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John Beech
Prolific User
Username: jbeech

Post Number: 151
Registered: 10-2016
Posted on Tuesday, 03 January, 2017 - 03:32 pm:   Edit PostDelete PostView Post/Check IP

$50 - is this the one? http://tinyurl.com/h8z7bfr

Is this the master cylinder for an early Silver Shadow
- Is this the master cylinder for an early Silver Shadow?
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gordon le feuvre
Prolific User
Username: triumph

Post Number: 147
Registered: 7-2012
Posted on Tuesday, 03 January, 2017 - 06:59 pm:   Edit PostDelete PostView Post/Check IP

Pretty certain it is, as I was always going to experiment with bigger diameter to reduce brake pedal travel-but never did.
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Paul Yorke
Grand Master
Username: paul_yorke

Post Number: 1708
Registered: 6-2006
Posted on Tuesday, 03 January, 2017 - 07:02 pm:   Edit PostDelete PostView Post/Check IP

Yes, but I'd suggest going for the slightly larger bore Land-Rover one.

Like this but I have no idea what this one's quality is like.

Better feel & easier bleed IMO

https://goo.gl/VoMYWG
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Paul Yorke
Grand Master
Username: paul_yorke

Post Number: 1709
Registered: 6-2006
Posted on Tuesday, 03 January, 2017 - 07:04 pm:   Edit PostDelete PostView Post/Check IP

Morning Gordon . . .. . Yes, It makes for a better feel, I've been fitting them for (I don't even want to think how many years!! lol) a long while.
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John Beech
Prolific User
Username: jbeech

Post Number: 152
Registered: 10-2016
Posted on Wednesday, 04 January, 2017 - 02:19 am:   Edit PostDelete PostView Post/Check IP

Thanks for the tip, Paul. I've placed an order for the 3/4" bore version instead of the 5/8" master cylinder. And with some savings eBay is running, delivered costs is going to be $31.79 - such a deal!
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Robert Noel Reddington
Grand Master
Username: bob_uk

Post Number: 1247
Registered: 5-2015
Posted on Wednesday, 04 January, 2017 - 07:12 am:   Edit PostDelete PostView Post/Check IP

i never thought of increasing master cylinder bore size to attenuate pedal travel.


I find it strange that some insist that only genuine brake pads should be used yet are happy to alter something so fundamental as master cylinder which WILL alter the front to back brake balance.

A bigger cylinder will reduce the braking effort of the master cylinder side of the rear brakes.

The master cylinder DOES contribute to the braking effort of the brakes and is not just for feel. I have read 21%.
However from experience of lots of brakes 5/8 to 3/4 and the car will still stop ok, because the driver will unknowingly just press the pedal a bit harder, but fast stops will cause the G valve to restrict the rear high pressure side of the rear brakes so in emergency situations I suspect no difference.

In the workshop manual is the description of a method of using the master cylinder to operate the ACV warning switches, meaning that the master develops enough pressure to work those switches. The master contributes more braking effort than some seem to think. Once the G valve has cut in then the only extra braking effort at the rear available is the master cylinder.
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David Gore
Moderator
Username: david_gore

Post Number: 2372
Registered: 4-2003
Posted on Wednesday, 04 January, 2017 - 08:42 am:   Edit PostDelete PostView Post/Check IP

It is my understanding the OEM Shadow 1 master cylinder was originally fitted to the ubiquitous Morris Minor 1000 - thank heavens the Morris Minor system was not fitted in its entirety .

The bore size was inconsequential as the full braking effort was provided by the high pressure hydraulic system and the longer pedal travel associated with the small bore master cylinder presumably was to reduce the probability of unnecessary heavy braking and associated discomfort by unwary/inexperienced drivers.
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Mark Aldridge
Grand Master
Username: mark_aldridge

Post Number: 383
Registered: 10-2008
Posted on Wednesday, 04 January, 2017 - 09:08 am:   Edit PostDelete PostView Post/Check IP

Interesting David, the Minor master cyl is a totally different design to the Landrover type, including the position of the mounting bolts. I wonder when the design changed on the Shadow. We are about to replace the master cyl on James 1970 Shadow and will probably fit the Landrover part. (34 Delphi)Mark
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Patrick Lockyer.
Grand Master
Username: pat_lockyer

Post Number: 1073
Registered: 9-2004
Posted on Wednesday, 04 January, 2017 - 05:16 pm:   Edit PostDelete PostView Post/Check IP

