Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[Andy H]

Can't remember, I think yes, but will check. Is this a good or bad sign?

If the pedal sinks when the brakes are applied but you are not losing fluid then that does point to the seals in the master cylinder (so not ideal)

Good servo assistance tends to amplify any sponginess  because you can apply more brake pressure without pressing very hard on the pedal. Try pressing the pedal without the engine running to feel what a rock hard pedal feels like (try it while moving and needing to stop to feel what brown trousers feel like  )

I think Chris is suggesting that you check things that are needed to stop safely but which make the pedal feel harder when they are not right.

I think you should look at flushing all the brake fluid from the system then bleeding the ABS pump and/or replacing the brake flexi hoses if you don't get a result from servicing the master cylinder. It is quite startling how much the hoses can swell during a brake test but people don't give them a second thought.

[Shackeng]

Strange if the hoses are degraded, as the brakes are exactly the the same, slightly spongy, despite the works mentioned, as when I bought it 4 years ago at 48k, and it is now only 57k. I'm inclined to think it is leaking seals somewhere but will check the vac for leaks. My TD which is 2 years older on 126k has rock solid brakes!

[chrisgixer]

Bah. Sorry. Andy making more sense here.

[Shackeng]

Can't remember, I think yes, but will check. Is this a good or bad sign?

If the pedal sinks when the brakes are applied but you are not losing fluid then that does point to the seals in the master cylinder (so not ideal)

Good servo assistance tends to amplify any sponginess  because you can apply more brake pressure without pressing very hard on the pedal. Try pressing the pedal without the engine running to feel what a rock hard pedal feels like (try it while moving and needing to stop to feel what brown trousers feel like  )

I think Chris is suggesting that you check things that are needed to stop safely but which make the pedal feel harder when they are not right.

I think you should look at flushing all the brake fluid from the system then bleeding the ABS pump and/or replacing the brake flexi hoses if you don't get a result from servicing the master cylinder. It is quite startling how much the hoses can swell during a brake test but people don't give them a second thought.

I should have mentioned, I have no worries about stopping, and if I only had the one car would probably not have noticed the difference, it just requires more pressure than the TD, and feels slightly spongy.

[Kevin Wood]

It might be worth bearing in mind that the TD and V6 have very different vacuum sources to power the servo. TD uses a vacuum pump, and V6 the engine maifold vacuum. It's entirely possible that this gives a different level of assistance in the first place.

If you have leaking seals, you should be able to press the pedal, and feel it slowly creep down over time as fluid leaks past the seal. If this doesn't happen, I'd say the seals are probably fine.

The other possibilities (no creeping pedal) are air in the system somewhere or bulging flexible pipes, as has been mentioned.

[Shackeng]

It might be worth bearing in mind that the TD and V6 have very different vacuum sources to power the servo. TD uses a vacuum pump, and V6 the engine maifold vacuum. It's entirely possible that this gives a different level of assistance in the first place.

If you have leaking seals, you should be able to press the pedal, and feel it slowly creep down over time as fluid leaks past the seal. If this doesn't happen, I'd say the seals are probably fine.

The other possibilities (no creeping pedal) are air in the system somewhere or bulging flexible pipes, as has been mentioned.

I assume this is with engine running Kevin?

[Diamond Black Geezer]

Just to add a question (which may help the OP) - are all master cylinders the same/interchangeable? Just wondering if a low mileage 2003 3.2 would bang straight on an L reg 2.0 8v etc... ?

[05omegav6]

Engine off I think... pump pedal until solid, then press and hold. If it softens or sinks further the seals are shot allowing for the two exceptions given above

[deviator]

Just to add a question (which may help the OP) - are all master cylinders the same/interchangeable? Just wondering if a low mileage 2003 3.2 would bang straight on an L reg 2.0 8v etc... ?

I seem to remember the design of them being different and requiring the pipes to be moved/extended.

[Diamond Black Geezer]

Hmmm, ok.  FLs have a brake boost feature, don't they? Something that gives a shorter stopping distance? Or is it just in a larger Servo, perhaps?

[05omegav6]

Just to add a question (which may help the OP) - are all master cylinders the same/interchangeable? Just wondering if a low mileage 2003 3.2 would bang straight on an L reg 2.0 8v etc... ?

I seem to remember the design of them being different and requiring the pipes to be moved/extended.

The differences primarily being whether three or four channel ABS and piston size being different according to both age and application iirc

Haynes gives basic specs and without looking, different for pre, mid and post facelift and also for engine variation... so age and fuel both play a part

[05omegav6]

Hmmm, ok.  FLs have a brake boost feature, don't they? Something that gives a shorter stopping distance? Or is it just in a larger Servo, perhaps?

Two stage master cylinder, but bear in mind my previous post

[Shackeng]

Diagnostic testing:
Engine off pedal is firm.
Start engine with pedal pressed, pedal sinks slowly and applies brakes.
Pump pedal to firm it up, but fails to hold firmly and still sinks.
Braking hard while driving, car stops fine but requires more pressure than I would like.

I think its seals somewhere.

[05omegav6]

Diagnostic testing:
Engine off pedal is firm. Does it stay firm if held down?

Start engine with pedal pressed, pedal sinks slowly and applies brakes. Normal, due to vacuum assistance.

Pump pedal to firm it up, but fails to hold firmly and still sinks. Normal, due to vacuum assistance.

Braking hard while driving, car stops fine but requires more pressure than I would like. A misconception, bourne out by driving cars with greater levels of assistance. These are perceived to have better brakes because the initial bite is sharper... also a misconception.
 
I think its seals somewhere. Replace fluid and bleed thoroughly. Report back.

[Shackeng]

Diagnostic testing:
Engine off pedal is firm. Does it stay firm if held down?Yes

Start engine with pedal pressed, pedal sinks slowly and applies brakes. Normal, due to vacuum assistance.

Pump pedal to firm it up, but fails to hold firmly and still sinks. Normal, due to vacuum assistance.Hmm, OK, but does not feel right

Braking hard while driving, car stops fine but requires more pressure than I would like. A misconception, bourne out by driving cars with greater levels of assistance. These are perceived to have better brakes because the initial bite is sharper... also a misconception.Hard to describe, but please accept that 60 years driving experience tells me that the brakes on this car are abnormally spongy
 
I think its seals somewhere. Replace fluid and bleed thoroughly. Report back.Already done, see post#3