During the rolling road testing of Friday 29/09/2000, we found two small oil leaks from the engine.  One leak was coming from the area of the oil filter, easily fixed, and the other was coming from the rear of the engine, possibly from the rear crankshaft oil seal.  On removing the gearbox, we found the rear of the flywheel to be clean with no oil, but the bell-housing and clutch cover were covered in black oil.  This suggested that the oil was coming from the gearbox, and not the rear crankshaft oil seal.  On removing the bell-housing, we found that the leak was coming from the gear selector shaft, which should have been sealed by the alloy plate which matches the gearbox to the bell-housing.  While we had the gearbox out, we decided to remove the gearbox top cover to check for any other problems.  Oops!  3rd and 4th gears were found to be very badly worn.

On striping the gearbox, we found the initial cause of the failure to be the lay-shaft inner rod being very badly damaged due to loss of oil, and heat.  The failure could have been due to three possible reasons.

1.  The lay-shaft inner rod, part of the original donor Sierra gearbox may have been faulty.  The lay-shaft gear cluster rotates on this rod via needle roller bearings located at the front and back.  On disassembly, the rod and front needle roller bearing were found to be badly damaged due to heat and lack of oil.  This failure allowed excessive play between the gears towards the front of the lay-shaft, so causing excessive wear to 3rd and 4th gears. 

2.  The needle roller bearing at the front of the lay-shaft inner rod was faulty, and failed.  This caused a heat build up on the lay-shaft inner rod which is also badly damaged, and as described above damaged 3rd and 4th gears on the lay-shaft.

3.  The oil leak from the front of the gear selector shaft, which is located at the top of the gearbox, may have starved the front of the lay-shaft inner rod and its needle roller bearing of oil, so causing the failure.

Whatever the actual cause, the failure would have eventually caused the gearbox to seize.  The fact that the gearbox had not already seized, says volumes about the quality of the design and manufacture of the Quaife gear kit used.