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Steve Janosik
New User
Username: catullus

Post Number: 5
Registered: 8-2017
Posted on Friday, 22 December, 2017 - 06:59 am:   Edit PostDelete PostView Post/Check IP

Please help me verify that part number UR 6103 is the correct "master cylinder for 1975 Shadow SRD-21809.
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Larry Kavanagh
Prolific User
Username: shadow_11

Post Number: 129
Registered: 5-2016
Posted on Friday, 22 December, 2017 - 08:54 am:   Edit PostDelete PostView Post/Check IP

According to Flying Spares and Introcar Ltd the master cylinder part number for Silver Shadows from Serial No. 1001 to 22117 is UR13167.
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Geoff Wootton
Grand Master
Username: dounraey

Post Number: 1886
Registered: 5-2012
Posted on Friday, 22 December, 2017 - 09:07 am:   Edit PostDelete PostView Post/Check IP

The part number Larry gives also concurs with the one listed in the RR parts manual.

If originality is not a big issue for you, you may want to consider using a 3/4" Land Rover S2 master cylinder. It is a perfect fit and makes for easier bleeding of the system and gives a better pedal feel. I've just fitted one on my car and much prefer it:

https://www.ebay.com/itm/282621225870
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Jim Walters
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Username: jim_walters

Post Number: 142
Registered: 1-2014
Posted on Friday, 22 December, 2017 - 09:43 am:   Edit PostDelete PostView Post/Check IP

I agree 100% with Geoff, I replied to the other post before I saw this one. See the link there for a less expensive one.

SRH8505 SRC18015 SRE22493 NAC-05370
www.bristolmotors.com
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Steve Janosik
New User
Username: catullus

Post Number: 6
Registered: 8-2017
Posted on Friday, 22 December, 2017 - 10:48 am:   Edit PostDelete PostView Post/Check IP

Thank you all very much indeed !

Methinks that the "UR 6103" was a false alarm resulting from a sincere and helpful person who was working under stress in a noisy location.
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Christian S. Hansen
Grand Master
Username: enquiring_mind

Post Number: 694
Registered: 4-2015
Posted on Thursday, 01 February, 2018 - 01:49 pm:   Edit PostDelete PostView Post/Check IP

Geoff and Jim...
Apparently the master cylinder on my '68 MPW CRX2541 has gone kaput. Pedal goes mostly to the floor where there is a bit of residual braking. The VERY experienced mechanic at the Colgetts' ACME Car Service in Hayward, CA is quite sure that symptom (and the prior two stage pedal feel) points to the master cylinder. I have an appointment for further examination and replacement later this month and before going with the $165 RR part from Albers, want to verify that the replacement part you referenced is indeed a perfect fit without any fussing, modifications, etc. At $140/hour I want to make sure it goes in smoothly, otherwise the savings on the Rover part will simply go to any workarounds that might be necessary with the Rover part in which case staying with the "plug and play" RR cylinder would be the choice. Let me know? Thanks!

.
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Christian S. Hansen
Grand Master
Username: enquiring_mind

Post Number: 695
Registered: 4-2015
Posted on Thursday, 01 February, 2018 - 06:57 pm:   Edit PostDelete PostView Post/Check IP

P.S. Jim...
I cannot seem to locate the "other post" you reference, but I did find a posted link from another thread to an EBay listing for the Rover MC for a tad under $40US which seems the one to use. What a deal. Will order it.

.
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richard george yeaman
Grand Master
Username: richyrich

Post Number: 916
Registered: 4-2012
Posted on Thursday, 01 February, 2018 - 07:16 pm:   Edit PostDelete PostView Post/Check IP

Christian unless you are fitting the parts yourself go with the plug and play, takes the shift the blame element out of the equation.

