Omega Owners Forum
Omega Help Area => Omega General Help => Topic started by: scott.eden on 12 March 2013, 19:32:47
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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.
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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 8)
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Hi,
What do you mean by connect bleed kit
knock bleeder loose
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Hi,
What do you mean by 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 :)
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ok ,thanks Webby
will brave the cold and give it ago
cheers, :y
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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.
:y
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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.
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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.
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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 :y
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 :y
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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. :-\
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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 ;D
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
:y
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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 ;D
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
:y
You're correct Webby - its a dead spot in callipers ;)
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I can't go any more mental than I already am Webby, I've been mad for years... ;D
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. :y
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I can't go any more mental than I already am Webby, I've been mad for years... ;D
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. :y
;D ;D ;D
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 :y
as i said though i'd still do it cos of protecting the mc :)
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I can't go any more mental than I already am Webby, I've been mad for years... ;D
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. :y
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.
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I can't go any more mental than I already am Webby, I've been mad for years... ;D
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. :y
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.
I don't see that, brake fluid is pretty damn runny, even at low temps.
Someone on the www must have researched this. Got an unbusy morning tomorrow, I may just have a go at finding some info. :y
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I can't go any more mental than I already am Webby, I've been mad for years... ;D
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. :y
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.
I don't see that, brake fluid is pretty damn runny, even at low temps.
Someone on the www must have researched this. Got an unbusy morning tomorrow, I may just have a go at finding some info. :y
nooooooooooo. dont do it abiton. i dont want to see the common heading: ''another brake fluid thread'' ;D ;D ;D ;D
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On a more my level of discussion do you clamp the brake hose with mole grips or something similar?
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I had to reuse the old pins. The ones that came with the pads were too short.
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On a more my level of discussion do you clamp the brake hose with mole grips or something similar?
I use mole grips .. :)
and large plumbers pliers to ease the pistons back ... there's a flat on the caliper and other the large jaw of the plumbers pliers sits nicely right across the piston ensuring it stays flat ... gentle squeeze and it eases in nicely
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Webby: ;D
I think it's an interesting subject. You must have studied master cylinders and their general arrangement, so you may be able to see that as long as pistons are pushed back rather gently/slowly there is no risk of damaging seals; so that only leaves the contention that there is this 'dead spot' of fluid that never moves from the piston bore. The latter seems pretty unlikely IMHO.
Edit: Diffusion, irrespective of convection, will tend to annul any gradients of pretty much anything that might vary within a fluid anyway, no? (Imagine a fart spreading around a room, or a wee in a swimming pool. ;D)
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Webby: ;D
I think it's an interesting subject. You must have studied master cylinders and their general arrangement, so you may be able to see that as long as pistons are pushed back rather gently/slowly there is no risk of damaging seals; so that only leaves the contention that there is this 'dead spot' of fluid that never moves from the piston bore. The latter seems pretty unlikely IMHO.
i'll be honest mate we havent looked at brakes at college yet (next few weeks i think). everything ive learned has been either from here or eric the car guy on youtube! ;D :y
i'm going to bale out of the ''is the fluid bad behind the piston'' cos i dont know. i'm only going on what i've learned and been told. :y
however this is exactly what i use.....
(http://i1086.photobucket.com/albums/j453/Webbybear/vicegripswithfuelline.png)
vice grips with two pieces of fuel line to protect brake hose :y
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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 increase the risk of seal damage or inversion in the master cylinder.
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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. :-\
It doesn't. You get the shagged (really shagged if its very dark) fluid stuck in the caliper. Its a hydraulic fluid in reality, its not going to mix much, it all stays pretty static.
Project TB2 - Tractor! - had brakes that were prone to going spongy when I got it. The fluid clearly wasn't that old, but clamping the hose, and pushing the front pistons back in, it was almost black. The rears were better, but noticibly darker.
Sponginess cured.
