Just for research purposes, I`m going to attempt a brake test from stock to uprated, only on my vert but it should shed some light on how much better/worse the upgraded set up should be....so at the moment I have good stock brakes on all 4 corners and next week I will have evo8 Brembos with grooved and drilled disc`s on the front and grooved/drilled discs and red stuff pads on the rear stock calipers..Oh, and all new braded hoses too

So my test will involve braking hard from 30 and 50 mph and see how long in seconds it takes to stop and the distance travelled, I would like to do some sort of brake fade test aswell, not sure how to do an accurate test on this without doing a track day, any ideas on more tests i could do whilst im playing?

 

Daz

Edited May 15, 201114 yr by daZvert

no:tt2: why do you want one? :winkiss:

 

lol, would love one and an S12 but both would be just for looking at really.

lol, would love one and an S12 but both would be just for looking at really.

 

My z31 is growing on me again, I go through stage`s of hating it then loving it, Its wierd, but they are sh!t to drive, a big spongey marshmellow :devil:

So he can burn it :lol:

 

 

Re Brakes my stock ones were good for about one heavy brake and my new ones all round everytime i slam on i almost head but the wheel and thats at anyspeed and for some reason it never ever locks up. it just stops lol!!!!

anyway it`s getting a good read this thread, I will start the test next week sometime and see what happens, thanks for all the expert input, you bunch of smartasses :winkiss:

speaking of brakes, recently before i took my zed of the road when i was reversing and braked it would make like a "twanging" noise like a spring and the pedal would lift and harden?, anyone got any ideas?, cheers chris

anyway it`s getting a good read this thread, I will start the test next week sometime and see what happens, thanks for all the expert input, you bunch of smartasses :winkiss:

 

Your welcome mate ;)

lol, would love one and an S12 but both would be just for looking at really.

 

can understand why you wouldn't want to drive it, but why would you want to look at it :tongue::lol:

speaking of brakes, recently before i took my zed of the road when i was reversing and braked it would make like a "twanging" noise like a spring and the pedal would lift and harden?, anyone got any ideas?, cheers chris

 

check the pad retaining pins and metal spring plate is in place in the caliper properly.

another funny one, I seem to get a 'Badoiiinnnggggg' noise, randomly, from what sounds to be the ABS unit, have had massive problems with my brakes, have just changed all the brake lines as they were pretty bad, calipers bled fine, but backs just wouldn't really work, all 4 calipers re-built too.... Am yet to finish putting it all back together, but hoping the new pipes with cure my problems, the old ones after taking them off, snapped with little force, pin holes in them perhaps, but what could this noise be? It is definately emminating from the boot....

same situation mine sunds from the back!

another funny one, I seem to get a 'Badoiiinnnggggg' noise, randomly, from what sounds to be the ABS unit, have had massive problems with my brakes, have just changed all the brake lines as they were pretty bad, calipers bled fine, but backs just wouldn't really work, all 4 calipers re-built too.... Am yet to finish putting it all back together, but hoping the new pipes with cure my problems, the old ones after taking them off, snapped with little force, pin holes in them perhaps, but what could this noise be? It is definately emminating from the boot....

 

Have you bled the abs unit in the boot??? Its under the plastic pannel in the boot on you right. its like a bulge and held in place by 3 10mm bolts :)

ahh ill give that a try tmrw and let ya know how i get on i didnt know that was there!

Braking performance will certainly be improved - forces generated are much greater - the car brakes harder with less brake pedal effort.

 

But have you actually compared minimum stopping distance ? - Providing these sport packs/AMG Range options dont include Suspension and wheel size changes...which Im sure they do, and would affect stopping distance.

 

Im sure the reason for manufacturers fitting bigger brakes is because its expected that the sports models are going to be driven a lot harder than regular models and perhaps at higher speeds. There are lots of benefits to bigger brakes but Im only talking about min stopping distance at road legal speeds here. The other reason I bet is - marketing. Customers expect big flashy brakes if they are buying a more expensive sports model.

 

As for ABS - ABS systems takes snapshot wheel speed sensor measurements in milliseconds of all wheels, and control what to do with this information with a set algorythm. The larger braking forces generated confuse the system which shuts of line pressure for set time periods based on the stock pressure-torque characteristics. The result is that its no longer capable of holding the tyre consistently at its peak traction.

 

Although this is in regards to much larger systems than the GTR setup, which appears to be a decent match for the stock Brake master cylinder and abs.

 

Ok - this has been bounced around a while but I really do not understand how this comes about.

