Mark_II_Mark
12-17-2009, 02:05 PM
Even though I'm pretty knowledgeable about most things automotive, I learned a very good lesson when I first purchased my car about what I consider to be the Mark II's biggest weak spot, the mid-shaft bearing insulator. The new Mark II owner should be aware of how it works and what can happen if it fails.
Shortly before I purchased my Mark II, the previous owner, a non-wrench turner, took the vehicle to his friendly local, neighborhood mechanic for a pre-sale checkup at my request. Among other things, the mid-shaft bearing insulator was determined to be in need of replacement, so a new replacement was ordered. The mechanic also purchased a new bearing from his local NAPA store. Understand that the part number for the bearing is the same today as it was back in 1956. Notice I said that the part number is the same, NOT the contents of the package.
When the new rubber insulator arrived, the mechanic proceeded to install the new NAPA bearing in the new insulator and then reinstalls that assembly in the car. He also s**tcans the old insulator & bearing, without paying much attention to it.
I finally get the car, have it delivered and ±300 miles into my ownership, the NEW mid-shaft bearing insulator assemply lets go at about 25 MPH and starts beating the hell out of the bearing housing, or the "hoop" as it's better known. I remove the insulator myself, which now has the texture and consistancy of a wet sponge. The bearing itself easily falls out but looks OK, so I can't figure out what happened and where the problem was.
A lot of time spent investigating Mark II parts and service manuals finally gave me a clue as to what happened. Remember I said that the bearing part number hadn't changed in 53 years, not the bearing itself. At some point the 2-piece stamped BEARING RETAINER which was originally INCLUDED with the bearing was discontinued and no longer in the box with the bearing, because while the bearing has multiple applications, the BEARING RETAINER WAS A MARK II SPECIFIC PART AND NOT NEEDED FOR ANY OTHER APPLICATION, so it was discontinued.
The friendly local neighborhood hayseed mechanic, not knowing any better himself, installed the new bearing WITHOUT THE BEARING RETAINER into the new rubber insulator. Since the new bearing was not restrained by the BEARING RETAINER inside the new insulator, it only took 300 miles of driving, with the bearing SPINNING INSIDE THE NEW INSULATOR, to generate enough heat to basically melt the insulator and cause the assemably to fail. I was fortunate that it failed at 25 MPH and not 111 MPH (the fastest that I've had my sled to date) as I've heard of more than one case where a transmission tailshaft housing has had to be replaced when a Mark II driveshaft decided to run amock at speed.
So, BEWARE of what awaits you and your Mark II. And you can't say you weren't warned...
Shortly before I purchased my Mark II, the previous owner, a non-wrench turner, took the vehicle to his friendly local, neighborhood mechanic for a pre-sale checkup at my request. Among other things, the mid-shaft bearing insulator was determined to be in need of replacement, so a new replacement was ordered. The mechanic also purchased a new bearing from his local NAPA store. Understand that the part number for the bearing is the same today as it was back in 1956. Notice I said that the part number is the same, NOT the contents of the package.
When the new rubber insulator arrived, the mechanic proceeded to install the new NAPA bearing in the new insulator and then reinstalls that assembly in the car. He also s**tcans the old insulator & bearing, without paying much attention to it.
I finally get the car, have it delivered and ±300 miles into my ownership, the NEW mid-shaft bearing insulator assemply lets go at about 25 MPH and starts beating the hell out of the bearing housing, or the "hoop" as it's better known. I remove the insulator myself, which now has the texture and consistancy of a wet sponge. The bearing itself easily falls out but looks OK, so I can't figure out what happened and where the problem was.
A lot of time spent investigating Mark II parts and service manuals finally gave me a clue as to what happened. Remember I said that the bearing part number hadn't changed in 53 years, not the bearing itself. At some point the 2-piece stamped BEARING RETAINER which was originally INCLUDED with the bearing was discontinued and no longer in the box with the bearing, because while the bearing has multiple applications, the BEARING RETAINER WAS A MARK II SPECIFIC PART AND NOT NEEDED FOR ANY OTHER APPLICATION, so it was discontinued.
The friendly local neighborhood hayseed mechanic, not knowing any better himself, installed the new bearing WITHOUT THE BEARING RETAINER into the new rubber insulator. Since the new bearing was not restrained by the BEARING RETAINER inside the new insulator, it only took 300 miles of driving, with the bearing SPINNING INSIDE THE NEW INSULATOR, to generate enough heat to basically melt the insulator and cause the assemably to fail. I was fortunate that it failed at 25 MPH and not 111 MPH (the fastest that I've had my sled to date) as I've heard of more than one case where a transmission tailshaft housing has had to be replaced when a Mark II driveshaft decided to run amock at speed.
So, BEWARE of what awaits you and your Mark II. And you can't say you weren't warned...