frequently asked questions
If you have any questions not answered on this page, or require further information, please email Powerstop at sales@powerstop.co.uk
Why Kevlar?
This world famous Dupont fibre is used in bulletproof vests and the space shuttle. Very expensive but an excellent binding fibre, low abrasive, non-metallic and therefore, CLEANER and easier on discs.
Kevlar fibre is six times as strong as steel when used in a brake pad in matrix form. Kevlar pads are never the cheapest but often the best
Can you explain friction level?
Typical friction levels of original road pads vary from 0.25 to 0.35 friction factor (µ). EBC Greenstuff has 0.46µ and users will notice an immediate improvement in braking. Remember friction level µ is only an 'indicator' not a guarantee of brake 'torque'. Many independent tests however have shown EBC Greenstuff to be one of the most grippy compounds on the market today and certainly the highest friction level available for Classic Car references. Greenstuff is particularly good at improving stopping performance on non-servo cars. We expect the sheer 'grip' of the pad to be at least 20% better than standard pads.
What is brake fade?
All pads contain some organic materials. Resins that bind pad compounds together are organic petro-chemical products. As these overheat, the resins revert to gas and cause the pads to 'aquaplane' on a gas film which is called fade. Some pads fade once or twice and then settle down (Green fade or bedding in fade). Other, cheaper pads suffer from continual dynamic fade, sometimes at surprisingly low temperatures.
Should I fit oversize brakes?
If you have lots to spend without doubt go for an oversize kit and multi piston caliper. You can never have too much stopping power. Oversize kits can upgrade stopping by 40-50%. Don't forget though, just installing EBC Greenstuff pads can upgrade your standard set up by 25-40%. Without doubt value for money and a simple first step to better brakes.
Which discs should I use?
Knowing where disc castings come from, not just where they are machined is a major problem for consumers. There are a wide range of qualities on todays world markets. Not all are equal. A good quality cast iron disc with or without grooves will work well with EBC Greenstuff. Just don't try to buy the cheapest discs or you may end up with a poor brake or a 'warped' disc. Powerstop discs are UK or EC sourced from premium manufacturers and subjected to rigorous quality checks.
Why the Gold, Zinc finish?
They look great and prevent corrosion in areas not swept by the pad BUT may take 3-400 miles to bed-in. Until all the gold is removed from the friction surface area stopping power may be reduced.
Some 'streaking' or lines may appear during bed-in as the coating wear off - these will also disappear within 3-400 miles. Using pads with the new 'EBC brake-in' coating will reduce the bed-in to 100 miles or less.
What causes brake dust?
As lower cost brake pads wear or carbonise at temperatures found in braking, dust is released. Many pad manufacturers use materials that cause dust in their pads. EBC Greenstuff contains NONE of these, hence pads run cleaner. Greenstuff pads do not surface carbonise until 900-1000°F so in normal use dust is almost entirely eliminated. Any dust that is generated in performance use is easily wiped / washed away without damage to alloy wheels. Tests show that a significant part of 'brake' dust is actually dust from the disc wear. Greenstuff has no ferrous content so disc wear (and disc dust) is reduced.
Is it worth fitting ventilated discs?
We are often asked if we sell a vented disc to convert from a solid disc. Reasons are usually the driver wants better brakes and expects the ventilated disc to run cooler. All fine but to convert one needs either to change or space out calipers and adapt other mechanical components - it can be an expensive exercise and what is not usually realised is that there is a significant increase in unsprung weight which will adversely affect handling and may require changes to spring rates and damper settings. All very tedious but fear not, help is at hand in the shape of modern brake pads such as EBC which will easily handle the higher temperatures generated and with really good friction - for cars with solid discs simply spending a bit more on a decent set of EBC pads could be all that's needed. Ask us for specific advice on particular applications.
What causes brake squeal?
On the occasions it occurs it is usually in older systems (say pre 1990). It can be caused by new pads being overheated when new - the binding resins in the friction compound lift to the surface, glaze the pad and the points of squeal can be seen as polished areas. Remedy - deglaze the pad by flatting off say 0.5-1.00mm on a medium/fine abrasive paper. Then clean the disc similarly (or use wire wool/brake cleaner fluid) with a stroking motion following the 'grain' of the disc. However there is no substitute for careful bedding in for say 200 miles with no overheating.
Another source of squeal is the lateral movement of the pad in a worn caliper and even sideways movement of the piston. Many classic calipers have been rebuilt more than once and original tolerances can be lost. A possible cure here is to fit modern stick-on pads to the back of the pad backplate - the idea is to let the piston cut an imprint on the backing which will then hold the piston steady in it's bore.
Yet another source of squeal can be the use of silicone fluid. It's higher viscosity and lower lubricity can delay piston retraction and thus cause overheating.