 

With regards to the ABS cutting in: regardless of stock braking or not the ABS system does not look at braking force, line pressure or vehicle decelleration - it has no way of measuring these so do not see how it can get "confused"

 

The ABS control unit looks at wheel speed signals - when it sees a wheel approaching lock up (even before lock occurs) it does not shut off pressure - the first stage of ABS is to hold the pressure - so whatever pressure is in the system will be held to see if that wheel will actually lock, if it does not then you would not even be aware at this stage that ABS has "cut in". If it does go on to detect lock then it will reduce whatever pressure (it does not know how much!) by opening the return valve & pumping the fluid back out of the system - it then goes into a closed loop mode to repeat as required.

 

Think of it this way - in a worse case scenario when it is cold & heavy rain on the road then the wheel could lock up instantaneously (sp?!) regardless of stock brakes or upgraded - if the ABS system can cope with this (which is what it was designed for) then I cannot see how it would have a problem during times of increased grip with greater forces!

 

Perhaps I'm missing something but from what I have seen people seem to over complicate how they think ABS works LOL!

 

Anyway - my system works wonders!! :whistling:

Edited May 16, 201114 yr by Paul C

Bud i sent a PM.......im well interested LOL

 

 

done, I think? will ring him 2morra bud!! just waiting for your addy to post back them back out to you, I sent a pm asking for it, I just assumed you were still in Germany and not bothered

 

Daz :cool3:

Have to agree with PaulC on this one.....

 

Excellent replies matey.

 

Alz.

Ok - this has been bounced around a while but I really do not understand how this comes about.

 

With regards to the ABS cutting in: regardless of stock braking or not the ABS system does not look at braking force, line pressure or vehicle decelleration - it has no way of measuring these so do not see how it can get "confused"

 

The ABS control unit looks at wheel speed signals - when it sees a wheel approaching lock up (even before lock occurs) it does not shut off pressure - the first stage of ABS is to hold the pressure - so whatever pressure is in the system will be held to see if that wheel will actually lock, if it does not then you would not even be aware at this stage that ABS has "cut in". If it does go on to detect lock then it will reduce whatever pressure (it does not know how much!) by opening the return valve & pumping the fluid back out of the system - it then goes into a closed loop mode to repeat as required.

 

Think of it this way - in a worse case scenario when it is cold & heavy rain on the road then the wheel could lock up instantaneously (sp?!) regardless of stock brakes or upgraded - if the ABS system can cope with this (which is what it was designed for) then I cannot see how it would have a problem during times of increased grip with greater forces!

 

Perhaps I'm missing something but from what I have seen people seem to over complicate how they think ABS works LOL!

 

Anyway - my system works wonders!! :whistling:

 

Good explanation of the ABS system, but let me explain the problem.....

 

The ABS sensors measure wheel speed only, at set time intervals of every few milliseconds and with this it knows the wheel deceleration. It does not measure measure vehicle velocity, vehicle deceleration or line Pressures.

 

It does'nt just release pressure to the caliper, it releases pressures for a certain amount of time in order to maintain an approproate pressure to bring wheel deceleration back to a correct level. How much pressure, and therefore how much time to open/close is calculated/programmed according to the stock brake pressure-torque characteristics.

 

And thats the problem, a vehicle running larger brakes does not have the same pressure-torque characteristics as the stock system, which the ABS is programmed for.

 

Any given line pressure in a stock brake system produces a different level of torque than the same line pressure in a larger brake kit.

 

And subsequently 10milliseconds of releasing line pressure does not result in the same wheel deceleration/reaceleration with a larger brake system that has higher braking torques and piston volumes.

 

The problems with Big Brake kits and stock ABS systems have been experienced by many and is well known about.

Edited May 16, 201114 yr by Yowser

Good explanation of the ABS system, but let me explain the problem.....

 

The ABS sensors measure wheel speed only, at set time intervals of every few milliseconds and with this it knows the wheel deceleration. It does not measure measure vehicle velocity, vehicle deceleration or line Pressures.

 

It does'nt just release pressure to the caliper, it releases pressures for a certain amount of time in order to maintain an approproate pressure to bring wheel deceleration back to a correct level. How much pressure, and therefore how much time to open/close is calculated/programmed according to the stock brake pressure-torque characteristics.

 

And thats the problem, a vehicle running larger brakes does not have the same pressure-torque characteristics as the stock system, which the ABS is programmed for.

 

Any given line pressure in a stock brake system produces a different level of torque than the same line pressure in a larger brake kit.

 

And subsequently 10milliseconds of releasing line pressure does not result in the same wheel deceleration/reaceleration with a larger brake system that has higher braking torques and piston volumes.

 

The problems with Big Brake kits and stock ABS systems have been experienced by many and is well known about.

 

yup, stoptech spend ages sizing piston sizes to avoid this

 

Not bothered reading the rest of the thread but if you see improved braking under the standing on pedal scenario at 70mph or less, then you had a problem with your stock brakes.

 

Bigger brakes only make a difference for repeated stops and better retardation for much lighter pedal pressure.

