Big Brakes.... Please can some one explain them

[ManwithSupra]

I am so confused about brakes, now i dont know a huge amount of info on brakes so bear with me...

 

I currently have a full UK setup which soon is going to be in need of new discs pads etc, when I do this I am going to refurbish the callipers with new seals etc. However I must admit I am drawn to the big brake conversion's and have been researching them when I get a chance now and then.

 

Now I know this subject has been resurrected time and time again on this forum however I have yet to see any "proof" on some of the claims with regards to performance made between the cheaper and more expensive 2 piece (non monoblock) calliper kit brands (Ksport, D2, Hispec vs AP, Brembo, Alcon etc), please bear in mind that most of us use the supra as fast road or sometimes track use and this post is written with that in mind.

 

As far as I know one of the major issues with braking is down to how much grip you have on the road, the better grip you have on the road the less chance of the brakes outperforming this grip and causing the wheels to lock.

 

Now as the stock UK brakes can outperform the amount of grip the tyres have on the road means that the limits of the car braking any more quickly (distance from xMPH-0) cannot be improved by the brakes even if you install a big brake kit.

 

Now the cheaper end of big brake kits have been mentioned on here as performing the same or slightly worse than UK spec brakes, however I can probably bet that these "cheaper" brakes are just as capable of causing the wheels to lock when braking hard (therefore outperforming grip as mentioned before, and if they didn’t then I am sure we all would of heard about it). So therefore in terms of outright braking performance these have to perform the same as OEM brakes as its the grip that determines this. So I beg to ask what makes the more expensive brakes better?

 

I assume the only reason why you would purchase a big brake kit is for repeat braking performance (like for use on a track) or for aesthetics.

 

Now I have seen from the comments on here that the more expensive callipers use better materials in order to decrease the amount of flex on the calliper than the cheaper brands, I cannot see any proof if this "stiffness" makes a huge difference in fast road and light track use and surely if the calliper is stiff enough to apply enough pressure on the pads to cause enough friction on the disc to lock the rotation of wheel when braking hard, then any repeat braking performance is down to the materials used in the pads and the way the discs dissipate the heat. Again in this regard what makes AP, brembo etc different to the cheaper brands when using the same sized discs and the same compound pads?

[Alex]

Increased fade resistance and reducing unsprung masses are the main benefits from BBK's. As you rightly say you're limited on actual retardation by the grip of the tyres.

 

Chris Wilson will explain why the caliper stiffness is most important so I won't try to give my 2p as I'll probably miss out a lot.

 

But safe to say the more expensive ones are LIGHTER and STRONGER which has got to be good. Monoblocks being the lightest. The AP's etc will have more science behind them too and will be tuned to push the pad on the disc in the best way with the right force.

[TopgunTT]

My Hi spec Mega Monsters were £1800 for the front so i wouldn't call that cheap? I think k-sport and d2 can be picked up for around £1000? Having said that the normal monster brake set up cost £1000 so i suppose thats about right. I wanted the big calipers and discs. My j-specs were shocking for stopping when i first picked up my Supra, Yes probably just needed replacing. However i wanted something more for show rather than track days thats why i went for my big brake kit.

I'm not very technical on brakes, I just know these look great and give me fantastic stopping power. Never had UK brakes so i couldn't compare the difference.

Edited July 20, 2010 by TopgunTT (see edit history)

[monsween]

My Hi spec Mega Monsters were £1800 for the front so i wouldn't call that cheap?

 

Mine came with the car

 

I have those plus j-specs on the back and its a little iffy sometimes under heavy braking.

 

I'll be upgrading the rears to UK's as soon as i have 7mins on this forum to buy them as they are hard to get a hold of

 

So if going big brake you have to consider all round IMO

[bignum]

Mine came with the car

 

I have those plus j-specs on the back and its a little iffy sometimes under heavy braking.

 

I'll be upgrading the rears to UK's as soon as i have 7mins on this forum to buy them as they are hard to get a hold of

 

So if going big brake you have to consider all round IMO

Yes i remember those when i drove the car before you got it, i told the guy selling it how rubbish the brakes were.

[Wez]

Most people over look Alcon when looking at brakes and in my mind they are up there with the best.

