Lagonda Rapiers

3 minute(s) of a 484 minute read

Well at last today I got to road test the Rapier's rebuilt gearbox. At first it was slipping in top gear, Perhaps I should explain in case some of you missed earlier that top gear is actually a cone clutch. Fortunately this can be micro adjusted using the self adjusting mechanism built into Preselector gearboxes, do this with the engine switched off, you simply select the required gear in this case 4th or top and "pump" the change (clutch) pedal up to 20 times. This can then be tested by starting the engine and with the hand brake applied, select top gear bring the engine up to 2,500 rpm and slowly release the pedal. Provided the engagement adjustment is somewhere near correct the engine should stall. You may have to go through the "pumping" process two or three times before you achieve a positive result. 

Once you have got to the stage where the engine stalls as soon as you start to apply load you can then proceed to the road test stage. Find a good steep "test hill". Driving at 30 mph in top gear there should be no sign of slipping. This can be further checked by applying some light pressure on the change pedal with the engine pulling hard in top gear. Naturally it will now slip but drive positively (without any slip) as soon as the pedal is released. You can test the engagement of any gear in this manner. 

I am pleased to report that following some (brutal) testing the box is driving well and the difference in the noise level in the lower gears is amazing, they are actually extremely quiet whereas before conversation at a normal level in first & second was impossible. I cannot wait for our next VSCC event in two weeks time.

Bernie J.

To explain the above Preselector transmissions rely on friction lined brake bands contracting on to the selected gear drum to engage that gear. As the friction material wears over time the bands require adjusting (tightening) to do this the nut at the end of each pull rod needs to be screwed down. This is done each time that particular gear is selected. Hopefully at least some of you will understand the attached diagrams and photographs. You may need to go back to my earlier post #34 with photographs of the dismantled gearbox to full appreciate all this.

Bernie J.