The master cylinder was used was more for primary pedal feel than for braking effect, the Citroen used a sprung rubber type of pad.
RR use it as 3rd type of footbrake backup within the braking system.
later cars did away with it.
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gordon le feuvre
Prolific User
Username: triumph

Post Number: 149
Registered: 7-2012
Posted on Wednesday, 04 January, 2017 - 07:30 pm:   Edit PostDelete PostView Post/Check IP

I can remember carrying out totally unscientific test on an early car fitted with master cylinder by stopping on hill, de-pressurizing h.p. circuits and then letting car roll down hill to see if I could stop it on m/cylinder circuit only. It would not, even at 10-15 mph. We had hours and hours of problems with pedal feel/travel. Cars that sit about and get surface rusting on discs are worse. Cars driven on motorways always have better feeling pedal. This was recognised by Factory, there are loads of Service Bulletins regarding pedal feel/action. So as Paul Yorke says, if the L/Rover cylinder works-fit it. Lots of owners complained that changing from another car they owned to the R-R, the pedal travel was too long, spent hours trying to bleed to improve etc and recheck all linkage settings in "rat trap".
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Geoff Wootton
Grand Master
Username: dounraey

Post Number: 1543
Registered: 5-2012
Posted on Thursday, 05 January, 2017 - 12:20 am:   Edit PostDelete PostView Post/Check IP

Gordon

I have often wondered whether these cars could be pulled up by the master cylinder alone. So now we know. I have to say I am not surprised, given these cars weigh over 2 tons.

Geoff
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Brian Vogel
Grand Master
Username: guyslp

Post Number: 2184
Registered: 6-2009
Posted on Thursday, 05 January, 2017 - 01:23 am:   Edit PostDelete PostView Post/Check IP

It always struck me that the master cylinder could not have had much of any effect on braking, or it could not have been deleted from the system with the rest of the system remaining almost identical.

Neither of my cars have one, obviously. I've also never felt that the pedal feel on the SY era Rolls-Royce cars I've driven is anything but vaguely similar to more conventional braking systems. It's much lighter pressure and the resistance doesn't increase in the same way even as it does increase. This may, of course, be the result of the two-series cars using a spring for pedal feel.

The cars stop, and stop well, so I don't give a flying rat's ass about pedal feel since I know that's how the pedal feels.

Not that I'd ever want to experience it, but I imagine there's not a huge difference in how the pedal feel would be if one somehow managed to exhaust the accumulators. When doing the brake pedal pump test it does get a bit lighter, but not by terribly much. It's certainly unlike the "pedal travels to the floor without any resistance" feeling one gets in a conventional system when the master cylinder begins to malfunction.

Brian
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Paul Yorke
Grand Master
Username: paul_yorke

Post Number: 1710
Registered: 6-2006
Posted on Thursday, 05 January, 2017 - 02:34 am:   Edit PostDelete PostView Post/Check IP

A master cylinder was necessary on the old 4s peed boxes.
.
Park was reverse without the engine running.

To start the car neutral had to be selected and obviously park is disengaged.

Imagine leaving your car standing for a few weeks and jumping into your Spirit or non master cylinder Shadow and disengaging park before starting the engine?
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Patrick Lockyer.
Grand Master
Username: pat_lockyer

Post Number: 1074
Registered: 9-2004
Posted on Thursday, 05 January, 2017 - 03:31 am:   Edit PostDelete PostView Post/Check IP

I thought the engine had to be started then foot brake applied with the handbrake always ON till ready to proceed.

Tip with the OE master cylinder bleeding, have blocks under the front wheels of the car raising a few ft.
This will make life easy with the removal of air in the system.
Keep an eye on the fluid level when bleeding.
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gordon le feuvre
Prolific User
Username: triumph

Post Number: 150
Registered: 7-2012
Posted on Thursday, 05 January, 2017 - 06:28 am:   Edit PostDelete PostView Post/Check IP

I attended an early -Feb 1967 2 week course on Shadow range at Hythe Rd in London. Can remember someone (Dennis Robinson) telling me that before a master cylinder system was fitted, a pre-production car had a tennis ball under the pedal to give some kind of conventional feel to pedal as R-R did not like the Citroen "ball" as fitted on Ds/Id models that was so on/off.
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David Gore
Moderator
Username: david_gore

Post Number: 2374
Registered: 4-2003
Posted on Thursday, 05 January, 2017 - 06:44 am:   Edit PostDelete PostView Post/Check IP

Gordon,

The tennis ball modification is mentioned in one of the books on the Silver Shadow.

I am away from my library at the moment so cannot check which book it is.

Someone may be able to post the details if they recall which book.

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