Volvo Amazon brake problem

[TCD]

Hi, I took delivery of a Volvo amazon estate a few days ago. It goes well but the brakes are terrible. Its almost impossible to lock the wheels up.
I have bled the system with a pressurized easy bleed kit and have also fitted new pads to the front. It has not made much difference.
the seller tells me he recently replaced the servo with an old one he had. I can hear it clonking when the pedal is pressed. Is this likely to be the cause of the problem? Thanks

[Rustinmotion]

Originally Posted by TCD

Hi, I took delivery of a Volvo amazon estate a few days ago. It goes well but the brakes are terrible. Its almost impossible to lock the wheels up.
I have bled the system with a pressurized easy bleed kit and have also fitted new pads to the front. It has not made much difference.
the seller tells me he recently replaced the servo with an old one he had. I can hear it clonking when the pedal is pressed. Is this likely to be the cause of the problem? Thanks

With the engine off push hard on the brake pedal and hold it, switch the engine on if the pedal drops further down the servo is working if nothing happens it's not, if someone can help you put the car on axle stands and see if you can rotate the wheels wile the other person applies a light pressure to the pedal
Does it pull to one side? Can you lock the rears with the parking brake? Are the front discs new? If they are old are they worn with groves? New pads will have to wear into the groves to give full grip ( better to change discs.
Is one side of the disc rusty ? That's a sign pistons are stuck on one side
When I 1st drove mine it had had the servo removed and you had to push very hard to stop it, I put a servo back on and the brakes are more like a modern car, some prefer it without but not me

[142 Guy]

Do you have a firm brake pedal? If the pedal is firm and you don't have issues with pad / shoe contamination I would look at the Booster; but, the Amazon is reportedly quite driveable with the booster completely deleted. Unlike the later 140 design, the Amazon booster is underwhelming. If you go back through the threads in this forum you can find a fairly recent discussion of the brake booster and its deletion.

What kind of pad did you install? For maximum grab at low temperatures it should be a semi metallic pad and definitely not a racing or performance pad. Due to a packaging error, I received an incorrect set of front pads for my 140. They were a semi race material. Bloody disaster - like somebody had applied grease to the rotors. Switched them out for some inexpensive Beck Arnley semi metallic pads and it was a night and day difference.

What is the condition of the flex lines? If they are quite old they tend to swell leading to fluid flow restrictions. Normally this results in wheels remaining locked after you release the pedal because fluid does not return to the cylinder.

If the pedal is soft / sinking to the floor then it is a brake system bleed problem or the master cylinder has failed.

[TCD]

Many thanks for responding. The calipers appear fine and the pistons pushed in no problem for fitting the new pads. Car pulls up evenly also. The discs have plenty of meat on them so probably have not done huge mileage. I should mention that the car passed an MOT a few months ago.

The old pads had plenty of miles left in them but were perhaps a little glazed. I only replaced them as I happened to have bought the incorrect set for another car and they were sitting on the shelf. Pads are standard road going. There is a very slight improvement with the new ones fitted. I took it a short distance up a quiet road and did a lot of braking. They should be worn in at least enough to make a difference.

Pedal is firm.

I will try starting it tomorrow with the pedal pressed.

As I said previously the previous owner recently replaced the servo with an old one he had. It may not even be correct for the car. I had a PV544 a couple of years ago with no servo and the brakes were superb. I would have thought the brakes would still be reasonable without the servo. Is having a faulty servo worse for braking than no servo at all?