Most motorists at some point will experience brake-judder / vibration under braking this may be light braking or hard braking and will be felt as shaking of the steering wheel and even pulsing of the brake pedal.
The Garage says my discs are warped
This is probably the most common statement we hear from consumers, who report that the garage has told them their discs are warped, in fact we have heard some really amusing comments such as;
The brake discs are made of chocolate
They have warped because they were cheap
They have warped because they are poor quality
I personally have seen a huge amount of brake discs in the 25 years I have been in this industry, and I can say hand on heart I have never seen a chocolate brake disc fitted to a vehicle, in fact the mechanics I know would most probably eat the chocolate brake discs before you could collect your car.
The most common causes for brake vibration is disc thickness variation which is known as DTV, this is where the brake discs have worn unevenly causing high and low spots on the discs, whilst it is possible to have a badly manufactured brake disc the cause of DTV after use will normally be a cause of poor fitting techniques by the person fitting your brake discs, this could be the mechanic has not noticed a problem with the caliper pistons or slides or something as simple as not preparing the hub service before mounting the new brake discs. The ensure the new discs are running true to the hub the mechanic should carryout a Dial Gauge Test where the mechanic can actually measure the runout to ensure this is within the vehicle manufacturers specification, if it is not the mechanic should then measure the hub runout without the disc mounted to determine in the runout is a cause of the disc or the hub. If the correct measurement cannot be obtained the discs should not be fitted until the cause has been ascertained as fitting will lead to DTV.
Should you be unfortunate enough to suffer from brake vibrations after a few months / 2-3 thousand miles it is possible to resolve the issue by first rectifying the original cause of DTV and then by aligning the discs to your cars hubs using specialist equipment known as a on car brake lathe.
Poor quality brake discs are really a thing of the past, because modern vehicles require brake discs that are manufactured to high standards, aftermarket manufacturers have had no choice but to invest heavily in their production plants.
Vehicles that were manufactured after 1st November 2016 have to be fitted with ECE R90 certified brake discs, ECE R90 brake discs are your assurance that the brake discs you are purchasing are manufactured to the same high standards as the original equipment brake discs. Aftermarket manufacturers are now producing brake discs for vehicles manufactured before the specified date as ECE R90 certified as a mark of quality, and reassurance for you.
There still a considerable amount of brake discs which are not ECE R90 certified and yet the quality is still excellent and will meet the same standards as the original equipment, so providing your vehicle was manufactured before the 1st November 2016 there is no need to worry if the discs you have purchased do not have the ECE R90 stamp.
To summarise Brake Discs are a wear and tear item and will begin to wear from the moment they are used, how quick they wear will depend on many factors but how they wear will depend on how they were originally fitted and which pad compound you are using. Brake vibration after use is not an indication that the discs were manufactured incorrectly.
We frequently have drivers contact us about brake discs stating that after fitting new discs and pads they notice one side is getting hotter than the other side.
The simple answer to this is question is, the increased temperature means that one side of the brake system is doing more work than the other side which is resulting in the temperature difference.
The reason why this is occurring would require detailed inspection of your braking system, but normally this is due to increased friction or insufficient friction balance, it’s probably natural to assume the side getting hot has the problem but it’s also probable that the cooler side has the problem which is making the opposite side work much harder than normal to reduce the speed.
Our advice would be to inspect both brake calipers for any defects, this could be torn piston seals, worn slider sleeves or sticking caliper pistons. Pistons that are not able to move freely will result in brake binding which will cause the pads to rub against the discs constantly causing higher temperatures than normal, uneven braking and eventually damage to the brake discs not to mention increased wear on your pads.
So if you have concerns that one side is getting hotter than the other please get the brakes checked by a reputable professional, preferably the mechanic should belong to a professional register such as the IMI or be ATA accredited to illustrate they have undertaken professional training and are continually developing their personal development.
Brake Fluid should be replaced every 2 years and is not mileage dependant, meaning even if you have driven your car for 1 year or more the fluid should still be replaced every 2 years, why?
OK, brake fluid is hygroscopic which in laymen terms means it absorbs water from the atmosphere, this absorption deteriorates the fluid by lowering the boiling point of the brake fluid it can also cause an increase in volume within your brake system causing complete brake lockup in rare circumstances. The lower the boiling point of the brake fluid the more likely the chances of vapour lock when this occurs the fluid boils separating the oxygen from the water (just like boiling your kettle) the oxygen now in the brake system greatly reduced the hydraulic efficiency of your brake system, this will be felt as a “Spongy Pedal” feel and you will also notice the brake don’t work as well as they should. This is because the pressure in your hydraulic system being applied by your brake master cylinder / brake pedal is being absorbed by the oxygen, the reason being oxygen is compressible and when confined behaves almost spring like where as brake fluid is designed not be compressible. A very easy way to understand this is, if you had a solid steel bar and pushed from one end parallel to the bar the other end would move at exactly the same timing and distance, however if you divided the solid bar and placed small balloons filled with air between each pocket and carried out the same test, the bar at the very front would not move immediately and would not travel the same distance as the rear.
The most common type of brake fluid is DOT4 but there is also DOT 3, DOT5 and finally DOT5.1 these fluids are different and its important that you understand why, these can be separated into 2 groups,
Glycol (polyethylene glycol) Based
Silicone (diorgano polysiloxane) Based
Glycol based fluids are the hygroscopic type which means they absorb water as discussed above, where as Silicone based fluids contain at least 70% by weight of a diorgano polysiloxane when replacing DOT 5 fluid extra care should be taken as this fluid does absorb air this is known as hydrophobic the most critical point however is Silicone based fluids and Glycol based fluids should NOT be mixed.
Below is the common boiling points for the fluid types.
Dry boiling point
205 °C (401 °F)
140 °C (284 °F)
230 °C (446 °F)
155 °C (311 °F)
260 °C (500 °F)
180 °C (356 °F)
260 °C (500 °F)
180 °C (356 °F)
Available from our stock are DOT 4 and DOT 5.1, we have standard replacement Mintex DOT 4 available in half litre and 1 litre’s and for the DOT 5.1 we have Ferodo racing fluid, which can be used on the road and track.