Richard.
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gordon le feuvre
Prolific User
Username: triumph

Post Number: 229
Registered: 7-2012
Posted on Thursday, 01 February, 2018 - 08:25 pm:   Edit PostDelete PostView Post/Check IP

I trust you guys out there are aware that the official Bentley Heritage site is also available to every one free by logging on. You can then look up original part numbers from original part catalogue, as sometimes neither Flying spares nor Introcar carry the detail. It's just another tool in the part number nightmare.
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Geoff Wootton
Grand Master
Username: dounraey

Post Number: 1893
Registered: 5-2012
Posted on Friday, 02 February, 2018 - 12:48 am:   Edit PostDelete PostView Post/Check IP

Christian

The Land Rover part I fitted was a perfect plug and play substitute. The pipe threads and flares were identical as was the thread on the push rod. It fitted perfectly. This is the one I purchased:

https://www.ebay.com/itm/282621225870

However, make sure your master cylinder is the same as mine if you decide to use the Land Rover master cylinder. My car is a 1974 SY1, SRX18501.

I could not find the master cylinder in my parts manual however Flying Spares list just one master cylinder (UR13167) for all cars 1965-75 (VIN 1001-22117).

Here's a pic of the original 0.625 master cylinder against the new 0.75 one.

master

The only mod I made was to remove the clip (arrowed), before fitting.

Geoff
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Geoff Wootton
Grand Master
Username: dounraey

Post Number: 1894
Registered: 5-2012
Posted on Friday, 02 February, 2018 - 12:57 am:   Edit PostDelete PostView Post/Check IP

Christian

I think the "other post" Jim refers to may have been this one:

http://au.rrforums.net/forum/messages/17001/29128.html?1508409271
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Christian S. Hansen
Grand Master
Username: enquiring_mind

Post Number: 696
Registered: 4-2015
Posted on Friday, 02 February, 2018 - 03:51 pm:   Edit PostDelete PostView Post/Check IP

OK...
I'm going with the 3/4" MC. Will report back results next month.
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Christian S. Hansen
Grand Master
Username: enquiring_mind

Post Number: 697
Registered: 4-2015
Posted on Friday, 02 February, 2018 - 04:11 pm:   Edit PostDelete PostView Post/Check IP

P.S.
I'll also be mixing up sufficient YAK363 to do the job. How much should I anticipate taking with me on the day of the MC swap? 3-4 quarts? If I have ACME do a brake fluid system flush and fill at the same time, how many more quarts should I anticipate needing?

.
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Larry Kavanagh
Prolific User
Username: shadow_11

Post Number: 144
Registered: 5-2016
Posted on Saturday, 03 February, 2018 - 04:31 am:   Edit PostDelete PostView Post/Check IP

System holds approx. 2 1/2 litres i.e., one litre for system 1 (front section of reservoir) and one and a half litres for system 2 (rear section of reservoir). So 5 litres should be enough for a flush and bleed. Ordinary DOT 3 or DOT 4 will do for the flush and then RR363 or YAK363(if you prefer) for the refill and bleed. Empty reservoir and clean before adding flushing fluid and let it drain completely through the system. Some cars take longer that others to drain fully, anything from a couple of hours to overnight.
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Christian S. Hansen
Grand Master
Username: enquiring_mind

Post Number: 698
Registered: 4-2015
Posted on Saturday, 03 February, 2018 - 03:22 pm:   Edit PostDelete PostView Post/Check IP

While ordering the master cylinder from EBay, I also saw a product called "Russell Speed Bleeders". Anyone tried them? They replace the bleed screw and are apparently spring loaded so that once loosened a bit, they then open and close by pedal pressure thus eliminating the process of manually opening and closing the bleed screw in between pedal pumps or when additional fluid is to be added to the reservoir. I may try them, but the questions are:
1) What is the threading for the OEM screw? The speed bleeders are all 10MM threading with pitch options of 1.0, 1.25, and 1.5. Which is the proper one?
2) Secondly there is also choice of hex size on the body of the bleeder body. What is the OEM size?

.
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Alan Dibley
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Username: alsdibley

Post Number: 123
Registered: 10-2009
Posted on Saturday, 03 February, 2018 - 07:06 pm:   Edit PostDelete PostView Post/Check IP

3/8 x 24UNF and 7/16 A/F respectively. So no metric stuff then.

