93 replies to this topic

[GeorgeBC]

Cheers

 

Ok so have you come across and what do you think of the casting for the AP 308 rotors i linked to? If you had to buy 308's to suit AP bells what would you buy?

 

Tempted to try the Reyland rotors but having to replace the bolts at £40 a time and the possibility they may not last very long or warp makes me think about sticking with what i know have been good for me to date. My car is only for track use really and i don't drive like a sunday driver but im no Chris_uk racing driver. My budget isn't unlimited but i would prefer to spend £600 on a product that will put up with more abuse than i can give it and last, rather than £300 on something i will be changing in 6 moths and spending the £600 anyway. Running Pagid RS14 pads on them.

 

Please make a decision for me as i hate doing it for myself. 

[Scuffers]

can't say as I have not looked/used a AP 308...

 

if I remember, I'll take a gander at one tomorrow

 

 

[Mike (Cliffie)]

With 300 BHP and track day use Graeme, I would look at a decent make of (not my place to define decent BTW) ali belled disc and a set of PF pads on two pots.

 

I have the EP discs on mine and have been chuffed to bits with the quality and performance last season.

 

All the four pots do is give better heat dissipation and the pads last longer. There is no increase in braking friction and what you do get, by adding more pistons to push, is a longer pedal travel.

 

 

[Graeme Lambert]

edit:

 

for example, Geary's NA VX has EP's cheap ali belled disks and padgid pads on it, and they are more than up to me abusing it on track, however, if he bolted a TVS on it, I doubt that would still be true.

 

So what you are saying is that a 300bhp VX wouldn't survive you at the wheel if it only had 2 pots and ali-belled discs on it, and that for that sort of power you would be using four pots? (or something else?)

 

G

[Scuffers]

 

So what you are saying is that a 300bhp VX wouldn't survive you at the wheel if it only had 2 pots and ali-belled discs on it, and that for that sort of power you would be using four pots? (or something else?)

 

G

 

it's not about the calipers, just the disks.

 

if we did need to up-rate them, I would be going with the AP 290 disk as the next step.

[Graeme Lambert]

  So what you are saying is that a 300bhp VX wouldn't survive you at the wheel if it only had 2 pots and ali-belled discs on it, and that for that sort of power you would be using four pots? (or something else?)   G  

it's not about the calipers, just the disks.   if we did need to up-rate them, I would be going with the AP 290 disk as the next step.

So 2 pots on AP 290 discs, would pretty much be the ultimate (reasonably) cost effective braking system (assuming correct pad selection)

[chris_uk]

With 300 BHP and track day use Graeme, I would look at a decent make of (not my place to define decent BTW) ali belled disc and a set of PF pads on two pots.   I have the EP discs on mine and have been chuffed to bits with the quality and performance last season.   All the four pots do is give better heat dissipation and the pads last longer. There is no increase in braking friction and what you do get, by adding more pistons to push, is a longer pedal travel.    

From what the guy at carbon lorraine was telling me (also backed up independantly by a guy at opie oils) they made it out that the heat dissapation was actually worse on belled discs as the ali was a worse conductor of heat than the rotor so the heat stats in the rotor.. The benifits of the ali belled system is to reduce unsprung weight and keep the heat away from the hubs. The guy at CL explained that they had a tvr with brake fading issues and after trying everything else they swapped the alibelled disk for a standard type disc and the problem never returned.

[Scuffers]

So 2 pots on AP 290 discs, would pretty much be the ultimate (reasonably) cost effective braking system (assuming correct pad selection)

 

would not say ultimate, just the next step...

 

after this are AP304's, then after that your into new calipers and fatter disks, ie, 315x28, then 330x28, etc etc.

 

ultimate is a bit of a bum term, ultimately you could have some carbon/carbon setup, but who in their right minds would go there? (on a VX...)

[chris_uk]

I had 330x28 for ages, didnt feel any better on the road but i never tracked it so no idea on track.

[Graeme Lambert]

Ok Simon, not ultimate, but best cost effective solution? Let's say someone had £1,200 to spend on a brake set up for a car that could be anywhere between 280-300bhp but could be upgraded in future to 380bhp? At what power (I suspect you'll say there's no definitive number) would you suggest 4 pots might be useful on a Vx/Elise?

[Scuffers]

Ok Simon, not ultimate, but best cost effective solution? Let's say someone had £1,200 to spend on a brake set up for a car that could be anywhere between 280-300bhp but could be upgraded in future to 380bhp? At what power (I suspect you'll say there's no definitive number) would you suggest 4 pots might be useful on a Vx/Elise?

as you say, it's not so much about power as the driver and the tyres (softer tyres = more brake loads)

 

let me put it this way, I don't see anybody here exceeding the limits of the 290's, (and yes I am sure somebody will now come along and show me the error of my ways!)

 

For ref, Mikes car was fitted with 304's all round....

