Proper Torque Converter Spacing for 700R4 LS Engine Swaps

Checking 700r4 Torque Converter Spacing for LS Engine Swaps

When swapping an LS V8 into an older vehicle originally equipped with a small block Chevy, one popular transmission choice is the venerable 700R4 (4L60) 4-speed automatic. This transmission features a 27-spline input shaft that matches well with most LS crankshafts.

A critical factor in mating an LS engine to a 700R4 is properly setting the spacing between the torque converter and flexplate. This spacing determines how far the converter seats onto the transmission's input shaft. Too much or too little spacing can cause driveability issues or damage.

Determining Proper 700R4 Torque Converter Spacing

The correct torque converter spacing for a 27-spline 700R4 application is 1.625 inches from the transmission mounting pads to the converter housing. This spacing allows for proper pump and stator clearances inside the converter.

To check torque converter spacing, first ensure the transmission is fully seated on the engine, with all bellhousing bolts torqued to specifications. Then, with the converter pushed completely into the transmission, insert a drill bit or other measuring instrument between the converter housing and flexplate. The space should equal 1.625 inches.

Adjusting Spacing with Washers

If the torque converter spacing does not equal 1.625 inches, adjustment is required. This is typically done using a standard flat washer placed between the flexplate and converter mounting pads.

Measure the gap first to determine the necessary washer thickness. For example, if the gap measures 1.75 inches, a 1/16 inch thick washer is needed to reduce spacing to the proper 1.625 inches.

Be sure to use a standard SAE flat washer made of steel or aluminum. Do not use lock washers as these can come loose. Select a washer diameter that fits snugly around the converter mounting pads.

Potential Issues with Improper Spacing

Improper torque converter spacing on a 700R4 can lead to several performance or reliability issues:

• Too little spacing causes the converter to seat too far onto the input shaft, reducing internal clearances and resulting in bumping or grinding between components.
• Too much spacing prevents the converter from fully engaging the input shaft splines, resulting in driveability problems and eventual spline wear or damage.
• Incorrect spacing may also lead to premature converter failure, leaking seals, or reduced transmission life due to excessive heat and vibration.

Confirming Proper Operation

Once the 700R4 torque converter spacing is properly set at 1.625 inches, confirm that the transmission and converter operate smoothly:

• Start the engine and allow it to reach full operating temperature.
• With the transmission in park/neutral, press the brake and engage the torque converter by increasing engine rpm. Listen for abnormal sounds.
• Take the vehicle for a test drive, evaluating smoothness of shifts and transitions. Roughness may indicate a converter issue.

Pay attention during the testing process to identify problems early. Readjust converter spacing if driveability problems persist. Proper spacing is key for reliability and longevity.

Troubleshooting 700R4 Torque Converter Issues

If vibration, noise, or shifting problems occur after installing a 27-spline torque converter on a 700R4 transmission, improper spacing is often the cause. However, other issues can produce similar symptoms.

Common Torque Converter Problems

Some typical torque converter problems that may occur despite correct spacing:

• Worn pump hub splines - Allows excessive converter movement and overheating.
• Damaged stator support - Creates binding and noise when converter is engaged.
• Failed bearings - Causes excessive play or roughness during operation.
• Converter clutch failure - Produces vibration and harsh shifts.

Inspecting the Torque Converter

If you are troubleshooting a 700R4 torque converter issue, inspect the following areas:

• Check for loose mounting pads or damaged pilot hub.
• Look for any cracks or leaks indicating housing failure.
• Confirm proper engagement with the input shaft.
• Inspect for signs of overheating or burned fluid.

A thorough visual inspection can help determine if converter replacement or rebuild is necessary. Compare to a known good unit.

When to Replace a Faulty Converter

Consider replacing the 700R4 torque converter if you find:

• Excessive runout or wobble during inspection
• Badly worn splines causing poor shaft engagement
• Damage to the pump hub, stator support, or clutch components
• Leaking at weld seams or between the halves of the housing

Replacing a faulty converter can quickly resolve vibration issues and restore proper transmission function. Always confirm correct spacing with the new converter.

FAQs

What is the correct 700R4 torque converter spacing?

The proper torque converter spacing for a 27-spline 700R4 is 1.625 inches between the transmission mounting pads and the converter housing.

How do I adjust 700R4 torque converter spacing?

Use one or more flat washers between the flexplate and converter to achieve the proper 1.625 inch spacing. Measure first to determine washer thickness needed.

What happens with incorrect 700R4 converter spacing?

Too little spacing causes internal interference and damage. Too much spacing results in driveability issues from poor spline engagement. Both can lead to premature transmission failure.

When should I replace a 700R4 torque converter?

Replace the torque converter if you find excessive runout, worn splines, damaged internal components, or leaks between the converter halves. This can resolve vibration issues and transmission problems.