Alan D.
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Christian S. Hansen
Grand Master
Username: enquiring_mind

Post Number: 699
Registered: 4-2015
Posted on Saturday, 03 February, 2018 - 08:58 pm:   Edit PostDelete PostView Post/Check IP

Alan...
Thanks. Checking further I see that they offer the bleeder in 3/8x24 so will go there. This is a first for me as I am more familiar with EPW and pre-war. How may bleed ports are on the early Shadows? I figure six (?) caliphers but what else? Must be one somewhere in the MC circuit and two more for the rear shocks? Any more?

.
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Patrick Lockyer.
Grand Master
Username: pat_lockyer

Post Number: 1750
Registered: 9-2004
Posted on Saturday, 03 February, 2018 - 09:55 pm:   Edit PostDelete PostView Post/Check IP

Ah common misconception, Once bleed screw is slackened with a master cylinder system, on its return stroke air is drawn back into the system via the threads of the nipple.

Do the low pressure job with a pressure system with the original master cylinder type used as RR intended.
They would have used the larger master cylinder if the design needed it.

As for the other eight bleeders being high pressure they can be bled via the sphere pressure with the foot pedal held down.
same with the two ram bleeders with a weight in the boot.
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Mark Aldridge
Grand Master
Username: mark_aldridge

Post Number: 499
Registered: 10-2008
Posted on Sunday, 04 February, 2018 - 02:47 am:   Edit PostDelete PostView Post/Check IP

A smear of silicon grease around the thread cures the air leakage when bleeding, and improves the performance of a vacuum bleed pump.
Mark
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Patrick Lockyer.
Grand Master
Username: pat_lockyer

Post Number: 1751
Registered: 9-2004
Posted on Sunday, 04 February, 2018 - 03:21 am:   Edit PostDelete PostView Post/Check IP

Mark Sorry did not make it clear, the bleeders I was inferring to were the speed bleeders, they have a type of sealant around the thread, with the slackening off and on and with air returning with the thread debris from the sealant going into the system.
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Christian S. Hansen
Grand Master
Username: enquiring_mind

Post Number: 700
Registered: 4-2015
Posted on Sunday, 04 February, 2018 - 06:12 am:   Edit PostDelete PostView Post/Check IP

Patrick...
Sorry. Your replies are obscure, although I gather that you either disapprove of the speed bleeders or feel that they are not necessary. Same for the 3/4" MC? You imply that there are 11 bleeders total?

.
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Geoff Wootton
Grand Master
Username: dounraey

Post Number: 1896
Registered: 5-2012
Posted on Sunday, 04 February, 2018 - 06:53 am:   Edit PostDelete PostView Post/Check IP

Christian

I have speed bleeders on the rear calipers for the low pressure M/C circuit. As I recall I bought them from Autozone. I think they are great. One man job, just pump the brake pedal carefully and keep an eye on the brake fluid level in the reservoir.

I've also fitted the 3/4" M/C and much prefer the pedal "feel" and ease of bleeding the brakes. This was recommended by Paul and I'm glad I took his advice.

My worry about pressurizing the reservoir for bleeding the M/C circuit is if you spring a leak, then you're spraying your car with brake fluid. I know the thing is to make sure all is sealed properly, but knowing my luck .
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Patrick Lockyer.
Grand Master
Username: pat_lockyer

Post Number: 1752
Registered: 9-2004
Posted on Sunday, 04 February, 2018 - 08:13 am:   Edit PostDelete PostView Post/Check IP

If one is worried about a 8lb leak, the only leak would be the sight glass if at all. [cover with cloth and remove for level check]
Unless of course the reservoir was over filled with a ropy gasket.
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Christian S. Hansen
Grand Master
Username: enquiring_mind

Post Number: 716
Registered: 4-2015
Posted on Sunday, 18 February, 2018 - 04:03 pm:   Edit PostDelete PostView Post/Check IP

On Feb 3 Larry replied that the entire system capacity is 2.5 liters.

My question: What percentage of that total is contained in the two reservoirs and what percentage is contained elsewhere in the system?

