The 4L80E center support holds the intermediate clutch race and is the #2 cause of 4L80E rebuild failures (after the case). Get it right or rebuild again in 30,000 miles.
What the center support does
- Houses the intermediate clutch
- Holds the sprag (one-way clutch)
- Pinned to the case
- Reacts torque from 1st and 2nd gear
Symptoms of failing center support
- Loss of 1st and 2nd (sprag failure)
- Slip in reverse
- Slipping in low and intermediate
- Metal in pan (often steel from sprag)
- Sometimes: no movement at all
Why it fails
Sprag failure:
- Sprag rollers strip races
- From shock load / HP / abuse
- Center support sees the damage
Pin holes wallow:
- Aluminum center support, steel pins
- Pin holes elongate
- Support rotates in case
- Eventually destroys the case
HP applications:
- Stock support: ~500 ft-lb limit
- HD truck use: 400-450 ft-lb sustained kills it
- Tuned: required upgrade
Replacement options
OEM center support:
- Aluminum, stamped sprag race
- $150-$300 part
- Same failure mode
- Light-duty only
HD aftermarket center support:
- Sonnax billet sprag race
- HD pin bosses
- $300-$600 part
- Required for HD use
Always replace:
- Intermediate sprag
- Intermediate clutch pack
- Center support pins
- Sealing rings
Install notes
- Trans must come out
- Major teardown required
- Inspect case pin holes for wear
- Helicoil case if pin holes are wallowed
- 10-15 hours shop labor
Cost
DIY center support + sprag + clutches:
- HD center support: $300-$600
- HD sprag: $80-$150
- Clutch pack: $80-$150
- Bushings/seals: $80-$150
- Fluid (7+ qts Dexron VI): $80-$130
- Total parts: $620-$1,180
Shop:
- Parts: $620-$1,180
- Labor: $1,500-$2,500
- Total: $2,120-$3,680
Pair with case repair if needed
- Helicoil pin holes if wallowed
- $200-$400 case work labor
- Read our 4L80E case crack guide
Need 4L80E center support, sprag, or HD rebuild kit? Shop our 4L80E catalog. HD center supports, sprag sets, complete rebuild bundles. Free shipping over $70.
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