Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[grifter]

Any idea why brake pad is no rubbing on whole disc face.

I've just renewed pads/discs and checked sliders were all ok, not seized or sticking, cleaned the whole calipers etc.



Strange how a pad could contact just over half the disc!

The rust spots are just where rain got in the wheels

[johnnydog]

Until a new pad wears to the profile of a new disc, it isn't unusual to have partial contact of the pad against the disc face for the first couple of hundred miles or so. I am certain that in the next few hundred miles of use, you will have a nice shiney disc across the whole area as the material of the pad wears slightly to match the disc profile.

[johnnydog]

That picture also highlights why coated discs are beneficial over non coated - if only to avoid the  premature rusting on the centre hub area and extreme edges of the discs after only a few days / miles..

[Doctor Gollum]

Are the discs/pads correct for the car?

https://photos.app.goo.gl/WC2KLh3A2rhWirVAA

3.2 v6, but 2.6 should be IDENTICAL.

Discs should be 296x28. Calipers and pads shouldlook like above. 

[grifter]

Are the discs/pads correct for the car?

https://photos.app.goo.gl/WC2KLh3A2rhWirVAA

3.2 v6, but 2.6 should be IDENTICAL.

Discs should be 296x28. Calipers and pads shouldlook like above. 

Yep, double checked sizes and against old parts, here's the order details:

Brake Disc Thickness [mm]:   28 mm
Brake Disc Type:   Vented
Centering Diameter [mm]:   70 mm
Depth [mm]:   58,5 mm
Diameter [mm]:   296 mm
Minimum Thickness:   26 mm

[grifter]

That picture also highlights why coated discs are beneficial over non coated - if only to avoid the  premature rusting on the centre hub area and extreme edges of the discs after only a few days / miles..

Never heard of that, what are they coated in? I know they usually coat with a light oil for storage, but I wipe that off only on disc face, obviously it wears off and the rust starts on the edges and hub bit, plenty of copper slip on mating faces however.

[johnnydog]

Coated discs simply have a rust / heat resistant paint coating all over - inside and out. You simply fit them straight from the box, and the pad contacts the relevant surface area, and leaves the remainder with the coating in place which then resists rusting. They have no other surface protection, such as wax or oils that need removing prior to fitment, which also saves time.
If you search 'coated discs', you'll find further information about them for future reference. Many brake manufacturers can now supply them.
I have used all sorts of different heat and rust resistant paints in the past when fitting new discs without this coating, but nothing has been as effective as the original coating applied by the brake manufacturers.

[Nick W]

That picture also highlights why coated discs are beneficial over non coated - if only to avoid the  premature rusting on the centre hub area and extreme edges of the discs after only a few days / miles..

Which makes sod all difference to the life of the disc. I've never seen the point in obsessing about it; if a disc is coated(like Pagid ones), great. If not, I just fit them and forget about them. Modern asbestos-free pads are what kill discs; unlike old parts, if you get two pad changes out of a disc you're doing well.


Worn pads missing part of the swept area of a disc seems to be a function of sliding calipers, as they all seem prone to it.

[johnnydog]

True, it does make 'sod all difference' to the life of the disc, that is why I said 'if only' to avoid the premature rusting...... but the main point is from an asthetics point of view. The wider the gap between the alloy wheel spokes, the large rusted area is there to see which in my opinion looks unsightly. If you own a car for merely travelling from A to B and have no pride in your car whatsover, then you won't be bothered. But I, for one, are proud of my vehicles appearance, whether than be an Omega or any other more modern vehicle with alloys, and there is no question about it - rusted 'top hats' on brake discs that are clearly visible through the spokes of the rim are unsightly. On the other hand, if you are in the now minority with steel wheels covered by plastic wheel trims, then this is less likely to be a 'visual' issue to the owner.

[Enceladus]

How many km's has the car done since you renewed the brakes?
The photo suggests the outer edge is starting to score.

