Rear C204/ W204 Drilled Brake Discs

[Ronan1982]

Hi All,

I am struggling to find Drilled Rear brake Discs, For my Mercedes C204.
Its only a 220.
I think only Tarox can help me.

I just wanted to match them up with the Front Discs, and yeah its just for looks as the current ones do a fair job!

Then Going to Put some Red Stuff Pads in also.

Was going to go down the route of getting a bigger piston Calipers, but prices are extortionate.

Any help would be greatly appreciated.

Many thanks,
Have a great weekend.

 

[ernie]

I would stick with what you have! If you change the standard discs to drilled, if they are not the same surface area, you will almost certainly upset the balance front - rear, particularly if you change to a larger caliper.

...apart from insurance implications.

Ernie

 

[Ronan1982]

Hi Ernie,

I just wanted to get the same rear discs (size/measurements etc) but just hoping a company out there has drilled ones? finish might be different. Not fit a bigger Disc though, as I would still be running the same OEM rear caliper.
Not sure if that would still play with the balance?

In regards to the Bigger caliper, I should have made it clear that it was for the front set up!

Cheers

 

[MancMike]

What Earnie means, is that if you drill a load of holes in something, there's less surface area for the pad to contact and produce friction with, as some of it isn't there anymore.

I think it would reduce the rear braking efficiency if anything but I'm no expert.

 

[PobodY]

I don't think it makes any kind of significant difference to the braking efficiency; that's as much to do with the moment you can apply by having a calliper at a distance from the centre of the axle.

If anything it's less prone to fade, but arguably more prone to cracking.

 

[ernie]

What Earnie means, is that if you drill a load of holes in something, there's less surface area for the pad to contact and produce friction with, as some of it isn't there anymore.

I think it would reduce the rear braking efficiency if anything but I'm no expert.

I was actually thinking that any disc with holes would be of a larger diameter, probably to suit a higher performance set up, which in turn would mean larger calipers. Sorry for the confusion!

Ernie

 

[Yugguy]

Not at all bud. Both standard solid and sport drilled front discs are 295mm.

I'd be interested in drilled rears just to match the drilled fronts I'm going to put on tomorrow

 

[hotrodder]

Friction is mostly independant of surface area... sliding a house brick along a surface is a common example, the bricks weight is a constant but surface area depends on which side it's layed on. Sat on it's small end it's weight is exerted over a smaller area, lay it on it's side and the force is spread over a larger area

This is why when your missus steps on your foot it doesn't hurt if shes barefoot or wearing slippers but is 'kin painful if she's wearing stillettos. As an aside it's also why fitting larger tyres to a car doesn't result in 'more rubber on the road'... the contact patch area is the result of the weight the tyre is supporting and the pressure in it. Fitting wider tyres changes the shape of the contact patch not it's size, a narrow tyre has a longer, thinner contact patch while a wider tyre has a shorter, wider one. A longer narrower contact patch means the tyre needs to flex more. This generates more heat and hinders cooling

Brake pad size doesn't affect things from a friction POV. Larger pads take longer to overheat and/or wear out

The number of pistons in a brake caliper is irrelevant to the amount of pressure applied to the pads. The bit that matters is the total piston area on one side of the caliper only (see Mr Newton's laws, specifically the 3rd one)

If the piston area in brake calipers is increased but the master cylinder is left alone then the force applied (for a given pedal pressure) increases but brake pedal needs to travel further [/hydraulic multiplication]

If the total piston area is preserved but one large piston is replaced by several smaller examples then 'more even' pressure can be applied to a larger brake pad to make the most of it (pad life, taper wear etc)

Several small pistons with the same total area as one larger piston changes the shape of the caliper and pads that fit it. From squarish to a longer but narrower rectangle. For a given max disc diameter this slightly increases the 'effective' disc radius which in turn increases brake torque slightly. The bigger multi piston caliper is also longer and shallower, the later point makes it stiffer

