Q: The Best Brake Grease

A: A common Google search term is ‘what is the best brake grease’.   But what are folks looking for – best pad grease? Likely folks are lookng for the best caliper pin grease. The fact is on a normal brake caliper there are three lubrication points – the sliding caliper pin, the pad and the end of the pad where it meets the clip. Is there one grease which is suitable for all three areas? No. Each point has different lubrication needs so three lubricants are needed. ProSlip PIN is not suitable to lubricate the ends of the pads where they meet the clips because it will quickly wash off. ProSlip CLIP has a dry lubricant low friction component in a high quality base oil which means it stays on the pad and clip surfaces. Could you use ProSlip CLIP on the caliper pins? No.

 

ProSlip PIN was developed specifically to be very low friction, much more so than the dry lubricant component of ProSlip CLIP.

 

ProSlip PAD has a dry lubricant component but it is not a low friction lubricant! The lubrication requirements of the pad-caliper are for a lubricant which controls Noise Vibration and Harshness – NVH. This has to be a lubricant capable of withstanding very high pressure given the brake force of a caliper.

 

The answer to the question what is the best brake grease is – ProSlip Brake Kit!

 

 

Q: Is ProSlip PIN compatible with all rubber or elastomer boots?

A: ProSlip PIN is a synthetic base and will not cause the elastomer boot to swell. PAD and CLIP have a mineral base oil and should not be in pro-longed contact with either the caliper pin boot or the pison boot. Many DIY folks are in the habit of covering all parts of the caliper in grease – this is not advisable! The ProSlip kit contains enough lubricant for several applications – you do not need to put grease everywhere, it will attract sand and grime.

Q: How often should I grease my brake caliper pins on my car?

A: . Most caliper designs for road cars have the elastomer boot as a non water tight fit. Depending on the road conditions water will eventually get behind the rubber boot and onto the caliper pin. This is especially true if you are crossing rivers, driving in snow and jet washing this area regularly. On a car with significant ground clearance you may be able to reach the rear caliper pins without taking off the wheel. On most cars with the front wheels on full lock this is also possible. This means re-greasing rhe pins is a 20 minute job. ProSlip PIN won’t degrade under temperature and dry out like petroleum based greases. It also has an anti corrision package. However exposed to high levels of salt will all greases will degrade to some extent – if you are driving  on very salty roads, re-grease your pins. Salt on the roads is the main cause of body corrosion. Cars imported from Japan where salt is not used are corrosion free even after ten years

Q: Brake Pad Grease

A: Pads are made of base steel and as they they wet corrode – this corrosion is hugely accelerated by salt on the roads. The pads sit in clips – or shims – made of sprung steel which is highly resistant to corrosion but water tends to get between the end of the pad and the clip. In hot countries water from rain quickly dries but elsewhere it sits and causes corrosion. By itself this is not a problem but the corrosin has the effect of making the metal swell – this is because the rust produced is less dense than the metal and slowly packs the pad tighter. This is the same reason a rusted bolt is harder to remove. It stands to reason that if the brake pads do not come out easliy from the clips at changeover then they are not moving freely in the clip. Why is this important? A pad which is hard to move means  more piston force is taken up moving the pad forward against the corroded ends as opposed to pushing against the disc. The pads should require minimal force to be moved in their clips.  Coating the pad ends with ProSlip CLIP helps prevent corrosion and reduces the friction between pad and clip making it easier for the pad to move in the clip.ProSlip CLIP contains a dry lubricant which makes it extrmemely resistant to being washed off.

Q: What is Brake Drag?

A: Sit back is a term we at ProSlip use to describe the passive micro movement of the caliper to completely release the disc after braking. Huge force is involved in pushing the pad against the disc but there is no active force pushing the pads apart – at least on road vehicles. Release of the disc relies on passive recoil of the caliper and pads. For this to be immediate the caliper pin grease must offer very low frictional resistance and the pads need to be able to move freely in the clips. If the caliper is seized the pad will continue to press against the disc long after the pedal is released. ProSlip PIN is made to be very low friction over a wide temperature range and used with ProSlip Clip facilitates caliper sit back meaning extra friction on the discs. Just lubricating the caliper pins whilst the pads are corroded in their clips will not produce the same results.