The reason for this question: At the moment I have absolutely no proper facilities to do a complete flush and bleed and wonder the merits of simply opening the reservoirs, cleaning them, and replacing the reservoir fluid only. If the percentage is 50/50 then over time the new fluid will mix with the old fluid and will be at least half replaced. If repeated, then the fluid mixture becomes 75% replaced, and if repeated again, becomes 87.5% replaced. Any merit here other than to save the effort of bleeding eleven ports?

.
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gordon le feuvre
Prolific User
Username: triumph

Post Number: 232
Registered: 7-2012
Posted on Sunday, 18 February, 2018 - 07:44 pm:   Edit PostDelete PostView Post/Check IP

My guess based on 50 years Shadow experience is at least 75% of system capacity will be in reservoir WIth BOTH SYSTEMS DEPRESSURISED and remembering that the better the pads, the more the calpiper pistons are pushed back reducing the amount of fluid in them and more in reservoir. Don’t forget to bounce/work rear suspension as well to exhaust any residual pressure in rams.. The correct way is to bleed full system, but it is (and always was) a pain. Never found easy way!
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Alan Dibley
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Username: alsdibley

Post Number: 125
Registered: 10-2009
Posted on Sunday, 18 February, 2018 - 08:14 pm:   Edit PostDelete PostView Post/Check IP

(SBH10630) The origin of this thread was a question about the master cylinder. I replaced the master cylinder with a rubber buffer similar to the factory modification item (like many other folk). Piping the large rear pistons into the G-valve circuit and switching the small ones to the other circuit took a few hours work. This followed two terrifying moments of "foot to the floor". That was ten (??) years ago. and I don't have to bleed that d****d master cylinder circuit any more.

I recommend it to everyone.

Alan D.
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Geoff Wootton
Grand Master
Username: dounraey

Post Number: 1902
Registered: 5-2012
Posted on Monday, 19 February, 2018 - 12:54 am:   Edit PostDelete PostView Post/Check IP

The problem with only replacing the fluid in the reservoir is the lines down to the calipers are dead ends. This means the fluid here is not re-circulated. This is also the part of the system where you need fresh fluid as this is where vaporization of any water in the brake fluid will take place, because of the heat generated by the calipers.

I understand Christian's problem of not currently having the facilities to work on his cars, however I think to just undo the bleed screws and bleed off the old fluid is a job that can be done on a driveway (in summer of course )
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Christian S. Hansen
Grand Master
Username: enquiring_mind

Post Number: 718
Registered: 4-2015
Posted on Monday, 19 February, 2018 - 02:35 pm:   Edit PostDelete PostView Post/Check IP

Geoff...
Thanks for making that point which makes perfect sense. While the MPW is up on the rack while ACME does the master cylinder for me, I will observe where the bleed ports are and have Mark crack the bleed screws to be sure that they are not frozen in. I will acquire the necessary speed bleeders and then down the road when I have the facilities to get under the car, I presume that it will be relatively straight forward to substitute the speed bleeders during which operation whatever air gets into the calliper will (presumably) be relatively limited and can be easily purged along with an additional few ounces to be sure that new fluid has found its way into the calliper lines. Is this plan expecting too much?

.
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Patrick Lockyer.
Grand Master
Username: pat_lockyer

Post Number: 1766
Registered: 9-2004
Posted on Monday, 19 February, 2018 - 07:50 pm:   Edit PostDelete PostView Post/Check IP

"I presume that it will be relatively straight forward to substitute the speed bleeders during which operation whatever air gets into the calliper will (presumably) be relatively limited and can be easily purged along with an additional few ounces to be sure that new fluid has found its way into the calliper lines. Is this plan expecting too much?"

Be carful you do not trigger and jam the brake pressure limiting valve when doing the main pressure system.
Running on 95% front brakes 5% rear would not be fun.
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Christian S. Hansen
Grand Master
Username: enquiring_mind

Post Number: 724
Registered: 4-2015
Posted on Thursday, 22 February, 2018 - 01:29 pm:   Edit PostDelete PostView Post/Check IP

Re: 1968 MPW Coupe CRX2541
Had the master cylinder replaced, reservoir cleaned, eight calipher lines flushed, topped up with RR363, and bled. The resultant pedal feel is rather odd.

