Carb Rebuild - 73 SS - Rolls-Royce and Bentley Forums
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post #1 of 18 (permalink) Old 01-18-2020, 01:18 PM Thread Starter
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Question Carb Rebuild - 73 SS

So I'm finally going to get the hydraulic brake pumps open on my 73 SS to see why they are not working.

Since I'm going to have to remove the carb to get access to the brake pumps I thought I'd take the opportunity to rebuild it. One of the fuel inlets leak. Probably just an o-ring.

So my first question is should I rebuild the carb at all or am I opening a can of worms? (if it works why fix it?)

If so can you recommend any guides to successfully rebuild the carb?

And finally any carb rebuild kit recommendations / preferences?

Thank you all!
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post #2 of 18 (permalink) Old 01-18-2020, 01:32 PM
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Do you have the castellated socket for the brake pumps? How do you know they are not pumping?

1980 SWII LRL-41587C FInj
1976 SS LWB LRE-23114 Harkness RR
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post #3 of 18 (permalink) Old 01-18-2020, 01:34 PM Thread Starter
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Yes I bought the socket. I've run all the tests following the various guides available. No juice.
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post #4 of 18 (permalink) Old 01-18-2020, 01:34 PM
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Hi Alex,


Rebuild the carbs it is quite a simple job and you will have the benefit of the modern materials on the diaphragms.


Kits are available but you will likely have to fit the modified parts that come in the kit as there was a slight difference in the well of the float chamber.


We have SU Burlen in UK who supply the kits and I know there is too a specialist SU suppliers in US.


I did mine before the days of digital cameras and online forums so no pictures. I know Dounraey has done his more recently so may have taken lots of pictures along the way.


Certain areas to be careful about is keeping the parts related to the same carb and don't mix them up.


All the best


Steve
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post #5 of 18 (permalink) Old 01-18-2020, 01:40 PM
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castellated=brake pump removal socket Wraithman wordage, lol

1980 SWII LRL-41587C FInj
1976 SS LWB LRE-23114 Harkness RR
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post #6 of 18 (permalink) Old 01-18-2020, 01:42 PM
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Even faulty pumps will generate some pressure. unless both pump rods are fractured. Did you check the filters in the reservoir?

1980 SWII LRL-41587C FInj
1976 SS LWB LRE-23114 Harkness RR
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post #7 of 18 (permalink) Old 01-18-2020, 01:45 PM Thread Starter
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Yes filters are clean, all nipples on the calipers have been opened to bleed. Nada. Zilch. I bought the car like this with no brakes. Previous owners didn't do any research on how the RR brake system works so had no clue.

Quote:
Originally Posted by Wraithman View Post
Even faulty pumps will generate some pressure. unless both pump rods are fractured. Did you check the filters in the reservoir?
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post #8 of 18 (permalink) Old 01-18-2020, 04:29 PM
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Quote:
Originally Posted by Alex Cat View Post
...all nipples on the calipers have been opened to bleed. Nada. Zilch...
Hi Alex - Iím a newbie here and still learning myself but I donít believe thatís a conclusive test for faulty pump(s). Thereís a lot of stuff between the pumps and the callipers that could be causing the issue. It could be a blockage rather than the pump(s). In my opinion your first port of call is the bleed screw at the ACVís. Just my 2 cents worth.
Cheers

Silver Shadow 1976,
Chassis SRH25478,
Royal Garnet,
First 10yrs used exclusively for Royal duties running members of the Royal family about whilst on official visits,
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post #9 of 18 (permalink) Old 01-19-2020, 01:24 AM
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Hi Jonathan


I would personally re-condition the carbs if I was unsure of their history.


As Steve said, a re-con kit from Burlen (sucarb) will have modern materials designed for E10 petrol which may soon be rolled out in the UK (as far as I am aware - I am in the US where it is in common use).


The workshop manual (section K4) and the Burlen website have lots of information on re-conditioning the carbs.


If you decide to go ahead let me know and I will put up pics to help guide you through the process. Also, don't remove the carbs individually - it's much easier to remove the carbs and central plenum as a unit (as shown in Steve's pics). The whole lot is held by a single bolt.


The relevant website is:



http://sucarb.co.uk/


Geoff

1974 Silver Shadow
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post #10 of 18 (permalink) Old 01-19-2020, 01:41 AM
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OK........ looks like we better confirm your brake pumps before moving onto the carbs.


Jonathan is right to question just how you came to the conclusion you have two faulty brake pumps.


I would also question your test of nothing (nada, zilch) at any brake bleed nipple. Your car has two systems and even if pumps, and accumulators were all faulty the very least you should be able to bleed through the low pressure side on the two lower rear calliper bleed screws. This circuit is independent.



If you have nothing here too then you have a lot more than just your brake pumps to think about.


I have two fabricated pipes I use whenever waking up a long term stored car that I fix to top of brake pumps and run back into the reservoir caps before turning over an unused engine (amongst many other pre checks). These will show fluid flow but not necessarily prove the brake system or pumps are perfect.


You need to tell us how you have carried out your analysis and indeed confirm you followed the correct procedure for bleeding system as you need to do it a special precise way on the high pressure side.


I think carbs can wait for now


Update...Sorry Dounraey I was typing same time as you so not contradicting



All the best


Steve

Last edited by Steve E; 01-19-2020 at 01:43 AM.
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