Q: Brake Squeal

A: Noise Vibration and Harshness is a term often used by engineering companies to describe a series of undesireable effects. Under force brake pads flex a great deal – twin piston calipers aim to reduce this by pinning the pad at each end. Pad flexing means less pad surface in contact with the disc requiring more braking force. The flexing also resists the efforts of the caliper to keep the pad against the disc. All this can be felt at the pedal – vibration and harsheness.

Q: Why do Calipers Seize

A: Calipers move when braking but as there is no ‘give’ in either the pad or disc you can’t see it – it’s a micro movement. The fact the caliper moves very little pre-disposes it to seizing – there is no significant displacement keeping the caliper pin lubricated as it slides back and for like a steam engine piston. A caliper just sits there, squeezes very hard and relaxes.

Q: Why lubricate the piston seal?

A: . Brake fluid in the caliper is kept from escaping by a silicon rubber seal around the piston. As the piston moves forward this seal deforms. When the caliper is new and the seal coated with brake fluid the seal offers little resistance to the movement of the piston.There is no space between the seal and piston and over time the brake fluid is forced out. A dry seal offers a great deal more resistance to the movement of the piston. On a new caliper it’s possible to push the piston back with your fingers. If you have to use a piston wind back device the piston seal is too dry and will make it much harder to push the piston forward and crucially for the caliper to ‘sit back’ after braking. Watch The ProSlip Way video to see how to re-lubricate the piston seal.

Q: Is ProSlip PIN synthetic?

A: ProSlip PIN is a Polyethylene Glycol – PEG – lubricant with lithium.  PEG’s are polymers of ethylene oxide, different structures and sizes give different properties to the PEG. ProSlip PIN is based on a PEG which makes the lubricant extremely slippy over a wide temperature range. The lithium soap makes ProSlip PIN stick to metal, resistant to heavy loads and prevent fretting corrosion

Q: Is ProSlip PIN OK to use on my Toyota, Honda etc

A: ProSlip PIN can be used where OEM specifies PEG with Lithium Soap which is the vast majority of vehicles.

Q: Why not use silicone grease on caliper pins?

A: Silicone grease is cheaper than  specialist lubricant, is rubber compatible and doesn’t melt at high temperature. It is not the right lubricant for caliper pins though – it’s a very poor metal to metal lubricant and crucially is not a very low friction grease and won’t prevent fretting corrosion . Keep it to use to use on plastic and rubber

Q: Why shouldn't I use copper grease on my brake calipers?

A: We covered this on the home page but will repea the basics here .Tiny copper particles in a basic grease is not a lubricant but a poor anti-seize compound. Copper greases claim  ‘high temperature’.  This is misleading –  copper melts at over 1,085 °C but the grease component will not withstand the temperatures experienced by a caliper pin – the grease will dry out causing the caliper to seize. Copper grease is very cheap but has few genuine applications in automotive maintenance.

Q: What grease should I use on my brake pads?

A: We expect lubricants to be wet or greasy but compounds such as graphite or molybdenum disulphide have a  molecular structure which makes them ‘natural’ lubricants in powdered form alone – mixed with a suitable carrier they offer advantages over ‘wet’ lubricants notably resistance to washing off.

Brake Calipers – Treat them to the Best -They’re Worth It!

Hit the brake pedal and some 4000lbs per square inch of pressure are applied to the brake disc – enough to crush bone. It takes that much as the small four discs have to slow the momentum of over a tonne of vehicle as it hurtles forward. So much heat results that the gas layer between the brake pad and the disc can become ‘super heated’ and resists braking force. This is causes brake fade and is the reason discs are drilled grooved and brake pads have a slot down the middle – to allow the gas to escape. Brake pads flex significantly when braking pressure which reduces the pad-disc contact area. Twin calipers aim to reduce the amount of flexing by spreading the braking force over a wider surface area of the pad

Brake pads are in permanent contact with the disc so are made of low friction material. Low friction but not zero friction. If you’ve ever had to push your vehicle you know that the hardest part is that initial push to get it moving. This is because the resting resistance at the pad-brake is a lot more than zero. If you were to take out your brake pads, it would make it a lot easier to get the vehicle rolling. Once moving the friction at the brake-pad becomes negligible compared to the comparatively huge forward momentum of the vehicle which is why you’re able to tell the kind passer-by ‘thanks I’ll take it from here!’