Would anyone care to characterize how their pedal feels on their master cylinder equipped Shadow?

All other cars that I have ever had that have had conventional hydraulic brakes have had a very "progressive" feel to the pedal...that is, the harder you progressively press on the pedal, the more braking results.

The "new" pedal is anything but that. The pedal has about 1/2 travel to the floor of free play and then it becomes very stiff. I have attached a graph of the "feel". "Progressive" is a bit like pressing on a piece of foam rubber. Imagine holding your finger 1/2" above the foam rubber. As you press down, the first 1/2" is free play before there is any braking feel or results. As you continue to press down, there is a progressive feeling such that the harder you press, the more the foam compresses, and the more braking results.

The "new" pedal feel is a bit like pressing on a piece of wood. Imagine the same scenario with your finger 1/2" above the wood. The first 1/2" is free play and then the feel becomes very firm as you contact the wood. As you continue to apply increasing pressure, the wood does not compress, but you do get increased braking. Am I articulating this effectively? I really don't like it. Any comments?

Brake Pedal Feel Graphed

.
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Alan Dibley
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Username: alsdibley

Post Number: 127
Registered: 10-2009
Posted on Thursday, 22 February, 2018 - 07:12 pm:   Edit PostDelete PostView Post/Check IP

Christian, both (A) and (B) suggest that there may be too much free movement in the pedal mecxhanism - nothing to do with the hydraulics, it needs a screw adjustment in the rat-trap to to reduce free motion.

(B) looks like air in the master-cylinder circuit. As evereyone says, it is very difficult to bleed this circuit, and even then it may get air in it later at the least excuse. That is why it is best to emulate R-R themselves and remove the master cylinder, as on later cars.

Alan D.
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Patrick Lockyer.
Grand Master
Username: pat_lockyer

Post Number: 1774
Registered: 9-2004
Posted on Thursday, 22 February, 2018 - 07:46 pm:   Edit PostDelete PostView Post/Check IP

Is all the above with the brake hydraulics and spheres up to pressure under application?

And with the original type master cylinder set clearance and bled correctly.
Preferably bleed with a continuous eight pounds pressure within the brake reservoir, starting with the n/s rear bled first.

My car with pedal application, first you feel the clearance then the pedal feel as the master cylinder applies and activates the brake distribution valves.

If not happy with the brakes check car on a roller brake tester if it has not already been done.
If not happy bleed the high pressure system again etc..
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Martin Taylor
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Username: martin_taylor

Post Number: 122
Registered: 7-2013
Posted on Friday, 23 February, 2018 - 05:27 am:   Edit PostDelete PostView Post/Check IP

Classic air in the MC circuit, your master cylinder is doing very little and the stop you feel is the steel/rubber end stop then the lever gives you high pressure brakes.
Put vacuum on the circuit and pull half a litre or so through, you will most likely see air bubbles after a fair amount of fluid.
Vacuum only, do not press the pedal.
If you open the rat trap you will see the lever hitting the stop which it shouldn’t.
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Patrick Lockyer.
Grand Master
Username: pat_lockyer

Post Number: 1777
Registered: 9-2004
Posted on Friday, 23 February, 2018 - 07:56 am:   Edit PostDelete PostView Post/Check IP

"you will most likely see air bubbles"

Yes and always from the bleed screw threads when under suction vacuum regardless of any air in the L/P circuit.
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Christian S. Hansen
Grand Master
Username: enquiring_mind

Post Number: 727
Registered: 4-2015
Posted on Friday, 23 February, 2018 - 02:49 pm:   Edit PostDelete PostView Post/Check IP

Alan...
I can appreciate that you are not a fan of the "feel cylinder" (aka master cylinder) arrangement on the earlier Shadows, the purpose of which was to "simulate" the typical progressive "pedal feel" of ordinary hydraulic brake systems. Just what is the alternative that you are preferring, how does it work, and can you articulate a description of the pedal feel that results? Thanks.

