Regular readers of this forum may have noticed that I have been fitting semi-Girling brakes to my RN saloon and had encountered a few problems. I am happy to report that they are now solved. Here is what I did:

First I obtained front and rear axles with semi-Girlings and the heavier radius arms. These were all overhauled as necessary and fitted to the car. The rear brake levers are at 6 o'clock, leaning backwards, achieved by using front cams but switched o/s to n/s & n/s to o/s. The rear cables pass through the original brass guide bush quite satisfactorily.

The original uncompensated RN cross shaft was checked over and encouraged to work properly.

I had to fit an adjustable front brake cable as the original was too short for the new axle set-up. The 'wiffletree' quadrant had to be eased a little with a file to accommodate the different diameter of new metric cables.

I originally used standard Girling brake levers both front and back. The rationale here was that these levers had been fitted to the front axle at Longbridge and should therefore work; and at the rear, well, they are a similar length to Girling rear levers but could be used with the original ball-ended cables so I didn't have to buy new ones, thus saving some £60.

The problems started when I tried to set the brakes up. I could not make them work properly at all! Not even if I tried to set up the front with the rears disconnected and vice versa.

In the end I stumbled upon the idea that the leverage produced by the RN cross shaft must be different to that of the late Ruby compensated cross shaft, and therefore the pull on the cables is different. This was proved to my satisfaction by the fact that the front brakes would not work alone, and the only difference from the Ruby from which they came was the cross shaft.

So I considered the idea of shorter brake levers, which has been mentioned on this forum before, and so fitted the short RN levers all round.

Hey presto! Problem solved! I have strong brakes with a really decent pedal height. I was warned that I might experience rear brake actuation on bumps and bends, due to the different arcs proscribed by the cable and spring, but so far I've noticed nothing amiss.

Roger Bateman

Location: Dorset UK

Well done for persevering and sorting it all out. Happy stopping!

Sounds like I need to do that to daughters RP which has a Semi girling front. It stops so so. But isnt a patch on the RL.

Then again its probably easier to fit a proper axle to it.

Pedal travel is generous and springy by modern standards but puzzled that could not persuade to work.

Re mixed sytems, when the much smaller cams are combined with longer arms the leverage and thus travel of semi Girling is much greater than early systems, esp with short arms, so, as earlier posts on topic, standard semi Girling on the front alone is dubious.

(The advantage of semi Girling lies mainly in the greater leverage from small cams)

Location: Auckland, NZ