Very squeaky brakes after new pads
Discussion
OllieC said:
it worked on two separate capris I had...
both had the metal shims fitted but the copper grease stopped the squeal, I have no idea how it works
it is good to put on the retaning pins (depending on the caliper design i suppose) to make them easier to remove when you need to change the pads again
yes I agree it is good to put on retaining pins to stop them seizing but what i'm trying to find ollie is someone that can offer a good enginnering explaination as to why copper grease on the back of a pad will stop brake squeal from the contact between the friction lining and the disc surface?both had the metal shims fitted but the copper grease stopped the squeal, I have no idea how it works
it is good to put on the retaning pins (depending on the caliper design i suppose) to make them easier to remove when you need to change the pads again
chryslerben said:
STOP STOP STOP now I know everyone is going to flame me and shout me down on this but covering the back of the pad in copper grease is going to do nothing toward stopping the squealing.
Theres a reason manufactures put sticky backings on pads, its to keep the pad in contact with the caliper so when you lift your foot off the brake pedal it also pulls the pad away from contact with the disc to eliminate squeal. Covering it in copper slip may actually make your problem worse.
Now a little copper grease on the ends of the pads where they locate in the carrier is ok to stop seizing.
Complete nonsense! Show me the mechanism which pulls the pad away from the disc.Theres a reason manufactures put sticky backings on pads, its to keep the pad in contact with the caliper so when you lift your foot off the brake pedal it also pulls the pad away from contact with the disc to eliminate squeal. Covering it in copper slip may actually make your problem worse.
Now a little copper grease on the ends of the pads where they locate in the carrier is ok to stop seizing.
chryslerben said:
yes I agree it is good to put on retaining pins to stop them seizing but what i'm trying to find ollie is someone that can offer a good enginnering explaination as to why copper grease on the back of a pad will stop brake squeal from the contact between the friction lining and the disc surface?
It won't , it will reduce the friction between the back of the pads and the caliper, which would be like scraping a blackboard without it.avocado said:
Complete nonsense! Show me the mechanism which pulls the pad away from the disc.
Ok then some manufacturers use spring clips, some us sticky adhesives but all when pedal pressure is removed will retract fractionally otherwise your pad would permanently be in contact with the disc mwcr85 said:
It won't , it will reduce the friction between the back of the pads and the caliper, which would be like scraping a blackboard without it.
But the pressure applied to the pad is only on one axis yes their would be a minute amount of flex on say a single piston caliper but not enough to simulate the blackboard effect.chryslerben said:
otherwise your pad would permanently be in contact with the disc
Yes, they are in permanent contact. There's no "pull back" mechanism. If there was a pull back, you'd get no brakes at all for the first inch or so of pedal travel!When you push the brake pedal a truly massive pressure is applied to the pad,; that's leverage from the pedal and amplified by the brake servo. When the pressure is released the pads just mind their own business with the limited disc rub causing no issues. After all, your wheel bearings manage to keep working for years with metal to metal contact and a dab of grease.
IMO the copperslip simply damps the vibrations that cause the squeel, all pads squeel it's just to high for human hearing, dogs will jump when you brake near them but you can't hear a thing, that and cheap pads do squeel, i've had a lot of problems in the past with apec pads and went back to mintex but apec seem to have sorted it now.
I've also found cheap aftermarket pads wear quicker than OE but OE pads wear the discs more, something has to wearout and if the pads are very hard it will be the disc, ni on all modern cars are very over servo'd to counter the hard pads when compairred to say 80's cars (soft pads, less servo, less disc wear but pad chamges are more frequent), of course this could be down to better balenced brake systems nowdays with rear discs that avoid the constanvt non adjustment drum brakes suffer from thus shoving all the braking to the front ?
I've also found cheap aftermarket pads wear quicker than OE but OE pads wear the discs more, something has to wearout and if the pads are very hard it will be the disc, ni on all modern cars are very over servo'd to counter the hard pads when compairred to say 80's cars (soft pads, less servo, less disc wear but pad chamges are more frequent), of course this could be down to better balenced brake systems nowdays with rear discs that avoid the constanvt non adjustment drum brakes suffer from thus shoving all the braking to the front ?
