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finest1

squealing brakes at low speeds

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hi all,

 

how you all doing?

I changed my front brake pads on 31/3/2017. actually my local mechanic did it. a month later it was squealing at low speeds 5MPH - 10MPH . the squeal sometimes is real loud! I took it to him to check and grease. he said you don't grease modern brakes. he checked the brake discs and said that the front 2 discs are showing signs of wear. that's fine I hadn't changed them for a while. so we changed them. this was 27/7/2017. squeal gone. a few days later squeal was back. exactly how it was before. I phoned him up and told him. he said this was normal as the brake pads have not adjusted to the new brake discs.  the bloody thing is still squealing. I do trust him as he has done work for me in the past and always given me free advice. mmm but I'm not sure. 

 

what do you think?

 

thanks in advance

 

 

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Hey,

I had (have) a similar issue after my calipers were changed.

First, you do need to grease the pads on the back of the shims.

You can also try sanding the face of the pads in case they are glazed or have other contaminants on them.

I had both of these done to mine and it has almost got rid of the noise.  I still occasionally hear a squeal, but it doesn't happen very often and is nowhere near as bad as it was.

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Sounds like he really don't wanna strip em down again and do a proper job!  

By proper I mean spend a bit of time ensuring all contact surfaces ( excluding the friction material of course) are cleaned with a small wire brush and then smeared with a bit of copper grease, the minimal time spent doing this can elevate this annoying squeal you now have and I bet he takes the time to do this procedure to his own daily driver to have a quiet ride! Basic's really but 9 times out of ten you won't get any squeal but on an auto car I feel the brakes are used a lot more at slow speeds than they would be on a manual car so best done.

paul m.

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The slide pins on the calipers ARE greased - both front and rear calipers. If your mechanic does not know this then don't think twice and change to someone else.

If its the grease on the pads (copperease) used to stop pad squeal that he means, then yes, this is still used.

Its an easy job you can do yourself and In doing it yourself then you know the jobs done with the right parts and grease. There could be an underlying issue tho - if the calipers have not been greased (slide pins) and by the sounds of it he has not done this and if you have taken it there before chances are he has not done it then either so you could have an issue with the calipers starting to sieze as they may not be releasing from the disk when applied at lower speeds

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thanks all,

 

@is200newbie he did check for seized calliper when he changed the front disks. he also checked the rear for seized and found no indication. he also asked to drive slowly down a slope in neutral. if it doesn't roll freely then I have seized caliper. I tried it and it rolled fine

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With the weight of the car it will roll "freely" down a hill - depends what he means by "freely".

If you are doing it this way then its best to drive along a flat straight - when slow and at a crawl then put car into neutral and see how it stops - if it stops with a jerk then you have problems - it it gradually stops smooth with no jerk then chances are its ok.

Check the alloys for heat after a run - all should be the same temp - if theres any that are hotter than the others then theres an issue with pads binding / seized calipers.

How long have you owned the car and when were the slide pins last checked and greased?

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ok I will give this a try

 

I've had the car since 2010.  I'm not sure when the pins were checked.

it had a service with lexus in july this year

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Your mechanic speaks with forked tongue, checking a calliper for seized pins, sliders or piston is not done by any method other than taking it all apart and examining it.

You need to see, with your eyes, if the parts move, or not.

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Shaun (newbie) and Garry are bang on here Rishi.

Lexus don't look at calipers or slide pin greasing .... they just want you to buy a new set.

Mate, you did both Upstream oxygen sensors .... this will be a walk in the park for you.

Just be methodical and take your time and before you know you'll be checking them every year. The more times you do it the easier and quicker it gets. Just make sure you get the correct Slide Pin grease and smallish tub of copper grease (you can get it cheap enough with Free P&P from Ebay) for the shims (each side) and a wee bit where the brake pad sits into its holding spring clip on the caliper.

Incidentally. You can have a seized slide pin and not know it. That's precisely what my rear lower slide pin had done. It was seized in the 'out' position so did not allow the caliper to close onto the disc ....allowing the wheel to spin freely.

Read this via Shaun's post....it's spot on and extremely instructive.

Get cracking and let us know how you get on. You'll be glad to have it done and know it really has been done properly.

Keith

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Most brake pads sit in callipers that move in and out via greased bolts or pins which are inside of moving rubber sleeves. If these are all gummed up and don’t move freely then this could stop the calliper form moving freely but should not create the sound you at saying unless they are well and truly rusted up. I would put money down on the brake piston being slightly rusty and therefore not moving back in after you release the brake pedal, or the pads are jammed slightly where they sit on the calliper as they are also supposed to move freely. Each time new pads are installed, or when the callipers are serviced, the area where the pads go should be cleaned up so that they move freely, and the pistons should be pushed in and out a few times just to free them up and to get fresh brake fluid in the gap and to remove anything you don’t want living in there. When you do this, don’t push the piston out too far as it WILL pop out and then you will need to put them back in, and then bleed the system. With regard to coper grease on the backs of the pads/Shims, this is just to stop squealing under braking and to reduce the friction which in turn stops most of the sound. I often used to jet wash it out by mistake lol and then used to do a 3hour drive to Donnington and then a 4 hour track session. You should try the Carbotech XP8 pads.....they make a nice sound even when doing 5mph. LOL. Another thought is that a disk is binding against some metal somewhere like the pad wear indicators on some pads you can get, or a stone is jammed between the disk and pad. Just tray everything I and normski2 mentioned as its going to be somthing like this.

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On ‎28‎/‎08‎/‎2017 at 4:53 PM, is200 Newbie said:

If you are doing it this way then its best to drive along a flat straight - when slow and at a crawl then put car into neutral and see how it stops - if it stops with a jerk then you have problems - it it gradually stops smooth with no jerk then chances are its ok.

hi, I tried the above. the car eventually just stops, no jerks or sudden stops. did it on a flat road.

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thanks for all your replies. brakes are still squealing. 

 @normski2no, didn't do the upstream. car is running really well though

when I visit my sister I will do the brakes then, I use her garage

 

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Yes you did, the upstream was the 2 sensors left and right of the engine block. That was the ones you sent me the video of.

It was the downstreams that you didn't do as they are under the floor where the front seats are located.

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