Introducing

- Myself, Bruce,

I am a Landrover repairer/ garagist . I see daily a Landrover from people around Lannemezan [ FR ] in my Workshop.

Besides this, I work in the agricultural sector.

- My good friend Herman,

He is a retired Math, Physics and Informatics teacher and retired skipper of tall Ships ( 2 or most masts )

He is my neighbour 10km away in Lannemezan, France

Together we have been hatching a plan!

The " Betty Boop" Bevel-Box Project

Betty Boop is a Morgan 3 Wheeler fitted with a V-TWIN engine which includes a bevel box conversion kit from belt drive to chain (engineered by ourselves).

For those not in the know a bevel-box is a one sided differential which drives only out of one side .

3 Wheeler 5-speed-Morgans do have such a bevel-box.

Herman started the project by creating an extra dashboard to figure out all the temperatures and pressures in his m3W. The far too high Bevel-box temperatures inspired him to research “the why” and finding a solution.

After spending many hours and many years with the beloved Betty-Boop, Herman is at breaking point with the noise that comes out of the bevel box.

The cause of the noise : Bearings and Alignment

The bearings which are located in the bevel box over a period of time collapse due to the extreme pressure of the belt drive.

What is not commonly known, the belts are mostly reinforced with KEVLAR due to the enormous pressure and forces involved in tightening of both the rear wheel shaft nuts , pinion and the belt itself which in turn results in a extremely hot belt hence the KEVLAR.

"Although KEVLAR is suitable for a wide range of temperatures, it has a negative thermal coefficient of expansion, meaning that it shrinks as the temperature rises and lengthens as it cools. Since this behavior is the opposite of most other machine components (especially made of metal) - which expand as temperature increases and contract as temperature decreases - KEVLAR reinforced belts may not be suitable in environments with significant temperature fluctuations " ...... HENCE bearing breakdown

Both myself and Herman have discovered that a chain drive cuts out the damage / excessive wear from overheating and excess tension on the belt.

When the car is not in use or driving idle there is no pressure on the bearings, seals or the crown wheel and pinion.

As opposed to the belt which remains at extreme pressure when not in use causing oil starvation in the bearings.

Leaking Oil Seals are also a problem:

A simple switch in oil which supports the temperatures displayed inside the bevel box.

After testing for 2 years Herman discovered temperatures of up to 120 ᵒC

By switching to a thicker oil and more of it 800ml, the results are pretty overwhelmingly brilliant!

Conclusion:

A 1000km test over a period of time has provided us with the following information:

- No noise from the chain driven bevel box.

- Temperatures inside the bevel box remain lower 65-75 ᵒC.

An optional extra : a forced air duct installed reducing the bevel box 30 ᵒC

The reduced temperatures explain a lot!

All the above at normal driving conditions.

If you wish to find out more about our bevel box reconditioning kit or are looking for a M3W reconditioned bevel box please do contact us.

Smooth Running Everyone!

Bruce Sherriff