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Light Weight Material for Disk Brake Rotors

Light Weight Material for Disk Brake Rotors

(OP)
I am interested in the carbon/carbon rotors or other lightweight solutions to reduce rotating mass in a drag race car.

I know carbon/carbon are used in F1, so should be durable enough for a drag race car, and should significantly reduce the inertia of the wheel hub assembly.

I guess I will also do a Google search, but I expect I will get more qualified and objective advice here.

I already asked this question in another thread in another forum, but I think this is a more appropriate place, and so as to avoid hijacking another thread, I will transfer the answer already received over to here, and then red flag that post and answer

Regards
pat   pprimmer@acay.com.au
eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

RE: Light Weight Material for Disk Brake Rotors

(OP)
Answer in other forum by ZoRG

Pat carbon/carbon won't work well for drag racing, they only have good braking at high temperatures. You will want to look at carbon/ceramic discs, they are slightly heavier than carbon/carbon 2g per cc vs 1.7g per cc. And go for 10000UK Pounds per wheel, discs and pads. You can get them for half the price if you are willing to machine it yourself, but you require diamond tooling, its almost as hard as silicon carbide.

If you are still interested in Carbon/Carbon, you will require high density medium quality and a coefficient of friction .35 or more(I'm sure you already know this), the cost is $250-$400 per kilogramme, and should weigh around 2KG per disk and pad. Good luck in finding a manufacturer willing to supply you with low quantities though usually its 500KG minimum, there is one company I know off that sells them at US $1200 per wheel, pads and discs so a lot more than the $250-$400 per kilogramme but at least they supply low quantities.

Let me know if you are interested and I'll provide you with the info on where to get it and save you some time. These are for only the discs, so you will have to make your own hats.

SilverSSguy titanium will wear pretty quick, I don't know if you are willing to accept this. I have a profile suited to titanium if you are interested to compare to yours, I use solid edge but can export to parasolid or IGES for import to solidworks.

Regards
pat   pprimmer@acay.com.au
eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

RE: Light Weight Material for Disk Brake Rotors

(OP)
ZoRG

Thanks for your help, but if the number of Zeros in the Carbon/Ceramic disk cost is correct, that makes them A$30,000 per wheel or $120,000 per car.  That is way above our budget.

I may have hijacked this thread, but as the original question was about reducing drive-line inertia by removing weight from the brake system, I felt it was relevant.

I will start a new thread just in case an affordable solution comes up.

Regards
pat   pprimmer@acay.com.au
eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

RE: Light Weight Material for Disk Brake Rotors

MMC ala' lotus? I do not know how their supplier is. Alcon has released a ceramic disc for a mercedes, perhaps they have more on the way.
What is the weight of the car and spped brakews need to operate from?

RE: Light Weight Material for Disk Brake Rotors

Sorry Pat it was a mistake, it should be +-1000UK Pounds per wheel for the finished product and +-500UK Punds per wheel for the material... sorry.

The lotus MMC discs are not manufactured anymore, I can't remember who made them, but they went bankrupt. Lotus also don't have any stock left.

RE: Light Weight Material for Disk Brake Rotors

(OP)
The car is currently topping out at a bit over 170 mph or 275 kph. It weighs 2600 lb or 1180 kg.

It currently has about 11.5" ventilated discs on the front, and slightly bigger but non ventilated on the back. They are cast iron units of mewdium to large family sedand from the late 70's early 80's. They do the job, but are very heavy. The backs get hotter than the fronts.

Even though the car probably has 55% of the weight over the front axle, it has much bigger rolling diameter and width on the back tyres.

Regards
pat   pprimmer@acay.com.au
eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

RE: Light Weight Material for Disk Brake Rotors

Thats about the same size as carbon/ceramic units (280mm, 11"), the carbon/carbon units that I am aware of are slightly lareger at 320-340mm if I remember correctly. For both the discs are fairly thick (30mm), the pads as well, 20-25mm.

RE: Light Weight Material for Disk Brake Rotors

I did some work on Duralcan Aluminum MMC rotors a while back.

Worked for a machine shop in Stoney Creek, Ontario.  They have done quite a lot of work on Prototype Aluminum MMC rotors for motorcycles, Chrysler (Anyone remember the Plymouth Prowler? - Aluminum MMC Rotors) and other car manufacturers.

The biggest problem with the rotors was the noises they made during operation.  

Anyway, track down BSB Manufacturing Ltd. and talk to Narinder Bhogal.  He might even be able to make them for you.

Their number is (905) 643-0101.

RE: Light Weight Material for Disk Brake Rotors

Just be careful that with the aluminium MMC they don't allow high heat operation like the carbon/ceramic or carbon/carbon discs. The last thing you wan't is a overheating pad when you are trying to slow down on a drag strip (if your strips are anything like they are here :).)

