ALTO 8L90 Performance Transmission Rebuild Kit - Level 2 (Added Clutch Capacity)
Every 8L90 transmission rebuild kit, including this automatic transmission master rebuild package, is shipped with clear, step-by-step instructions designed to simplify installation and minimize issues. This guide helps ensure proper torque converter mating, careful seal installation, and accurate alignment of valve body components during the rebuild process.
If you’re new to working on complex transmissions like the 8L90, or concerned about risks such as improper fluid levels or seal damage, we strongly recommend adding the optional Service Manual. This comprehensive resource advises on signature details, from handling metal clad seals and bonded pistons to dealing with torque converter sizing and valve body nuances, helping you resolve problems effectively and maintain long-term reliability.
Installing this kit correctly helps protect your warranty, reduces the likelihood of costly repairs due to user error, and maintains customer satisfaction by minimizing return visits. You gain full access to all necessary parts, including seals, pistons, and gaskets, equipped for compatibility across a variety of GM models equipped with the 8L90 transmission.
Whether you’re a seasoned tech optimizing multiple vehicles or a DIYer tackling your first rebuild, proper guidance ensures that quantity of parts and cost considerations line up with real-world performance and reliability. Let us help make your rebuild a smooth, successful experience.
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In stock items ship within 1-2 business days.
Picture for representation purposes only. Actual contents may vary as we continue to develop our products.
SKU: ALTO-2 8L90-HPK-LS-P
Picture for representation purposes only - actual contents may vary as we continue to develop our product.
Detailed Clutch Pack & Overhaul Kit Breakdown – 8L90 Transmission Rebuild
The Circle D 8L90 transmission master rebuild kit is a complete high-performance upgrade for your automatic transmission, designed for precision, durability, and customer satisfaction. This kit includes five expertly engineered clutch packs and a full overhaul kit, offering total access to the parts required for optimal performance and long-term reliability. Whether you’re upgrading one vehicle or handling multiple repairs in your shop, this system is built to meet the demands of today’s power-hungry 8L90 transmission applications.
C1 Clutch Pack – 1-2-7-8-R
Includes:
This is the latest GM OEM clutch pack design, engineered with thicker steel plates for improved heat resistance and warp prevention, ideal for handling increased torque converter load and extended duty cycles.
C2 Clutch Pack – 1-2-3-4-5-R
Includes:
3 Clutches
2 Steel Plates
1 Apply Plate
A standard-capacity clutch pack built to OEM specs for direct replacement in compatible models. Maintains original gear ratios and shift feel while simplifying installation during rebuild projects.
C3 Clutch Pack – 1-3-5-6-7 (CDT Modified Alto Power Pack)
Includes:
This upgraded clutch pack adds one additional clutch over traditional 4- or 5-clutch drum configurations. Featuring G3® friction material, it reduces wear and enhances heat resistance for improved shift performance in higher horsepower vehicles.
C4 Clutch Pack – 2-3-4-6-8 (CDT Modified Alto Power Pack)
Includes:
This flexible design lets you configure the clutch for either +1 friction (with wave plate) or +2 frictions (without wave plate). Ideal for high-performance rebuilds seeking improved power delivery with fewer issues under heavy loads.
C5 Clutch Pack – 4-5-6-7-8-R (CDT Modified Alto Power Pack)
Includes:
This pack adds both an additional clutch and steel plate while keeping the factory wave plate intact. G3® friction ensures problem-free engagement and extended clutch life, ideal for aggressive street or off-road applications.
Overhaul Kit Components
This complete transmission master rebuild kit is assembled using premium materials and designed for easy install and long-term results.
Key Components:
Hi-Per Blue® Piston for C1 (1-2-7-8-R): Built from high-performance Blue AEM material for superior thermal and chemical resistance. Offers a better fit and longer life compared to standard bonded pistons.
GM Filter: Ensures clean transmission fluid circulation to prevent debris buildup and transmission issues.
Metal Clad Seals, O-Rings, and precision gaskets: Designed for tight fitment, reduced leaks, and greater reliability across all GM 8L90-equipped models.
This package gives you all the parts, seals, and accessories needed to perform a complete, high-quality 8L90 transmission rebuild, reducing cost, eliminating common problems, and increasing the quantity of reliable installations in your shop or garage. Every part is backed by Circle D’s trusted brand reputation and covered under warranty for added peace of mind.
Frequently Asked Questions
Is the Alto Power Pack compatible with all 8L90-equipped vehicle models?
Yes, the Alto Power Pack included in this 8L90 transmission rebuild kit is designed to be fully compatible with all GM vehicles using the 8L90 automatic transmission. The clutch packs and steel plates are engineered for precise fitment across various model years, ensuring proper gear engagement and torque transfer.
What makes the Hi-Per Blue® bonded piston an upgrade over standard bonded pistons?
The Hi-Per Blue® piston is manufactured with upgraded AEM material that offers enhanced resistance to heat and chemicals. This results in improved sealing performance, better durability during high-load shifts, and longer service life, especially in vehicles where the torque converter generates more heat under stress.
Can this kit help resolve existing transmission issues like delayed engagement or gear slipping?
Absolutely. Common transmission problems like delayed engagement, soft shifts, or slipping gears can often be traced to worn clutches, damaged seals, or warped steel plates. This transmission master rebuild kit addresses those issues directly with premium G3® friction material, thicker steel plates, and upgraded seals, helping to restore optimal pressure and gear timing.
Does this kit include all the metal clad seals and o-rings needed for a full rebuild?
Yes, this rebuild kit includes all necessary seals, including premium-grade metal clad seals and o-rings for critical pressure points. These parts ensure a complete seal during installation and help prevent fluid leaks and pressure loss, both of which can lead to recurring transmission problems if not properly addressed.
How does using this kit affect the overall cost and longevity of a transmission rebuild?
While this performance rebuild kit may have a higher upfront cost compared to basic kits, it significantly reduces the risk of premature failures and costly rework. By using premium components and providing full access to critical upgrade parts, the kit delivers longer-lasting results and better customer satisfaction, making it a smarter investment for long-term use.
