Brake Pads

[Peter Mallett]

Right then folks. Brake pads.

When I first got into tin top racing I found that the best pad for my application was the Ferodo DS11, which was extremely hard and would eat discs in a pretty short time. However I was racing a MG Metro and running the standard non-vented disc. I could really hammer the brakes and never worry about fade.

I then modified the car and ran vented discs with two pot callipers. Again the DS11 pad would work but by far the best was the Mintex pad (number escapes me). This was because the Ferodo would run too cool and take a little more time to bite than the Mintex. Of course the Mintex wore out that much quicker.

Running the Capri, which weighs in at 1072 KG plus me, I run Willwood four-pot callipers on vented and cross-drilled discs. When I ran the original Mark 2 Capri I used the standard front brakes with Ferodo DS11 pads. It’s a matter of record that this nearly cost me more than money when the brakes failed at the end of Park straight at Cadwell and pitched me over the tyre wall into the spectator area. I still brake far too early for this corner, which must be costing me 2 seconds, a lap!

The pads I have found to be the most user friendly are Ferodo 3000ff, which are hard but have an initial bite that comes in almost immediately. Last weekend I tried EBC Yellowstuff pads, which are carbon based. As many will be aware there are a fair amount of corners at Cadwell but also some fairly long distances between them. I entered the Mountain at a fair old lick and braked, only to find that the pads were not hot enough! I spun up the hill, which is pretty unique.

Not having time to change back to my original pads I continued and qualified pretty well down the grid of 25 cars. The brakes, needless to say, were appalling and on inspection afterwards, I had hardly touched the surface!

I changed back to my original pads for the race and felt so much more comfortable. This is not so much a query, nor is it an endorsement for Ferodo. However, it does demonstrate how something as fundamental as brake pads can be different for different people.

It would be interesting to hear the experience of others.

[Sparky]

Our driver doesn't brake until he comes off the track!

I think the principles of grasstrack driving are much different to those of tarmac - our cars tend to use feint motion to 'slow' for the next bend. And being on oval, the only time you need your brakes is when some Arse turns sideways in front of you - kind of a self-induced T-bone!

We have got a fresh set of pads in the pitbox, but they've never been needed!

Sorry Pete!

What about your grooving or drilling? (not the kind you do on a Saturday night, mate!)

The main reason for fade is the build up of the gases between the pad and the disc. The grooves/drillings don't just carry away debris (most peoples view) they allow the 'boundary layer' of superhot gas to escape, thus allowing the pad to contact the disc fully. Could it be your pads aren't getting hot enough coz of this?

[Warwick]

Our local brake guy has some trick paint you put on your calipers and it changes colour depending on what temp your brakes get to,going by this he then goes you need compound xxx and your problems are over,this approach worked well for one crew i race against,they found the pads they were running couldn't get hot enough to work properly after a compound change(staying with the same brand) the problem was solved.

[DAVID PATERSON]

In my class of racing we are restricted to solid (non-ventilated) discs, not cross drilled or slotted. Because the budget is very limited I have been using standard street pads and at Lakeside Raceway I've had no major problems with fade, also I get a year out of a set of pads and several years out of a disc. Qld Raceway however is a completely different story, with standard pads, I'm up for AT LEAST one pad change PER MEETING! Even a set of metal pads will not last a whole meeting and I get brake fade after 3 laps! We're now working on cooling ducts and hopefully they'll help, because the rules won't allow us to do anything else. Another thing about standard street pads is that you don't have to warm them up, they work best when they're stone cold.

[yelwoci]

Pete,

Firstly, I was following you for 4 laps into Park, you seemed to me to be braking very hard and deep into Park. You problem seemed to be that your terminal velocity was only about 125mph.

For what its worth to you and to the 'freshman/persons(;-))' out there I'd like to give my experience of brakes in a vehicle which is about 1000kg wiv me (distr. 60:40), has little engine braking and can clear 135mph on UK tracks.

I was advised by a brake 'guru' in Bromsgrove, who if my memory serves me right was an AP apprentice on the long tail Le Mans MG C? (Pete help!), to go for the stiffest calipers possible. He specifically advised against the then current Wilwood calipers as he reconned that the small WW calipers were designed for the rear of US sedans and flexed too much for primary use.

I use 4-pot AP Forest units on 260mm (10.25") discs at front and completely standard series II single pot sliding yoke calipers at rear.

I started with split brakes, no servo, with 2x 0.625 m/cyl driving Mintex 171s at front, std rear. Everyone told me the 171s were too hard. As the race progressed the rears disappeared (until I girated to cool them off!). I thought the fronts were fine.
I replaced the rears with Hawk Blues (only ones availbale for rears), which took more heating that the 171s and then bit...autogirate again.
By this time I had destroyed a set of front discs and following advice I used M1151 which I didn't like.
I moved to Hawk Blue all around and to reduce the initial bite dropped the rear m/cyl to 0.75.

Braking is fantastic now ( I've also freezed the discs to make them last)

Use Very stiff calipers.
Mount them well (not the best in mine)
Adjust the caliper piston pressures via m/cyl sizing to suit the pads
Pay attention to the bedding in procedures.

Hope this is of intertest
IanC

[Peter Mallett]

Er.

I know I was slow in practice. That's what I said. I was one of very few people who improved their times in the race, because the pads were working. Please buck up Yelwoci.

BTW. I eased off on lap six because I'd beaten hell out of my heavily treaded front tyres.

[torana]

in the historic touring car movement in Melbourne most peole are using a Carbon Kevlar Pad. The Torana originally came with 10" solid disc brakes with two spot Girling calipers. These work fairly well although under the 2000 regs we are allowed the freedom to used any production caliper of the period(1964-1972). Although the discs can't be changed to ventilated discs. So the majority of racers are heading towards Girling 4 spot callipersas fitted to volvos of the period.

Under the regs covering 1959-1964 cars such as Cortina GT are still using carbon kevlar with some racers using a Hawk Pad. I will find out some mere deatils and add them at a later date. Have to go to the State Rcae Committee Meeting at 7:30 pm local in 15 mins time.
BFN