RE: Light Weight Material for Disk Brake Rotors

Do you use a chute or is it all mechanical braking? and does the car need to be driven on the road at all? or road registerable?
I'm assuming each run has a longish break before the next run and thus everything has time to cool down?
My first though was why not try a 50% solution and see if you can measure the improvement rather than fork out the money for the exotic. Wilwood have some cheap/light large diameter vented rotors and bells that are for nascar (similar weight/speed) oval racing. Some of these with lighter calipers?
I take back what I said re the ceramic, given that porsche GT3 drivers in the UK having their disc's replaced are reportedly up for 27,000 uk pounds for a set (seems an unbelieveable price, but that is what is reported)

RE: Light Weight Material for Disk Brake Rotors

(OP)
We have a chute, the car is technically street registered, but we dare not take it onto the street as it would be defected and never again registered again, so street legality or use is not an issue.

We have at least an hour between runs, so it cools right down.

At 50 passes a year, that is only 50 stops, so wear is not an issue, so thinning the pads, narrowing the callipers and shortening the pistons will all reduce weight a bit.

An aluminium hat with aluminium spokes in the shape of centrifugal fan blades, and with light weight steel or carbon friction surfaces attached might work at a reasonable price.

I am much more concerned with rotating mass rather than non rotating, so the Holden OEM aluminium callipers are OK at this stage, maybe with the rework above. Rotating mass is of much more interest, and the rotors and hats are also a lot heavier than the callipers.

Regards
pat   pprimmer@acay.com.au
eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

RE: Light Weight Material for Disk Brake Rotors

I was thinking if 500-1000pounds a wheel is too much for you, you can maybe contact a few places that does explosion bonding, get a aluminium center with a 2mm steel friction disc explosion welded to it in a sandwitch. I was told this is possible.

Just something else to consider.
For interrest how much are your discs currently weighing?

RE: Light Weight Material for Disk Brake Rotors

(OP)
I haven't actually weighed them yet, but they are standard OEM cast iron ventilated disks with integrated hats on the front, and non ventilated with integrated handbrake drum on the rear. They feel heavy, probably 10 or 15 lbs each.

My main concern is whether or not the rotors will get hot enough for the aluminium to heat up to a level where it's strength becomes dangerously low.

Regards
pat   pprimmer@acay.com.au
eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

RE: Light Weight Material for Disk Brake Rotors

That could be a possibility, but they should cool pretty fast as well, especially on a drag car, saying that I would not be the one trying it out first time round, fyi the carbon/ceramic discs are around 4.2lbs or so, I don't know how much aluminium mmc discs weigh though. The CC discs should be even less around 3.6-3.8lbs, but you will have to go larger, which will also put them around 4.5 or so in the end.

Do you think it will this make a conciderable difference? I am considering if its worthwhile for me to go for them as well, I also wan't to take part in track events and the car does not have much torque so it might make a bigger difference for methan you.

I assume you are running a V8?

RE: Light Weight Material for Disk Brake Rotors

That could be a possibility, but they should cool pretty fast as well, especially on a drag car, saying that I would not be the one trying it out first time round, fyi the carbon/ceramic discs are around 4.2lbs or so, I don't know how much aluminium mmc discs weigh though. The CC discs should be even less around 3.6-3.8lbs, but you will have to go larger, which will also put them around 4.5 or so in the end.

Do you think it will this make a considerable difference? I am considering if its worthwhile for me to go for them as well, I also wan't to take part in track events and the car does not have much torque so it might make a bigger difference for methan you.

I assume you are running a V8?

RE: Light Weight Material for Disk Brake Rotors

The Aluminum MMC discs weighed about the same (and were solid) and were significantly cheaper than carbon/ceramic.  They didn't have too much of a problem with heat.  The composite did a woderful job of increasing heat capacity as well as wear resistance and the aluminum worked well with the heat dissipation. (I believe Duralcan is still patented so I won't go into composition and structure).

Basically they could match any cast iron rotor application for heat and wear requirements.  Just make sure you use organic pads.  Also there was a lot of testing on racing motorcycles.  I believe the heat requirements on those would be equivalent or similar to a drag race application.

I don't know if they will work but for the cost it would probably be worth investigating - we were making rotors for about $100 US ea.  The one problem I see is that there isn't a lot of support out there for these rotors.

RE: Light Weight Material for Disk Brake Rotors

If you can get them for that price, its unbeatable... I am quite interrested and will contact Mr Narinder Bhogal soon.

RE: Light Weight Material for Disk Brake Rotors

I agree, that is an outstanding price. I am tempted even though I don't really need them!

RE: Light Weight Material for Disk Brake Rotors

(OP)
That price is certainly within our budget. I will take some temperature readings, then decide if it is safe to use them.

