annealed brake discs

Post by **polo2k** » Sun Jul 12, 2009 3:46 pm

Hi all, ive got question that is not about a minor but might relate to them so i thought In would post it here.

I have an 01 Golf TDi which has a bit more get up and go than when it left the factory. I have fitted the front brakes of an Audi TT which are 56mm bigger overall diameter but identical in all other respects. I have used the calipers that are meant to be used on these discs (same as the oem golf ones)

While I was doing some checks recently I noticed that the pads are 75% worn but the discs are at about 80% and they are the first set of pads on the discs. Im more used to getting 2 or 3 sets of pads out of a disc!

The discs are grooved (so should eat pads) and the pads are a fast road organic compound.

is it possible that ive annealled the disc and softened it? I dont get any vibration at all. Ive checked for bluing but theres none there. I have had cars getting brakes hot enough to get fade on OMP kevlar pads and get the discs glowing!

What is the solution? try a different combination of discs and pads? add plenty of ducting to the caliper/disc?

thoughts please

Post by **bmcecosse** » Sun Jul 12, 2009 4:00 pm

Modern pads have no asbestos - and tend to have iron powder in them instead. They DO wear the discs more than before! At least the discs won't go rusty. Just try using the brakes less ! Anticipation is the name of the game.

Post by **polo2k** » Sun Jul 12, 2009 4:05 pm

Im only concerned as im too young to have ever used asbestos pads and ive never had discs wear faster than pads. I presume its to compound so ill have to choose something else next time.

I try and anticipate but spirited driving in a tonne and a half of peoples wagon on the back roads of wiltshire tends to lead to heavy break use.
When I had my polo I lived in the french alps and managed to get the car to do stoppies on 239mm front discs without any weight reduction just by playing with compounds and suspension settings.
stoppies aint quick by any definition but they sure relieve the tedium in the hairpins!

Post by **eastona** » Sun Jul 12, 2009 4:35 pm

What's a stoppie?

My SAAB had Ferodo DS2500 pads with brembo discs, no grooving or drilling, that stopped very well, even when very

hot.

I used to be quite hard on brakes.

but still had three sets of pads to disks. Wearing discs at that rate is quite unusual, they must be very aggressive pads?

I'm not so bad now, and have tempered my enthusiasm!

Andrew

Post by **d_harris** » Sun Jul 12, 2009 4:36 pm

Stoppies are like wheelies, but its the back wheels that come up.........

Post by **jonathon** » Sun Jul 12, 2009 4:41 pm

Why not use the std Audi TT pads ?.

Post by **Peetee** » Sun Jul 12, 2009 5:54 pm

which has a bit more get up and go than when it left the factory

Does the traction control system utilise the brakes?

linearaudio · Post by **linearaudio** » Sun Jul 12, 2009 6:54 pm

Try a harder grade of pads next time maybe? If your pads are meant for the (considerably) smaller diameter disc then the angular velocity of the Audi discs may be too great for the material. Soft can wear hard in certain situations, this sounds like one of them!

Post by **polo2k** » Sun Jul 12, 2009 8:11 pm

The audi pads are even softer and use the same compound as the golf. I used to be able to cook them reliably!
The traction control is purely on the throttle.

The DS2500 are a nice pad but expensive too!

I think ill have to have a look at what there is out there at the mo since its been a while since ive bought brakes.
The only difference between the golf and TT brakes are the disc and the caliper carrier. even the pads and clipers are the same part number.

Post by **bmcecosse** » Sun Jul 12, 2009 9:13 pm

I assumed you meant that the discs were at 80% (ie 20% worn) of the original thickness. If they were non-standard discs then they may have made from the tins John West rejects! Just fit plain discs - there is no advantage in grooved/drilled etc etc discs!

Post by **jonathon** » Sun Jul 12, 2009 10:32 pm

there is no advantage in grooved/drilled etc etc discs!

can you explain why you believe this to be the case.

Post by **bmcecosse** » Sun Jul 12, 2009 11:04 pm

It's been discussed lots Jono - on many forums/sites. It's just a sales gimmick.

Post by **jonathon** » Sun Jul 12, 2009 11:25 pm

So what do you say to this. I know it centres on Rossini but the underlying principal is sound.

Performance Brake Discs On Cars Could Help Save Lives
Published: 25th March 2005
Rossini Performance Brake Discs

Around 38,000 people are likely to be seriously injured or killed on British roads this year. Government research has found that one-in-three of all serious accidents will be caused by a driver simply not being able to stop in time.

Many manufacturers are fitting brake discs imported from China where labour rates and steel is cheap compared to Europe. Vehicle brake discs are not covered under a manufacturer’s warranty as they are a wear and tear item, like tyres and exhausts and since brake discs can wear in less than 25,000 miles, car dealers therefore benefit from charging a motorist for replacement.

Car manufacturers could fit performance brake discs that could improve road safety. Only a few prestige vehicle makers such Porsche and BMW fit drilled and grooved performance discs instead of standard discs - and only then to their top of the range models. Virtually all other vehicles on the road use the same old technology that has been fitted to cars for the last 20 years.

