Chevy Corvette Transmission Problems

When it was introduced in 1953, the Chevrolet Corvette was intended to be nothing more than an attention-grabbing “halo car”. But the little fiberglass bodied sports car (remember, sports cars were an entirely new market segment back then) hung on to become America’s halo car (sorry Dodge Viper fans). Everybody from athletes to A-Listers to astronauts have owned one of these iconic road-rockets. And they’re affordable enough on the secondhand market that many people can afford to join the exclusive ranks of Corvette ownership. However, Corvette transmission problems do still happen. So let’s take a closer look.

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What Transmission Do I Have?

The Chevrolet Corvette: How it all started

While serving overseas, many GIs fell in love with the small, nimble sports cars from English brands like Jaguar, MG and Triumph. In an effort to lure more of these veterans into the showroom, GM decided to create its very own “sports car”, complete with a convertible top and high-tech fiberglass body (that was the equivalent of carbon fiber in the 1950s). The C1 Corvette was pretty much a parts bin special, and was powered by a modified version of the ‘Stovebolt Six’ 235ci inline-6. Dubbed the ‘Blue Flame 150’, Chevrolet increased the horsepower from 115-hp to 150-hp by adding a high lift camshaft, solid lifters, and three Carter side-draft carburetors.

C1 Corvette Transmission: Specs, Repair Info & History

C1 Corvette Manual Transmission Options
GM 3-speed manual
GM/BW T-10 4-speed manual

C1 Corvette Automatic Transmission Options
Powerglide 2-speed automatic

The engineers did’t think that a typical Chevrolet transmission could stand up to the Corvette’s claimed 110 mph top speed, so they used the famous Powerglide 2-speed automatic (to save weight, they gave it a lightweight aluminum case in 1962). That decision didn’t go over too well with the buying public, which prompted Chevy to introduce a V-8 engine in 1955, along with a 3-speed Synchomesh manual transmission (from a Chevy truck). This Corvette 3-speed transmission would be the standard gearbox until 1969. The good old GM Powerglide transmission stuck around until 1967. It wasn’t a very popular option, however a few big block equipped C2 Corvettes were built. The 1957 Chevrolet Corvette had a tantalizing new option, in the form of the $188 ($1,713 in 2019 money) BorgWarner T-10 4-speed manual transmission. It quickly became the must-have option, and over 40% of the remaining C1 Corvettes had this transmission.

C2 Corvette Transmission: Specs, Repair Info & History

C2 Corvette Manual Transmission Options
GM 3-speed manual
GM/BW T-10 4-speed manual
Muncie M20 4-speed manual
Muncie M21 4-speed manual
Muncie M22 Rock Crusher 4-speed manual

C2 Corvette Automatic Transmission Options
Powerglide 2-speed automatic

The Muncie M20 4-speed was sold from 1963 – 1974, and featured a wide ratio spread: 1st = 2.56, 2nd = 1.91, 3rd = 1.48, 4th = 1.00. This gearbox was replaced in 1974 by the Borg-Warner M20, which can be distinguished by its nine bolt side cover (the Corvette Muncie M20 side cover only has seven bolts). The optional Muncie M21 close-ratio 4-speed was also produced from 1963 – 1974, and was replaced by the Borg-Warner M21 4-speed transmission. The ratio spread for the Corvette Muncie M21 was 1st = 2.20, 2nd = 1.64, 3rd = 1.28, 4th = 1.00.

And last but not least, the famous Muncie M22 Rock Crusher 4-speed was a Corvette option from 1967 – 1971. It’s straight cut gears made an unusual sound when the cogs were being swapped, which is where the nickname “rock crusher” comes from. This design helped it stand up to the immense torque that was being produced by the optional big block V-8s. According to the Internet, only 336 of these gearboxes were factory installed.

