TH350 Governor Weights: Tuning Shift Points

The TH350 governor weights control shift points. By selecting the right weights for your build, you can dial in shifts exactly where you want them. Here's the guide.

What governor weights do

The TH350 governor:

  • Senses vehicle speed via output shaft rotation
  • Generates governor pressure proportional to speed
  • Signals valve body to upshift at proper speed
  • Read our 700R4 governor guide for related concept

The weights:

  • Centrifugal force opens them as speed increases
  • Heavier weights = open at lower RPM = earlier shift
  • Lighter weights = open at higher RPM = later shift

Tune shift points by weight selection.

Weight options

Stock TH350 weights:

  • Application-specific
  • Truck vs car combinations
  • 6-cylinder vs 8-cylinder

B&M weights:

  • Multiple options available
  • 4-pound, 6-pound, 8-pound combinations
  • Pair primary and secondary for specific shift RPM

Performance kits:

  • Multiple weight options included
  • Customizable
  • Cost: $40-100

Read our TH350 vs TH400 comparison

Selecting weights for your application

Daily driver / stock engine:

  • Stock weights ideal
  • Don't change unless symptom

Mild performance (cam, headers):

  • Stock weights usually OK
  • May want slightly later shifts
  • Lighter weights

Strong street performance:

  • B&M kit
  • Mid-range weights
  • Shifts at 4,500-5,500 RPM at WOT

Race / drag:

Tow / heavy load:

  • Slightly heavier weights
  • Earlier shifts to keep RPM lower
  • Plan for lower MPG

How weight changes affect shift

Lighter weights:

  • Higher RPM shifts
  • Better performance
  • Worse MPG
  • Engine works harder

Heavier weights:

  • Lower RPM shifts
  • Better MPG
  • Less stress on engine
  • Less performance

Balanced weights:

  • Stock-ish behavior
  • Daily driver friendly

Installation procedure

Tools needed:

  • Pliers for retaining clips
  • Service manual
  • New gasket if reusing housing
  • Clean work surface

Steps:

1. Drop trans pan (drain fluid)

2. Access governor at rear of trans (through cover)

3. Remove cover and gasket

4. Pull governor assembly

5. Carefully disassemble weights

6. Install new weights per spec

7. Reassemble governor

8. Reinstall with new gasket

9. Refill fluid

Time: 2-4 hours

Difficulty: Moderate (specific to TH350)

Common mistakes

Mismatched weights:

  • Primary and secondary must work together
  • Mixing wrong combinations = wrong shifts
  • Use complete kit from quality vendor

Wrong combination for application:

  • Sometimes too light shifts at redline
  • Sometimes too heavy lugging
  • Test drive after install

Installation errors:

  • Spring placement matters
  • Wrong direction = no governor function
  • Service manual critical

Skipping fluid change:

  • Some fluid lost during work
  • Top off and verify

TV cable / TV lever consideration

Critical:

  • TH350 governor works with throttle valve (TV) input
  • TV must be properly adjusted
  • Wrong TV = wrong shift behavior even with right weights

TV adjustment:

  • Specific to application
  • Service manual required
  • Critical accuracy

Read our 700R4 governor guide — same TV concerns apply.

Beyond weights: complete shift control

B&M shift kit (HD-2):

Manual valve body:

  • Race-only
  • Removes automatic shifts
  • Full driver control
  • Cost: $300-600

Sonnax shift improvers:

  • Specific corrections
  • Pairs with weights
  • Cost: $40-200 per component

Common application combos

Camaro 5.7L street:

  • B&M 4-pound primary
  • 6-pound secondary
  • Shifts around 4,200 RPM at WOT

Truck 350 small block:

  • Stock or slightly heavier
  • Shifts around 3,800 RPM at WOT
  • Better MPG focus

Performance 350 small block:

  • B&M 4-pound primary
  • 8-pound secondary
  • Shifts around 5,000-5,500 at WOT

Race / sled pull:

  • Lightest weights available
  • Manual valve body
  • Custom for application

Read our TH350 vs TH400 comparison for trans capability context.

Verification after install

Test drive:

  • Note shift RPM at WOT
  • Verify shift quality
  • Multiple driving conditions

Adjust if needed:

  • Different combination
  • Different weights
  • Iterative

Long-term verification:

  • 500-1,000 mile test
  • Various conditions
  • Fine-tune

Cost considerations

Stock weight replacement:

  • Stock weights: $20-40
  • Gasket: $10-15
  • Fluid: $20-30
  • Total: $50-85

Performance kit:

  • B&M weights set: $60-100
  • Gasket: $10-15
  • Fluid: $20-30
  • Total: $90-145

Full performance build:

  • Performance weights: $60-100
  • Shift kit: $80-200
  • Premium fluid: $50-80
  • Total: $190-380

Read our transmission parts buying guide

Need TH350 governor weights or shift parts? Shop our complete catalog. B&M weight kits, shift improvers, complete rebuild kits. Free shipping over $70.

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