.
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Paul Yorke
Grand Master
Username: paul_yorke

Post Number: 2013
Registered: 6-2006
Posted on Friday, 23 February, 2018 - 07:02 pm:   Edit PostDelete PostView Post/Check IP

Hi Christian. Describing the brake travel is very tricky as you say.

If in your first question you are saying the pedal goes 1/2 way to the floor with the car standing still.

And that there is 1/2" of travel whilst the vehicle is moving.

I would say that it sounds good.

Pedal feel whilst the car is not moving is irrelevant on all RR up until the Seraph.
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Christian S. Hansen
Grand Master
Username: enquiring_mind

Post Number: 728
Registered: 4-2015
Posted on Friday, 23 February, 2018 - 07:51 pm:   Edit PostDelete PostView Post/Check IP

Paul...
No. You misunderstood. Probably my use of the term "1/2" in two different contexts was confusing.

The context of the pedal feel was that the pedal goes 1/2 (half way) to the floor before there is any resistance to the pedal feel and at that point, any additional pressure results in no further movement downwards of the pedal and from that point resembles pushing on a piece of wood in terms of movement, although increased pressure, if not manifested in pedal movement, does seem to result it additional braking pressure for purposes of stopping forward movement of the vehicle. However, I did not do any panic stops in testing the pedal feel as it was the "feel" rather than the "effect" with which I took issue.

The other context within which I used the term "1/2" was entirely theoretical in an attempt to articulate the nature of the pedal feel as being non-progressive (like pressing on wood) rather than progressive (like pressing on foam rubber). In this case, the 1/2" (one half inch) was simply an interpretation of free play for purposes of the graph whereas in reality, the free play (distance before any effect or resistance is felt) was 1/2 (halfway) to the floor.

.
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Patrick Lockyer.
Grand Master
Username: pat_lockyer

Post Number: 1780
Registered: 9-2004
Posted on Friday, 23 February, 2018 - 10:19 pm:   Edit PostDelete PostView Post/Check IP

Done a check on the pedal movement on the SS1 and the SS2.
First with the engine running and the systems up to pressure.

The pedal movement until the brakes started on the SS2 was 16mm.

On the SS1 with the master cylinder circuit a reading of 24mm before the systems kicked in.

This is with all callipers and pads free with new hoses on the SS1.
What does the book say or others that have good brakes?
Both cars seem to stop on a sixpence if needed.
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Paul Yorke
Grand Master
Username: paul_yorke

Post Number: 2014
Registered: 6-2006
Posted on Friday, 23 February, 2018 - 11:21 pm:   Edit PostDelete PostView Post/Check IP

All clear now Christian. LOL

Ok in that case the master cylinder needs rebleeding. Paying attention to my tip of clamping the opposite side flex hoses whilst bleeding ....and then swap.

or/and

Check that there is the correct free play on the threaded master cylinder rod.
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Patrick Lockyer.
Grand Master
Username: pat_lockyer

Post Number: 1781
Registered: 9-2004
Posted on Saturday, 24 February, 2018 - 12:07 am:   Edit PostDelete PostView Post/Check IP

If bleeding the low circuit with the use of the master cylinder make sure the high pressure system is fully de pressurised.
Free play on the m/c push rod must not be less than 0.4mm.
IMO far the easiest way is to pressure bleed the M/C circuit.
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Martin Taylor
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Username: martin_taylor

Post Number: 123
Registered: 7-2013
Posted on Saturday, 24 February, 2018 - 07:28 am:   Edit PostDelete PostView Post/Check IP

Pull the bleeder out and apply thread tape if you get air from it under vacuum, Patrick, the high pressure circuits make no difference when bleeding the low pressure circuits, why would you need to deplete pressure?
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Martin Taylor
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Username: martin_taylor

Post Number: 124
Registered: 7-2013
Posted on Saturday, 24 February, 2018 - 07:36 am:   Edit PostDelete PostView Post/Check IP