Regards
pat   pprimmer@acay.com.au
eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

RE: Light Weight Material for Disk Brake Rotors

Please do let know how it all turns out, I am quite interrested.
I may have found another supplier willing to supply carbon/ceramic discs a little cheaper, but obviously no where near the Aluminium mmc prices. Hoping to get it for US $500 per wheel unfinished and $1000 per wheel for a machined product. I can afford that :)

RE: Light Weight Material for Disk Brake Rotors

What is the upper temp capability of MMC rotors as described?

RE: Light Weight Material for Disk Brake Rotors

For Aluminium MMC Its not the rotors, I think the pads can only handle 400C.

RE: Light Weight Material for Disk Brake Rotors

that is not much temp, have lotus solved this problem?

RE: Light Weight Material for Disk Brake Rotors

No, lotus went back to iron discs because the supplier of the mmc discs went bankrupt. It doesn't sound that high, but it is, since the mmc discs cool quite fast, the elise is also a very light car.

Maybe on a heavier car it might be a bit of a problem, I am not sure. You have the same problem with carbon/ceramic discs if you try and use organic pads (Same grade as MMC discs can be used on carbon/ceramic discs), the pads just can't handle much over 400C. However if you use carbon/ceramic pads, you can go over 800C. If you look at the porche carbon/ceramic discs as well, they don't use carbon/ceramic pads, and their have been plenty of reports of the pads catching on fire. It doesn't seem to do any harm though.

RE: Light Weight Material for Disk Brake Rotors

The MMC rotors had a really high heat capacity.  That was one of the Engineering specs that drove the concept.  

As I recall from 6 years ago, under similar braking conditions MMC would only reach about 2/3 of the temperature a cast iron rotor would see. This was due to the better heat capacity and dissipation characteristics.  It would take more heat to move the rotor temperature on an MMC rotor than it would in a cast iron.

I know you are thinking - wait we are talking about aluminum. The key to a MMC product is not the main matrix, it is in the additives.  The aluminum was excellent at heat dissipation but the additive was excellent for temperature stability and heat absobtion.  Each used its strength in this application.

Where a Cast Iron rotor might see 400 deg. C a MMC rotor might only see 275.

RE: Light Weight Material for Disk Brake Rotors

I thought this was cause they dissapated alot of the heat into the wheels?

RE: Light Weight Material for Disk Brake Rotors

(OP)
I would assume the heat has to go somewhere, if there is not more surface area to dissipate it to the air, it must be lost to the wheel or the hub and wheel bearings.

Regards
pat   pprimmer@acay.com.au
eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

RE: Light Weight Material for Disk Brake Rotors

What is the MMC rotor life like compared to cast iron? I am curious why alcon et al have not produced an after market MMC rotor, everything I am hearing sounds positive for some motorsport e.g. hillclimb

RE: Light Weight Material for Disk Brake Rotors

(OP)
And drag racing.

For drag racing life is not even really an issue, as they might only do 6 or 8 stops at a meeting and 50 to 100 stops per season.

Regards
pat   pprimmer@acay.com.au
eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

RE: Light Weight Material for Disk Brake Rotors

Quote (NeilRoshier):

What is the MMC rotor life like compared to cast iron? I am curious why alcon et al have not produced an after market MMC rotor, everything I am hearing sounds positive for some motorsport e.g. hillclimb

There are a number of reasons. The first and strongest is cost.  In an automotive aftermarket environment a single rotor would probably cost over $200US.  The average person would not see a significant benefit to justify the cost.

The second reason - pads to match up with the rotors are expensive.  See item 1 comment about average person.

Last I checked there were some lingering engineering issues such as excessive noise.

Because of the application originally mentioned is more weight driven and the availability of funds is appropriate I figured this might be something to check out.  As mentioned I am not completely up to date on all the information but I gave information on where someone could start to find out more.

RE: Light Weight Material for Disk Brake Rotors

$200 is nothing compared to aftermarket steel rotors. And excessive noise can be a selling point in "some" circles. I have a feeling there is a bit more to it than that. That $200 price tag does not sound correct, especially if you factor in diamond tooling. for a disc set on one car you will require 1-2 diamond tips, and 2 - 4 drills. They don't come cheap. Being in the manufacturing industry I can see where this becomes a problem, indexing the cutting tip after every cut becomes very time consuming.

RE: Light Weight Material for Disk Brake Rotors

Aluminum has a higher heat capacity than iron on a weight basis.But since aluminum has only 1/3 the density of iron, an aluminum rotor of the same size will have less heat capacity than an iron one. My recollection is that Duralcan developed a formula that used heat capacity and thermal conductivity to come up with the necessary configuration for an mmc rotor to replace an iron one and offer a weight savings with no thermal penalty.

RE: Light Weight Material for Disk Brake Rotors

As a affordable alternative, have a look at ebay, there are carbon rotors going from $50-$200 US. Just make sure you can get some matching pads.

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