C3 Corvette Transmission: Specs, Repair Info & History

C3 Corvette Manual Transmission Options
GM 3-speed manual
GM/BW T-10 4-speed manua
Muncie M20 4-speed manual
Muncie M21 4-speed manual
Muncie M22 Rock Crusher 4-speed manual

C3 Corvette Automatic Transmission Options
Powerglide 2-speed automatic
GM TH350 3-speed automatic
GM TH400 3-speed automatic
Chevrolet 700R4 4-speed automatic

By the time the C3 Chevy Corvette rolled around, a bunch of new transmissions were offered, to help buyers take advantage of all the available power in the numerous engine offerings. The Muncie M20 4-speed was sold from 1963 – 1974, and featured a wide ratio spread: 1st = 2.56, 2nd = 1.91, 3rd = 1.48, 4th = 1.00. This gearbox was replaced in 1974 by the Borg-Warner M20, which can be distinguished by its nine bolt side cover (the Corvette Muncie M20 side cover only has seven bolts). The optional Muncie M21 close-ratio 4-speed was also produced from 1963 – 1974, and was replaced by the Borg-Warner M21 4-speed transmission. The ratio spread for the Corvette Muncie M21 was 1st = 2.20, 2nd = 1.64, 3rd = 1.28, 4th = 1.00. And last but not least, the famous Muncie M22 Rock Crusher 4-speed was a Corvette option from 1967 – 1971. It’s straight cut gears made an unusual sound when the cogs were being swapped, which is where the nickname “rock crusher” comes from. This design helped it stand up to the immense torque that was produced by the optional big block V-8s. According to the Internet, only 336 of these gearboxes were factory installed.

In 1975, the BorgWarner Super T-10 had fully replaced all of the Muncie transmissions in the Corvette lineup. The wide ratio version was the equivalent of the Muncie M20, and featured a gear ratio spread of: 1st = 2.64, 2nd = 1.75, 3rd = 1.34, 4th = 1.00. The close ratio BW Super T10 4-speed had the following gear ratios: 1st = 2.43, 2nd = 1.61, 3rd = 1.23, 4th = 1.00.

Starting in 1968, the Turbo Hydromatic 3-speed automatic was available in the C3 Corvette. The additional gear significantly improved drivability over the old 2-speed Corvette Powerglide transmission, and made the iconic sports car more attractive to a larger number of buyers. Cars fitted with a small block V8 got the Corvette TH350 transmission, which had a gear ratio of; 1st = 2.52, 2nd = 1.52, 3rd = 1.00. Cars fitted with the 390-hp and 400-hp big block 427 V8 got the stronger TH400 transmission in 1968. A new heavy duty Corvette TH400 transmission was released in 1969 for the high horsepower 435-hp Corvette L71, 430-hp Corvette L88, and the 435-hp Corvette L89. The gear ratios for this transmission are; 1st = 2.48, 2nd = 1.48, 3rd = 1.00.

In 1982, an all new C4 Corvette automatic transmission was created by essentially adding an overdrive gear to a TH350, creating the 700R4 transmission. The difference between a Chevy truck 700R4/4L60E and a Corvette 700R4 are the tail housing, output shaft length and speedometer drive gear location. To improve the performance and torque capacity over the standard transmission, a unique Corvette servo setup was used, along with different valve springs, accumulators, and low boost valve (among other things). If you see a Corvette transmission for sale, and have thought about perhaps putting a Corvette transmission in your Silverado, you need to be 100% sure that you are actually buying a Corvette transmission (obviously, the first giveaway would be the tail shaft).

C4 Corvette Transmission: Specs, Repair Info & History

C4 Corvette Manual Transmission Options
Doug Nash 4+3 4-speed manual
Corvette ZF6 6-speed manual

C4 Corvette Automatic Transmission Options
Chevrolet 700R4 4-speed automatic
Corvette 4L60 4-speed automatic
Corvette 4L60E 4-speed automatic

