I have read that fitting big brakes can upset the ABS and it kicks in too early and in effect makes your brakes not work very well at all.

 

Anyone know what this is all about?

 

Is it when you go over a certain diameter?

The standard size front discsare 280mm, I upgraded mine to 296mm with calipers from a skyline, while its not the biggest upgrade it doesnt effect the abs, but braking is greatly improved.

 

Also I noticed whilst bleeding the brakes off, as my mate was pumping the foot pedal, the movement of the servo was unreal due to the bulkhead flex, so I fitted a master cylinder stopper which has totally eliminated this and braking feels much firmer and more responsive.

 

Hope this helps.

I too have fitted the brembo ugrade and the ABS actually works now.

 

Don't think I could ever get the brakes to work well enough before for the ABS to kick in. No matter how hard I stood on them.

 

The other option is to remove the ABS.

 

Darrell

Ive got a big brake kit, master cylinder brace and R33 brembos fitted. Cant say ive noticed any problems with ABS kickin in too early. Car stops on a pin tho :nana2:

Thanks for your thoughts guys, I am looking at rotors of about 320mm.

 

I have read somewhere, and I have done a search too, that sometimes the ABS will be fooled into thinking there is something wrong, ie lock up imminent, by the unexpected signals from the ABS sensor on one, or both, of the front wheels with the bigger discs. Something to do with the degree of retardation or something clever I dont understand.

Thanks for your thoughts guys, I am looking at rotors of about 320mm.

 

I have read somewhere, and I have done a search too, that sometimes the ABS will be fooled into thinking there is something wrong, ie lock up imminent, by the unexpected signals from the ABS sensor on one, or both, of the front wheels with the bigger discs. Something to do with the degree of retardation or something clever I dont understand.

John Dixon posted about this a while back IIRC. I'll see if I can find the post...

 

Steve :)

John Dixon posted about this a while back IIRC. I'll see if I can find the post...

 

Steve :)

Found it - http://www.300zx.co.uk/forums/showthread.php?t=48071

 

HTH

 

Steve :)

 

*EDIT* The article John links to has moved here - http://www.stoptech.com/tech_info/wp_abs_bigbrakekits.shtml

Thanks, be handy....:-)

I'm running on 345mm AP Racing disks. The braking is awesome, never had any problem in the wet, ABS or otherwise and never had any brake fade (6 pot though).

ABS doesnt care what size your brakes are, all it knows is, if you're stomping on the stoppers, and the wheels start to lock then the ABS releases the brakes and re-applies them.

if you increase the size of your brakes and increase your stopping power then the tyres are more likely to skid than before. therefore the ABS will seem to be kicking in earlier. but over all your braking power will still be greatly improved by the big brakes.

Thanks Konrad, thats good to know.

 

But Fraser I have to disagree, to a point. I would have agreed with you but when I read the article I need to re read, it becomes apparent that its not quite so simple. I think. Lol.

 

Anyway, hopefully Steve will find it and we can all read it.

If only i could read before posting. Thanks Steve

 

So, what does this mean in the real world to us? Have any of us had this problem, (I see JD implies he has).

 

Anyone?

if only i could read

LOL ;)

ABS doesnt care what size your brakes are, all it knows is, if you're stomping on the stoppers, and the wheels start to lock then the ABS releases the brakes and re-applies them.

if you increase the size of your brakes and increase your stopping power then the tyres are more likely to skid than before. therefore the ABS will seem to be kicking in earlier. but over all your braking power will still be greatly improved by the big brakes.

 

i agree, cant see that having bigger brakes (or more braking force) is going to make any difference. the ABS control module simply measures each individual wheel speed sensor & if lock up is about to occour the hydraulic unit will kick in to release the pressure.

 

its no different to braking hard with stock size brakes!

But if you read the article I can see it "might" make sense?

 

What we/I need is for people with big brakes to tell of their experience. PLEASE...

But if you read the article I can see it "might" make sense?

 

What we/I need is for people with big brakes to tell of their experience. PLEASE...

 

Ive never had any problems with the ABS

But if you read the article I can see it "might" make sense?

