Brake fade

davekmoore · Postby **davekmoore** » Mon Sep 19, 2016 11:51 am

BARMY has little Wilwood 6 pots with QFM A1RM 780 degree C pads on the front and new Sport rotors with race pads on the rear. Braided lines all round. Good wide tyres. No fluid leaks. 244rwkw. About 1220kg with driver and half a tank of fuel. Corner weighted. Near race alignment. Stops perfectly except as described below.

The pads are the best so far by a long way for stopping and for not wearing out in a single event. But there are still signs of what seems like fade 2/3rds of the way into a longer braking event such as turn 1 at Sandown or turn 4 at PI. Both are from high speed to low speed. Especially if I miss my braking point, pressing the pedal harder in the last 1/3rd does not produce more braking. In fact, it seems to produce less. It seems not to get near to ABS intervention, which is a good thing really. But it also doesn't seem to be getting near the braking abilities of the tyres, which is less good.

The pad suppliers are suggesting either going to a 800 degree pad, or that there's a vacuum issue.

They ask: "Does it definitely feel like pads, and not a vacuum related issue? That more sounds like you haven't had any overlap between throttle and brake and lost a bit of vacuum assistance."

Of course, I'm also aware of there being a driver issue with using too much brake to slow down too much, but it sometimes happens when I do hit my braking point, as well as when I brake too late. And are they suggesting I should deliberately be off the throttle, pause, then be on the brake?

Or do I just go for the 800 degree pad and/or try to improve ducting? There are presently small circular holes where the foglights used to be, leading to 2.5" pipes which exit at purpose made backing plates. Would these actually grab more air if I added a larger or better placed gathering area, or would the size of the pipes limit the airflow too much?

Thoughts appreciated from those who understand these things.

Trackphotos · Postby **Trackphotos** » Mon Sep 19, 2016 12:01 pm

I've cooked A1RMs at QR in a stock-power NB. They aren't enough if you're pushing a standard car hard, let alone a massively powerful, slightly heavier one on a torturous track like Sandown. You need ducting. Wouldn't hurt to go to a better pad than the A1RMs too, but it tends to get expensive. I have managed braking from higher speeds in less distance at QR, on 7 lap sessions instead of 5, and not had any fading from Winmax W5s without any ducting. I have just gotten some Singular motorsports ducts in preparation for some long sessions at QR in a month or two, but even without the ducts, the W5s can do what the A1RMs can't. Unfortunately they're $220/set instead of $119 for the QFMs.

Postby **NitroDann** » Mon Sep 19, 2016 12:13 pm

davekmoore wrote: And are they suggesting I should deliberately be off the throttle, pause, then be on the brake?

If they are move on.

I think you just need a more serious pad and get whatever ducts on that you can. You have 400 crank hp/tonne car it needs a lot of brake pad. There truly are very few road cars on the planet with this sort of straight line speed. If you want proof line up some cammed up VF commodores at the lights and you will see what I mean.

Dann

Magpie · Postby **Magpie** » Mon Sep 19, 2016 12:25 pm

Sounds like pad fade, agree with what Trackphotos has suggested. Notwithstanding it maybe worth checking the vacuum on the booster line, however this normally would make them spongy and just required more effort (no assistance) to push the pedal in.

Using some heat paint on the discs and temperature strips on the calipers will help you track where the issue is. However it does sound like a pad issue and not a fluid issue. Whilst it could be pad knock pad by the description this could be ruled out as this situation is more akin to no brakes on the first application (flat to the floor) then the brakes act normally on the second application. I have only ever had this a few times at Eastern Creek going into T4. Are you running up on any kerbs before using the brakes?

Trackphoto's has also dríven mine (albeit for a few laps) with W6.5's on the front and W3's on the rear.

http://www.motorsportbrakes.com.au/product-spotlight-winmax-w5/

davekmoore · Postby **davekmoore** » Mon Sep 19, 2016 1:05 pm

That's pretty much a consensus then, and makes sense. Need better pads and/or better ducting.

Anyone know of a company who will put friction material on Wilwood 6712 backing plates, or will supply the whole thing, fairly quickly, and at a sensible price?

hks_kansei · Postby **hks_kansei** » Mon Sep 19, 2016 1:31 pm

With the ducting you could look into putting a belmouth or scoop of some kind around the foglamp hole entrance.

Basically widen the area the air is being pushed in from.