 

As for Hi-Spec my car was the first MKIV to ever have them fitted, they used it to get the pattern and measurements many moons ago, I had an ally bell and fixed mount rotor which fitted with the stock larger brakes, they didn't even last one trackday and may as well been made from chocolate, the design itself is flawed in that you have a two different metals bolted together that heat up and contract at different rates, warp city

[Kirk]

If you want to see a real BBK then look no further than paul mac's adapted amg brembos, .

Aswel as just looking awesome they seem to have a better bite and some weight savings which is surprising for 8 pot fronts and 4 pot rears

Edited August 5, 2010 by Kirk (see edit history)

[Guest Snaps]

The benefits of BBk's are:

 

-less fade

-less weight, both rotational and not

-better braking feel

 

Comparing a BBK to the UK brakes is pointless, unless your supra is a dedicated track car, or you're really pushing it to it's limits on the track, you aren't likely to see much benefit from a BBK compared to UK brakes with pads, rotors and lines upgraded.

[dangerous brain]

The benefits of BBk's are:

 

-less fade

-less weight, both rotational and not

-better braking feel

 

Comparing a BBK to the UK brakes is pointless, unless your supra is a dedicated track car, or you're really pushing it to it's limits on the track, you aren't likely to see much benefit from a BBK compared to UK brakes with pads, rotors and lines upgraded.

 

There is also the "private road" that everyone seems to spend some time using their machines at 140 leptons plus on. Try stopping even fast road pad equipped UK spec brakes from speeds above 140 leptons and you'll hit growling at around 70juddering at about 60 and massive fade about 40-50. Wether or not that is the case with the more expensive brake kits or not I do not know.

[dandan]

Most people over look Alcon when looking at brakes and in my mind they are up there with the best.

 

Good shout Wes. I am slowly piecing together a full Alcon setup based around the Monoblock 6 piston front caliper and Monoblock 4 piston rear caliper. I have the calipers and am now waiting to buy the correct sized discs and make the bells etc.

 

The calipers really do look to be an excellent design with integral stiffening bridges, concealed dust seals, and they are a low profile meaning big discs can be squeezed under smaller wheels.

[Wez]

Very nice Dan, I was looking at the 4 pot as possible replacements for my UKs when I can no longer get the PF pads I like using. It would seem that the Alcon 4 pots also have larger piston areas compared to stock and should hopefully be lighter

 

Does anyone know the stock UK setups brake pad area?

[Matt H]

Not sure if this had been added to the list, but a 'big' brake kit will utimately provide better stopping from really high speeds. If you're a normal everday driver, this may be the only area you find a kit improves the situation over the stock UK specs.

 

The supra isn't any 1.2l corsa, the brakes were designed to work well in a performance situation. A lot of people go for big brake kits because they look awesome. Seeing monster discs and calipers wedged behind the rims is jsut sexy.

[Luxluc]

Not sure if this had been added to the list, but a 'big' brake kit will utimately provide better stopping from really high speeds.

 

I confirm this Matt.

 

That's the first thing I was really astonished when I went from my euro-spec / uk-spec setup to the full Stoptech setup front and rear.

 

When braking hard at higher speeds (120+ mph), the difference compared to the euro-spec setup was immense.

It wasn't that noticable at normal cruise speed, but I was really surprised how much breaking power the BBK kit gives at (very) high speed, where the euro-spec brakes had problems even on aftermarked pads.

[paul mac]

If you want to see a real BBK then look no further than paul mac's adapted amg brembos, .

Aswel as just looking awesome they seem to have a better bite and some weight savings which is surprising for 8 pot fronts and 6 pot rears

 

steady on mate they're only 4 pot on the rear

[jevansio]

I confirm this Matt.

 

That's the first thing I was really astonished when I went from my euro-spec / uk-spec setup to the full Stoptech setup front and rear.

 

When braking hard at higher speeds (120+ mph), the difference compared to the euro-spec setup was immense.

It wasn't that noticable at normal cruise speed, but I was really surprised how much breaking power the BBK kit gives at (very) high speed, where the euro-spec brakes had problems even on aftermarked pads.

Defo, braking from 180+ with UKs I found to be on the limit of what they can do, hopefully I'll get to put the APs to exactly the sme test some day

[dandan]

steady on mate they're only 4 pot on the rear

 

Paul,

 

Do you know what the piston diameters are in your front calipers? I've got a monster list of caliper piston areas for various brake kits and OEM calipers but haven't found anything about these....

