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This 4L60E Rebuild Kit Includes the Following:

  • New 4L60E Overhaul Kit
  • Alto Red Eagle Clutch Kit with Powerpacks
  • High Performance Kolene Steel Kit
  • New 4L60E Filter
  • New 4L60E Bushing Kit
  • New 4L60E Thrust Washer Kit
  • Sonnax 4L60E Performance Pack
  • Sonnax Rear Stator Support Bushing
  • Sonnax Oversized 2nd Gear Servo
  • Borg Warner Upgraded 29 Element Sprag
  • Sonnax 1-2 Pinless Accumulator Piston Kit
  • Sonnax .490 Larger Boost Valve
  • High Output Pump Slide Spring
  • 4th Gear Servo Return Spring

The 4L Platform

The 4L60/65/70E is a series of automatic transmissions from General Motors. Designed for longitudinal engine configurations, the series includes 4 forward gears and 1 reverse gear. The 4L60E is the electronically commanded evolution of the Turbo-Hydromatic 700R4, originally produced in 1982.

Most of the 4l60/65/70Es you see in service today were originally manufactured in the Toledo, Ohio, plant for General Motors.

These transmissions cannot be differentiated from the outside by the average eye. The 4L65E shares the same exterior parts but has stronger internals, such as 5 pinion planets compared to 4 in the 4L60E. These also can carry several different input shafts depending on which version you have. The early 4L60Es had a 298mm input shaft for non-LS platforms while the later LS models utilized a 300mm one. The later 4L70E also utilized an input speed signal on the input shaft.

An updated 4L60E, the 4L65E (RPO M32), was phased in the 2001 model year when coupled behind the 6.0 Vortec. Five-pinion front and rear planetaries, along with an additional 3-4 clutch allowing 7 clutches in the input housing and induction-hardened input shaft assembly, were improved to withstand up to 380 ft-lbs (515 N-m) of torque.

The Category 1 Kit

This Category 1 SunCoast 4L60/65/70E kit has everything you need for a successful high performance rebuild. This kit was designed for customers looking for a complete solution to their 4L60/65/70E transmission issues. Aside from all-new electronics, these kits include the same recipe we build with at SunCoast daily.

The Apply Band

The 4L60/65/70E transmissions utilize an apply band when shifting from 1st to 2nd and again when shifting from 3rd to 4th. This band is wrapped around the reverse input drum that sits directly behind the front pump assembly.

This band is known to be the weakest link in this unit, a problem that becomes even more prominent when you start deleting torque management or adding power modifications. Here at SunCoast with our 4L60/65/70E transmission rebuilds, we use a High Performance Alto Red Eagle Wide band with reinforced band anchors to improve reliability and performance. 

The 2nd Gear Servo

The 2nd gear servo is responsible for applying force to the band via hydraulic pressure. One of the first modifications we often see is the switch to the infamous "Corvette" 2nd gear servo. We have learned however that even those have a high failure rate as they were original equipment in the 4L65/70E transmissions. 

In this SunCoast Category Kit we upgrade to the Sonnax Super servo. This servo has an impressive 18% more apply area than the OE "Corvette" servo and features a dual seal design, ensuring a more positive band apply/release and eliminating cross-leaks within the bore.

This new servo is manufactured from billet aluminum and features a chromoly steel apply pin that has added seals to reduce leakage of 3rd gear pressure. This is the fastest band release in the industry.

The Performance Pack

The Sonnax Performance Pack for GM 4L60E, 4L65E and 4L70E transmissions is a must-have for any heavy-duty vehicle and the very best foundation for high-performance racing. All components work together to carefully tune line pressure, accumulator pressure and shift calibration. It’s the ultimate way to get an impressive transmission that responds to throttle and increased load with quick, firm shifts.

Rear Stator Support Bushing

The original GM 4L60, 4L60E, 4L65E, 4L70E rear stator bushing comes in narrow and wide versions in both common bronze and harder aluminum type materials. All versions commonly fail or wear out prematurely. Available aftermarket replacements typically have a poor quality fit and are also known to wear.

For maximum durability Sonnax offers rear stator support bushing 77002BT-01, a better fitting and extremely wear-resistant, PTFE-lined bushing to stop future wear in its tracks.

The Sonnax bushing is the best option for supporting the 20 lb. input housing and for improving the reliability of these common units.

The Sprag

The factory sprag assembly is notorious for flipping and, as a result, causing catastrophic failure to your 4L60E transmission that could be fairly expensive to repair.

This SunCoast 4L60E transmission category rebuild kit comes with an upgraded Borg Warner 29-element sprag with a dual cage design. This dual cage design allows the 29 elements to apply in a more even manner, eliminating the elements from flipping.  

The Clutch Kit

This is a complete 4L60/65/70E super rebuild kit containing Alto Red Eagle clutches, with the 3-4 clutch pack that includes 8 clutches. This kit will include everything else you need to rebuild your 4L60E transmission. A new filter is included, as well as a bushing kit and thrust washer kit. The band in the kit is a high performance Red Eagle band. 

Alto Red Eagle® material offers similar mid-point coefficient at high horsepower applications. In addition, the Alto Red Eagle® material gives superior friction wear characteristics at high energy engagements. The leading competitor's material degrades thermally and physically after reaching approximately 2.25 HP/in2. 

Below we offer some engineering data collected with this particular clutch.

Six Level High Energy Test
On Frictional Properties And Wear

Lbs./Sq. Inch Pressure Required To Stop Flywheel In One Second

Levels Cycles OEM Manufacturer A
Pressure Required (Lbs./Sq.In.)
OEM Manufacturer B
Pressure Required (Lbs./Sq.In.)
ALTO Red Eagle
Pressure Required (Lbs./Sq. In.)
1 10 64 70 66
1 100 65 71 65
2 10 72 84 74
2 100 73 84 74
3 10 85 96 86
3 100 92 101 93
4 10 102 116 104
4 100 110 122 108
5 10 118 133 117
5 100 124 135 118
6 10 136 148 131
6 100 143 152 134

NOTE: The Lower Lbs./Sq.In. Required to stop the flywheel, the higher the frictional properties.

Results: Pressure required to stop the flywheel on "ALTO RED EAGLE" are slightly lower than "Manufacturer A" and well below "Manufacturer B."

Conclusion: The frictional properties of "ALTO RED EAGLE" are slightly higher than "Manufacturer A" and well above "Manufacturer B."

1 .261 30,232
2 .302 35,048
3 .344 39,865
4 .385 44,681
5 .426 49,498
6 .510 59,131

Test Schedule and Duration:
Test conducted in six energy levels. Each level consists of 100 clutch engagements at 60 second intervals, from 4600 RPM with a clutch lockup time of one second, the indicated pressure required to stop the flywheel in one second.

The Super Servo



Shipping Information

  • Item Requires Shipping
  • 30.0 lbs.
  • W12.0000” x H12.0000” x L10.0000”

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