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What You Need To Know Before You Buy A GM With A 700R4 Transmission

Posted by on Friday, December 14th, 2012

The 700R4 transmission was first introduced by General Motors in 1982 and used up through 1992. It is sometimes also referred to as the 4L60. The 700R4 was one of General Motors first over drive automatic transmission and was used in everything from Corvettes to pickup trucks. The first 700R4 had their share of issues. Here is a list of things to look for when considering buying a car with this transmission.

700R4 automatic transmission

Source: Tehpear.com

The first 700R4 had an input shaft with 27 splines. This design was subject to failure because it really need more spline to handle the load properly. In 1984 they introduced a 30 spline input shaft which was much stronger. Steer clearing of the early models with the 27 spline input shafts.

27 spline input shaft for 700R4 Automatic Transmission

Source: Impalassforum.com

Because the 700R4 was put behind cars that were abused like the Corvette and Camaro, and pushed to their limits while serving duty in pickup trucks, the 700R4 can easily be overheated. Overheating is the number one cause of transmission failure, making an aftermarket cooler highly recommended.

The 700R4 used a Throatall Valve cable, or TV cable for short. This cable must be adjusted properly or the transmission will fail. If anyone has messed with the TV cable, it is highly recommended that it be reset, and properly adjusted.

700R4 Transmission TV cable adjustment

Source: Jalopyjournal.com

The 700R4 often suffers from the loss of the 3-4 clutch pack. The only fix is to rebuild the transmission or replace it with a re-manufactured unit. I recommend using performance 3-4 clutches and a shift kit to modify the holding pressure of the clutch pack.

700R4 Transmission performance clutches

Source: Google

The governor has a tendency to stick. When this happens it takes a lot more rpms to make the transmission shift. Common failure points on the governor are the gears, the springs coming loose or debris preventing the valve that the governor is connected to from moving.

700R4 Transmission govenor

Source: Hotrodders.com

The valve body on the 700R4 can easily warp. Many times this is caused by overheating the transmission. To fix this problem, the valve body needs to be removed from the transmission and sanded on a perfectly flat surface. All of the valves should be removed and a fine grade emery cloth should be used to clean up the bores and the valves.

700R4 Transmission valve body

Source: Thirdgen.com

Due to the age of the 700R4, a common problem is leaking from seals and gaskets. Especially prone to leakage is the front and rear seals. The rear seal can easily be replaced by just removing the driveshaft. The front seal is a whole different story. To replace the front seal the transmission needs to be removed from the vehicle. I highly recommend you take a good look at the front of the transmission for fluid leaks. Transmission oil is usually red (or green) while engine oil is a golden color. Cars with low mileage are more prone to leaks than high mileage cares. Why? Because if a car sits, the seals dry up and leak. A car used on a daily basis usually does not have this problem

Do your homework before buying a car with a 700R4. Sometimes a low price will justify the cost of replacing the transmission. If the transmission does need to be replaced I highly recommend replacing it with a re-manufactured unit.

 I highly recommend you replace your customer’s transmission with a re-manufactured transmission. A re-manufactured unit will include major alterations and upgrades designed to make them both stronger and more durable. A re-manufactured transmission will also include a much better warranty: three years compared to an average 90 days for a rebuilt transmission. In the rare event that a re-manufactured transmission fails within the warranty period, they will cover your R&R cost to replace your customer’s transmission. And remember, the companies that re-manufacture transmissions are very easy to contact. They are just a quick phone call or email away.

5 Responses to “What You Need To Know Before You Buy A GM With A 700R4 Transmission”

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  4. david darick says:

    I have a 1992 corvette with a 700r4 and it has a TV cable that has no adjustment button and I am having a hard time finding one to hook up to the ASR unti which the throttle cable, cruise control, gas pedal cable and TV cable all connect to the ASR motor. The TV cable binds when the throttle is at 80% open and I am not getting full throttle because of the TV cable seems like it is to short or the throw is off. Any comments? Or suggestions?
    Thanks

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