Derby clutch diagnosis

Christopher Hadfield · Posted: Thu Jun 17, 2021 4:01 pm Post subject: Derby clutch diagnosis

My 1935 3.5ltr car starts slipping badly with no free play in the pedal after approx 50 - 100 miles of use after being adjusted.
Can anyone tell me why it might
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Christopher Hadfield

Nicholas Simons · Posted: Thu Jun 17, 2021 6:18 pm Post subject:

Have you tried readjusting the clutch to regain the 1/2" minimum lift at the pedal?
Does your car have the standard 3 1/2 litre clutch or the later lightweight one, B2EF to B159FC?

Christopher Hadfield · Posted: Fri Jun 18, 2021 5:37 am Post subject: Derby clutch diagnosis

Yes I have to adjust it every 100 miles or so.
I assume it is the standard clutch but don't know the difference.
Although not very worn it will probably be over 50 years old as it was off the road for over 45 years until 3 years ago
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Christopher Hadfield

Nicholas Simons · Posted: Fri Jun 18, 2021 8:16 am Post subject:

You can ascertain whether it has the lightweight clutch from the chassis number. I gave the relevant range for this clutch.
The lightweight clutch is susceptible to rapid wear if not driven correctly. With any Royce clutch you should never slip it more than the absolute minimum required to get yourself going. These cars have bags of low down torque so use it and lift the clutch pedal rapidly at low revs when moving off.

Christopher Carnley · Posted: Fri Jun 18, 2021 8:32 am Post subject:

The clutch itself in either its Rolls-Royce "heavy" or "light" type is not adjustable after initial installation, only the clutch pedal travel.

To remove the heavy clutch, you have to drop the sump, ie crankcase lower half. It is called "heavy" as it weighs a "ton".

Nicholas Simons · Posted: Fri Jun 18, 2021 10:53 am Post subject:

Not sure that's correct, Chris. The gearbox and bell housing must be removed, then the clutch assembly can be removed from the rear face of the flywheel. This is a long job as you need to remove things like the brake rods from the servo, and pedal shaft, etc. The linings need to have their rivets drilled out. Initially, the new clutch is set by adjusting the retraction levers, and then the adjustable link to the pedal.

Christopher Carnley · Posted: Fri Jun 18, 2021 12:16 pm Post subject:

I should have said the flywheel of course, with the clutch inside it.

The picture thing isn't working today.

Christopher Hadfield · Posted: Fri Jun 18, 2021 3:06 pm Post subject: Derby clutch diagnosis

Thanks for the replies, I guess it is the lightweight then as B139CW
Wish I'd replaced it when I had the engine out but an extra £1200
or so seemed extravagant after what I had spent on the engine
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Christopher Hadfield

Christopher Carnley · Posted: Fri Jun 18, 2021 3:36 pm Post subject:

Christopher,

It is the heavy one, the light type started a B2EF. I would send some pictures of the ones that I have done, but the facility is not working today.

Is the car still on BKP 1, I see that you have had the car for quite a time now.

If you send me your email address on carnley3rt@btinternet.com, I will send you Ken Leas expose on the clutches in the DBS "On The Road" .

I imagine that Nicholas would also like a copy (to see if it is OK.).

Chris.

Nicholas Simons · Posted: Fri Jun 18, 2021 4:24 pm Post subject:

The heavy clutch is much more durable that the light clutch, but you still need to learn how to use a Royce clutch, ie, keep the slip to an absolute minimum and engage at low revs.
Once it's knackered you need to change it otherwise further damage will be done, such as warping the driven disc. £1200 is a bargain.

davidmcrobert · Joined: 29 May 2019 Posts: 1 Location: Oxon, United Kingdom

I have the 'heavy clutch' on my 1934 lightweight special. Any kind of vigorous use causes overheating and excessive wear. Alpine Eagle are currently working on a replacement modern clutch arrangement designed to replace both the early 'heavy' clutch and also the later 'light' clutch. Engineering work is currently ongoing and they hope to have a fully tested and proven new durable clutch arrangement to offer those that are interested by mid 2022. I'm really hoping this will be a major step forward.

Christopher Hadfield · Posted: Fri Dec 17, 2021 3:50 pm Post subject: Derby clutch diagnosis

It did turn out to be a light clutch so presumably changed in the past, and it was completely Kn*****ed, down to the metal warped and cracked. It has been replaced by Elliot Dale and runs beautifully
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Christopher Hadfield