stoping distance on "big brake kits"

As the owner of a "big brake set up" i am wondering if anyone has subjectively tested the 60-0 stoping distances compared to stock with one of these kits fitted, we all hear "yeah their great" and "they really pull the car up well" but i want to know cold hard facts and stoping distances, i know stoping distance is not everything and fade will come in to it as well but i would expect any brake upgrade to at least stop the car in the same distance as stock (UK)

i know this may be the wrong time of year as tyre grip is not at its optimum but i intend to do some tests whenever weather permits and once i have the correct drive bobbins (insufficient float clearance) fitted to the fronts, of particular interest would be brake kit type and tyre make/size, i bet if we collectively did some testing this could be interesting and perhaps surprising.

A brake upgrade will make absolutely no difference to stopping distance. The limiting factor is grip - you can easily push the brakes hard enough to lock the wheels with standard brakes. Where they win is with repeated braking - they can shed heat more effectively and therefore fade less.

Totally agree with Simon.

1 other point though is that ABS might be upset by using non OE brakes as might the brake bias...these could actually lead to a reduction in overall braking ability.

A brake upgrade will make absolutely no difference to stopping distance. The limiting factor is grip - you can easily push the brakes hard enough to lock the wheels with standard brakes. Where they win is with repeated braking - they can shed heat more effectively and therefore fade less.

I appreciate that Simon but what i'm getting at here is i bet there are cars out there that take a longer distance to stop than they did with stock brakes, and i hope mine isn't one of them

Do you have an accelerometer to hand Paul? Provided you can find a safe bit of road to try it on you can get measure several 60-0 stops (ideally one after the other) to see what sort of times you're getting. It should also show up when fade is starting to happen.

On my jap brake setup the ABS could would kick in at about 50mph on a dry road so don't expect big brakes would make any real difference on a single stop from 60mph.

I appreciate that Simon but what i'm getting at here is i bet there are cars out there that take a longer distance to stop than they did with stock brakes, and i hope mine isn't one of them

Ah, I'm with you. I would have thought you'd be OK though, I can't see them being any worse than normal. I think the reason a lot of people think the big brake kits work better is that they can brake harder with less effort on the pedal. If you don't press the pedal hard enough then I guess they'll stop you faster than the standard setup.

In addition, big brakes will stop you better from higher speeds. Cant see them doing anything significant on lower speeds like 60mph, thats down to your grip and abs as simon said

If the bias is right, and you can modulate the pedal satisfactorily (assuming no ABS), and they have enough torque to lock the wheels, until fade becomes an issue tiny discs and calipers will have almost the same stopping distance as gigantic ones.

I appreciate that Simon but what i'm getting at here is i bet there are cars out there that take a longer distance to stop than they did with stock brakes, and i hope mine isn't one of them

Are you going to persuade one of the Evo Brembo 'upgraders' to take part Paul?

They best way to test them would be to use a controlled track environment, or atleast a closed road. Hit the line at say 60mph and hit the brakes then measure stopping distance. Do this 5 times repeatedly then take the average, this should give a good measurement of braking power and resistance to fade. There is a clip on utube somewhere that an independent aussie magazine did this test on an evo 8 with stock discs, then with DBA discs (the one Gaz is trying to run a group buy on )...with the DBA's it stopped in something like 15% shorter distance.

I am going to hold my hand up and say i would be willing to participate in this experiment as i am one of those evo Brembo 'upgrade' people. However, i dont expect them to be any better than UK brakes but they came up brand new at an unmissable price, expecially as i am running jspecs at the moment. Once there on i will voice my opinion further .

Don't get me wrong Sean, from J-Specs it probably is an upgrade. It's the ones who junk UK specs for them just to get the logo I wonder about

Mind you, having Indiana Jones hanging off the front of the car and using his shoe on the wheel is probably an upgrade from J-specs

-Ian

Don't get me wrong Sean, from J-Specs it probably is an upgrade. It's the ones who junk UK specs for them just to get the logo I wonder about

 

Mind you, having Indiana Jones hanging off the front of the car and using his shoe on the wheel is probably an upgrade from J-specs

 

-Ian

Fair point Ian and i would have to agree at this time.

I am in a lazy mood and cant really be bothere to go on a hunt but does anyone know the stock piston size on the UK specs? One thing i did notice is that the Brembo pistons are considerably larger than those of the j-specs. The calipers are alot lighter than the j-specs too

Good point sean my understanding is its down too piston size rather than quantity, I spoke to someone that designs and builds brakes and he was basically saying anything over 6 pots is just for show

Any views on that

Don't get me wrong Sean, from J-Specs it probably is an upgrade. It's the ones who junk UK specs for them just to get the logo I wonder about

the only other deciding factor would be the weight of the calipers. Are the brembos considerably lighter than the UK?

But surely the huge solid mass of a UK calliper has more capacity to absorb heat than a light-weight one, but maybe it can't dissipate that heat as easily.

