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Blue 2004 V70R. 5 speed auto. UK model. 98RON.
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Discussion Starter · #1 ·
Just thought I'd write this to help someone who may be experiencing the same symptoms.

I've owned this car 6 years. From new the brakes were not good, the pedal would go down towards the floor with lots of pressure. I replaced the fluid, bought new discs and pads. I rebuilt the callipers with all new pistons and seals, cleaned the seats and nipples. Replaced rubber flex pipes with new braided. I bled it lots. Didn't stop the pedal going down but improved the brakes overall slightly.

In the vacuum department. All new vac pipes. PCV new. Little plastic Y piece, vac ejector they call it. Rubber grommet connecting brake servo to piping. Not a Volvo part as not available instead it's BMW/RR/MINI part, look at Peppermint's videos on YouTube for part, then from the same guy, replaced the lip-seal on the pedal-side of the servo. Then finally replaced the vacuum pump.

The pedal still went down, the car feels like it brakes from the back first. I always suspected the master cylinder but didn't like taste of £300 from Volvo. So bought a patent part, that was £70, same piston size, but four port. I blocked off the two unwanted ports. Bled it.. You guessed it still goes down towards the floor! I put up with it for a while until advice was telling me 'It's not a Volvo part etc..'. I caved and bought the Volvo MS. Pre-bled the cylinder by hand on the bench by feeding the two outputs back into the top and then pressing it numerous. I didn't know on the first cylinder I bought that I should have hand bled it. Anyway, fitted and bled, and... Pedal goes towards the floor!

After a few days 'recovery', sure you know the feeling. I saw a video on 'burping' the cylinder and both sides of the ABS motor/box. A friend on the pedal pressing, crack the nuts, drive the pedal down, hold, do up the nuts. This did improve overall breaking, pedal problem remained!

I was installing VM/VIDA onto another laptop of mine with a better battery. I noticed this version had far more content than my other, more listed in the parts list etc. I was looking at the BCM (see pic below this paragraph) and it parameters and looked in activations. I had seen these for years, you can enable/fire each solenoid inside the ABS/MOTOR box = BCM. When you do you can hear each clicking for a few seconds then stops. One fires the brake pump too. So. I had an idea, pump up the pedal. Fire each solenoid IN then OUT. When bleeding start at the furthest wheel from the MS, mine is RHD so that is rear left wheel. That's where I started the solenoids activations. The INs just clicked, nothing happened to the pedal, but when I did the OUTs the pedal dropped down with each click! I thought I think I have just displaced some air. Repump the pedal and run again. I did this say 5x to all wheels, don't forget the AYC and other solenoids and the pump while you're at it. Then I took the wheels off and bleed the brakes using two pipes from the nipples into a T piece and to a waste bottle, pressure pump already set to 10 PSI on the master reservoir. using 2 spanners, open and close each nipple alternately, a lot easier and less mess than swapping a pipe and spanner over each time. All four wheels off helps here, you can go round again for another wave if you want to.

121597


Now the pedal is at the top and hard as **** :) Not driven it yet, but it has never ever been like this. It does not go down unwittingly with pressure now.

Consider that fixed. Hope this helps.
 

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Nice fix! I will try this on my R that has a bit of a soft pedal. Activate in/out when the pedal is held to the floor?


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Blue 2004 V70R. 5 speed auto. UK model. 98RON.
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22 Posts
Discussion Starter · #3 ·
Give it a go. Engine off. Pump up the pedal until as hard as it will go, hold the pressure, activate IN, it probably won't move but if it does, bonus! After IN, do OUT, the pedal on mine dropped 4-5 distances in conjunction with the pulse, go down with the movement and hold the pedal until it stops, then I relaxed the pedal and re pumped it before starting again, even with the same solenoid, re pump it up each time and push down with the movement given. Not sequentially fire until your are at the floor.
 
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Give it a go. Engine off. Pump up the pedal until as hard as it will go, hold the pressure, activate IN, it probably won't move but if it does, bonus! After IN, do OUT, the pedal on mine dropped 4-5 distances in conjunction with the pulse, go down with the movement and hold the pedal until it stops, then I relaxed the pedal and re pumped it before starting again, even with the same solenoid, re pump it up each time and push down with the movement given. Not sequentially fire until your are at the floor.
Awesome, excited to try this out


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