Replacing Cavalier brakes

The message from "Iain McLaren" contains these words:

Drilling discs doesn't improve stopping power.

As for caliper overhauling - personaly I wouldn't bother unless I knew I had trouble with 'em.

For prices on discs - try

Thanks. There's good prices in that site - way less than I'd found on others anyway!

Cheers,

Iain

In my experience (and I've had five Cavaliers):

If the brakes grind, replace the pads If the brake pedal judders, replace the discs/drums and front calipers If the brakes fade after a while, slow down :-) If the brakes need heavy pressure or pumping to work properly, replace fluid.

The first and last points should be caught well before a problem arises.

Oufits such as Kwik Fit and ATS -whatever you may think about them, specialise in that sort of job. Probably cheaper to let them do it whilst you sit in the warm with a cup of coffee. DaveK.

It's unlikely all calipers in a newish car like this would give trouble at the same time. And a seized caliper would show by the car pulling to one side - or very uneven pad wear. If it has sliding calipers, the slides could be sticking - but this would be something you'd attend to at a pad change.

When changing pads, you have to push the caliper pistons back to their rest position. It should be obvious by the effort needed if any are sticking.

So saying, disc brakes usually don't drop off in performance as they wear (in normal use). The first indication is a grinding noise.

Of course they dont, thats why the guys in m'sport do it, for a giggle i'd guess!!, or maybe it does improve stopping power by allowing the gasses that build up between the pads and the discs under heavy breaking at high speeds to dissapate thus allowing the pads to sit on the discs without the gasses getting in the way, just a thought!!!!

Hi,

I had the front calipers off a while ago for a bit of a re-grease of the sliders etc. The pistons felt fairly stiff then - much stiffer than new anyway (I replaced a very similar-looking caliper on my dad's granada a year or so ago, so I've got a fairly good idea what a free one feels like).

Symptoms are:

Stopping ability has detiorated over the years (got the car about 5 years ago and the discs/pads were changed all-round then) Tried to stop the other morning after a long drive in rain/snow/salt. Not much happened for an alarming distance until the discs/pads cleaned off. Rear discs looking distinctly like they're not doing *that* much. Also corrosion around the outer circumference (the MOT guy won't like that much).

There's no obvious pulling or overheating of the discs though, and no grinding noise.

The reason I asked about grooved discs is that I never get even 50% wear out of a set of pads - they're always knackered by glazing well before getting down to the metal ;-) Maybe a different brand would be better... Can't remember which I got last time...possibly Halfrauds... A fluid change would probably be an idea too (if the bleed nipples will budge without shearing...)

Cheers,

Iain

They shouldn't be greased - merely cleaned and the seals checked for condition or just replaced. The sliders are stainless, so don't need protection. Grease will speed up the collection of dirt which may cause jamming.

Different makes require a different effort to retract. Sliding caliper types may have only one piston, but a large one. Fixed callipers will generally have multiple pistons which are easier to retract.

It occasionally happens that water gets on the discs, and this has to be burnt off before they work properly. Assuming the shields if fitted are in good condition it's just one of these things.

All older disks will show corrosion round the unswept parts. And yes, the rears do less work - but should still be clean on the working part.

I've never ever had glazed pads. You don't drive with the brakes applied all the time, do you?

The message from "Iain McLaren" contains these words:

What on earth do you /do/ to them? I've never managed that even in my yoof.

Nothing really (the wife drives the car more than me)... Perhaps glazing is the wrong term... The part-worn pads look kinda shiny and don't 'feel' that 'frictiony'... Maybe that's not 'proper' glazing!

The message from "Iain McLaren" contains these words:

No - that's what brake pads look like when they're in use.

In article , Iain McLaren writes

They don't. Most of the stopping is done by the front brakes.

That's normal.

It sounds to me like you're not using the brakes hard enough. Take the car for a fast run and do some stopping from speed to wear the pads in.

A fluid change every ~2 years is a very good idea if you have ABS, as it helps prevent buggering up the ABS pump (=expensive.)

especially if they are vented and you wear then down to the vanes, you get the great situation where the brake disc is stationary and the hub/wheel is still rotating and a nice noise!

By drilling you decrease the surface area the pads are acting on so stopping power must decrease, unless the gassing problem is present which I would think hardly ever happens on a road car. The only reason I can see for drilled discs on a road car is cosmetic IMHO.

That's as they should be.

Glazing occurs IIRC where the pads have been overheated to the point where the biding material (glue) comes to the surface. Commonly caused by prolonged light application - like driving an auto with your foot on the brakes.

Friction is independant of area. It's influenced by the materials and pressure only - ignoring heat for a minute. If you apply a given pressure to something but reduce the contact area, the PSI between the friction materials goes up to compensate. Standard physics school experiment - or was in my day.

The message from Mike Tomlinson contains these words:

That's why cars really only need drum brakes at the back. Even then they have to be throttled back to stop them working too hard.

Are they stainless pins, running dry, on a Cavalier? The floating callipers on my Celica run on steel pins, with bellows type seals either end. The pins should be cleaned and regreased with a lithium based grease when refitting. And, providing the seals are in good condition, they are impervious to dirt or water. Mike.

Ahhh... The 'glazed' look confused me (to the point of a 'glazed' look) :-)

Hmmm....think I might start with a fluid change then...and check the current disc thicknesses against what they should be...

Cheers,

Iain