Rubber Clutch Hub - Determining Damage
88porsche02Subject: Determining Rubber Clutch
Hub Damage
Model
All
Group
3
Part Identifier
3056
Number
8811
August 12, 1988
The purpose of this bulletin is to aid you in diagnosing causes of rubber hub deterioration of clutches. The examples reflect conditions which are a result of excessive slippage. This may be caused by a mechanical problem or abusive treatment of the clutch.
Defects in material or workmanship are warrantable, whereas abuse is not.
Generally, molten rubber of the hub and/or blistering and heat cracking will be accompanied by other indications of abuse such as distinct signs of overheating on the clutch lining and heat spots and/or discoloration of flywheel, pressure plate, or both. Examples with descriptions are shown in the pictures that follow.
FIGURE 1:
- Rubber hub broken loose from the metal disc plate.
- Corrosion on the metal disc plate (arrows) caused by overheating.
- Rubber adjacent to the metal disc is cracking, shiny, and sticky.
Cause: Abuse, unless mechanical failure of throwout bearing or bearing sleeve is evident.
FIGURE 2:
- Rubber hub broken loose from the metal disc plate.
- Pieces of the rubber hub are broken out.
- Rubber surface adjacent to the metal disc is cracking, shiny, and sticky.
Cause: Abuse, unless mechanical failure of throwout bearing or bearing sleeve is evident.
FIGURE 3:
- The rubber hub shows large cracks adjacent to the metal disc.
- The rubber surface is shiny and sticky in that area.
Cause: Abuse, unless mechanical failure of throwout bearing or bearing sleeve is evident.
FIGURE 4:
- The rubber hub shows small cracks adjacent to the metal disc (arrow).
- The rubber surface is shiny and sticky in that area.
Cause: Abuse, unless mechanical failure of throwout bearing or bearing sleeve is evident.
FIGURE 5:
- Metal on clutch disc corroded to reddish-brown color (arrows) caused by excessive heat.
- No black, shiny adhesive visible on metal disc.
- Clear signs of rubber twisted off the clutch plate metal.
Cause: Abuse, unless mechanical failure of throwout bearing or bearing sleeve is evident.
FIGURE 6:
- Metal clutch disc partially corroded to reddish-brown color.
- Clear signs of rubber twisted off the clutch plate metal (arrows).
Cause: Abuse, unless mechanical failure of throwout bearing or bearing sleeve is evident.