Have to agree with PaulC on this one.....

 

Excellent replies matey.

 

Alz.

 

I spend all day having to read about, write about and calculate this sort of stuff as a Motorsport engineering undergraduate, but It does'nt really matter if nobody believes the theory behind it....

 

.....its all been tested, proven and documented, both in the public domain, from Automotive Magazine and media tests and withinin Engineering and Motorsport technical papers and publications.

 

There are many advantages to larger brake kits, but the facts are that Big brake kits do not really reduce min stopping distance (at road legal speeds at least), and they can interfere with ABS system performance when the Braking torque and volume characteristics do not match the stock system.

Good explanation of the ABS system, but let me explain the problem.....

 

The ABS sensors measure wheel speed only, at set time intervals of every few milliseconds and with this it knows the wheel deceleration. It does not measure measure vehicle velocity, vehicle deceleration or line Pressures.

 

It does'nt just release pressure to the caliper, it releases pressures for a certain amount of time in order to maintain an approproate pressure to bring wheel deceleration back to a correct level. How much pressure, and therefore how much time to open/close is calculated/programmed according to the stock brake pressure-torque characteristics.

 

And thats the problem, a vehicle running larger brakes does not have the same pressure-torque characteristics as the stock system, which the ABS is programmed for.

 

Any given line pressure in a stock brake system produces a different level of torque than the same line pressure in a larger brake kit.

 

And subsequently 10milliseconds of releasing line pressure does not result in the same wheel deceleration/reaceleration with a larger brake system that has higher braking torques and piston volumes.

 

The problems with Big Brake kits and stock ABS systems have been experienced by many and is well known about.

 

I still dont see the difference!

 

"a vehicle running larger brakes does not have the same pressure-torque characteristics as the stock system"

 

what pressure-torque characteristic are you referring to??

 

The pressure in the system is going to be the same as the master cylinder is producing the initial pressure & then the ABS pump takes over to control hydraulic pressure to each individual brake.

 

Torque?! torque is a turning force, presumibly you mean at the brake itself - the ABS system does not see any torque, just the speed from the WSS.

 

So still do not really see how it can effect anything?! :wack:

Dont worry about it paul its confused the hell out of me aswell, all i need to know is i have bigger brakes and it stoped better than the std set up without any abs problems.

 

I also had the big disc conversion with stock callipers and they also stoped the car quicker than the stock ones.

 

All this threory crap means nothing to me. proof is in the pudding imo as stock car will no way stop as quick as i can :)

I still dont see the difference!

 

"a vehicle running larger brakes does not have the same pressure-torque characteristics as the stock system"

 

what pressure-torque characteristic are you referring to??

 

The pressure in the system is going to be the same as the master cylinder is producing the initial pressure & then the ABS pump takes over to control hydraulic pressure to each individual brake.

 

Torque?! torque is a turning force, presumibly you mean at the brake itself - the ABS system does not see any torque, just the speed from the WSS.

 

So still do not really see how it can effect anything?! :wack:

 

The pressure is in the system is the same, but the amount of torque applied for that pressure is greater with the BBK.

 

By torque I mean the braking force that decelerates the wheels - the clamping force of the caliper on the disc.

Dont worry about it paul its confused the hell out of me aswell, all i need to know is i have bigger brakes and it stoped better than the std set up without any abs problems.

 

I also had the big disc conversion with stock callipers and they also stoped the car quicker than the stock ones.

 

All this threory crap means nothing to me. proof is in the pudding imo as stock car will no way stop as quick as i can :)

 

LOL!! I agree bud, just wondering where this theory comes from as I cant see how on earth it would make a difference!!!

 

You have K sport 8 pots all round dont you?! must take you 500 meters to stop at 30mph!! :whistling:

All this threory crap means nothing to me. proof is in the pudding imo as stock car will no way stop as quick as i can :)

 

There is plenty of proof out there. If I had a proper internet connecting now I would search for some brake stopping disance Comparison tests.

The pressure is in the system is the same, but the amount of torque applied for that pressure is greater with the BBK.

 

By torque I mean the braking force that decelerates the wheels - the clamping force of the caliper on the disc.

 

But that is no different to the ABS having to cope with different forces & from wheels that lock up quickly in slippery conditions at low braking forces or in real good grip situations with high forces! regardless it is still just looking at the wheel speed signal as a reference to holding pressure then reducing pressure then alowing pressure again.

 

I still think this is being over complicated!! Especially when there are many real world examples with no issues!!

 

I have looked into this & Mercedes use the same ABS control unit for vehicles with the exact same software regardless of brake size!! This would not make sense & the ECU would differ if having larger brakes had a negative effect on the braking system!

I've got a GTech meter that measures 60-0 braking time amongst other things Daz, you are welcome to borrow it if you want for the testing?