For the all-new C4 Corvette, the Super T10 was replaced by the super high-tech Doug Nash 4+3 transmission. Chevrolet needed to meet both tight production deadlines and strict EPA fuel economy standards, which meant they didn’t have time to develop an all new C4 Corvette transmission. So they turned to racing driver-turned-auto parts supplier Doug Nash, who basically took a Borg Warner Super T10 4-speed and added an extension to the back, which housed an extra gearset that provided an overdrive ratio for 2nd, 3rd and 4th gears (hence the name Corvette 4+3). It operates by using hydraulic pressure from an internal pump, which is driven by the rear wheels. This operates one of two clutch packs which can engage or disengage overdrive. Delco Electronics developed the computer logic programmed into the Corvette ECM, which reads vehicle speed, throttle position and engine temperature, so the computer can determine if the necessary parameters are met to engage overdrive. Since the overdrive unit is essentially an additional automatic transmission, it actually uses traditional automatic transmission fluid, which must changed (along with the filter) every 10,000 miles or 12 months. Failure to do so can result in a number of common Corvette 4+3 transmission problems, like failed 4+3 clutches and bearings. If the clutches burn out, you will loose reverse and engine braking, so proper maintenance is necessary to keep these gearboxes in good working order.

The Corvette 4+3 reliability record wasn’t all that great, so the 1989 Corvette could be had with a new ZF 6-speed manual gearbox. Like the Doug Nash 4+3, the Corvette ZF6 transmission also used electronics to try and improve the fuel economy. To that end, the Corvette CAGS system (Computer Aided Gear Selection) would read a number of parameters like engine temperature, vehicle speed, and throttle position, then automatically cause (you) to upshift from 1st > 4th when only 35% throttle was being applied.

Minor changes were made to the Corvette 700R4 transmission later in life, and it was renamed the Corvette 4L60. The 1994 Corvette 4L60E transmission was upgraded to full electronic controls, and a more advanced PCM style computer was used.

C4 Corvette Diagnostic Trouble Codes | DTC

C4 Corvette Technical Service Bulletins | TSBs

TSB 01-07-30-023B – Harsh 1-2 upshift with P1870 DTC – 4L60E Transmission RPO M30
1996 Buick Roadmaster – 1996 Cadillac Fleetwood – 1999-2000 Cadillac Escalade – 1996-2000 Chevrolet Camaro – 1996-2000 Corvette – 1996-2000 Pontiac Firebird – 1996-2000 Chevrolet and GMC Light Duty Truck Models – 1996-2000 Oldsmobile Bravada
Problem – Drivers may experience an unusually harsh 1-2 shift because the ECU has commanded maximum line pressure in order to compensate for excessive wear in the bore that contains the TCC isolator and regulator valves inside of the valve body.
Solution – Replace the 4L60E valve body with revised TCC regulator and isolator valves.

TSB 00-07-30-022D – No reverse, second or fourth gears – 4L60E Transmission & 4L65E Transmission
1993 – 2005 GM passenger cars and light duty trucks
Problem – Drivers may experience the loss of reverse, second and fourth gears. First and third gears will seem to function normally
Solution – The reaction sun gear may fail inside of the sun shell. It will need to be replaced with a stronger heat-treated 4L60E / 4L65 sun gear.

C4 Corvette Transmission Problems

Intermittent harsh shifting – 4L60E Transmission
Problem – A common 4L60E transmission problem is an intermittent hard 1-2 shift, often accompanied by engine bogging. This condition can be caused by the torque convertor clutch applying during the shift.
Solution – To remedy the problem, the wiring harness needs to be inspected from the transmission case connector to the rear of the engine on the driver side. It’s possible that the wires for the TCC solenoid and pressure control solenoid have become frayed on a body seam. If this is the case, the wiring will need to be repaired, and the harness repositioned.

C5 Corvette Transmission: Specs, Repair Info & History

C5 Corvette Manual Transmission Options
Borg Warner T56 6-speed manual
Tremec T56 6-speed manual

C5 Corvette Automatic Transmission Options
Corvette 4L60E 4-speed automatic

Since the C5 Corvette was switched to a rear transaxle setup to improve weight distribution, a new gearbox was needed. The Borg Warner T56 6-speed manual was pressed into service for the 1997 model year, and the Tremec T56 (the same transmission, built under license by another company) took over a short time later. The C5 Corvette 4L60E received some minor case modifications, which would reduce the weight by some 3.3 lbs. Other than that, this gearbox would remain in use until the C6 Corvette 4L65 transmission debuted in 2005.