Anything which increases the pad-disc friction will make it harder for a vehicle to move off from stationary and when driving you have to rev to overcoming that ‘rolling resistance’. The revving engines of vehicles moving off – at traffic lights, roundabouts, over speed bumps – makes a massive contribution to air pollution. Pad-disc friction affects acceleration from standstill.
It stands to reason that anything you can do to reduce rolling resistance will improve fuel economy, acceleration and emissions. Your choice of brake caliper grease and  how you apply it affects rolling resistance of your vehicle – here’s why.
Lots of heat is generated when braking.-  see https://www.youtube.com/watch?v=-1N5nBDLQMg. This heat will eventually cause petroleum based grease to dry out. Not necessarily a problem if the brake grease has a ‘dry lubricant’ –  it still operates as a lubricant.
Copper grease became the choice for lubricating calipers and this still persists to-day, unfortunately. Copper particles do not slide easily over each other and so copper grease cannot act as a dry lubricant. It is a better anti-seize compound, the idea being that copper resists corrosion, which must be the reasoning behind why it is mistakenly used on the brake pin – not so much lubricating as stopping them seizing.
Heat reaching the caliper pin means any suitable caliper pin grease must be ‘high temperature’ and this inevitably means a synthetic grease. Silicone grease resists high temperatures, is compatible with rubber and is cheap. It is very poor metal to metal lubricant however which is why it is not used in CV joints or bearings. Most ‘high temperature’ brake greases are usually simply cheap silicone.
If your caliper pin grease does not contain an ingredient to protect the metal surfaces of the pin and the pin seat then fretting corrosion can occur which shows as pitting on the surface of the caliper pin. Fretting corrosion is a severe wear pattern which occurs when two heavily loaded metal surfaces undergo repeated micro movements – exactly what happens when you hit the brake pedal.
Your caliper pin grease needs to be not only ‘high temperature’ and hence synthetic but also have an additive package which protects the metal. These requirements already rule out 99% of brake greases on the market. Even adding dry lubricants to silicone such as PTFE will not prevent fretting corrosion.

It is unclear what the ingredients of those greases with ‘Ceramic’ in the title contain. Many state they are ‘metal free’ but the significance of this is unclear. They are cheap however which suggests they have not been specifically engineered for brake caliper pins at least – that takes an investment in time and money usually reflected in the retail price. The science of lubrication is a huge topic and specialist lubricants can be very expensive.

While there is 4000lbs of force pushing the pads against the disc there is no force pushing them off. The only force which allows the pads to sit back off the disc after braking is the weight of the pads and the caliper. However for this to happen relies on two things. Firstly the caliper pin grease must allow this recoil of the pad – if it has dried out then it will resist this passive movement. Secondly if the ends of the pads are corroded into the clips then the pads will move forward to grip the disc under the large braking force but not allow the pad to readily sit back off the disc – caliper relaxation we call it.
It goes without saying if the pads are corroded into the clips so you have to knock them out with a hammer then more force is need to actually push them onto the disc in the first place. Not good, you don’t want to be jumping on the brake pedal. At rest the caliper should be adding zero extra friction to that of the pads resting on the disc. For this two occur the pads must be able to move in the clips and the caliper pin must be able to allow the pads to passively sit back.
This provides a clue as to a key physical characteristic of your ideal caliper pin grease – it must facilitate the micro movements of the caliper in both directions, one under force the other passive. As we’ve implied many greases will allow the caliper to grip, but very few will aid the ‘relaxation’ of the caliper. ProSlip PIN was developed precisely with this in mind and was synthesised to have a very high lubricity – be extremely slippy. This is noticed at the pedal in improved ‘pedal feel’ – the pedal feels less hard. This is because with the caliper properly greased the ‘recoil’ of the caliper relaxing is communicated by the brake fluid to the pedal.Other branded brake greases are not engineered with such low friction, to make a grease with this particular characteristic isn’t easy. With ProSlip you’ve found the answer to your search. One last thing – a dry piston seal offers very significant resistance to the piston moving . Watch ‘The ProSlip Way’ video here to see our method for lubricating that seal. Hope we’ve answered some of your questions here!