[chris_uk]

Surely its nothing to do with power.. Its to do with weight.. If you had 120bhp but weighed 2tonne had to slow down from 100mph you would need better brakes than a car at 500bhp weighing 900kg slowing down from 100mph. Plus, your braking efficiency is controlled by what tyres are on thd car, mega good brakes with winter tyres isnt going to stop you as well as much lesser brakes on 888's for example. Just get the 4pot ap front calipers, 2pot rear, good pads (cl, pf, pagids etc) some normal discs, rf1000 fluid, hook up a cold air feed and ur ready to go.

[chris_uk]

When i say normal discs i mean sizes of 308/288.

[Steffen]

 

No doubt about the fact that it is very important to have good pads and disks, but to say there is no need for 4pot isn't correct in my opinion.

 

To have 2Ap with good pads and disks is good solution, the same with 4pot is the better one.

 

 

 

define better? (with metrics)

 

What makes a 'PROPER' disk?

 

one made from quality castings using decent materials.

 

problem is that in the disk market, there are a lot of foundries, even within 1 make (like AP) they use some truly horrible castings at the cheap end, even though others are really top quality.

 

other problem is raw cost is not a good indicator of quality.

 

 

 

To define better....... what I've to do?

 

To find the old files from my performance box when I run with 4 2Ap (front and rear) instead the actualy solution?

Hope you belive me that there is a difference of 0,2g (-1,5 instead of -1,3g).

 

The reason is that with 4 2Ap you can't use the same pads on the front and at the rear axle.

With the  4 pot on the front and the 2 pot at the rear you can use the same pads and the car brakes still better,

than with the 4 2Ap which in any case are much better than every solution with the original brembo at the rear!

 

Another reason is that there isn't any problem with fading. Of course only if there is always fresh brake fluid and a cooling duct.

[AllanM]

I am looking for a quality one piece disc. Anybody have any experience with the quality of the new EBC High Carbon Blade discs ?

 

http://www.camskill....-full--2460.jpg

[Scuffers]

Surely its nothing to do with power.. Its to do with weight.. If you had 120bhp but weighed 2tonne had to slow down from 100mph you would need better brakes than a car at 500bhp weighing 900kg slowing down from 100mph. Plus, your braking efficiency is controlled by what tyres are on thd car, mega good brakes with winter tyres isnt going to stop you as well as much lesser brakes on 888's for example. Just get the 4pot ap front calipers, 2pot rear, good pads (cl, pf, pagids etc) some normal discs, rf1000 fluid, hook up a cold air feed and ur ready to go.

that's almost so wrong it's funny!

 

Power is how the car moves, if you can only input 200Hp, the brakes only have to deal with the resultant kinetic energy that 200Hp can add to the car.

 

the reason sticky tires increase brake loads is that your compressing more kinetic energy into a shorter timeframe, ie, your braking harder for less time, so whilst (for a given speed) the total load is the same, the instant absorption rate is somewhat higher.

 

a given disk can only shed heat at a given rate associated with it's surface area, it's venting efficiency, the temp differential (between the disk and the ambient air) etc etc.

 

a bigger disk with bigger vents will be able to move more air, thus cool better, so for a given heat load, it will be able to dissipate that faster, thus it will run cooler (for the same brake event)

 

next part of the equation is the mass of the disk, heavier the disk, the more thermal mass it has, so for a given load, it will not heat up as much, but obviously, will take longer to cool.

 

this is a good think for a big heavy car as the instant brake loads will massively exceed the venting capacity so the disk needs to 'store' some of that load and then shed it later, for a given application, a heavy disk's temp will not vary as much as a light one.

 

the downside to heavy disks is weight (obliviously, and it's rotational inertia), and for a given size of disk, the vents will be smaller, so it's cooling airflow is less.

 

the balance is then between the brake instant load capacity and the venting ability.

 

a disk that runs over a big temp range (per lap) will not last as long as one that's got a lower temp spread, continual heat/cool is what eventually cracks disks, better disks will stand more before they crack than cheap ones.

[chris_uk]

Never had any experience with them other than the pads..

[chris_uk]

Scuffs... What exactly was so wrong it was funny?? I said heavy cars need better brakes... You said the same... Speed is speed it doesnt matter how you get there 100mph is 100mph be it in a nissan micra or a bugatti veyron.

Edited by chris_uk, 08 May 2014 - 07:59 AM.

[Scuffers]

Scuffs... What exactly was so wrong it was funny?? I said heavy cars need better brakes... You said the same... Speed is speed it doesnt matter how you get there 100mph is 100mph be it in a nissan micra or a bugatti veyron.

Yes, but for a given straight on a cct, the veyron will be going faster into the braking zone...

[chris_uk]

Oh well done captain fcuking obvious.... How did i not. Take that into account ... Oh yea.. I wasnt even talking about that was i...