C5 Corvette Diagnostic Trouble Codes | DTC

C5 Corvette Technical Service Bulletins | TSBs

TSB 01-07-30-023B – Harsh 1-2 upshift with P1870 DTC – 4L60E Transmission RPO M30
1996 Buick Roadmaster – 1996 Cadillac Fleetwood – 1999-2000 Cadillac Escalade – 1996-2000 Chevrolet Camaro – 1996-2000 Corvette – 1996-2000 Pontiac Firebird – 1996-2000 Chevrolet and GMC Light Duty Truck Models – 1996-2000 Oldsmobile Bravada
Problem – Drivers may experience an unusually harsh 1-2 shift because the ECU has commanded maximum line pressure in order to compensate for excessive wear in the bore that contains the TCC isolator and regulator valves inside of the valve body.
Solution – Replace the 4L60E valve body with revised TCC regulator and isolator valves.

TSB 00-07-30-022D – No reverse, second or fourth gears – 4L60E Transmission & 4L65E Transmission
1993 – 2005 GM passenger cars and light duty trucks
Problem – Drivers may experience the loss of reverse, second and fourth gears. First and third gears will seem to function normally
Solution – The reaction sun gear may fail inside of the sun shell. It will need to be replaced with a stronger heat-treated 4L60E / 4L65 sun gear.

TSB 08-07-30-008B – Diagnostic information for P0894 and P1870 DTC – 4L60E Transmission | 4L65 Transmission | 4L70E Transmission
2003-2007 GM Passenger Cars and Light Duty Trucks – 2003-2007 HUMMER H2 – 2006-2007 HUMMER H3 – 2005-2007 Saab 9-7X – with 4L60-E, 4L65-E or 4L70-E Automatic Transmission (RPOs M30, M32 or M70)
Problem – This relates to drivers who experience unusually harsh 1-2 shifts, along with a P0804 and/or a P1870 DTC.
Solution – It is possible that a leaking TCC solenoid, a torque converter clutch valve or damaged turbine shaft O-ring seal could cause these two diagnostic trouble codes. However, it could also be caused by a failed torque converter.

C5 Corvette Transmission Problems

Intermittent harsh shifting – 4L60E Transmission
Problem – A common 4L60E transmission problem is an intermittent hard 1-2 shift, often accompanied by engine bogging. This condition can be caused by the torque convertor clutch applying during the shift.
Solution – To remedy the problem, the wiring harness needs to be inspected from the transmission case connector to the rear of the engine on the driver side. It’s possible that the wires for the TCC solenoid and pressure control solenoid have become frayed on a body seam. If this is the case, the wiring will need to be repaired, and the harness repositioned.

C6 Corvette Transmission: Specs, Repair Info & History

C6 Corvette Manual Transmission Options
Tremec T56 6-speed manual
Corvette TR-6060 6-speed manual

C6 Corvette Automatic Transmission Options
Corvette 4L65 4-speed automatic
Corvette 6L80 6-speed automatic

In 2006, a number of improvements were made to the C6 Corvette T56 transmission, including a stronger single piece countershaft and double or triple-cone synchronizers for all forward gears. The Corvette Z06 T56 transmission also got a much stronger output shaft to handle its extra power. For 2008, the new C6 Corvette TR-6060 transmission offering increased reliability and torque capacity, especially in the C6 Corvette Z06 TR6060. Using a new synchronizer design to reduce shift effort not only improved the drivability, but it also provided extra room inside of the transmission case to use much stronger components.

