Brake discs for endurance racing?

[harboged]

Hi,
We're doing 8h endurance races with our 172 and we use endurance pads, such as CL Brakes RC6E or Ferodo DS1.11. The pads are awesome but they are really hard on the discs so I'm wondering if anyone can give some advice on good quality discs that will last longer? To fulfill the rules they need to be of the same design and dimensions as the originals, so preferably no drilled or grooved discs.

Cheers

 

[mikekean]

Standard or Brembo are going to be your only options i think. Can you get away with 2 piece? i run plain 2 piece rotors on my rally car.

 

[harboged]

Standard or Brembo are going to be your only options i think. Can you get away with 2 piece? i run plain 2 piece rotors on my rally car.

Thanks for your advice. Unfortunately 2 piece discs are not allowed. Do you know which manufacturer makes the standard discs?

 

[mikekean]

Textar i think but dont hold me to it lol.

 

[George@RTR_Parts]

Get some Brembo plain HC discs fitted along with some DS1.11 pads, they're not harsh on the discs like the cl compounds

 

[mikekean]

Not that i've seen it happen on a Clio but i've seen the set of Brembo HC's crack very badly when using CL RC6 on a 260hp EP3 used for track work.

 

[harboged]

Get some Brembo plain HC discs fitted along with some DS1.11 pads, they're not harsh on the discs like the cl compounds

Thanks for your advice. We will try that. Besides, I prefer the feel of the Ferodos.

 

[George@RTR_Parts]

Thanks for your advice. We will try that. Besides, I prefer the feel of the Ferodos.

No worries, they're great pads and what I run myself on track. Strong bite, nice feel and release characteristics, last well and kind on discs. What else could you want .

I can also supply those for you , get in touch if after some :up:

 

[harboged]

I'm bumping this thread because we are really suffering from disc wear. We continued to run Ferodo DS1.11 pads because we like the feel and they last all 8 hours of racing. However, our discs are badly worn after 3 hours already, and strong pulses and vibrations during braking start to occur by that time.

We have used OEM sized discs from Brembo, Ferodo and something else (ATE or similar) with the same result.

Does anyone have any advice on discs that will last better for at least all 8 hours of racing with these pads?

The car is a 172 with the 17 Cup brake setup, ie no ABS. It's got duct cooling and TD 1.2 16" wheels. The brakes get really warm but the pads have no problem to last 8 hours.

If nothing works then we might have to upgrade to a big brake kit in order to not stress the brakes as much as now, but that would be a shame since we are more than happy with the brake force as it is now.

Cheers

 

[JB21]

I've managed to warp a set of Focus ST 320mm Brembo HC discs on the road in less than 1000k miles, my own fault though as I abused them learning how to left foot brake, then held the car on the foot brake whilst stationary, DOH!

Just ordered some Textar replacements from Mister Auto for £40 a set.

 

[JamesBryan]

Are they actually warped, as in have you tested the runout on them as standard and then again with a worn set?

3 hours doesn't sound like long to wear out a set of discs.

How many track miles would that be?

 

[harboged]

Are they actually warped, as in have you tested the runout on them as standard and then again with a worn set?

3 hours doesn't sound like long to wear out a set of discs.

How many track miles would that be?

I can not swear they are warped but they start to pulsate during braking. What I can say though is that there are deep grooves caused by the pads. You can easily feel the with your finger nails and the entire disc surface is full of them making the surface very uneven.

3 hours on this track is equal to approx 220 miles.

 

[JB21]

They could just have pad deposits on them, when warped under heavy high speed braking the steering wheel vibrates violently in your hands, if you're just feeling pulsing under your foot then doesn't sound like warping just pad deposits on the disc. Do a run-out test and check for DTV (Disc thickness variation) using a micrometre, if all good then just sand the discs back a bit until smooth again and also check the pads for crumbling, if good re-fit and they should be OK.

 

[JamesBryan]

I'm wondering if it's pad deposits due to pads breaking down under the heat maybe?

Maybe try a different pad just to be sure.

Pagid RS-29 yellow are an endurance pad and they are very good. Not cheap though.

 

[harboged]

They could just have pad deposits on them, when warped under heavy high speed braking the steering wheel vibrates violently in your hands, if you're just feeling pulsing under your foot then doesn't sound like warping just pad deposits on the disc. Do a run-out test and check for DTV (Disc thickness variation) using a micrometre, if all good then just sand the discs back a bit until smooth again and also check the pads for crumbling, if good re-fit and they should be OK.

The steering wheel vibrates violently when braking.
These grooves are not possible to sand. I will take a photo of the sometime.