[dandan]

Very nice Dan, I was looking at the 4 pot as possible replacements for my UKs when I can no longer get the PF pads I like using. It would seem that the Alcon 4 pots also have larger piston areas compared to stock and should hopefully be lighter

 

 

One has four 31.8mm pistons (this is what I have for the rear) and the other has a 41.8 and 38.1mm staggered combo. Their piston area relative to the UK front caliper is 86% for the staggered and 55% for the 31.8mm version.

 

 

Does anyone know the stock UK setups brake pad area?

 

Not off the top of my head but I have it somewhere...

 

If you want - I can tell you what size disc would be needed on the front with the Alcon 4 pot Monoblock to give you the exact same braking torque as the UK setup (with all other things equal such as pad compound).

[Wez]

One has four 31.8mm pistons (this is what I have for the rear) and the other has a 41.8 and 38.1mm staggered combo. Their piston area relative to the UK front caliper is 86% for the staggered and 55% for the 31.8mm version.

 

What are the stock piston sizes then, so the Alcons are smaller?

 

 

If you want - I can tell you what size disc would be needed on the front with the Alcon 4 pot Monoblock to give you the exact same braking torque as the UK setup (with all other things equal such as pad compound).

 

That would be interesting, go on then

[Terminator]

 

.................. I've got a monster list of caliper piston areas for various brake kits and OEM calipers.........................

 

Could this be a tech sticky of the future?

[Wez]

Could this be a tech sticky of the future?

 

Great idea, we could compile a nice table like the ECU register and Weight Table.

 

[Kirk]

steady on mate they're only 4 pot on the rear

 

Oh yeah .. oops

[Tricky-Ricky]

IMO big brakes are only as good as the system they are used on, and more importantly the un sprung weight of the vehicle.

 

You would be very surprised just how much difference to braking performance you would notice by changing the wheels for a much lighter set;)

 

 

If you change say to say a 40mm dia larger disc with a big six pot calliper you are dependant on the total size/area of the calliper pistons for the braking force (and for the pendents yes the larger disc's plays a big factor as well but bare with me;))

 

Now if you are using a std master cylinder etc, if this isn't up to shifting the extra fluid mass, you will have worse braking than the std system despite the increase in disc size as you are losing the advantage of the both! so be very careful in choosing a tried and tested set up that is known to work with the std master cylinder etc, unless of course you are intending to change everything, but its surprising just how many people don't even think about this.

[ManwithSupra]

Thats a good point, however are there any manufactures that make a higher flow master cylinder?

[Scott]

Defo, braking from 180+ with UKs I found to be on the limit of what they can do, hopefully I'll get to put the APs to exactly the sme test some day

 

I haven't tested quite that high up but I did do a 140-0 on a test track and the brakes performed excellent. I don't think they would have taken another run at it right away though.

 

I'm thinking about a BBK kit but the stopping power would need to be at least as good as the UK's for me to even think about spending that sort of money. It is for aesthetics for me, but I need decent performance too even though it's for fast road only.

[dandan]

IMO big brakes are only as good as the system they are used on, and more importantly the un sprung weight of the vehicle.

 

You would be very surprised just how much difference to braking performance you would notice by changing the wheels for a much lighter set;)

 

 

If you change say to say a 40mm dia larger disc with a big six pot calliper you are dependant on the total size/area of the calliper pistons for the braking force (and for the pendents yes the larger disc's plays a big factor as well but bare with me;))

 

Now if you are using a std master cylinder etc, if this isn't up to shifting the extra fluid mass, you will have worse braking than the std system despite the increase in disc size as you are losing the advantage of the both! so be very careful in choosing a tried and tested set up that is known to work with the std master cylinder etc, unless of course you are intending to change everything, but its surprising just how many people don't even think about this.

 

Good point, but I haven't come across any calipers that have a bigger piston area than the UK specs yet so I doubt people will run into issues with their master cylinders when swapping out a UK setup. However, I don't have any info for Paul's AMG babies, Stoptech or any 10 or 12 pot calipers yet.

Edited August 5, 2010 by dandan (see edit history)