The new Corvette 4L65 was a stronger version of the outgoing Corvette 4L60E, and featured a number of improvements including the Performance Algorithm Shifting program for better response. It was replaced a year later with the C6 Corvette 6L80 transmission, which was considerably more advanced. Aside from the two additional forward gears, the Corvette 6L80 employed clutch-to-clutch shifting, for lightning fast response from the paddle shifters. It also had a 32-bit TCM (transmission control module), that was mounted outside of the transmission to keep it cool during “spirited” driving.

C6 Diagnostic Trouble Codes | DTC

C6 Corvette Technical Service Bulletins | TSBs

TSB 00-07-30-022D – No reverse, second or fourth gears – 4L60E Transmission & 4L65E Transmission
1993 – 2005 GM passenger cars and light duty trucks
Problem – Drivers may experience the loss of reverse, second and fourth gears. First and third gears will seem to function normally
Solution – The reaction sun gear may fail inside of the sun shell. It will need to be replaced with a stronger heat-treated 4L60E / 4L65 sun gear.

TSB 08-07-30-008B – Diagnostic information for P0894 and P1870 DTC – 4L60E Transmission | 4L65 Transmission | 4L70E Transmission
2003-2007 GM Passenger Cars and Light Duty Trucks – 2003-2007 HUMMER H2 – 2006-2007 HUMMER H3 – 2005-2007 Saab 9-7X – with 4L60-E, 4L65-E or 4L70-E Automatic Transmission (RPOs M30, M32 or M70)
Problem – This relates to drivers who experience unusually harsh 1-2 shifts, along with a P0804 and/or a P1870 DTC.
Solution – It is possible that a leaking TCC solenoid, a torque converter clutch valve or damaged turbine shaft O-ring seal could cause these two diagnostic trouble codes. However, it could also be caused by a failed torque converter.

TSB PIP495F – Flare and/or harsh 2-3 shifts – 6L80 Transmission
2006 – 2009 Cadillac STS-V – 2006 – 2009 Cadillac XLR-V – 2007 – 2009 Cadillac XLR – 2006 – 2009 Chevrolet Corvette – 2008 – 2009 Hummer H2 – 2008 – 2009 Pontiac G8
Problem – Drivers can experience an unusually harsh 2-3 shift or flare. They may also experience an usual delay when shifting from Park, Drive and/or Reverse. The symptoms are more likely to happen in colder climates, however they can still happen at any temperature.
Solution – These 6L80 transmission problems can be caused by a leaking 1-2-3-4 and 3-5-R clutch seal rings. The clutch packs, discs and drums should also be inspected for signs of damage. Many remanufactured 6L80 transmissions come already modified to correct the causes of these problems.

TSB PI488C – No forward or reverse and/or slipping – 6L80 Transmission | 6L90 Transmission
2010 – 2014 Cadillac CTS-V – 2010 – 2014 Cadillac Escalade (all models) – 2010 – 2013 Chevrolet Avalanche – 2010 – 2014 Chevrolet Camaro – 2010 – 2014 Chevrolet Corvette – 2010 – 2014 Chevrolet Express – 2010 – 2014 Chevrolet Silverado – 2010 – 2014 Chevrolet Suburban – 2010 – 2014 Chevrolet Tahoe – 2011 – 2014 Chevrolet Caprice PPV – 2014 Chevrolet SS – 2010 – 2014 GMC Savana – 2010 – 2014 GMC Sierra – 2010 – 2014 GMC Yukon – 2010 – 2014 GMC Yukon XL – 2010 – 2014 GMC Yukon Denali
Problem – Trucks equipped with the 6-speed 6L80 or 6L90 transmission may experience no forward or reverse engagement, or slipping between the gears.
Solution – This problem could be caused by a cracked or split transmission filter. If this is the case, the transmission pump should be disassembled and inspected for possible damage. Inspect for any of the following conditions: – scored pump rotor or pump vanes – scored pump cover or pump rotor pocket – cracked pump slide.

