Short version

Buy new slide pins and new caliper carrier to combat brake drag? Also, buy new anti seize brake pad seats (the chrome bits the brake pad ears sit in) or will cleaning and relube work? Not brake caliper or wheel bearing.

 

Longer more detailed version

Hi all, 

After noticing my Fabia Vrs pulls to left even after tracking I discovered the rear left disk was getting consistently hotter than the other rear disc, even hotter than front discs. The car has had new calipers all around 3 to 4 yrs ago.

I discovered a seized brake slide pin that the caliper bolts screws into.

I have unseized and removed the corrosion and lubed with lithium grease until today I have replaced with newly bought ceramic brake grease and silicone grease around the rubber boot around end of slide pin.

The car has been driven with improvement and rechecked to discover less brake drag, checked by jacking up and spinning wheel. I got over twice the rotations I had but it is still not as free spinning as the rear right wheel, unless brake pads, caliper, are removed.

 

Btw, it is not wheel bearing.

 

There is 2to3mm more wear on the outside brake pad than the inner one. See photo

Having trawled internet outer brake pad wear is stated as due to the slide pins seizing. This fits my symptoms.

https://www.yourmechanic.com/article/how-to-recognize-brake-pad-wear-patterns-by-cheryl-knight

Inner pad wear is due to caliper piston seizing or insufficient movement back towards caliper, apparently. This happened a few years ago.

 

Convinced it was caliper I bought one as I didn't want to be without car. Today I have fitted the new caliper just to rule it out. Bled brakes etc and even fitted spring clips on hand brake. 

 

There is still brake drag as evidenced by grating noise of pad touching disc. 

 

Not sure what to do next other than buy new parts. But, I don't want to buy parts unnecessarily. 

 

Btw the pads have worn evenly just more on the outer most pad.

 

Should I buy new slide pins. eBay sell for just over a tenner. But I have read the caliper carrier bore might have corroded and bore increased.

 

I serviced the front brakes also last week and to my surprise one slide pin was seized. Now, when I put grease in the bore the slide pin goes in the trapped air provided alot of resistance to the slide pin. This is good as it will release the caliper and 'slide' it away from brake disc on releasing foot brake. *** The rear left slide pins do not seem to have much resistance when pressing them into the caliper carrier using the same brake grease. Hence the question of what to buy / do next...

I have not yet tackled the rear right brake, so I cannot compare how much slide to expect.

 

Could it just be the rubber boot on slide pin. This is 3 to 4 yrs old as I got new ones with the pads I bought.

 

Your thoughts as always much appreciated.

@bmbmdmb - The caliper carrier is a plain plate, machines to allow its attachment to the hub and slide pins.

 

Your differential wear of the pads is almost certainly an issue with the caliper seizing on the pins, the piston not returning properly (seized in bore, or handbrake auto adjuster seized, or handbrake balancer seized). I'd need access to the car to tell which.

How tight are the pads in the carrier? Sometimes there's a benefit to cleaning underneath the chrome sliders to ensure they're sitting as flush as can be and also having a dry fit of the rear pads into the chrome sliders. It's not uncommon for aftermarket (or even genuine) pads to be a tad too big and need a little tickle with a file in order to slip in without undue force. If you need to bang or tap them in they're too tight in my opinion.

 

That way, along with the actual slider pins being free should allow the caliper to do it's job - assuming the caliper itself is functioning properly.

 

Also how much grease are you putting round the sliding pin itself? Too much and the pin will be held in the carrier with suction, a light smear is all that's required at most, again ensuring the sliding pin are totally clean and free from any corrosion

8 hours ago, KenONeill said:

Your differential wear of the pads is almost certainly an issue with the caliper seizing on the pins, the piston not returning properly (seized in bore, or handbrake auto adjuster seized, or handbrake balancer seized

The caliper pin was seized and cleaned of corrosion. Only a little corrosion, but enough to raise its surface and seize it. 

From experience of having a seizing caliper piston on opposite wheel a few years ago it is not the piston. With the rears a good indicator of seizing is by manually pulling on the handbrake mechanism of caliper when it's off carrier. It is no different to new caliper I installed.

Handbrake auto adjuster. Had a look at this just behind handbrake. Both cables move freely when handbrake pulled and released. There is no gap when handbrake released on the caliper, indicating the handbrake is releasing. Also, I've installed spring clips, just in case. No real difference made except handbrake released faster.

If handbrake related would this not affect both pads?

 

Driven the car today and to be honest it is better. But, spinning the wheel I can still hear the brake pad just kissing the disc.

6 hours ago, Lofty said:

cleaning underneath the chrome sliders

Yes, removed a wire brushed and cleaned and inserted correctly. No grease applied to this part, because brake dust just sticks to this grease and probably interferes with movement of pads.

 

6 hours ago, Lofty said:

If you need to bang or tap them in they're too tight in my opinion.

Brake pads slip into chrome slides well.

 

6 hours ago, Lofty said:

how much grease are you putting round the sliding pin itself

Previously, just a little copper slip (don't use this)

This time lots of ceramic brake grease melting point 1500 Celsius was pushed into slider pin hole in carrier. A little silicone grease around the slide pin rubber boot.

 

It is the difference in behaviour of the front slide pins and the rear that has got me thinking. The front brake carrier slide pins make a good seal when inserted and want to eject themselves. Is this desirable? 

The rear left caliper slide pins don't seem to want to form a seal, nor eject themselves out the carrier when pressed in, like when caliper is refitted. So the opposite behaviour to the front caliper slide pins. 

It is this difference that made me consider buying a new carrier complete with slide pins and rubber boot.  I'd have to buy new pads to get the chrome slides. Pads are aftermarket veTech from GSF. 

 

I'm tackling rear right slide pins tomorrow so I can't comment on this side as yet. 

 

What should the slide pins do? Should they resist compression into the carrier but due to lube not corrosion / seizing?

 

Thanks for replies so far

Update

 

Just cleaned up rear right brake which I've not had a problem with.

 

I can now compare both sides of same axle.

 

I've revisited rear left brake also just to be sure. It appears that the seized slider pin in rear left that causing brake drag is pushing air out of carrier when pressed in. The top slider pin presses in and retracts more than the other slider pin. 

 

There is slight play side to side so maybe carrier slider bore has corroded and opened up bore size.

 

Other brake on same axle - both it's slider pins retract out after pressure released like the good slider pin on rear left problem brake.

 

I swapped top and bottom slider pins which gave same result. Both slide pins on same brake have slightly different groves. Top slider pin is tapered in steps. Bottom slider in is also tapered but flatter on two sides somewhat. 

 

I'm going to buy a new carrier and with comes with new slide pins.

 

I checked that the pads were not jamming on the chrome slides.

 

I'll report back when new parts fitted.

 

Ps down on power - check your brakes.

Try only light braking and when you reach your destination touch the brake disc surface, be careful not to burn yourself. 

If you use the brakes alot then this disguised the issue. An infrared thermometer showed all four discs at 50C on her return on a recent hot day.

Update:

The above work done solved problem..

The rear brake discs are now both same temperature after driving.