The other thing to consider is the rubber stop block can limit the master cylinder reaching the end of travel hence making it much harder to bleed (with the pumping method).
I use an old fridge compressor pulling on a plastic bottle, this will apply up to 30inches of vacuum, a long clear hose to see what’s going on and life is easy.
When bleeding high pressure circuits I have a very long piece of tubing, I wait until new fluid comes out then simply poke the end back into the reservoir and leave my foot on the brake for a minute or so with the engine running.
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Christian S. Hansen
Grand Master
Username: enquiring_mind

Post Number: 730
Registered: 4-2015
Posted on Saturday, 24 February, 2018 - 02:21 pm:   Edit PostDelete PostView Post/Check IP

Patrick...
When you refer to "free play on the M/C pushrod must not be less than .4mm" which free play are you referring to? At point #1 in the very first diagram of Geoff's "How to set up master cylinder" thread

http://au.rrforums.net/forum/messages/17001/29128.html?1508409271

or the clearance at #3? If at #1, how is that free play measured and adjusted?

P.S. I don't know why the above link is not active, but if you scan upwards towards the beginning of this thread, it IS active in a post from Geoff Wootton.

.
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Christian S. Hansen
Grand Master
Username: enquiring_mind

Post Number: 732
Registered: 4-2015
Posted on Saturday, 24 February, 2018 - 03:51 pm:   Edit PostDelete PostView Post/Check IP

P.S. Here is the referenced link and diagram:

http://au.rrforums.net/forum/messages/17001/29128.html?1508409271

MC Setup

.
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Patrick Lockyer.
Grand Master
Username: pat_lockyer

Post Number: 1782
Registered: 9-2004
Posted on Saturday, 24 February, 2018 - 06:12 pm:   Edit PostDelete PostView Post/Check IP

The minimum 4mm clearance is required for the swivel action needed for angle variation of the working push rod.
This is set by the manufacturer but needs to be reset when another push rod or another master cylinder is used, some m/c are supplied with out the push rod.
To obtain the correct clearance, this I did years ago, we had different size shim washers to obtain the clearance.

With no swivel clearance the piston and seal would not travel freely through its travel within the bore.
Once set up if needed then the next clearance of the assembly can be set.
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Alan Dibley
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Username: alsdibley

Post Number: 128
Registered: 10-2009
Posted on Saturday, 24 February, 2018 - 08:22 pm:   Edit PostDelete PostView Post/Check IP

Alan...
I can appreciate that you are not a fan of the "feel cylinder"

Christian, I like(d) the feel of the master cylinder system, except on the two occasions when the pedal went to floor (or so it felt). The first was after I had owned the car for a couple of years, the second was months after I had replaced the M/C with a new expensive "factory" part. The second time was near the bottom of a long downhill stretch which was really enjoyable. Until....

The feel of the brakes after the mod, is like the pedal on a hydraulic/pneumatic Citroen. I have had over a dozen BX and CX Cits and the brakes feel superb after you are used to the firm touch. The rubber buffer which replaces the m/c needs to have about the same squidginess as a well-set-up m/c. Then the feel is beautiful. And the master cylinder NEVER goes to the floor. And I never have to bleed it.

The later set-up is described in the manuals. Later Shadows and all(??) Spirits were fitted with the "no m/c" system, and I think there was a retrofit kit or instructions. I did it with the bits I had in the workshop. The plumbing is straightforward but a bit fiddly. The manufacture of a replacement buffer was trial-and-error.

Alan D.
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Patrick Lockyer.
Grand Master
Username: pat_lockyer

Post Number: 1783
Registered: 9-2004
Posted on Saturday, 24 February, 2018 - 09:13 pm:   Edit PostDelete PostView Post/Check IP

"With no swivel clearance the piston and seal would not travel freely through its travel within the bore."

But not with this type of M/Cylinder.
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Christian S. Hansen
Grand Master
Username: enquiring_mind

Post Number: 733
Registered: 4-2015
Posted on Saturday, 24 February, 2018 - 09:40 pm:   Edit PostDelete PostView Post/Check IP

Patrick...
Thanks for clarifying. I was going to call BS on the idea given that the MC rod connects to the MC with an articulating swivel socket joint.

Also, why would you set the clearance with shim washers given that there are two adjustments (#2 on stop, and #3 off stop) each with lock nuts? You must be think of something else non-applicable to the instant circumstances?

