Rear Brake Pad Wear

[Ivor_E_Tower]

I've now seen a number of postings, not just on this forum, where it has been stated that the Galaxy's rear disc pads wear out faster than the fronts.

Is this true, and anyone know why? Front brakes usually take much more of the load, plus weight shifts forward when braking, increasing the work that the front pads have to do. So why should the rears wear so fast? I have had at least one other car with rear discs, and that went to over 100,000 miles before the rear pads needed changing.

[Guest SA Intruder]

Clearly something related to the sizing of the rear pads.

 

All brakes are standard parts. The rear ATE calipers are basically the same as other cars on these. The other cars generally rely on the size and thus effectiveness of the rear brakes to ensure the front/rear balance is maintained.

 

Where a heavier vehicle demands more rear brake power, the load sensitive or fixed rear balance valve is set to lessen the reduction effect, and apply more rear brake power.

 

Using the handbrake to apply a constant retardation when in motion will clearly wear the pads very fast, and risk overheating the pads and warping the discs.

 

It aint meant for that...

[Ivor_E_Tower]

It seems I'm becoming notorious for the "handbrake trick" - So far I've done it once in the Gal in about 7 months of ownership, and it's for all of about 2 tenths of a mile!

Do you know if the Gal has a fixed or variable apportioning valve for the rear brakes, also does the handbrake work on the rear pads or are there separate pads in a drum (as Volvo used to do in the 1970's for instance)?

 

We still seem no wiser as to why the rear pads (allegedly) wear so fast - I believe that about 70 percent of braking is done by the front brakes, maybe more at higher speeds and sharper braking, due to weight transferrance. Perhaps a particularly soft material is used at the rear - can't believe that thinner material is used.

[seatkid]

I was most :D surprised when the MOT report told me my rear pads were likely to require changing soon. The front pads were still very healthy. I took SA's word for it that this is common. :)

 

Here's a few things I dug up from the TIS..

 

Front disc 288mm x 25mm ventilated, caliper piston dia 57mm

Rear disc 268mm x 10mm plain, caliper piston dia 36mm

Front pads appear very roughly 2 x area of rear pads (guestimate)

No mention of pressure balance valve in TIS - is there one? (do they need one with ABS?)

 

So by my rough calcs braking effort is split approx. 80% front 20% rear

 

Possible technical explanations for this apparent heavy rear wear?

 

1. Rear pads might be thinner (I think they probably are)

2. Rear pads might be softer and/or the disc harder

3. Rear pads/discs (as factory fit) might be made by a different OEM to the front

 

The handbrake cable is attached to a lever on the caliper (i.e. directly operates the rear disc brakes)

 

Other possibilities are

 

4. For some time I suspected my handbrake was adjusted too tight (1 click to normally park, 2 clicks to firmly apply, 3 is a struggle), Ford TIS confirms this - should be between 3 to 6 clicks full on. Those useless twats at the dealers have overtightened.....so maybe I get a lot of wear driving after a service!!

 

5. Maybe the lever mechanism design on the handbrake tends not to fully release the pads.

 

6. Sticky calipers, I've never seen a vehicle where the inner/outer pads have worn at the same rate - its usually one side worn and other side only half worn. The floating calipers dont float that well when clogged up with brake dust and you only brake lightly!

 

Or a combination of all of these.... :D

 

When I get around to inspecting them properly myself, I'll report back.

 

**Caveat! :D Concerning "OEM" brake pads sourced from alternative suppliers - I found out in my mindless trawling that manfacturers often claim their products (e.g. brake pads) are OEM when, for example, they only really supplied 1996 model Ford fiesta 1.1 popular pads as OEM. So they might not really be supplying you with genuine OEM Galaxy pads! This doesn't mean to say their products are no good, but perhaps someone can tell us who genuinely OEM's Galaxy pads (and which models?)

[Guest SA Intruder]

You're overcomplicating it.

 

The pads/discs and entire rear brake set up is standard parts-bin stuff.

 

The amount of work they do is greater than other applications, and they tend to wear faster.

 

The fact that the front/rear pads wear at different rates is irrelevant...and not a fault.

 

Where does it say that the front pads on cars should/must wear sooner than the rears?

 

The handbrake operates on the rear discs. There is no additional integral drum for handbrake operation. My handbrake has only ever come up 2 notches from new. If either rear wheel is lifted, the wheel spins completely freely - I always set handbrake cables AFTER adjusting the rear shoes/bedding in rear pads, with the handbrake cable well backed off. With the wheels hung, I set the handrake to the nominal number of notches (3 or 4 generally) and adjust the cable or cables until the wheels lock at that setting. Then release the handbrake to ensure the wheels rotate freely. Repeat as necessary.

[Guest mick]

Interesting to see that the handbrake works on the rear discs, and not on separate, smaller drums. Did Renault or Citroen not have this affair only to have their cars get a mind of their own and roll away down hills? Does the Gal have a separate set of pads / calipers for the h/brake, or does it utilise the f/brake ones?

[Guest SA Intruder]

Footbrake ones - like 90% of rear disc setups.

 

And yes, the handbrake will partially release if you lightly apply the handbrake while the discs are stinking hot a la BX/Xantia (which operated on the Front discs because their braking system was fully powered and failure of the power brakes required the additional power/stability of the front discs).

[Guest mick]

Didn't realise that BX / Xantia had their handbrakes on the front.

[seatkid]

The pads/discs and entire rear brake set up is standard parts-bin stuff.

 

The amount of work they do is greater than other applications, and they tend to wear faster.

 

The fact that the front/rear pads wear at different rates is irrelevant...and not a fault.

 

Where does it say that the front pads on cars should/must wear sooner than the rears?

Still thinking about this one... :)

[seatkid]

The pads/discs and entire rear brake set up is standard parts-bin stuff.

So what other makes/models are these parts used on?

 

The amount of work they do is greater than other applications, and they tend to wear faster.

So are they underrated?

 

The fact that the front/rear pads wear at different rates is irrelevant...and not a fault.

 

Where does it say that the front pads on cars should/must wear sooner than the rears?

80% front 20% rear braking effort?

[Guest Andy]

I think that when you guys take your vehicles to the dealer for a service, it is actually the apprentice that fits your rear pads and DOES NOT ADJUST IT PROPERLY.

Cars first registered from April 1st 2001 require brake products that meet Regulation 90 approval

What is the mark standard?

There is now a European Standard for Aftermarket Brake Pads which is known as ECE Regulation 90.

 

The standard states that the Aftermarket friction material should be within

[seatkid]

The standard states that the Aftermarket friction material should be within

[Guest Andy]

Is it compulsory to have an mark?

 

ECE Regulation 90 is compulsory for all brake pads and shoes fitted to vehicles registered after September 1999.

 

:rolleyes: :lol: ;) B)

[seatkid]

Still prefer real O.E. pads...

 

Getting back to the subject of the thread. What SA said about hot brakes and parking brakes seems to ring true. The other night returned from a mates where I would be using brakes more than other runs i.e. got hotter. Noticed as I parked up, that parking brake was a good click tighter. In my case, one click was firm on and I could hardly manage two clicks.

 

I think I'm getting to the bottom of this fast wear issue......

[Ivor_E_Tower]

..and the moral of this is to always park with the car in gear (or in "Park" for those with autos) as well as applying the handbrake.

[seatkid]

Except I'm prone to forget to check and sometimes start the car without the clutch in! OOPS! :lol: Oh s**t! :rolleyes: