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Old 07-09-2011   #1
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500 Disc Brakes - Problems & Solutions

I've noticed there's been a lot of posts on this topic & perhaps it's time I shared my thoughts on what seems to be a common problem. If you've experienced any of the following:

- squeaking & grinding noise from the brakes
- pedal vibration under heavy braking
- excessive pad &/or disc wear
- excessive build up of brake dust on the wheels
- poor fuel consumption

then you might want to read on.

My investigations have thus far been confined to the front brakes on the 1.2 500 & Panda (which have identical systems EXCEPT there is no brake wear warning wire on the Panda), but I'd expect to find something broadly similar with the rear setup on the 1.4.

I've now stripped down the brakes on both my cars in order to address one or more of the issues identified above. Here's what I've found.

The brakes are of a single piston floating caliper design, sliding on a single bolt at the top, and retained by a simple pin at the bottom. The bolt on which the caliper slides is well greased when new & is fully enclosed in a protective rubber sleeve. The pads are released by removing the lower pin & (carefully) rotating the caliper out of the way.

I find that on both my cars, once the pads have been removed, the caliper slides freely on its bolt - there is no problem with the design of the caliper and this part of the system works exactly as its designer intended.

Further dismanting involves removing the caliper by unscrewing the single bolt on which it slides, then removing the reaction frame by unscrewing the two bolts which secure it. Once you have removed the reaction frame, inspect the surfaces on which the pads slide & the real cause of all the problems will be obvious.

The reaction frame is made from a grade of cast iron which has a very low corrosion resistance, and even on an almost-new car, these sliding surfaces will be significantly corroded - preventing the pads from sliding freely. This doesn't really affect safety, as there's a huge amount of hydraulic pressure available to force the pads into the disc & stop the car, but there's no comparable force available to help them release afterwards, so instead of moving back out when you take your foot off the pedal, they bind in the frames & cause the brakes to drag - leading to all the problems identified in the introduction. In the worst case, the pads will actually seize solid in the frames & then the hydraulic pressure will start bending the pads. Mark Elvin posted a good picture of what happens if this occurs, here:

http://img.photobucket.com/albums/v3...n/IMAG0156.jpg

The only solution that's actually going to work for any length of time is to remove the reaction frames, thoroughly clean the sliding surfaces, apply a generous helping of copperease & carefully reassemble, taking great care not to get the copperease on the discs. I've now done this to both my cars, and the improvement in braking performance is quite noticeable, particularly when braking gently.

I've attached some pictures to show the process - just click to enlarge. I've included a 'before & after" shot after cleaning out just one side of the frame. The extent of corrosion buildup is remarkable after only a short time in service - the car had done less than 3000 miles when they were taken.

It took a considerable effort with the rotary wire brush to remove the dirt & corrosion & IMO you can't properly fix this without removing the reaction frames from the car, even if you're just changing the pads.

From experience, if you do the cleaning without applying the copperease, the brakes will work perfectly for about a week - then they will start corroding again & you'll soon be back where you started.

In particular, please don't try to fix this problem by pressure washing the brakes. It won't work and you run the considerable risk of forcing water past the seals, which will quickly ruin the caliper.

Hope you find this useful. Follow the instructions carefully & I'll practically guarantee an end to most of the common brake problems reported here.
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Thanks MarcoVenturi, emgreg, 44sunsets, Bella500, deeyup and 5 others thanked for this post
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Last edited by jrkitching; 07-04-2016 at 23:01. Reason: bad grammar
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Old 07-09-2011   #2
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Re: 500 Disc Brakes - Problems & Solutions

Excellent post.
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Old 08-09-2011   #3
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Re: 500 Disc Brakes - Problems & Solutions

I wish i had the tools to do this. Failing that I feel like printing this off and taking it to my local dealer when i next visit to have my brakes checked out.

Many thanks....
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Old 19-06-2012   #4
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Re: 500 Disc Brakes - Problems & Solutions

Just spent the last 40 minutes or so doing this. Didn't take the reaction frames off and properly clean them up, just scraped as much crud out as I could and greased the reaction frames up as well as putting a dab of grease on the sliding pin at the top of the caliper for good luck.

10 minutes was spent listening to my dad tell me how to do a job I already knew how to do and another 10 minutes was spent looking for tools which I'd forgotten I'd need

You will need

Tools for taking the wheel off
Needle nose pliers for removing the clip from the bottom pin
A needle nose punch to punch the seized pin through the reaction frame
A hammer to whack said punch through
A g-clamp to push the caliper back
Copper grease to lube the top and lower pins and the reaction frames.

If you want to do it properly like jrkitching recommends you'll need a socket to remove the caliper assembly from the suspension upright and some cable ties or a bungy cord to hand the caliper so it doesn't damage the brake hose

I suspect if I went out and did the other side it might take me 20 minutes at most. Went for a little testdrive before and no more grinding from the left hand front pads.... result!

Didn't seem to have hugely affected the pads and unlike the original pads the brembo's are wearing practically evenly at this stage (about 10k miles since being changed) and look good for a lot longer than the original pads lasted.
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Old 20-06-2012   #5
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Re: 500 Disc Brakes - Problems & Solutions

A bit of feedback. Went for a bit of a drive last night and drove to work this morning. Went from 45.7mpg last night to 48.8 mpg this morning on the trip computer. The total distance travelled is 95.7 miles and I've done 33.7 miles since I did the caliper so by my calculations the car has done 54mpg since it's had the pads lubed up.

Annoyingly when I gave the car to the wife last friday it was already doing 54mpg anyway but she seems to love pressing the middle pedal more than is necessary and accelerating just before she knows she's going to need to brake
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Old 20-06-2012   #6
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Re: 500 Disc Brakes - Problems & Solutions

My brakes are quite noisy recently. Mind you i have the 1.4 so front and rear discs. I havent checked them out (i changed both less than a year ago, rear 9 months and front 5 months)
but i did wash the car yesterday which seemed to have reduced the amount of squeeking. They must collect a lot of dust. When i take the car for its next service i'll arrange to get them properly looked at and lubed up.
It is, for me, one of the main problems of the car (this brake issue).
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Old 20-06-2012   #7
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Re: 500 Disc Brakes - Problems & Solutions

I would like to take this opportunity of complementing Jrkitching and Maxi for their quality posts. Resurrecting a thread like this does more for the 500 than any 'tuning' posts. I wonder how many 1.4s are there out there will squeeling rear brakes when a simple 6 monthly regime could significantly increase fuel consumption. I would guess that the 1.2 isn't as bad since the front discs are generally getting a good workout. It's a maintenance task that shouldn't be delayed and best done sooner than later.

Quote Originally Posted by ahmett View Post
When i take the car for its next service i'll arrange to get them properly looked at and lubed up.
It is, for me, one of the main problems of the car (this brake issue).
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Old 20-06-2012   #8
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Re: 500 Disc Brakes - Problems & Solutions

Quote Originally Posted by 306maxi View Post
A bit of feedback. Went for a bit of a drive last night and drove to work this morning. Went from 45.7mpg last night to 48.8 mpg this morning on the trip computer. The total distance travelled is 95.7 miles and I've done 33.7 miles since I did the caliper so by my calculations the car has done 54mpg since it's had the pads lubed up.
Another benefit will be that you'll get less brake dust on your wheels .

Chipping away at all these sources of unnecessary friction & fitting better plugs can add up to a noticeable saving in fuel. On my regular 25 mile journey today I got 67.2mpg outward & an incredible 69.7mpg on the return; before fitting the Iridiums I had to drive very carefully indeed to see 65mpg on the trip computer.
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Old 20-06-2012   #9
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Re: 500 Disc Brakes - Problems & Solutions

Quote Originally Posted by jrkitching View Post
Another benefit will be that you'll get less brake dust on your wheels .

Chipping away at all these sources of unnecessary friction & fitting better plugs can add up to a noticeable saving in fuel. On my regular 25 mile journey today I got 67.2mpg outward & an incredible 69.7mpg on the return; before fitting the Iridiums I had to drive very carefully indeed to see 65mpg on the trip computer.
Only my long run back in January with winter tyres on I had over 70 at one point Car has been serviced a few weeks ago and has done just over a 1000 miles since and I'm going to be doing 2 or 2 and a half thousand miles over the next week and a half if I actually get off my bum and book things tonight
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Old 20-06-2012   #10
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Re: 500 Disc Brakes - Problems & Solutions

Interesting, but isn't this just changing/cleaning the brakes or am I overlooking something here?
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Old 20-06-2012   #11
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Re: 500 Disc Brakes - Problems & Solutions

Quote Originally Posted by T14086 View Post
Interesting, but isn't this just changing/cleaning the brakes or am I overlooking something here?
Yup, that's all it is
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Old 21-06-2012   #12
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Re: 500 Disc Brakes - Problems & Solutions

Quote Originally Posted by T14086 View Post
Interesting, but isn't this just changing/cleaning the brakes or am I overlooking something here?
You're right in saying that cleaning the brakes will fix the problems described here.

What this thread is all about is keeping them fixed. If all you do is the cleaning, you'll be right back where you started within a few weeks.

This picture is the key. If you don't do this, any benefit you get will only be temporary.

What Maxi's post shows is that even if you can't be arsed to dismantle the brakes & clean the frames properly, just lubricating the frames will make a noticeable difference.
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Last edited by jrkitching; 21-06-2012 at 06:46.
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Old 21-06-2012   #13
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Re: 500 Disc Brakes - Problems & Solutions

Quote Originally Posted by jrkitching View Post
Another benefit will be that you'll get less brake dust on your wheels .

Chipping away at all these sources of unnecessary friction & fitting better plugs can add up to a noticeable saving in fuel. On my regular 25 mile journey today I got 67.2mpg outward & an incredible 69.7mpg on the return; before fitting the Iridiums I had to drive very carefully indeed to see 65mpg on the trip computer.
And the plugs basically cost only a tank of fuel? Sorry to be annoying but can you tell me which ones are the iridum for the 1.4 so i consider ordering it when i change mine?
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Old 21-06-2012   #14
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Re: 500 Disc Brakes - Problems & Solutions

Quote Originally Posted by ahmett View Post
And the plugs basically cost only a tank of fuel? Sorry to be annoying but can you tell me which ones are the iridum for the 1.4 so i consider ordering it when i change mine?
Covered in huge detail in this thread but to cut to the quick, just buy a set of 4 NGK DCPR7EIX plugs, available from here for 25.56 including UK delivery.

I can't make it any easier than that .
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Last edited by jrkitching; 21-06-2012 at 09:22.
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Old 21-06-2012   #15
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Re: 500 Disc Brakes - Problems & Solutions

Quote Originally Posted by jrkitching View Post
Covered in huge detail in this thread but to cut to the quick, just buy a set of 4 NGK DCPR7EIX plugs, available from here for 25.56 including UK delivery.

I can't make it any easier than that .
Thank you!
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