If more than 50km then I'd consider removing the pads, caliper and disc for further examination.
Is the boss of the hub clean? And the mating surface on the inboard of the disc?
What about the inboard side of the disc. What's the sweep pattern?
Are the the two set screws that hold the caliper frame even and fully tight?
What make of pads do you have?
Is the friction material thickness consistent across both pads?
Do the edges of the backplates move freely in the calipers? IE no protruding lumps.
Have you properly cleaned off any crud on the caliper itself?
Are the anti-squeal shims, if present, correctly positioned?
Are the caliper sliding pins still moving freely? And tightened home?

[grifter]

How many km's has the car done since you renewed the brakes?
The photo suggests the outer edge is starting to score.

If more than 50km then I'd consider removing the pads, caliper and disc for further examination.
Is the boss of the hub clean? And the mating surface on the inboard of the disc?
What about the inboard side of the disc. What's the sweep pattern?
Are the the two set screws that hold the caliper frame even and fully tight?
What make of pads do you have?
Is the friction material thickness consistent across both pads?
Do the edges of the backplates move freely in the calipers? IE no protruding lumps.
Have you properly cleaned off any crud on the caliper itself?
Are the anti-squeal shims, if present, correctly positioned?
Are the caliper sliding pins still moving freely? And tightened home?

About just over 100 miles.

I'm quite particular about rebuilding brakes or anything so should be ok, but I'll double check it all again, just in case the slider is sticky. The make of pads was delphi.

[jb]

you may need half a dozen emergemcy stops from high speed to now really bed in the pads....

[cam.in.head]

True, it does make 'sod all difference' to the life of the disc, that is why I said 'if only' to avoid the premature rusting...... but the main point is from an asthetics point of view. The wider the gap between the alloy wheel spokes, the large rusted area is there to see which in my opinion looks unsightly. If you own a car for merely travelling from A to B and have no pride in your car whatsover, then you won't be bothered. But I, for one, are proud of my vehicles appearance, whether than be an Omega or any other more modern vehicle with alloys, and there is no question about it - rusted 'top hats' on brake discs that are clearly visible through the spokes of the rim are unsightly. On the other hand, if you are in the now minority with steel wheels covered by plastic wheel trims, then this is less likely to be a 'visual' issue to the owner.

absolutely agree. i made the mistake myself after buying new discs for mine and ended up removing them again and using vht silver paint on the hubs and unswept part and edges.it doesnt last as long as proper coated discs as mentioned but looks ok .they are just starting to show some rusting thou but at nearly 5 years and 5000 miles it will be a while till they need changing !

and yes in reply to the above.they will bed in and become shiny all across .the sooner the better driving wise thou so the rust doesnt get a hold .once pitted they stay pitted !

[iansoutham]

Check the inside of the disc, I bet that is worse.

Looks like either caliper or, more likely, pad sticking in the carrier.

Have seen it before on other cars, MK3 Golf rear discs being a prime example

[grifter]

I took it apart yesterday, everything checked out ok. Then decided to take it along a long back road near me, and give the brakes a few work outs, I should really remember currently my abs isn't working lol as I done an emergency stop and locked both wheels up in spectacular fashion, ended up with a flat scrubbed into one of my tyres!

Had a bit of a fling with a tesla back down the hills and some hard braking ensued so hopefully that had helped!

[cam.in.head]

how do they look now ?

[grifter]

how do they look now ?

I think I can see it is starting to contact the disc more, there is slight sanded look of the outer edges of the bit it wasn't previously contacting, so here's hoping. Other side of disc looks fine, pad was full contact.

[Doctor Gollum]

Sounds like the calipers weren't cleaned properly and/or the outer pad was on the piss

Remove, reclean and refit. Although if the pad is worn unevenly, then you need to replace it

[dave the builder]

I've had pads that are too tight out the box and need a light file to knock the burs or paint off
something is clearly wrong and needs addressing for the un-even pad wear/contact

[grifter]

Pads are not sticking in holder, I've checked twice, they are a nice fit with no sticky bits.

[johnnydog]

As I said previously, it's not unusual for partial surface contact on the disc initially when new pads are fitted, even if the sliding pins are free, the pads are a nice snug fit without being tight, and you are certain the caliper carrier contact points to the hub knuckle are clean and not contaminated. I wouldn't worry about it if you are happy all is well with the fitment - the pad will very soon, if not already, sweep the whole disc face which should then be self evident through the rim.