 

[JB21]

The steering wheel vibrates violently when braking.
These grooves are not possible to sand. I will take a photo of the sometime.

Sounds like both discs and pad are goosed then as the pads will have matching grooves and would take a while to smooth out again on new discs, maybe try Pagid OE discs as I've ran these on a really heavy (1700kg) Mazda 6 MPS with aggressive pads for long periods on track and they held up great. Or maybe just bite the bullet and get some aftermarket discs, stoptech, EBC etc...

 

[JB21]

I've got a set of CL RC8 with meat left on them if you wanna do a trade for the knackered DS1.11S, as I could smooth them out on the road.

 

[harboged]

Sounds like both discs and pad are goosed then as the pads will have matching grooves and would take a while to smooth out again on new discs, maybe try Pagid OE discs as I've ran these on a really heavy (1700kg) Mazda 6 MPS with aggressive pads for long periods on track and they held up great. Or maybe just bite the bullet and get some aftermarket discs, stoptech, EBC etc...

The funny thing is that the pads are really flat, no grooves in them. I'd be happy to buy aftermarket discs if I could be sure they will last longer.

 

[harboged]

I've got a set of CL RC8 with meat left on them if you wanna do a trade for the knackered DS1.11S, as I could smooth them out on the road.

Thanks but I will pass. We tried CL pads and they also lasted well but made the same result to the discs. I run CL brakes on my trackday Opel Speedster and love them though

 

[JB21]

The funny thing is that the pads are really flat, no grooves in them. I'd be happy to buy aftermarket discs if I could be sure they will last longer.

Weird then, I've grooved my Brembo's before but only because I'd burnt the set of pads on track to the metal then had to drive home. Ive also grooved discs when the pad has crumbled and debris has got trapped between disc and pads surface.

 

[James363]

It would sound to me like you are getting the discs too hot, and they are becoming soft. Does your driver brake heavily with his left foot in corners? Try to bed the discs and pads in before the race, getting them up to operating temperature and back down to cold a few times, if you aren't doing this already. You've tried all my go to brands already!

 

[harboged]

It would sound to me like you are getting the discs too hot, and they are becoming soft. Does your driver brake heavily with his left foot in corners? Try to bed the discs and pads in before the race, getting them up to operating temperature and back down to cold a few times, if you aren't doing this already. You've tried all my go to brands already!

I cannot speak for the other two drivers but I usually don't brake in the corners at all, and no left foot braking for sure. I try too brake hard during a short amount of time and not drag the brakes.

Yes, the brakes get very hot that's true so it could be true what you say that the discs get too soft, whereas the pads can cope with the heat.

We bed in the pads according to Ferodo's recommendations but perhaps we need to get the discs even warmer and then let them cool.

 

[withoutabix]

What about

http://www.nitrac.co.uk/

Might be worth talking to them to see if they could even treat some OEM discs for you.

Fair few minis run these discs at time attack and are highly thought of

 

[PAUL JA]

What about

http://www.nitrac.co.uk/

Might be worth talking to them to see if they could even treat some OEM discs for you.

Fair few minis run these discs at time attack and are highly thought of

Funny I was just reading this thread and thinking of Nitrac !! Great minds

Also. I will say that RS29 pads are an endurance pad and pretty kind to disks - my favourite track pad

 

[James363]

Metals do not respond well to thermal shocks, so I should think the more gradually you introduce them into action, the better they will stand up.
With the non vented discs on our historic race cars, we tend to take them out on a practice session and gradually warm them, before taking them up to full pace for a few laps.

 

[bloke]

how do you normally bed pads in?

 

[Pauleds]

Are you holding the car on the brakes in the pits on changeover? Red hot coming off track, then holding on the brakes ain't gona be good for them.

 

[James363]

It's true, we use chocks on long strings to make them easy to remove on ours in the pits. Works very well on uphill pit lanes, but is prone to mistakes on the downhill ones.

 

[harboged]

What about

http://www.nitrac.co.uk/

Might be worth talking to them to see if they could even treat some OEM discs for you.

Fair few minis run these discs at time attack and are highly thought of

Funny I was just reading this thread and thinking of Nitrac !! Great minds

Also. I will say that RS29 pads are an endurance pad and pretty kind to disks - my favourite track pad

Thanks for your advice, guys! I will look into both Nitrac and RS29 pads

 

[harboged]

how do you normally bed pads in?

We have followed Ferodo's recommendations here:
http://www.ferodoracing.com/products/car-racing/pad-bedding/

 

[harboged]

Are you holding the car on the brakes in the pits on changeover? Red hot coming off track, then holding on the brakes ain't gona be good for them.

We try not to hold the car on the brakes in the pits. We put something in front of the wheels usually.