While bigger discs increase torque radius their main purpose is to provide a larger heat sink... more mass and a larger surface area to radiate heat. Generating enough brake torque to overcome a tyres grip with little pedal pressure is easy. Dealing with the heat generated is the difficult bit which is why quicker cars need bigger brakes. Kinetic energy increases with the square of velocity i.e. double the speed and theres 4 times as much energy that brakes need to turn into (mostly) heat in order to stop

Drilled discs are mostly a pointless fashion accessory these days. In the old days when pad outgassing was more of a problem it served a purpose by providing an escape route for gases. These days all they do is cost more and increase the odds of discs cracking before they're worn out. Min disc thickness is often less than undrilled discs too further compounding their pointlessness. On a 'real' race car they also save a few precious grammes but due to their drawbacks are usually only fitted to the rear brakes that contribute relatively little to stopping a front engined car due to weight transfer

 

[Yugguy]

Good post. I'm happy to admit I'm fitting drilled just for the look.

 

[Ronan1982]

Good post. I'm happy to admit I'm fitting drilled just for the look.

Thanks for the replies guys!

If you find any Yugguy please post up the link. I can only find them on the Tarox website but cost a fair bit more than the OEM ones.

Its just a personal Preference and a tad bit of OCD, just think it would look smarter all 4 corners the same.

 

[PobodY]

My preference would actually be grooved and dimpled rather than cross-drilled. - On the Nissan that actually gives a bit more bite than standard "flat" discs.

 

[Deleted member 113659]

Try Black Diamond website.

 

[ash59fifty-uk]

Save your money and get the car remapped instead

 

[whitenemesis]

Cross drilled discs are potentially weaker than solid or grooved.

How many drivers or service technicians clean out the holes at each service, as required in the service TDs?

 

[A250 Bennyboy]

Red stuff pads are designed for the track and work best at high temperatures, green stuff pads are designed for road use.

When I put drilled disc's and green stuff pads on my ST and informed my insurance company they canceled my cover.
It's classed as a paformance upgrade

Had a right job finding an insurance company that would insure me.

 

[markjay]

Some years ago I had front discs on my Alfa drilled by an expert, very complex process, as apart from the obvious pitfalls (cracking) there is also balancing to be considered. The location of the holes were marked in advance very carefully and with great precision, then the disks were mated to each other back-to-back using bolts and drilled through.

On another car I used grooved (not drilled) Tarox discs at the front, with Tarox pads, they worked well and resolved the brake fade issue the car had with the original discs (engine was modified and output increased etc), but they did need some worming-up before reaching peak performance.

As for the rear brakes.... the harsher you brake, the less they matter.... their primary function is to keep the car stable during braking, and in recent years they are also part of the ESP system.

So I don't think that 'tempering' with the rear brakes will make much difference to braking efficiency as long as you keep a balanced setup, but you can confirm this with a 'before' and 'after' test at an MOT station.

And yes you should inform your insurer.

 

[ernie]

Many years ago I had a problem with the rear drum brakes on a Morris 1800 Landcrab, remember these? The n/s kept locking up, but I knew the o/s was working OK. I was just about at my wit's end because I couldn't understand what the problem was.

Evntually I stripped both wheel cylinders and discovered that the n/s was the wrong cylinder - it had a larger diameter than the other. Presumably, as the master cylinder was common, the pressure exerted must have been the same but over the greater surface area of the wrong piston, hence the locking up.

Ernie

 

[Ronan1982]

Save your money and get the car remapped instead

Car is mapped already, was done by GAD Tunning!

 

[PobodY]

Red stuff pads are designed for the track and work best at high temperatures, green stuff pads are designed for road use.

When I put drilled disc's and green stuff pads on my ST and informed my insurance company they canceled my cover.
It's classed as a paformance upgrade

Had a right job finding an insurance company that would insure me.

I run Yellow Stuff on the road in the Nissan (with Blue Stuff for track days). - Never had a problem with them; better than OEM.

No issue at all with insurance because it improved the safety of the car.

 

[Tedswagon]

All you need to know about it

https://youtu.be/78wbht355R8