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Actually, it was more than spongyness, it was the pedal going to the floor after half a dozen roundabouts
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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. :-\
It doesn't. You get the shagged (really shagged if its very dark) fluid stuck in the caliper. Its a hydraulic fluid in reality, its not going to mix much, it all stays pretty static.
Project TB2 - Tractor! - had brakes that were prone to going spongy when I got it. The fluid clearly wasn't that old, but clamping the hose, and pushing the front pistons back in, it was almost black. The rears were better, but noticibly darker.
Sponginess cured.
OK, that's useful info. Your reported driving style would also tend towards 'maximising the chance of convective mixing', I think?
I don't get why a hydraulic fluid won't mix within itself though. It's just a fluid. Try peeing in the bath and keeping the yellow patch distinct from the rest. :D
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.... so you may be able to see that as long as pistons are pushed back rather gently/slowly there is no risk of damaging seals; ....
I hope your hair shirt is laundered & ready to wear!!! ::) ::) ::) ::)
I push the pistons back & don't usually open the bleed nipple either! ::) ::) ;)
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I had to reuse the old pins. The ones that came with the pads were too short.
because not everyone knows that later 2/6 & 3.2 cars have vented rear discs ..... the short pins are long enough for the older solid discs :y :y
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I had to reuse the old pins. The ones that came with the pads were too short.
because not everyone knows that later 2/6 & 3.2 cars have vented rear discs ..... the short pins are long enough for the older solid discs :y :y
Eurocarparts sell two different pins.... tell them if youve got vented or non-vented and theyll supply the correct pins seperately :y
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I had to reuse the old pins. The ones that came with the pads were too short.
because not everyone knows that later 2/6 & 3.2 cars have vented rear discs ..... the short pins are long enough for the older solid discs :y :y
Eurocarparts sell two different pins.... tell them if youve got vented or non-vented and theyll supply the correct pins seperately :y
but there are also some garage mechs that have fitted solid discs to the back of a car that should have vented ...... all OK to start with until the pads wear & one of the pistons makes a bid for freedom from the caliper. Result is brake fluid everywhere & no brakes.
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I had to reuse the old pins. The ones that came with the pads were too short.
because not everyone knows that later 2/6 & 3.2 cars have vented rear discs ..... the short pins are long enough for the older solid discs :y :y
Eurocarparts sell two different pins.... tell them if youve got vented or non-vented and theyll supply the correct pins seperately :y
but there are also some garage mechs that have fitted solid discs to the back of a car that should have vented ...... all OK to start with until the pads wear & one of the pistons makes a bid for freedom from the caliper. Result is brake fluid everywhere & no brakes.
sorry andy. all i meant was if you needed replacememt pins (cos your ones were nackered) you can get the correct replacements from ECP :y
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sorry andy. all i meant was if you needed replacememt pins (cos your ones were nackered) you can get the correct replacements from ECP :y
No Webby .... it was my fault! I was going off on a tangent. ;D ;D
Rear pins last forever ...... I don't think I've ever needed to replace mine. :-\ I've replaced the anti-rattle clip though.
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sorry andy. all i meant was if you needed replacememt pins (cos your ones were nackered) you can get the correct replacements from ECP :y
No Webby .... it was my fault! I was going off on a tangent. ;D ;D
Rear pins last forever ...... I don't think I've ever needed to replace mine. :-\ I've replaced the anti-rattle clip though.
;D ;D
exactly the same mate.... the pins clean up real nice.... the anti-rattle clip though dissintergrated in my hand as i was cleaning it up ::) ;D
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..... the anti-rattle clip though dissintergrated in my hand as i was cleaning it up ::) ;D
Ooops! ;D ;D
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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 increase the risk of seal damage or inversion in the master cylinder.
Exactly. You increase it from "I never even considered it" to "vaguely plausible".
I've never bothered, or know anyone else who has. I dislike the idea of crushing a rubber hose(even though I was given the specific tool some time ago) far more than worry about the seals in the M/C.
