911uk

GT3 master cylinder on to a C4

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4 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis

THIS DISCUSSION / SOURCE-DERIVED OVERVIEW

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YOUR RESEARCHGT3 master cylinder on to a C4

Leading reported evidence

Replace state around a certain pressure

Suggestion or failed attempt

No successful repair reported for this finding.

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Reported fixes: 0
Unsuccessful attempts: 1
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Suggestion
I think that the potential problem is that there is a brake switch which is read by a control unit, this control unit expects to see the switch change state around a certain pressure.
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GT3 master cylinder on to a C4

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Leading evidence: 'Replace state around a certain pressure' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Replace state around a certain pressure' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.

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1 matching discussions · 4 captured posts examined · 0 partial discussions

Frequently discussed actions (1)

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Replace state around a certain pressure

No successful repair reported for this finding.

0
Reported fixes: 0
Unsuccessful attempts: 1
Discussions

Read evidence and context

Discussions that contain suggestions: 1

0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.

0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.

Suggestion
I think that the potential problem is that there is a brake switch which is read by a control unit, this control unit expects to see the switch change state around a certain pressure.
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GT3 master cylinder on to a C4

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Counts describe captured discussions, not unique people or a diagnosis. Author identities are not reliably stored. Exact duplicate evidence is counted once across matching discussions; one discussion counts at most once per action/state. Multiple repairs reported together remain a combination. Suggestions and failed attempts do not establish a fix. Matches cover whole discussions and can include related faults, model variants and incomplete threads.

4 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.

911uk: 1 discussions

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Generation: 20261026T161109Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources

POST 1 / ORIGINAL POSTEROriginal post

Is it possible to do this, I've read a few posts saying that if your car has PSM then the larger master cylinder creates more pressure and this trigger a pressure sensor some where causing PSM issues. I'm currently doing a brake fluid change and just remember reading about people upgrading the master cylinder. If it's likely to cause problems I'm happy to leave well alone.

POST 2Original post

I think that the potential problem is that there is a brake switch which is read by a control unit, this control unit expects to see the switch change state around a certain pressure. By changing the MC the relationship between the pressure and the switch state changes and this can mean that the switch position needs tweaking. I'm not 100% sure on the details of this, so treat this info more as a starting point for investigation than hard and fast information. MC

POST 3 / ORIGINAL POSTEROriginal post

Thats good enough for me, I'll just leave as is as there nothing wrong with what's there. Cheers

POST 4Original post

I'm thinking of doing this mod to see if it improves pedal feel- I have no PSM to upset though.

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