 

What we/I need is for people with big brakes to tell of their experience. PLEASE...

 

LOL! well I disagree with what that article says!! :p

 

it certainly doesnt tie in with ABS ESP training I have attended. I can see no reason why it would need to calculate the rate of decceleration, it only needs to know when lock is going to occour by comparing wheel speed sensors.

I was assuming that the author of the article knew more than I do, but basically I agree that ABS should not behave as the article says. But, then I think, "well maybe"

 

Maybe they are just after more business. I wanted to try and make sure before I went ahead and bought some bigger brakes.

LOL! well I disagree with what that article says!! :p

 

I can see no reason why it would need to calculate the rate of decceleration, it only needs to know when lock is going to occour by comparing wheel speed sensors.

 

agreed totally!

i wonder if they have got mixed up with the EBFD or whatever it is system, that electronic brake force thing.

 

That might get upset due to the cars ability to stop quicker BUT i would highly doubt it since pads and disks change in their ability to brake over time and usage, so the system has to automatically caibrate is self.

ABS works in real time, it checks the sensors if there is a problem then it trys to solve it. The ABS then checks again to see if the issue is resolved, if the issue is sorted then it removes its counter measures.

 

If the system were to fail when larger disks were used (or indeed better pads, lets face it an old set of OEM pads vs a new set of mintex or ebc or whatever is going to massivly affect braking performance) then it wouldnt be dynamic.

 

So if it were not dynamic it would sense a problem, react to it and then not check again, so in affect you would loose braking one the affected wheels, hardly a safe system!

 

So whoever says it is affected by greater stopping performance doesnt know what they are talking about!

Having read one of the other topics on caliper move out kits, I find that one a bit unlikely too.

 

And hows this fro the StopTec site.

 

"in more than 40 years of professional racing, including the Shelby/Ford GT 40s – one of the most intense brake development program in history - I have never seen a warped brake disc".

 

Well I have, maybe I should send "her" a couple. Lol.

Remember though if you change the size of the callipers then the piston volume will also change so the effect of the ABS WILL be wrong as the amount of fluid it releases per pulse is calibrated for the stock piston volume.

I'm certainly happier without it anyway, try it see what you think then make a decision.

Remember though if you change the size of the callipers then the piston volume will also change so the effect of the ABS WILL be wrong as the amount of fluid it releases per pulse is calibrated for the stock piston volume.

I'm certainly happier without it anyway, try it see what you think then make a decision.

 

yes, but again I cant see for the life of me why an ABS unit would work in volumes!! it holds & decreases pressure, again, it doesnt need to know the volume of fluid its moving! there would be too many variables, its far simpler than that really!

Because the modulation is not analogue, its digital pulses so each pulse will move a set volume giving a known reduction in pressure over the system.

I write control algorithms for a living so have some idea how these things work and they're never simple! Like saying just compare wheel speeds, yes fine but what if all 4 lock, that's why you look at ROC of deceleration, trying to predict the point of lock up, sort of like derivative action on a PID controller.

When I was looking at brakes, I came to the conclusion that just putting big brakes on the front will upset the braking of the car. I then went and bought the Stoptech big brake kit, as its designed to work with the existing abs to give the balance braking the manufacturer setup.

 

Not tried the brakes yet, so dont know how good they perform.

 

Barry

Because the modulation is not analogue, its digital pulses so each pulse will move a set volume giving a known reduction in pressure over the system.

I write control algorithms for a living so have some idea how these things work and they're never simple! Like saying just compare wheel speeds, yes fine but what if all 4 lock, that's why you look at ROC of deceleration, trying to predict the point of lock up, sort of like derivative action on a PID controller.

 

ok, if it calculates on volume then it would need some way of measuring the volume, & i know there isnt! like i said, there would be too many variables - ie battery voltage differences would effect the volume of fluid displaced, fluid temperatures, position of the pistons in the calipers, etc etc.

 

also have just checked on a early C class merc & they use the same ECU on a bog standard C180 as they do on a AMG36 with much bigger calipers!