Rear n/s brake binding

As per the subject, the rear n/side brake has been binding of late could be felt and the disk was getting warm.

First dry relatively warm day, yesterday I stripped it down expecting to find the slider pin causing the problem. The slider pin was fine and caliper moved easily but when I removed the pads I found this.

Not seen this before on any car, checked the other side and these are perfectly normal for three year old low mileage pads(both replaced at the same time with new disks).

Any thoughts, other than the obvious ie they need replacing.

Dave

I can’t help thinking if it’s not faulty pads (doesn’t look likely) then your discs are not good, worse maybe on the inside face.

I had a Vauxhall and the pads were low, took it in and they replaced them. Little did I know the rear faces of the front discs were corroded that badly it destroyed the new pads in no time, not happy especially with the garage concerned but that’s another story.

If you’ve checked the discs then ignore advice above.

Hi Dave

That is unusual wear on the one pad. If there has been binding and proof of that is heat generated, something is sticking. 

From my experience of the MK2 especially with cars kept outside, water gets to the discs and pads through the alloys when car is parked. If the slider pins are fine I can only suggest that there is corrosion on the piston body causing a ridge and stopping the piston body retracting. Perhaps the handbrake was left on for a while? I would pump the piston out a controlled amount, removed the gaiter and inspect. Usually possible to scrape off corrosion and use some silicon or red rubber grease to prevent recurrence.

The pad wear is odd, not the usual wear I would expect from rusty discs. Check the discs both sides for corrosion though but I can only suggest that this is the piston side pad that has simply cooked. I would suggest that there is no way that pad can be saved. The lost material will leave parts of the disc out of contact throughout its circumference allowing rust to set in big time.     

Thanks for your helpful thoughts Mick & Rhino,

Outside face of the disc looks normal, difficult to tell inside without taking the carrier off, it looked ok but I was running out of time ie getting dark and cold.

Yes the car is kept outside so corrosion on the piston is a possibility that I had not considered, but I always leave the car parked in gear with the handbrake off when at home.

I will await the next ‘working outside’ day and strips it all down to inspect the inside face and as you suggest the piston, depending on what I find I will replace pads or disc and pads etc.

Ideally I would prefer to leave it until the spring when I have new stainless hoses to fit and a fluid change to do. Perhaps inspection followed by monitoring will see me through after all it only goes out one day a week on a fifty mile round trip.

Thanks for help

Dave

Sorry Dave you are out of order here in preferring to leave it for a while. Your brakes are faulty end of story.

If the slide pins are red rubber greased and are sliding ok and the disc pad wings are clean and sliding on the carriers they may need a touch of ceramic grease on the sliders.

Then it is either a bad disc of a stuck piston. Do not use silicon grease on the piston/bore interface but at worst red rubber grease in there.

It is most likely a sticky caliper and unless you have experience of striping and rebuilding rear calipers get an exchange one fitted or do not use the car!

Do not drive the car with faulty brakes either park it until the spring or find time from your busy schedule to do it or get it to a garage.

Do not drive it 50 miles in that state!

Be Careful !!! Brake failure could result in a fatality…possibly to an innocent party. If in doubt do NOT use. Replacement could be called for.

Regards John Duggan

 

Thanks for your comments and concerns Eddie & John,

Whilst I must agree there is a problem with the rear n/s brake, I would beg to differ in that the cars brakes are faulty. I used the car last Tuesday on it’s regular weekly outing and the brakes were fine with no sense that they were anything other than working normally. I would very much doubt that the damage to the pad has happened recently but has been more of a gradual process, however I take your point and will investigate further before enjoying the joys of my ‘5’

Thanks

Dave

Care to explain why Drum?

Anything is better than dry rust and the silicon grease is also specifically recommended for slider pins where contact with rubber gaiters.

I have actually used waxoil under the piston gaiter where nothing better available that would not attack rubber. Remembering of course that we are rust protecting the section of piston outside of the seal and in contact with the gaiter.    

 

Rear n/s brake binding … Part 2

So considering the advice above I decided last Sunday to order new pads. I opened the lap top to be greeted with an email announcing a Flash 20% brake sale and the new pads arrived later in the week. Family/grandchildren commitments resulted in starting the work this morning.

I removed the caliper, unbolted the carrier and removed the disk, what I found surprised and puzzled me.

The outside face as already viewed on the car

The inside face devoid of any gouges or raised lumps

Cleaned up and ready for refitting

I am still no wiser as to what caused the deep gouges   but I have reassembled everything with the new pads and I will do the other side tomorrow weather permitting.

Oh yes, I even bought some of Eddie’s recommended red grease.

I will monitor for binding and in the Spring strip it all down to be painted and new hoses fitted.

Thanks all for your thoughts and advice.

Dave

 

The disc looks surprisingly good although unable to expand the photo.

My only comment is that the front face looks a bit darker(burnt) than the inner face which would indicate binding on that side and a slider pin issue.   

Looks like you picked up a stone

Thanks Rhino/Richard,

Still getting to grips with new photo posting site, second attempt.

Front does show some signs of heat damage, not sure when as this is the second time that it has happened that I am aware of.

Rear shows signs of pitting or deposits, hope this is clearer

But most of this appears to clean off.

Anyway will monitor the situation in between enjoying the fun.

Thanks again

Dave

 

I hope the "flash sale " people have sent the right pads. I was also tempted but in my case they sent the wrong pads so they had to go back.  Got the right ones from Halfords which were actually the same price for the same make !  Just wondering Dave what make of pads were on the car ? 

Hi Raymond,

Yes the correct pads arrived, not exactly next day delivery but p&p was free.

Bought the Eicher pads at £13.15 these being the cheapest as I was unsure what I might find regarding the disk. Thought they would tied me over to the Spring then I would replace pads and disks with something better if necessary.

Not sure what was on as the writing has long since worn away, bought them from well known parts supplier but they were nothing special nor genuine Mazda pads.

Time and use will tell.

Dave

I bought one of these. Used it on the NC and the MINI. Made putting the piston back very easy even if they are not the wind back type.

https://www.ebay.co.uk/itm/21PCS-Universal-Disc-Brake-Caliper-Piston-Rewind-Tool-Kit-Set-Auto/112796898449?hash=item1a43381491:g:3B0AAOSw9p9aeAAw

https://www.ebay.co.uk/itm/21PCS-Universal-Disc-Brake-Caliper-Piston-Rewind-Tool-Kit-Set-Auto/112796898449?hash=item1a43381491:g:3B0AAOSw9p9aeAAw

Or this one?