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[scott.eden]

Hi Guys,

Got to replace my rear brake pads is there anything differnt that i need to do compared to the fronts? Handbrake?rear wheel drive etc..

I have a V6 2.6 Elite auto 2003

Going to brave the cold tommorrow and give it ago.

[Webby the Bear]

just doing the pads is easy.

jack up rear, axel stands, chock.
wheel off
knock securing pins out
remove retaining spring
remove pads
crimp off brake hose
connect bleed kit
knock bleeder loose
push pistons back (i found mine i just about push with my thumb... just. so use pliers or brake spreader tool
lightly file crap out of caliper
spray with brake clean
lube up pads with copper grease
refitting is reversal of removal.

pump up brake pedal
top up brake fluid

have a beer 

[scott.eden]

Hi,

What do you mean by

Code: [Select]

connect bleed kit
knock bleeder loose

[Webby the Bear]

Hi,

What do you mean by

Code: [Select]

connect bleed kit
knock bleeder loose

Well it's there to expel the crap fluid from behind the pistons and ensure brake fluid isn't forced towards the master cylinder.

HOWEVER i've not seen many people do it and they just push the piston back.

so its up to you whether you do it or not. i do though

[scott.eden]

ok ,thanks Webby

will brave the cold and give it ago
cheers,

[Webby the Bear]

no worries mate.

only thing i struggled with was getting the new pads in height wise. thats where the CAREFUL filing comes in, just enough to get rid of the crap. then clean that away with brake clean.

 

[TheBoy]

Rather than any filing, I'd suggest a wire brush to clean up caliper, but dont get it near the rubber boot on the piston. The pads should fit without any filing!

Reason for clamping hose, and opening bleed screw when pushing calipers back is twofold:
Prevent damage to master cylinder seals
Removes the worse of the brake fluid (the bit nearest the pisons), and this part doesn't get renewed with a brake fluid change.

[ffcgary1]

If your just changing the pads them there is no need to open the blead nipple to push the piston back, and unless your planning to bleed the rear brakes then leave well alone, you need to loosen the res cap under the bonnet but dont remove it, then with a C clamp slowly and gently push the piston back making sure the fluid in the res does not over flow the cap iF it looks like it will, stop and remove some of the fluid untill the piston can retract all the way without overflowing. REMEMBER FLUID IS VERY GOOD AT REMOVING PAINT.
Using a small wire brush remove all the loose dirt and grime from the calipers and finally spray with brake cleaner and allow to dry.
Smear a little copper slip brake grease to the rear of the pads and on the edge of the backing plate and also inside the caliper where the pad sits and then fit pads.
Clean and smear a little copper slip to the pins and refit all parts that you removed and then pump the pedal a couple of times to seat the piston to the pad
Repeat the above to to the other side, finally check the fluid level in the res and add NEW FRESH FLUID IF NEEDED.

[Webby the Bear]

If your just changing the pads them there is no need to open the blead nipple to push the piston back, and unless your planning to bleed the rear brakes then leave well alone, you need to loosen the res cap under the bonnet but dont remove it, then with a C clamp slowly and gently push the piston back making sure the fluid in the res does not over flow the cap iF it looks like it will, stop and remove some of the fluid untill the piston can retract all the way without overflowing. REMEMBER FLUID IS VERY GOOD AT REMOVING PAINT.
Using a small wire brush remove all the loose dirt and grime from the calipers and finally spray with brake cleaner and allow to dry.
Smear a little copper slip brake grease to the rear of the pads and on the edge of the backing plate and also inside the caliper where the pad sits and then fit pads.
Clean and smear a little copper slip to the pins and refit all parts that you removed and then pump the pedal a couple of times to seat the piston to the pad
Repeat the above to to the other side, finally check the fluid level in the res and add NEW FRESH FLUID IF NEEDED.

isnt this the perfect time to get rid of that fluid though as the pistons wont be pushed back at any other time 

as for the file it worked really well for me. was perfect sized to slip in and you can clearly see if your coming close to the piston boot 

[Abiton]

Surely convection currents within the fluid will ensure that it is mixed to a good extent?  In other words, there simply won't be any localised concentration of 'bad' fluid near the piston. 

[Webby the Bear]

Surely convection currents within the fluid will ensure that it is mixed to a good extent?  In other words, there simply won't be any localised concentration of 'bad' fluid near the piston. 

firstly these are just my thoughts... so no one please go mental if i get it wrong 

but

i'd have said that there would be bad fluid. convection is dealing with heat dissipation If i'm correct. i cant see there being any actual flow of the fluid, especialy as the piston doesnt move that far and when it does move inwards it's very gradual.

those are just my thoughts and guesses though.

and to be honest, for the extra 2 mins it takes i'd rather do it if only for the protection of the MC

 

[dbug]

Surely convection currents within the fluid will ensure that it is mixed to a good extent?  In other words, there simply won't be any localised concentration of 'bad' fluid near the piston. 

firstly these are just my thoughts... so no one please go mental if i get it wrong 

but

i'd have said that there would be bad fluid. convection is dealing with heat dissipation If i'm correct. i cant see there being any actual flow of the fluid, especialy as the piston doesnt move that far and when it does move inwards it's very gradual.

those are just my thoughts and guesses though.

and to be honest, for the extra 2 mins it takes i'd rather do it if only for the protection of the MC

 

You're correct Webby - its a dead spot in callipers

[Abiton]

I can't go any more mental than I already am Webby, I've been mad for years...

Convection currents occur in fluids when there are temperature differentials, warm fluid rising (because of reduced density) and being replaced by cooler fluid that falls round the outside of the rising central column.  I can't see any reason why this wouldn't happen within automotive brake systems, as the hottest bit is also the lowest bit.

I may be wrong, but basic physics says I might be right. 

[Webby the Bear]

I can't go any more mental than I already am Webby, I've been mad for years...

Convection currents occur in fluids when there are temperature differentials, warm fluid rising (because of reduced density) and being replaced by cooler fluid that falls round the outside of the rising central column.  I can't see any reason why this wouldn't happen within automotive brake systems, as the hottest bit is also the lowest bit.

I may be wrong, but basic physics says I might be right. 

 

So convection (without the aid of like a water pump in the cooling system for example) would actually move the brake fluid then cos of the temp. differences.

fair enough 

as i said though i'd still do it cos of protecting the mc

[Entwood]

I can't go any more mental than I already am Webby, I've been mad for years...

Convection currents occur in fluids when there are temperature differentials, warm fluid rising (because of reduced density) and being replaced by cooler fluid that falls round the outside of the rising central column.  I can't see any reason why this wouldn't happen within automotive brake systems, as the hottest bit is also the lowest bit.

I may be wrong, but basic physics says I might be right. 

Simply put, the pipe bores are too small. For convection currents to work there has to be room for the fluid to actually move in two distinct "cylinders" .. the inner one is the hot fluid rising, around the outside is a hollow cylinder of cold fluid falling ... has to do that or you end up with a vaccum at the bottom !! pipe bore of a brake pipe is not wide enough to set that up IMHO, so the fluid in the caliper ends up getting hot then cold ... lots.. Also, fluid does not "move" as such in the brake system , it is compressed and moves the piston a miniscule amount each time, the only real "movement" being the replacing of pad wear ...  so well worth replacing that small amount of fluid every time.