Clutch Pedal Return Spring, C5 Corvette and others, Including C6 Corvette [10376347 ]
C5 1997 - 2003 12555205
C5 2004 - 2004 10376347 Used for C6 Corvette as well

GM TSB :

#PIP3821B: Removal Of The Clutch Over Center Spring - keywords cylinder hydraulic master pedal - (Apr 15, 2008)
Subject: Removal of the Clutch Over Center Spring

Models: 1997-2004 Chevrolet C5 Corvette
2005-2008 Chevrolet C6 Corvette
Equipped with a Manual Transmission

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This PI was superseded to update model years and tac notes. Please discard PIP3821A.
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The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Condition/Concern:

It appears that some Corvette owners are removing or disconnecting the clutch over center spring on their vehicles.

This is not a recommended practice and customers should be advised of the implications of such an action.

Recommendation/Instructions:

The clutch master cylinder has a compensation port that is positioned within 1 MM of the top of the stroke.
The compensation port allows internal pressure in the clutch hydraulic system to be exhausted into the master cylinder and also provides for system refill as the clutch disc wears.

One purpose of the over center spring is to return the clutch pedal to the very top of the stroke to expose the compensation port.
The second purpose of the spring is to provide for the designed clutch pedal feel.

Removing or disconnecting the spring may allow the clutch pedal to hang in an at rest position with the piston short of the compensation port.
If the internal pressure is not exhausted the CSC may get stroked too far and a clutch hydraulic system failure may result.

The C5 clutch hydraulic systems were built by AP.
The C6 systems were manufactured by FTE. Also, the pedal must be in the full up position, with the compensation port exposed, to bleed properly.

Anytime a dealer gets a hydraulic system complaint, the tech should inspect to insure that the spring is in place and properly connected.
Related customer complaints might include poor shift performance, improper clutch release or transmission synchronizer damage.

Please follow this diagnostic or repair process thoroughly and complete each step.
If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.

If your older C5/C6 has a shifting problem it just might be the clutch return spring has degraded

Be aware C5s and C6s each use a different spring diameter
Question would be would the larger one work in place of the smaller one C5s had ?

We need to do the swap and see and at the least see how clutch pedal return is with a newer return spring installed