The transmission should also be evaluated for any possible distress to the clutches. GM’s testing and analysis found that split or damaged filters may be caused by a damaged transmission pump. This can send a high pressure fluid spike down the filter neck on a cold start, resulting in the filter body cracking or the filter seam splitting. The filter is not defective and this is not a filter quality issue. Important: Do not replace the filter without inspecting the pump. Failure to inspect the pump and clutches could lead to a repeat of this condition.

TSB 09-07-30-004J – Slips in Reverse or Third, Delayed Reverse or Drive Engagement, DTC P0776, P2715, P2723, Harsh 2-3 Shifts – 6L80 Transmission | 6L90 Transmission
2006-2009 Cadillac STS-V – 2006-2009 Cadillac XLR – 2006-2009 Cadillac XLR-V – 2007-2008 Cadillac Escalade, Escalade ESV, Escalade EXT – 2006-2009 Chevrolet Corvette – 2007-2008 Chevrolet Silverado – 2008 Chevrolet Suburban – 2007-2008 GMC Sierra – 2007-2008 GMC Sierra Denali – 2007-2008 GMC Yukon Denali – 2007-2008 GMC Yukon XL Denali – 2008 GMC Yukon XL – 2008-2009 HUMMER H2 – 2008-2009 Pontiac G8
Problem – Vehicles equipped with the 6L80 or 6L90 transmission may slip when Reverse is selected or have no/delayed reverse engagement, harsh shifts from 2-3 / 4-5 or slips while in fifth, and slipping acceleration when passing. Possible DTCs include P0776, P2715 or P2723.
Solution – This transmission problem may be caused by a cracked 1-2-3-4 / 3-5-R clutch housing.

C7 Corvette Transmission: Specs, Repair Info & History

C7 Corvette Manual Transmission Options
Corvette TR-6070 7-speed manual

C7 Corvette Automatic Transmission Options
Corvette 8L90 8-speed automatic

The all new C7 Corvette was one of the most powerful cars that GM had ever made, and it needed an appropriately strong gearbox to withstand the insane amount of torque coming from the various engines. To put that into perspective, the “base” C7 Corvette has 455-hp and can hit 60 mph in under four seconds. So the C7 Corvette TR-6070 7-speed manual transmission was developed. It featured a number of technological and manufacturing advances, like carbon and bronze synchronizers, and two-piece gears. The Corvette TR6070 7-speed manual transmission also has an active rev matching program, for those who can’t heel-and-toe.

A year after the C7 was released, an all new Corvette 8L90 8-speed automatic was launched in 2015. This high-tech transmission utilized clever design and lightweight materials to create a wide ratio transmission that could be used with a lower rear axle ratio for better performance, without sacrificing fuel economy. Unfortunately, there have been a number of issues with the C7 Corvette 8L90 transmission, and several Corvette class action lawsuits allege that General Motors was aware of a design flaw with the 8L90 torque converter.

Need a replacement transmission? Get an estimate for replacement transmissions and local installation. Look up your transmission model by vehicle make and model.

What Transmission Do I Have?

C7 Corvette Diagnostic Trouble Codes | DTC

C7 Corvette Technical Service Bulletins | TSBs

PIP5437B – Harsh shifts – 8L45 Transmission | 8L90 Transmission
2016 – 2017 Cadillac ATS – 2016 – 2017 Cadillac CT5 – 2016 – 2017 Cadillac CT6 – 2015 – 2017 Cadillac Escalade – 2016 – 2017 Chevrolet Camaro – 2017 Chevrolet Colorado – 2015 – 2017 Chevrolet Corvette – 2017 Chevrolet Express – 2015 – 2017 Chevrolet Silverado – 2017 GMC Canyon – 2017 GMC Savana – 2015 – 2017 GMC Sierra – 2015 – 2017 GMC Yukon Denali
Problem – One of the more common 8L transmission problems is excessively hard or abrupt gear changes.
Solution – The TCM may need to be recalibrated with the latest control software. It could also be caused by one or more of the clutch fill times not being learned by the TCM. In which case, the Service Fast Learn (SFL) procedure will have to be performed. Should the problems persist, the valve body will need to be replaced