Even a big funnel with he end cut off to be he same diameter as the foglight hole would do the job (to see if it helps for a low price, then if it does look into a less "I glued a funnel to my car" method to do he same)

davekmoore · Postby **davekmoore** » Mon Sep 19, 2016 1:45 pm

hks_kansei wrote:With the ducting you could look into putting a belmouth or scoop of some kind around the foglamp hole entrance. Basically widen the area the air is being pushed in from. Even a big funnel with he end cut off to be he same diameter as the foglight hole would do the job (to see if it helps for a low price, then if it does look into a less "I glued a funnel to my car" method to do he same)

Thank hks. So you're happy that the smaller size of the existing ducting won't reduce the flow by too much if a bigger collector is created? Of course there will be decent pressure at the higher speeds where the issue is arising, so that may help overcome the flow issue?

Anyone done anything along these lines? Care to post pics?

hks_kansei · Postby **hks_kansei** » Mon Sep 19, 2016 2:52 pm

If you want to know the maximum airflow of he pipework you'll be best to find a calculator on Google (I assume there would be something on the web you can enter X diameter, x length and get a theoretical maximum flow)

The collector would just make sure that whatever the pipe can flow (it may be already at its limit?), it's being forced to flow somewhere around that amount rather than if its only catching a portion of the air it potentially could.

greenMachine · Postby **greenMachine** » Mon Sep 19, 2016 3:33 pm

The three steps to fixing my brake problem were:

Singular 75mm brake ducts, with 75mm hose to foglight holes. I used aviation bellmouths from a supplier in Brisbane.
Decent pads - ask Daniel at Deckspeed about the Carbotechs he sells.
Vacuum pump, preferably with a 2-4l reservoir. I don't have a turbo, but I do have cams with a big overlap, so very poor vacuum.

Don't worry about getting friction material on those backing plates, just get a supplier that sells a pad for that calliper. If they can't find one in their catalogue, you have the wrong supplier.

My symptoms were a hard pedal, poor stopping and no ABS pulsing. The vac pump/reservoir fixed that. The ducting to the brakes was to prevent problems emerging now that the brakes are working, so far so good. The pads are unchanged, it was just a matter of getting the pressure to them consistently, every time, all the time.

:mrgreen:

Magpie · Postby **Magpie** » Mon Sep 19, 2016 4:03 pm

I will have a set of 2.5" Trackspeed brake ducts soon, swapping them out for the 3" Singular versions.

davekmoore · Postby **davekmoore** » Mon Sep 19, 2016 4:40 pm

greenMachine wrote:The three steps to fixing my brake problem were:

Singular 75mm brake ducts, with 75mm hose to foglight holes. I used aviation bellmouths from a supplier in Brisbane.
Decent pads - ask Daniel at Deckspeed about the Carbotechs he sells.
Vacuum pump, preferably with a 2-4l reservoir. I don't have a turbo, but I do have cams with a big overlap, so very poor vacuum.
Don't worry about getting friction material on those backing plates, just get a supplier that sells a pad for that calliper. If they can't find one in their catalogue, you have the wrong supplier.

My symptoms were a hard pedal, poor stopping and no ABS pulsing. The vac pump/reservoir fixed that. The ducting to the brakes was to prevent problems emerging now that the brakes are working, so far so good. The pads are unchanged, it was just a matter of getting the pressure to them consistently, every time, all the time.

Thanks for the thoughts.
Will look into bellmouths.
Won't be going to Deckspeed again.
Any need for a vacuum pump on a car with a turbo?

davekmoore · Postby **davekmoore** » Mon Sep 19, 2016 9:01 pm

Mine has 2.5" Trackspeed ducts. The 3" ones cause the need for more mods to clear them. Will look at some way of diverting more air into them. Would be very happy to see pics of anything anyone else has done to make this happen.

Talking with Marty at Motorsport Brakes about compounds. His 6712 backing plate is a tiny bit different from the Wilwood one. Anyone used his 6712s?

Am I right in thinking that having a turbo will not on its own cause a lack of vacuum?

Postby **NitroDann** » Mon Sep 19, 2016 9:14 pm

davekmoore wrote:

Am I right in thinking that having a turbo will not on its own cause a lack of vacuum?

Correct.

davekmoore · Postby **davekmoore** » Mon Sep 19, 2016 9:17 pm

Took your time there Dann!

How come, now you're a sponsor, your sig doesn't mention your magic tricks? Or do you just rely on certain people dropping your name from time to time?