I am sure that this was discussed in much detail several years ago, in the early days of .net. I can't find it now, but there was a table giving braking forces for a variety of ,stock car brakes and after market brakes. If I remember correctly the stopping force was measured in BHP. F1 brakes topped the list, followed by top of the range Porsche brakes, the UK MKIV brakes were well up the table near the top and only a few hourses from an aftermarket six pot. May be one of the other long serving members remember this and may have a link to the table. I am sure there will be other "stock" systems that out brake the UK MKIV set up. From what I remember of the discussioin, it was agreed that the advantage of the six pots would only really be noticed on a track where heat was a big issue build up was an issue, on the road the difference was cosmetic.

I am sure that this was discussed in much detail several years ago, in the early days of .net. I can't find it now, but there was a table giving braking forces for a variety of ,stock car brakes and after market brakes. If I remember correctly the stopping force was measured in BHP. F1 brakes topped the list, followed by top of the range Porsche brakes, the UK MKIV brakes were well up the table near the top and only a few hourses from an aftermarket six pot. May be one of the other long serving members remember this and may have a link to the table. I am sure there will be other "stock" systems that out brake the UK MKIV set up.

Braking performance comparison:

Vehicle-----Braking horsepower

Ferrari F1-----7000+

Porsche Twin Turbo GT1-----2060

Brembo/AP 6 pot 385mm discs-----2040

Mercedes Brabus V12-----1950

Supra TT 4 pots with Mintex grooved discs-----1760

Wilwood Rallystop 4pot 355mm discs-----1750

Brembo/AP 6 pot 355mm discs-----1680

Maclaren F1-----1670

Supra TT 4 pots-----1665

Wilwood Rallystop 4pot 320mm discs-----1640

Brembo/AP 6 pot 320mm discs-----1590

Porsche 996 C2/C4-----1590

Ferrari 456GT-----1480

Supra / Soarer TT 2 pots-----1010

Lamborghini Muira (1966)-----780

Ford Mondeo 2Ltr Saloon-----700

I am sure that this was discussed in much detail several years ago, in the early days of .net. I can't find it now, but there was a table giving braking forces for a variety of ,stock car brakes and after market brakes. If I remember correctly the stopping force was measured in BHP. F1 brakes topped the list, followed by top of the range Porsche brakes, the UK MKIV brakes were well up the table near the top and only a few hourses from an aftermarket six pot. May be one of the other long serving members remember this and may have a link to the table. I am sure there will be other "stock" systems that out brake the UK MKIV set up.

This may be the list you mean:

http://planetsoarer.com/suprabrakesII/SupraBrakeUpgrade.htm

That the one, the MKIV is a bit lower than I thought but still very good.

good info good too see the brembo 6 pots came out well

good info good too see the brembo 6 pots came out well

The AP/Brembo 6 pot with 355mm discs (bigger than stock Supra) come out worse.

This may be the list you mean:

 

http://planetsoarer.com/suprabrakesII/SupraBrakeUpgrade.htm

Great link buddy..many thx.

They best way to test them would be to use a controlled track environment, or atleast a closed road. Hit the line at say 60mph and hit the brakes then measure stopping distance. Do this 5 times repeatedly then take the average, this should give a good measurement of braking power and resistance to fade. There is a clip on utube somewhere that an independent aussie magazine did this test on an evo 8 with stock discs, then with DBA discs (the one Gaz is trying to run a group buy on )...with the DBA's it stopped in something like 15% shorter distance.

from what i have read i would say this is the definative test, we can theorise forever about brake force but its out on the road it matters, i think i may have posted this at the wrong time of year, when its dry and warmer i am going to do some testing and if need be install a bias valve until i get the best stoping distance i can, i found some really good info whilst doing the brakes on my car and one of the most thought provoking was on http://www.stoptech.com/tech_info/tech_white_papers.shtml, as follows ~

The most dramatic front-bias impacts are usually brought about by “big brake kits” which are not properly matched to the intended vehicle. Any time that a bigger front rotor is installed, there is a simultaneous need to decrease the effective clamping force of the caliper (installing smaller pistons is the easiest method) to offset the increased torque created by larger rotor effective radius. Unfortunately, too many upgrades do not take this factor into account, and those poor cars end up with both bigger rotors and larger pistons which serve to drastically shift the bias even more forward. While rock-solid stable under braking, stopping distances will go up dramatically.

http://www.apracing.com is also a good site

from what i have read i would say this is the definative test, we can theorise forever about brake force but its out on the road it matters, i think i may have posted this at the wrong time of year, when its dry and warmer i am going to do some testing and if need be install a bias valve until i get the best stoping distance i can, i found some really good info whilst doing the brakes on my car and one of the most thought provoking was on

http://www.stoptech.com/tech_info/tech_white_papers.shtml[/url

Looks like some interesting white papers on there Paul, i will have a proper read when my brain is in full gear .

That braking force list is pretty much irrelevant though. It doesn't really matter if your brakes manage 1600 "braking horsepower" (whatever that is) or 1 million. If they are strong enough to lock the wheels it makes no difference. What matters is the amount of heat they can dissipate.

Also, it doesn't say anything about how the test was done. Plus there's no link to the actual results, it could just be a load of made up numbers in a table for all we know!