928 Super Bearing
The differences between the original torque tube bearing unit and our Super Bearing unit are readily apparent when shown in a side by side comparison. The original bearing unit shown above was taken from a torque tube which had pronounced vibrations during operation. Once the torque tube was removed and inspected it was found that this bearing unit had moved back into the torque tube more than 20 inches from the engine end. This bearing unit had been previously rebuilt and re-installed into the torque tube. That the bearing moved from it's position at the front of the torque tube meant the outer rubber had shrunk and allowed it to move in the torque tube under operation, mainly due to the harmonic vibrations inherent in the drive line.
We wanted to show this bearing unit in this comparison since from a casual observation it looks to be in serviceable condition for re-use in a torque tube rebuild, which it wasn't. Since to remove and replace a torque tube from the Porsche is an expensive and time consuming service, we designed our Super Bearings to take away the guess work and pit falls in rebuilding a torque tube reusing the old parts as other rebuilders do.
The 928 Super Bearings were also designed to do away with the problem prone Porsche vibration dampener which was placed into the 928 torque tubes to quell drive line vibrations. Below is a picture of an original 928 torque tube vibration dampener still in one piece. One can see the effects of many years of being in the 928 torque tube by the pronounced wear and flattening of the rubber holders meant to keep this vibration dampener from sliding in the torque tube.
We have found these vibration dampeners come apart with heat and age. When this happens the heavy weight that is normally suspended within the torque tube by the rubber holders slides up and down the torque tube under acceleration and braking which moves the bearing units from their normal locations. This damages the bearing units and drive shaft as well as causing vibrations in the drive line. Below is a picture of a vibration dampener which had broken free from it's holders.
Bearings were designed and engineered so three make up the weight of this vibration dampener so it does not have to be re-used. This does away another drive line problem for the 928 owner.
Price:
Three (3) 928 Super Bearings - $750.00
Note 1: The Super Bearings come with instructions and some items to help with their installation. Although rebuilding a 928 torque tube is straight forward in theory, some have found the actual execution to be difficult. It is directly dependent on the mechanical skill and experience of the installer, as well as the condition of the torque tube. Please see our section on torque tube rebuild services if you would rather have us do your rebuild.
Note 2: Porsche used different sized drive shafts in the 928 automatic versions according to model year (MY). All 928 automatics before MY 1987 used 25mm drive shafts. MY 1987 torque tubes have been found to have both a 25mm or 28mm drive shaft depending on when the torque tube was manufactured in 1987. MY 1988 and later 928 automatics, to include the GTS variants, used 28mm drive shafts.
Prior owners could have replaced the torque tube in your 928 with one from a different MY having a different drive shaft since the 25mm and 28mm drive shafts are interchangeable. This is why the owner must confirm what size drive shaft is in their 928 automatic before ordering the Super Bearings. The differences between the drive shafts can be seen in our 928 Driveline Information section.
Note 3: All model year 928 5-speed variants use the 25mm drive shaft.