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Personally I really don't feel comfortable with the idea of crushing my flexible brake hoses with pliers :-\
Why bother? Attach a bleed hose to the bleed nipple, open the bleed nipple & gently press the pistons back then close the bleed nipple. Job done, caliper purged of old fluid & no damage done to flexible hoses :y
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Personally I really don't feel comfortable with the idea of crushing my flexible brake hoses with pliers :-\
Why bother? Attach a bleed hose to the bleed nipple, open the bleed nipple & gently press the pistons back then close the bleed nipple. Job done, caliper purged of old fluid & no damage done to flexible hoses :y
There are times though that you need to remove a caliper & you need to prevent the brake fluid from draining out of the system and IIRC someone from the forum then had the job of having the system bled with the aid of something to modulate the ABS pump - you'll not successfully do it without if the system is fully drained, and it will if you leave the flexi pipe disconnected.
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Personally I really don't feel comfortable with the idea of crushing my flexible brake hoses with pliers :-\
Why bother? Attach a bleed hose to the bleed nipple, open the bleed nipple & gently press the pistons back then close the bleed nipple. Job done, caliper purged of old fluid & no damage done to flexible hoses :y
There are times though that you need to remove a caliper & you need to prevent the brake fluid from draining out of the system and IIRC someone from the forum then had the job of having the system bled with the aid of something to modulate the ABS pump - you'll not successfully do it without if the system is fully drained, and it will if you leave the flexi pipe disconnected.
Fair comment.
I have got some short lengths of brake pipe that I have soldered up so I can screw them into/onto the end of a flexi hose to stop that happening.
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Fair comment.
I have got some short lengths of brake pipe that I have soldered up so I can screw them into/onto the end of a flexi hose to stop that happening.
[/quote]
So you won't need to use a brake hose clamp :y :y :y
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Personally I really don't feel comfortable with the idea of crushing my flexible brake hoses with pliers :-\
Why bother? Attach a bleed hose to the bleed nipple, open the bleed nipple & gently press the pistons back then close the bleed nipple. Job done, caliper purged of old fluid & no damage done to flexible hoses :y
There are times though that you need to remove a caliper & you need to prevent the brake fluid from draining out of the system and IIRC someone from the forum then had the job of having the system bled with the aid of something to modulate the ABS pump - you'll not successfully do it without if the system is fully drained, and it will if you leave the flexi pipe disconnected.
Fair comment.
I have got some short lengths of brake pipe that I have soldered up so I can screw them into/onto the end of a flexi hose to stop that happening.
Likewise, have been using them for years :y :y
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I hate the thought of clamping hoses I am not sure but are the brake hoses reinforced and does clamping damage the reinforcement. I wonder what these tyre fitters do to our braking systems we probably wouldnt like to know.
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I hate the thought of clamping hoses I am not sure but are the brake hoses reinforced and does clamping damage the reinforcement. I wonder what these tyre fitters do to our braking systems we probably wouldnt like to know.
whether they're reinforced or not i have no idea. but i can say that i dont squeeze the crap out of them... just enough to ensure all the flow goes the other way out of the bleeder :y as per my pic before i also use two pieces of fuel line to protect my hose... gotta protect ya hose ;D ;D ;D
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I forgot to add to my post that there is always the chance of breaking off the bleed nipple but I am probably thinking back to the days when bleed nipples were quite small and I can remember some snapping. A little plus gas would not hurt.
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You increase the risk of seal damage or inversion in the master cylinder.
^^^^ What TB says ^^^^ (https://dl.dropbox.com/u/43954633/bangshead.gif)
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I forgot to add to my post that there is always the chance of breaking off the bleed nipple but I am probably thinking back to the days when bleed nipples were quite small and I can remember some snapping. A little plus gas would not hurt.
No, you're quite right. There's still plenty of opportunity to break off a nipple. :-X
Actually, loosening them every time you wind back the piston will help prevent them seizing.
FWIW, I don't bother clamping the hose. With the bleed nipple open there is much less resistance to flow out of the nipple compared with up into the reservoir through the master cylinder so I doubt any old fluid gets pushed back into the system.