Improving the brake discs fitted to your vehicle could prevent an accident. When driving at speed and sudden braking takes place, you can experience brake fade. This is when your vehicle simply will not stop as quickly as it should.

Brake fade occurs because the brake discs heat up. The hot surface of the brake disc glazes the friction material of the brake pads. In wet driving conditions the brake pads can lift from the brake disc. Stopping your vehicle can take twice as long. A third of all motorway accidents could be a result of ‘brake fade’ and could be prevented.

A UK manufacturer has developed a new range of specially multi-drilled and grooved performance brake discs. It is claimed the drilling cools the brake disc quickly. Grooves in the disc reduce brake pad glazing and repels brake dust and moisture. The grooving helps improve brake grip - instantly.

Titanium in the disc provides added strength and durability to prevent brake disc warping - the main cause of brake judder. The supplier claims the Rossini Performance Brake discs can improve stopping distance by as much as 40%. The unique brake disc design has the manufacturer’s logo embedded in to the disc face so any sign of uneven wear is quickly detected - and when the logo disappears the discs are down to minimum thickness - and legally in need of replacement - an additional safety feature that is not used by any car manufacturers in the UK.

The supplier of the Rossini Performance Brake Discs has moved more than 80% of their production to the UK in order to maintain high quality standards. The company expects most car manufacturers will move on to performance discs in the next few years as motorists demand improved safety. Just like an airbag and seatbelts, performance discs are likely to become standard kit - until then it’s down to the owner to upgrade.

Mark Cornwall of www.carparts-direct.co.uk, the UK mail order distributor of the Rossini Signature Performance Brake discs said: "The technology is well proven. Virtually all race and rally cars now run on drilled and grooved performance brake discs. Not only do the Rossini brake discs provide excellent stopping power for safer driving they look terrific too - and cost little more than dealers charge for a standard brake disc."

Rossini supplies drilled and grooved performance signature discs for virtually every vehicle on the road - including family saloons, performance cars, 4x4’s, classic cars and of course competition vehicles.

Source www.carpages.co.uk

Post by **bmcecosse** » Mon Jul 13, 2009 12:09 am

Like I said - sales gimmick! However - there is no doubt better steel with suitable alloying elements will make longer lasting/higher coeff of friction discs - and obviously they will cost more than discs made from the Tins etc. I won't argue with that!

Post by **RogerRust** » Mon Jul 13, 2009 7:53 am

bmcecosse wrote:Like I said - sales gimmick!

Oh just stop it BMC or this will just turn into a slanging match and get very boring.

(this is a personal plea - not wearing my moderators hat by the way)

Post by **jonathon** » Mon Jul 13, 2009 8:17 am

If the original question is answered with facts then we can easily draw a conclusion.
Hope you didn't include me in the 'boring slanging match' Roger

Post by **d_harris** » Mon Jul 13, 2009 8:28 am

Quick question, if grooved/drilled discs don't have any benefit how come you never see solid disks on race cars? Most of whom have pretty decent R&D budgets......

Post by **Peetee** » Mon Jul 13, 2009 11:04 am

To my mind your brakes can have the best heat dissipation design in the world but if the wheel and the shape of the adjacent car panels do not encourage airflow to the brake then you're wasting your time.

Post by **Kevin** » Mon Jul 13, 2009 1:10 pm

bmcecosse wrote:Like I said - sales gimmick! However - there is no doubt better steel with suitable alloying elements will make longer lasting/higher coeff of friction discs - and obviously they will cost more than discs made from the Tins etc. I won't argue with that!

Just a personal observation but I do get the impression that you don't seem to like improved modern brakes Roy or anything that makes the driving experience a little nicer in these days of heavy traffic, and as you used to be a safety officer in your previous working life I confess to being a little confused by your remarks.
To me safety is rather important issue but I appreciate that others don't think the same way.

Post by **polo2k** » Mon Jul 13, 2009 9:53 pm

Looks like I lit the blue touch paper there,

oops
I am currently using grooved discs as a continuation of testing to find my own prefered style
I used to eat through solid discs (with the central vanes) and turn them blue with very little effort.
I found drilled only discs would disipate the heat very well but I didnt feel that the increase in cooling made a massive overall increase in performance as I would have to be on the brakes as hard and as long to slow the car equally, the only difference being that the pads and discs survived!
I tried drilled and grooved discs and have had some good and some bad ones, the worst I have used started cracking around the drill points when half worn! I was told this could be harmonic imbalances amplified by the drills and grooves.
The discs im using have performed admirably (grooved and dimpled) and I like the feel of them. They have lasted about 18 months and I would like to prolong this for longer next time as they are about £150 a pair. (must be expensive bean tins)
I am happy with these discs and may try grooved only next time I just thought I might as well improve on them if I can

Kevin: safety is important on brakes and I agree to your last statement. if I ever end up getting chatty and matey I will change MOT station because id rather fail than die!
The brakes i am discussing here are perfectly adequate for safety but more brakes cant be a bad thing can they?