Moonstone Steve.

iTrader: (2)

2wd saph and the brakes are no as they should be, the pedal feels spongy and when coming to a hault the motor starts to run and pushes against your foot whilst on the pedal, I dont have any lights on its almost as if it has no assistance until it comes to a slow stop speed.

Any help greatly received

Steve

johnwilks

i had weird problems with my brakes, pedal pushing back pump running at odd times, turned out that a complete change of fluid fixed all problems, looked at old fluid and water was floating in it, as brake fluid takes on water, and my car had been lying for a while,
just a thought.

Moonstone Steve.

iTrader: (2)

The fluid isnt that old tbh m8, but i have thought about doing it, i haven't a clue how the pedal should feel on a saph cossie as its always been like it.

Steve

phil_focus

when you say the motor kicks in and pedal pushes back do you mean the abs is kicking in??

dojj

iTrader: (3)

change the fluid as it seems that your turbo is boiling the pump

also look at putting a bigger heat shild in the way to stop it from happening again

Moonstone Steve.

iTrader: (2)

Phil, normal driving at speed and braking the pedal is spongy and has little affect on the brakes, when you come down to a crawl say 10mph the pump starts priming and you can feel the pedal pulsing which i assume is the abs kicking in, obviously the wheels arn't locking up.

Steve

phil_focus

well the low speed pulsating sounds like an abs issue which could be down to a sensor. fixed that problem on my brothers nissan. did exactly the same thing and it was due to a duff sensor.

spongy pedal is probably due to old fluid or air in the system somewhere. when was it last changed? for the small cost of a ltr of fluid and the little time it take with a gunsen eezybleed i'd change it!

also, what condition are the discs and pads in and are any callipers seized?

Moonstone Steve.

iTrader: (2)

Fluid was changed when i did a resto 4yrs ago, disc and pads changed the same time and done little miles.

Steve

phil_focus

fluid definately needs changing then as it absorbs moisture over time regardless of use.
get it changed and see if that improves things then we can go from there.

i still think theres an abs fault though but one thing at a time.

dojj

iTrader: (3)

don't use anything other than the pump for the rears and your foot for the fronts

Moonstone Steve.

iTrader: (2)

Cheers guys, will change the fluid tomorrow weather permitting, will also check the sensors with my volt meter.

Steve

timotei1980

iTrader: (1)

Did you solve the problem?

i've got the same thing on mine under around 10mph i sometimes get kickback through the pedal, no abs light + i've already cleaned all the rings and sensor.

Its only just started since replacing std calipers with AP's.

martysmartie

iTrader: (1)

It's a ABS issue, either a dirty sensor or dirt in the 'teeth' of the ABS rings I should imagine.

Martin

timotei1980

iTrader: (1)

I've still got to fit my big brake conversion that uses 4x4 calipers to the rear so it'll get bleed again then.

Do you happen to know the resistance valve for the sensors so i can check those to rule them out?

Thanks.

dojj

iTrader: (3)

just etst all the sensors to see what they read, any that read out will be the prime suspects

there were 3 values if i remember, 2 for the sierra and another for the granada as they had more shielding on them to stop any electrical interference as they ran more leccy bits

Moonstone Steve.

iTrader: (2)

Never have or did sort it, cleaned everything about 10 times, checked the sensor resistance all perfect but still have the issue, someone did say it could be air trapped in the abs block which is a pain to get out.

Steve

dojj

iTrader: (3)

if the valve block has air in it it's a bastard to get out

mark r

you should be changing the fluid every 2 yrs.

timotei1980

iTrader: (1)

Well i've just tested the sensors and the results are:

Left front (pins 7 and 25) = 1016Ω
Right front (pins 5 and 23) = 1036Ω
Left rear (pins 4 and 22) = 1042Ω
Right rear (pins 6 and 24) = 1024Ω

This was through the ABS ECU multi-plug and they all appear to be within tolerance.

martysmartie

iTrader: (1)

Those values are fine, you need to actually inspect the sensors and ring gear for dirt.

Martin

timotei1980

iTrader: (1)

I cleaned the sensors and rings last weekend.

Also note that it does'nt kickback all the time, its tends to do it the first time i brake in the morning and then only every now and again when driving but only at slow speeds.

I think i did have a slight leak on the front brake lines after i replaced them but i niped them up and its seems to be fine now (keeping an eye on it).

As said i'm going to replace the rears and then bleed the system and hopefully cure the problem.

Thanks for your help.

martysmartie

iTrader: (1)

No problem, you can try it but I doubt fluid would cause it.

I have (and always have had the same problem) I have cleaned 3 or the 4 sensors but cannot remove the offside front one, and don't want to force it as I think it will damage it or worse I am left with part of it stuck in the bore, and they are astromically expensive to buy new as well!

It's a discrepency of wheel speed between different wheels that is being detected, so binding brakes for example would cause the same issue.

Martin