Finally, after over 5 months the car runs again.
The changes and my initial impression of how they work are as follow:

Moss gearbox rebuilt by Vintage Jag Works in Idaho: Works better than it
has in the last 20 + years. Shifts smoothly and the synchro action is almost up to 30 years old technology.

Polyurethane suspension bushings: Car feels tighter, flatter, cornering.
Transient response is much better. No apparent change in ride comfort no noise, no harshness. They ARE red, and do show a little bit, particularly in the front.

Aluminum flywheel: Definite improvement in throttle response, 1st & 2nd
gear acceleration markedly improved, Starter works much more quietly. Double clutching downshifts are far easier. (This is a Wooopeee type of change. With the dual exhaust 120, it really changes the character of the engine for the good, and the snappy response makes it such a pleasure to downshift. It really crackles!)

9.5" Diaphragm clutch: Much lighter pedal action, excellent bite,
easily modulated. This is a great change. (It's also 3 lb lighter than the stock 10" spring type clutch) Note! To perform this change with a stock flywheel you must re-drill the flywheel for the 3 alignment dowel pins the 9.5 clutch cover uses and you MUST use the release bearing for the 9.5 clutch. The RB for the 10" clutch will NOT work. (Don't ask)
The Aluminum flywheel and the 9.5" clutch together removed 21 lbs of rotating weight from the engine.

Replacement voltage regulator: works perfectly, New fused links replace
the fuses that were in the 9 post regulater (which has been saved to modify internally and be re-installed when I install the alternator and finally send away the prince of darkness)

Replacement non-rubber steering link bushings: Slightly less self
centering. Slightly more accurate steering and less softness in the wheel.

I found some insulation sheets in a local speed shop. Not cheap, I
placed it all around the transmission tunnel and under the carpets on both sides of the cockpit. Polyfoam around the shifter hole, with a cut-out for the shift lever to come through.

Odyssy sealed battery: (Hawker ODYSSEY PC925MJT) This is a single 12 volt replacement for the dual 6 volt batteries. It is smaller (shorter) and lighter than the original 6 volt batterys. It offers sealed construction & 925 cold cranking amps of power. (Ah the wonders of modern technology) No more acid fumes, no corrosion of terminals & battery box, less weight. It fits into one of the original battery boxes with room to spare. I did have to shim up the battery to the proper height to connect the cables however. It is advertised as NOT losing power during storage. I tested this attribute. My 120 sat for 5 1/2 months with without a battery charger. I also used some battery power during the re-wiring & testing of lights etc. When I went to start the car for the first time after this time, it was as if it had not been sitting at all. Within 5 miles, the ammeter was back to it's normal 2 ~ 3 amp charging position. An excellent purchase! This change removed 30 pounds of weight from the car. (one battery)

Together, I saved 51 pounds of road hugging weight from my cat with the battery, flywheel and clutch change.

In all, a great day! Hooo Boy was it great to take it out and play with
it again after so long. These past 5 months was the longest time (and the
first time) that the car has been off the road in the 14 years since the cat followed me home and my wife said that I could keep it. :-^

Roger

Submitted by rfhcvh@aol.com on Sat, 09/04/2004 - 23:06

A nice story about your 120. I am interested in using the Odyssy battery in my XK 120 OTS, and need to know possible sources for this battery. Also would like the phone number for Vintage Jag Works and it's Idaho location Thanks for your help. Bob Hardiman