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michael vass
Prolific User
Username: mikebentleyturbo2

Post Number: 159
Registered: 7-2015
Posted on Sunday, 08 May, 2016 - 04:53:   Edit PostDelete PostView Post/Check IP

Hi All
Removed the rear pads on my car today , just for a check and clean up, found the back of the pads seeming to show the bottom pistons (inner and outer) working harder than the top 2? is this normal or is there an imbalance or other fault?
See attached picture.
Thanks in advance
Ps
I have looked at the diagram and even more confused there seems a joint between both systems but only 1 goes through the G valve? (I've circled the joint. So this means the rear brakes work off 1 system only? not dual syatem?
Thanks
Mike
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David Gore
Moderator
Username: david_gore

Post Number: 2034
Registered: 4-2003
Posted on Sunday, 08 May, 2016 - 07:10:   Edit PostDelete PostView Post/Check IP

Michael,

On DRH14434, the "G" valve was mounted at the back of the low pressure master cylinder and only functioned on the low pressure circuit.

When the master cylinder was deleted on later cars, I would have expected R-R to adopt a dual circuit system in common with other vehicles. If your diagram is correct, it appears the rear brakes are on a single circuit which splits into 2 with the "G" valve protecting one circuit and not the other.

I may be reading the diagram incorrectly and will defer to anyone with more knowledge than I.

P.S. Have deleted the duplicate thread as requested.
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Patrick Lockyer.
Grand Master
Username: pat_lockyer

Post Number: 994
Registered: 9-2004
Posted on Sunday, 08 May, 2016 - 07:54:   Edit PostDelete PostView Post/Check IP

Maybe just a simple brake hose failing!
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michael vass
Prolific User
Username: mikebentleyturbo2

Post Number: 162
Registered: 7-2015
Posted on Sunday, 08 May, 2016 - 08:03:   Edit PostDelete PostView Post/Check IP

Thanks both, I don't understand how you can get equal pressure to all the pistons if you restrict the pressure to some and not others? .or I am reading it wrong ?
Thanks
Mike
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Patrick Lockyer.
Grand Master
Username: pat_lockyer

Post Number: 995
Registered: 9-2004
Posted on Sunday, 08 May, 2016 - 15:57:   Edit PostDelete PostView Post/Check IP

Drag trailing and leading part of the pad with doggy hose.
Maybe confirmed by position and side of fitment of pad.

LHM can still cause sticking caliper pistons if not changed after time.
Also hose failings, Citroen avoided hoses in most LHM etc use.
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Paul Yorke
Grand Master
Username: paul_yorke

Post Number: 1521
Registered: 6-2006
Posted on Sunday, 08 May, 2016 - 17:22:   Edit PostDelete PostView Post/Check IP

Are the pads tapered and thinner at the 'extra pressure' end?

99% of the time the g valve will not affect braking.

It only comes into play braking down steeper hills and in emergency stops.
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michael vass
Prolific User
Username: mikebentleyturbo2

Post Number: 163
Registered: 7-2015
Posted on Sunday, 08 May, 2016 - 19:11:   Edit PostDelete PostView Post/Check IP

Hi Paul
At the moment they are not tapered, forgot to mention this is a new caliper.
Why do I need a G valve with ABS?
Thanks
Mike
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gordon le feuvre
Prolific User
Username: triumph

Post Number: 112
Registered: 7-2012
Posted on Thursday, 12 May, 2016 - 19:50:   Edit PostDelete PostView Post/Check IP

The manual states that "g" valve in in second circuit "to maintain optimum braking" even as stated car has abs? Does seem to be overkill as the whole point of a "g" valve is to prevent locking/skidding of rear wheels and so does abs!Never seen tapered pads on Spirit, look for anything obvious like sticking piston, air in system, reduced pressure on that circuit?
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michael vass
Prolific User
Username: mikebentleyturbo2

Post Number: 167
Registered: 7-2015
Posted on Friday, 13 May, 2016 - 04:58:   Edit PostDelete PostView Post/Check IP

Hi Gordon
It's a nearly new caliper, I've bled the system , there will be reduced pressure because of that G valve but it seems by design that way.
I'd love to know how that valve maintains optimum braking with ABS? only working on 4 of 8 pistons ,surely if it were that good it should work on all 8?
Thanks
Mike

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