NHK - broadly speaking you are absolutely right. The manufacturers put a lot of work into designing a brake system which waears at a sensible rate and doesn't squeal. As you say, pads do love to squeal given half a chance! Aftermarket products are much more likely to squeal than OEM. Grease on the back of the pads may suppress noise in some cases but it shouldn't be necessary in the first palce.
By the way, rear brakes do virtually nothing, especially on a small hatchback carrying just the driver. Most of the weight is at the front to start with and under braking the rest of the weight transfers to the front of the car. This is amongst the reasons why manufacturers tend to dial out oversteer.
By the way, rear brakes do virtually nothing, especially on a small hatchback carrying just the driver. Most of the weight is at the front to start with and under braking the rest of the weight transfers to the front of the car. This is amongst the reasons why manufacturers tend to dial out oversteer.
Try some different pads,preferably the OE stuff.I have learned the hard way several times in the past by trying to save a few quid by fitting aftermarket brake pads (mintex being the worst) and been left with horrendous brake squeal which no ammount of copper grease or shamfering the edges of the pad will solve.
It seems to be the case that some aftermarket pads are just simply not compatible with the discs and shouldn't even be sold IMO.
It seems to be the case that some aftermarket pads are just simply not compatible with the discs and shouldn't even be sold IMO.
chryslerben said:
Ok then some manufacturers use spring clips, some us sticky adhesives but all when pedal pressure is removed will retract fractionally otherwise your pad would permanently be in contact with the disc
The run out in the disc is what pushes the pad away, if you had a perfectly manufactured disc with no run out you would have this problem. ETA: AT the garage I worked at and at college we always put copper grease on the back of pads. Its common practice.
Ozzie Osmond said:
Manufacturers put considerable efffort into engineering brake materials which don't squeal. Aftermarket parts are not so rigorously tested.
That's the same bs story Honda tried to tell me when changing pads on a Jazz for stupid money.The pads and calipers were branded Nisin, not Honda. The motor factors sold me the same Nisin pads for a fraction of the price. I don't think any car maker makes the brake pads they use in the cars they make.
Ozzie Osmond said:
Yes, they are in permanent contact. There's no "pull back" mechanism. If there was a pull back, you'd get no brakes at all for the first inch or so of pedal travel!
When you push the brake pedal a truly massive pressure is applied to the pad,; that's leverage from the pedal and amplified by the brake servo. When the pressure is released the pads just mind their own business with the limited disc rub causing no issues. After all, your wheel bearings manage to keep working for years with metal to metal contact and a dab of grease.
I'm not talking inches or even mm buddy I'm talking 10ths to 100ths of mm. Ask any race driver why they tap the brake pedal after a hard corner? When you push the brake pedal a truly massive pressure is applied to the pad,; that's leverage from the pedal and amplified by the brake servo. When the pressure is released the pads just mind their own business with the limited disc rub causing no issues. After all, your wheel bearings manage to keep working for years with metal to metal contact and a dab of grease.
You may or may not believe what I say buy I've been doing this a long time commercially and on proffesionally on track
P I Staker said:
The run out in the disc is what pushes the pad away, if you had a perfectly manufactured disc with no run out you would have this problem.
ETA: AT the garage I worked at and at college we always put copper grease on the back of pads. Its common practice.
Can I just stop you there mate your obviously still at college and copper grease on pad backings stopping squeal is bull, 99% off squeal you will experience on customers vehicles will be caused by friction lining contact with disc normally through either mismatch, pad glaze or just cheap sETA: AT the garage I worked at and at college we always put copper grease on the back of pads. Its common practice.
te pads. chryslerben said:
And if anyone really is in doubt just talk to the brake manufactuers they will tell you the exact same as what I'm saying ( I'm talking reputable manufactuers)
My brakes were squealing, I applied copper grease to the back of the pad and the squealing stopped so there's evidence to suggest it works. When trying to find a cure to the problem I was told by several mechanical minded people that copper grease was the way to go. Gassing Station | General Gassing | Top of Page | What's New | My Stuff