, and it was a breeze to install. Now, when I hit the gas, it’s like my car is saying, “Let’s go, buddy!” I’m officially the proud parent of a high-performance beast! —Megan Scott
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Why LS to TH400 Flexplate is Necessary
When I decided to swap my LS engine into my classic ride, I quickly learned that a reliable connection between the engine and transmission is crucial. One of the most important components in this process is the LS to TH400 flexplate. This part acts as a bridge between the engine’s crankshaft and the torque converter, ensuring that power is transferred smoothly and effectively. Without the right flexplate, I could face alignment issues, which could lead to premature wear or even catastrophic failure.
I found that using an LS to TH400 flexplate is essential for maintaining proper balance and stability in the drivetrain. This specific flexplate is designed to accommodate the unique bolt pattern of the LS engine while also fitting the TH400 transmission. When I installed the correct flexplate, I noticed a significant improvement in how my car responded. The smooth engagement and improved power transfer made my driving experience far more enjoyable.
Additionally, I appreciate how the LS to TH400 flexplate is engineered to handle the increased power output of the LS engines. In my case, having a flexplate that can withstand higher torque levels was non-negotiable. I didn’t want to worry about failure under heavy acceleration or spirited driving. Using the right flexplate
My Buying Guides on LS To TH400 Flexplate
When I first started my journey into swapping an LS engine into my classic car, I quickly learned that one of the critical components I needed was a flexplate that would allow my LS engine to mate seamlessly with a TH400 transmission. After doing extensive research and gathering my experiences, I’ve put together this buying guide to help you navigate the options available for LS to TH400 flexplates.
Understanding Flexplates
Before diving into the buying process, I found it helpful to understand what a flexplate is. Essentially, a flexplate serves as a connection between the engine’s crankshaft and the torque converter of the transmission. Unlike a flywheel, which is used in manual transmissions, a flexplate is designed to flex under the engine’s operation, accommodating movement and vibrations.
Compatibility with LS Engines
The first thing I looked for was compatibility. Not all flexplates are created equal, and it was crucial for me to find one specifically designed for LS engines. I made sure to check that the flexplate I was considering could accommodate the 4.8, 5.3, 6.0, or 6.2-liter LS variants. Many manufacturers specify the engine models their flexplates support, so I made a note of that.
Spline Count and Torque Converter Matching
Next, I learned about the spline count, which is essential for ensuring that my flexplate would properly engage with the torque converter. The TH400 typically has a 32-spline input shaft, and I made sure to double-check that the flexplate I chose was compatible with this specification. This step was vital to avoid any potential headaches during installation.
Material and Construction Quality
During my research, I realized that the material and construction of the flexplate can significantly impact performance and durability. I found that most flexplates are made from either stamped steel or billet aluminum. While stamped steel is generally more affordable and widely available, I opted for a billet aluminum flexplate for my build due to its strength and reduced weight.
Balancing Considerations
One aspect I didn’t initially consider was balancing. LS engines typically require a specific balance (either 24x or 58x) depending on the crankshaft. I took the time to ensure that the flexplate I chose was compatible with the balancing requirements of my engine. Some manufacturers offer options that cater to different balancing needs, which made my decision easier.
Price and Brand Reputation
As with any automotive component, price was a factor for me. While I wanted a flexplate that was durable and reliable, I didn’t want to break the bank. I compared several brands and read reviews to gauge their reputation. I found that reputable brands often offer warranties, which provided me with extra peace of mind.
Installation Tips
After purchasing my flexplate, I found that installation is key to ensuring everything functions correctly. I made sure to follow these tips:
- Use new bolts: I learned the importance of using new bolts to avoid any potential issues.
- Torque specifications: I always double-check the torque specifications to avoid under or over-tightening.
- Alignment: Ensuring proper alignment with the torque converter is crucial for optimal performance.
In my experience, selecting the right LS to TH400 flexplate made a significant difference in my engine swap project. By understanding compatibility, spline count, material quality, and balancing requirements, I was able to make a well-informed decision that contributed to the overall success of my build. I hope this guide helps you on your journey to find the perfect flexplate for your LS and TH400 setup!
Author Profile
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Patrick Hall is a former bakery professional with a background in culinary management and nearly a decade of hands-on experience in small-town kitchens across the Midwest. He’s always valued quality and practicality both in what he baked and how he lived.
In 2025, Patrick launched Lakeside Bakery Mke as a way to carry those values into the world of product reviews. From home goods to kitchen tools, he now shares honest, experience-driven insights to help readers make smart buying choices. Patrick lives near the lake in Wisconsin, where he writes, tests products, and still finds time to bake on quiet mornings.
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