.
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Maxwell Heazlewood
Prolific User
Username: tasbent

Post Number: 152
Registered: 9-2017
Posted on Saturday, 24 February, 2018 - 09:57 pm:   Edit PostDelete PostView Post/Check IP

Ah....Crewe, the masters of complicated systems for a simple solution
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Patrick Lockyer.
Grand Master
Username: pat_lockyer

Post Number: 1784
Registered: 9-2004
Posted on Sunday, 25 February, 2018 - 03:44 am:   Edit PostDelete PostView Post/Check IP

Also, why would you set the clearance with shim washers given that there are two adjustments (#2 on stop, and #3 off stop) each with lock nuts?

So the swivel joint has 0.13 to 0.25mm clearance for movement for the angle change of the rod.
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Patrick Lockyer.
Grand Master
Username: pat_lockyer

Post Number: 1785
Registered: 9-2004
Posted on Sunday, 25 February, 2018 - 03:58 am:   Edit PostDelete PostView Post/Check IP

Alan, Maxwell yes the Citroen set up was far more simple, never had any brake bad failures in years of CX etc motoring.
A few pump belts but one quiet running pump!



Alan I agree the SS2 is a far better system with the pedal feel.
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Paul Yorke
Grand Master
Username: paul_yorke

Post Number: 2015
Registered: 6-2006
Posted on Monday, 26 February, 2018 - 07:54 pm:   Edit PostDelete PostView Post/Check IP

Don't confuse brake failure with brake feel failure.

If the master cylinder goes you will still have brakes. Plenty.

As long as the stop is in place.

The trouble is that faced with a floppy pedal people try and pump it back up.

Just hold the pedal down and keep pressing.

Back to the stop. Early cars had a metalastic stop. These give a better feel if the master cylinder circuit fails BUT they do deteriorate and fall apart allowing the centre (most important part) to slide back between the rubbers. This gives too much travel.

You can replace it with a new one. Replace it with a solid block of metal (like the later cars) or pull the centre layer back out and drill through the whole block and make it solid with nuts and bolts.

You can remove the block to aid bleeding but the clamped hoses method is easier.

Have fun.
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Patrick Lockyer.
Grand Master
Username: pat_lockyer

Post Number: 1790
Registered: 9-2004
Posted on Tuesday, 27 February, 2018 - 02:40 am:   Edit PostDelete PostView Post/Check IP

Paul, does the brake failure [pedal to the floor] present its self when front rear calipers seize boiling old 363 fluid.
This would be on the later SS2 system.

BTW never happened with Citroen running LHM.
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Patrick Lockyer.
Grand Master
Username: pat_lockyer

Post Number: 1802
Registered: 9-2004
Posted on Saturday, 10 March, 2018 - 08:06 am:   Edit PostDelete PostView Post/Check IP

To answer the above:
But of course the RR363 DOT brake fluid is hygroscopic.

DOT 5 [Citroen, later RR etc LHM] is hydrophobic and does not absorb water from the atmosphere like regular DOT brake fluid will.
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Paul Yorke
Grand Master
Username: paul_yorke

Post Number: 2023
Registered: 6-2006
Posted on Saturday, 10 March, 2018 - 10:12 am:   Edit PostDelete PostView Post/Check IP

Patrick. Sorry, I typed out a long answer at the time.

Yes the brakes will loose efficiency and end up with a long delay if fluid boils o a calliper.

As mentioned . .hold the pedal down. Drop down a gear which not only provides engine braking but also revs the engine faster replenishing the accumulators and compressing the water vapour in the calliper being the brakes on. s.


"DOT 5 [Citroen, later RR etc LHM]" These are different fluids to each other.
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Patrick Lockyer.
Grand Master
Username: pat_lockyer

Post Number: 1803
Registered: 9-2004
Posted on Saturday, 10 March, 2018 - 06:25 pm:   Edit PostDelete PostView Post/Check IP

Yes Paul thanks for my mistake as I should have said "mineral oil" LHM fluid.
DOT 5 being silicone fluid.

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