grooved brake discs qn.

[shirt]

just a quick one: what effect does the number of grooves in the disc have on braking performance and pad life?

car is a 600kg locost. the discs i'm looking at are from the same manufacturer and are available in either 8, 12, or 16 grooved versions.

[HustleRussell]

with the right pads, you shouldn't need grooved discs to stop a Locost. They'll just make the discs weaker, more noisy, and more prone to warping.

[Ozzie Osmond]

Grooved discs are generally used for "appearance" only, unless you buy very expensive very high performance items.

The more "groove" you have, the less "disc" you have making friction against the pads. Which is a bad thing in 99% of applications.

The purpose of the groove is to help clear water (it it's getting rained upon), brake dust (if your pads abrade very quickly) and any gases released from the pad when it is heated to extreme temperatures.

[Vitorio]

HustleRussell said:

with the right pads, you shouldn't need grooved discs to stop a Locost. They'll just make the discs weaker, more noisy, and more prone to warping.

I'd agree with this, if you have a decent sized disc it should stop a 600kg car easily, and if you are doing repeated breaking a vented disc will do more then a grooved/drilled one.

[djdestiny]

I put grooved discs on a car years ago, it made no difference at all apart from the extra noise (which was annoying)

[shirt]

interesting.

fwiw, the car is track only and the tracks here are wide and fluid so most of the braking is done late and hard.

discs currently are std. sierra items - 240 x 24 vented front and 253 x 10 solid rear. it has std. sierra calipers that are being refurbed and i reckon i'm going with ferodo ds2500's [recommended by a few friends].

i read that these pads do not create a lot of dust but given that noise isn't an issue i thought the grooves would help given the small disc sizes.

my aim is to have strong brakes with good feel and low fade without having to stump up for aftermarket calipers. i'm fitting a hydraulic handbrake and brake bias valve as i plan to start autocross/autotests.

ambient temps will be 25-30deg all season if that makes any difference. no rain but plenty of dust. tyres are grippy r888's but will be fitting slicks when these wear out.

Edited by shirt on Wednesday 29th August 11:57

[TEKNOPUG]

I'd spend the money on better pads personally. If people with the same cars are saying they are good, give them a try. They are certainly cheap enough to experiment with. They are at best, a fast road pad. However, given how light your car is, they may suffice. I'd look for a track focussed pad, such as ones from Pagid or perhaps try the EBC Blues if on a tighter budget. Make sure you are using a decent brake fluid with a high boiling point too. Standard Sierra calipers and discs should be fine for your car, given it's weight. Concentrate on the friction material and fluid, as they will be the first things to fail under repeated high-speed braking.

[shirt]

cheers. just looked at burton and europerformance and seems the pagids and blue stuff are only made for the cossie caliper. what is the ds3000 like as a track only pad?

[TEKNOPUG]

When you said Sierra, I assume you had the Cossie ones.

Get the Cossies ones - much better choice of pads available

They can't be that expensive?

[TEKNOPUG]

shirt said:

cheers. just looked at burton and europerformance and seems the pagids and blue stuff are only made for the cossie caliper. what is the ds3000 like as a track only pad?

DS2500 fast road/track
DS3000 race
4003 race for lightweight cars (single seaters)

I'd go for the DS3000s Ferodo are your only choice.

[fushion julz]

My car is twice the weight of yours...

I use DS2500 pads and they are excellent...no fade after continued hard lapping on tracks such as Cadwell Park or Brands Hatch. My discs are Black Diamond grooved on the front and standard BMW on the rear...but the standard front discs are also pretty good with the DS2500...

I've tried DS3000 (as well as EBC Red and Pagid) and I'd say they are pretty good too...only they take ages to heat up properly and until then they are wooden, lacking in feel and are prone to snatching. Unless you are sure you can keep the brake tempreature up, I'd stick with DS2500.

ETA: Dust isn't an issue with either Ferodo compound, but the EBCs are awful for dusting

[HustleRussell]

I use my Caterham exclusively on track, I'll either be racing, qualifying or testing. I have Spitfire front brakes (small, solid discs) and Morris Ital drums on the back. The higher powered cars with semi-slick tyres run Spitfire front and Sierra rear. None of us have fade problems, and none of us have any difficulty locking up on hot tyres.
You have much more braking power than me. I suggest DOT 4 or Castrol SRF as an upgrade, along with Ferodo or Mintex pads. Upgrade the fronts first, you may find that you want to keep standard rears so you don't end up with too much rear braking effort.

[shirt]

TEKNOPUG said:

When you said Sierra, I assume you had the Cossie ones.

Get the Cossies ones.....They can't be that expensive?

looks like £200-300 for a refurbes pair and a wilwood big brake kit is £500. tbh i'm spending rather a lot elsewhere on the car which is why i was just aiming for caliper rebuild and pads/discs. the discs that are on there look fine and if grooved offer no benefit i'll just keep them on and save some cash.

russell and others, much obliged for you input. i have decided on keeping the oem discs and will fit ds2500 pads. i don't think i'll be generating enough heat on a trackday to go up to 3000s and i can always revisit if autocrossing demands it.