help needed 1963 cloud III brakes
Discussion
I'm currently helping a friend get her 1963 rolls royce cloud III back on the road.
The car is by all accounts the same vehicle that was on the stand at the motorshow of the same year, does anyone know the car or have any history?
Apparently the car has been to america and back in its's lifetime but any more information was lost when the previous owner passed away.
Any way back to my main question:
I'm having problems regarding the brakes.
More specifically the front ones, the braking system on the car seems to be quite different to anything i have come across before, could anyone explain how it works and more importantly what could be at fault?
Also what does the part on the gearbox do? what is it? a clutch? pump?
The car is by all accounts the same vehicle that was on the stand at the motorshow of the same year, does anyone know the car or have any history?
Apparently the car has been to america and back in its's lifetime but any more information was lost when the previous owner passed away.
Any way back to my main question:
I'm having problems regarding the brakes.
More specifically the front ones, the braking system on the car seems to be quite different to anything i have come across before, could anyone explain how it works and more importantly what could be at fault?
Also what does the part on the gearbox do? what is it? a clutch? pump?
Edited by robrabbit on Monday 8th December 20:44
The front brakes are hydraulically assisted from the servo on the gearbox. The rear brakes are rod operated. Drums all round. Similar chassis/brakes arrangement to the MKVI/R type & Cloud I/II.
The faster you go, the more powerful the front brakes, but as you slow and come to a standstill, the brakes become less powerful, and are almost scarily absent just as you almost come to a stop.
And they are rubbish at stopping the car from rolling back on an incline too, so the handbrake needs to be working properly.
The faster you go, the more powerful the front brakes, but as you slow and come to a standstill, the brakes become less powerful, and are almost scarily absent just as you almost come to a stop.
And they are rubbish at stopping the car from rolling back on an incline too, so the handbrake needs to be working properly.
As BG has indicated, the brakes do indeed work very differently from the brakes on "normal" cars.
The front brakes will only work when the car is in motion, which foxes many MoT testers, who normally test brakes on a rolling road, i.e. at a standstill, one axle at a time - when they test the back brakes, they work fine, but the fronts don't work at all.
Briefly, it works like this. The brake pedal actuates the rear brakes (unassisted) and engages the clutch on the mechanical servo which is driven off the back of the gearbox. This adds power assistance to the rear brakes and also works the front brakes.
When properly set up, this system works very well indeed. If the brakes on your friend's car are not working when on a rolling road, or at very slow speeds, don't worry, but if they don't work well at anything over walking pace, then there is a problem and it is very likely that this is due to poor operation of the servo clutch, which can often get oiled up if there is a leaky seal or some other cause for oil to seep into it. This could easily be the case in a car that has stood around for some time unused.
My advice would be to take it to an expert who knows about ths system - he will be able to sort it easlily enough and you cannot be too careful when it comes to brakes. That means an R-R expert, because no other car (except Hispano-Suiza, who invented the system, but there aren't too may H-S experts around) has brakes like this.
The system originated in the '20s, when R-R wanted 4-wheel brakes to fit to the Ghost and with the new Phantom in mind. Rather than "re-invent the wheel", R looked around for the best system avialable (which he dcided was the one Marc Birkigt had invented), bought a licence to use it and then went on to improve it for use on his cars. The proof of its effectiveness is that it was still being used forty years later (when, of course, history repeated itself: R-R adopted the Citroen system for the Shadow and it is still in use on Bentleys today, I believe).
The front brakes will only work when the car is in motion, which foxes many MoT testers, who normally test brakes on a rolling road, i.e. at a standstill, one axle at a time - when they test the back brakes, they work fine, but the fronts don't work at all.
Briefly, it works like this. The brake pedal actuates the rear brakes (unassisted) and engages the clutch on the mechanical servo which is driven off the back of the gearbox. This adds power assistance to the rear brakes and also works the front brakes.
When properly set up, this system works very well indeed. If the brakes on your friend's car are not working when on a rolling road, or at very slow speeds, don't worry, but if they don't work well at anything over walking pace, then there is a problem and it is very likely that this is due to poor operation of the servo clutch, which can often get oiled up if there is a leaky seal or some other cause for oil to seep into it. This could easily be the case in a car that has stood around for some time unused.
My advice would be to take it to an expert who knows about ths system - he will be able to sort it easlily enough and you cannot be too careful when it comes to brakes. That means an R-R expert, because no other car (except Hispano-Suiza, who invented the system, but there aren't too may H-S experts around) has brakes like this.
The system originated in the '20s, when R-R wanted 4-wheel brakes to fit to the Ghost and with the new Phantom in mind. Rather than "re-invent the wheel", R looked around for the best system avialable (which he dcided was the one Marc Birkigt had invented), bought a licence to use it and then went on to improve it for use on his cars. The proof of its effectiveness is that it was still being used forty years later (when, of course, history repeated itself: R-R adopted the Citroen system for the Shadow and it is still in use on Bentleys today, I believe).
Edited by Bluebottle911 on Tuesday 9th December 22:35
Thanks John, I had forgotten how it worked, I sold my MKVI about seven years ago. Your comment about the servo clutch getting oiled up has jogged my memory, IIRC there is a modern fix for this, some sort of silicone band, but I can't remember exactly. That part of the braking system was beyond my DIY skills, but everything else was easy enough to strip, clean & maintain.
I am now on to my fifth R-R product equipped with the H-S derived brakes and I never cease to be impressed.
Which reminds me. You and I both have Bentleys with ABS (introduced in 1987?) and active ride (1990?), but the fact is that these were hardly innovations, as they had first appeared about 60 years earlier - my '36 car has both!
If you consider the logic of the H-S braking system and remember that the braking effort is heavily front-biased, then it follows that, when the rear brakes come close to locking (in 99.9% of cases they will lock first) the drive from the back of the gearbox slows almost to zero and so the servo clutch disengages, taking away the power assistance, so they unlock and hey presto - anti-lock brakes!
I shall grant you that it does not work as effectively as the ABS on our Turbo Rs, but . . .
Then turn your attention to the shock absorbers on a Derby Bentley. Not only can the driver manually select soft or firm ride (and there is a marked difference if the shockers are in good nick) or any setting in between (which we cannot do on our Turbo Rs), but there is also an engine driven pump which stiffens them up as your speed increases - active ride!
As the say, "there's nothing new under the sun".
Which reminds me. You and I both have Bentleys with ABS (introduced in 1987?) and active ride (1990?), but the fact is that these were hardly innovations, as they had first appeared about 60 years earlier - my '36 car has both!
If you consider the logic of the H-S braking system and remember that the braking effort is heavily front-biased, then it follows that, when the rear brakes come close to locking (in 99.9% of cases they will lock first) the drive from the back of the gearbox slows almost to zero and so the servo clutch disengages, taking away the power assistance, so they unlock and hey presto - anti-lock brakes!
I shall grant you that it does not work as effectively as the ABS on our Turbo Rs, but . . .
Then turn your attention to the shock absorbers on a Derby Bentley. Not only can the driver manually select soft or firm ride (and there is a marked difference if the shockers are in good nick) or any setting in between (which we cannot do on our Turbo Rs), but there is also an engine driven pump which stiffens them up as your speed increases - active ride!
As the say, "there's nothing new under the sun".
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