الموضوع: العربيه بتزحف مع الفرامل

المشاركة الأصلية كتبت بواسطة MMamdouh

spongy brake pedal is a different issue

by default cars are setup to have more brake bias towards the front due to the weight transfer under braking which reduce the amount of grip of the rear tires... if a car had 50/50 brake bias it would lock its rear brakes prematurely and odds are you are going to spin out and lose control so the bias is their to keep you safe

this bias is done through the proportional valves found on the brakes master cylinder, on a 1.5 SOHC lanos you will have 3/40 proportional valves... this means that at 40 bar the proportioning effect starts and once this happen only 30% of the added brake pressure will go to the rear tires

this percent of proportioning is too much for normal driving conditions... this is why it is almost impossible to lock your rear tires under braking specially if you got drum brakes.. in a perfect world you should lock the rears at the same time as you lock the front... or at least lock the rear AFTER you have locked the front or else you will be spinning like hell

this safety feature is their to save you under extreme conditions like when you are on low grip surface (rain or dust) or going fast on a down hill... those are conditions that will increase the front brake bias thus the rear will be more pron to lockup so this is why the bias is too much... manufacturers sacrifice a bit of braking power in exchange of safety

spongy brake pedal is simply an issue with air in the brake lines... you need to bleed the brakes... if you do experience this after hard braking then your pads are too soft and they over heat... you should be using a stiffer compound

MMamdouh

say concerning the proportional valves,it seems that they are extremely important because the determine the needed forces for the brakes.i hard that one of the members removed them.It was amazing as he said that he liked the idea yet he was criticized severely by most of the members.Can you explain this again?
Thanx for your cooperation

المشاركة الأصلية كتبت بواسطة MMamdouh

in very simple terms... if you have 50/50 brake power between front and rear you will defiantly lock the rear wheels under hard braking and when that happen you will spin the car and lose control and most probably you will crash

when you remove the proportional valves you increase the rear brakes power... OK this will increase the overall braking power but this will be on the expense of your safety... once you brake on lose surface or a down hill you will develop a catastrophe

MMamdouh

God forbids.
Thanx for your cooperation