Sticking slider pins
Sticking piston ( rubber boot fails causing piston to seize )
Pads struck in caliper and wearing uneven.
All common problems with 45/ZS rear disc set up unfortunately.
I am so glad I have drums on my mk2 but on the down side my daughters mk2 ZS has discs and I am the one who has to fix it lol. Hopefully it will be just a clean and lube for you. Two weeks ago I had to change another caliper and pads plus release two slide pins on her ZS. Trouble is she just drives it until something goes wrong or I manage to get my hands on it to check it over as she doesn't live with us now.

 

As above a new set of pads, and some grease and a couple of hours of tinkering time should restore it. It has only just failed I think.

 

Only just failed?!?!?! On 13%?!?!!?

Yep, just checked, only needs to be 16% on a dual system car. #surprised

 

As both foot and hand brakes are below par I would agree with Bren and Dan.

Personally I am lazy when it comes to brakes so tend to get replacment calipers, euro car parts are resonable.

I would also consider new flexiable hoses, the ones on the car are nearly 20 years old so will bulge under braking, even new standard rubbber ones will be an improvment transfering more effort to the calipers.

Finally I'd get the garage to do a brake fluid change to get the calipers bled properly. I will do a rough bled at home and then drive very slowly to the garage, not too much of a problem as I drop the car off at 6am.

Brake fluid should be changed every 2 or 3 years, I tend to pay between £35 and £40 depending upon which garage I use.

 

Thanks.

I forgot to mention that while driving back, it sounded as though the brakes were binding slightly - I think it was the rear, but it's obviously hard to say. I don't think this changes anything though.

 

Replacing Front Pads
It seems one pad has failed (friction layer separated). I don't think this was actually causing a problem, but it's now replacement time.

The problem I have is pushing the piston back in. I have a suitable G-clamp, but having briefly tested it, the piston didn't want to move. I can certainly apply more force using vice-grips, but how much is too much? Or to put it another way, how must resistance should I expect?

Also, having studied internet videos, some people open the bleed nipple (and clamp the hose) while some people simply remove the brake fluid reservoir cap. I'm planning to removing the cap unless there's a good reason to do it the other way. Any thoughts?

 

Ideally you should be able to push it back by hand.
A few years ago my front left went back by hand okay, but the right needed to be forced back in a G-clamp. Two years later I had to replace the front right when it seized up.
Light pressure front a G-clamp should be fine. Any more and I'd look to replace the calliper.

 

The master cylinder cap has a breather built in, so unless you're planning on some very rapid caliper piston movement there's no need to remove the cap.

 

I fitted new pads for daughter today and I used a piston wind back tool. Only £7 off eBay, so much easier with one of these. I opened bleed nipple and wound in piston by hand.

 

rear discs

DO NOT use a G clamp to push rear pistons back, they screw in, use a large screwdriver or flat bladed instrument. The screw part is the automatic adjuster mechanism

 

Yes, I got that. I've now sorted out the front brakes (fitted new pads) I but may have to pass on the rears due to the combination of rust, access and limited tools. On the other hand, after tightening the lever and a lot of careful "brake-testing" the handbrake is now much better. Unfortunately, the offside caliper is now binding slightly, so we'll see!

Anyway. I'm about to have another go at fixing the boot catch, which has been iffy for a while, but with all the jacking I've been doing, I think it's changed the alignment just enough so that it no longer locks at all. (Previously, I had a sneaky trick that worked surprisingly well.)

 

When I did the rear discs for my daughter last week, after fitting new pads, changing one caliper for spare I had in the shed and sorting two sticking slider pins I then found the passenger side wasn't holding as strong as the driver side.
The handbrake was almost fully tightened and then I tried releasing the adjuster fully off, checked both lever arms on calipers were resting against their stops, next I pumped foot brake a few times, checked wheels were spinning freely and then turned adjuster a couple of turns and bingo. She now has a fantastic handbrake on a few clicks plus the adjuster has loads of adjustment left. I must have forgot to pump brakes before adjusting the handbrake when fitting the new pads.
Bonus today I managed to change the stuck trailing arm bushes, so I need to get the mot done now which should not be a problem.

 

I had a binding caliper after changing my discs and pads, caused by a stuck piston. Bought a new set of front calipers and reconditioned the old ones. There was a ring of corrosion around the piston causing it not to retract.

 

I looked for used calipers from a trusted ebay supplier and then noticed this
- available for other side as well, limited quantities - under £34 a side.

 

The joys of 400/45/ZS rear calipers. Guess what I've just had to fit to my ZS180? *facepalm*

 

My offside rear caliper is binding and I've hit a brick wall. I don't think the piston has seized, I think it's just the pads rusted into place.

I can undo the top bolt, but the bottom refuses to budge. I could probably manage like that, except that I can't release the handbrake cable either. I did remove the funny little spring which seems to do the job of a split pin (weird) but I cannot remove the rod it passes through. This is slotted for a screwdriver, but there's no thread visible!

If there's no thread at all, I might be able to release it with a few gentle taps of a hammer. Any thoughts?

As things stand, I'll have to book it in for new pads at a cost of nearly £100, which is as much as the car is worth! But on the plus side, I bought a replacement boot catch on eBay, so that's sorted now (although the switch doesn't work).

 

The handbrake cable pin does get stuck in there over time, I always grease those along with spring and arm when I work on the brakes as it makes things easier in the future.
The pin is just a push fit, spray it with wd40 or similar and work it with screwdriver and it should come out. As for caliber wbolts these also need greasing when they are replaced to aid future removal. Try a good quality 12mm ring spanner and give it a sharp tap with mallet or hammer, that's worked for me in the past.
You are probably correct about pads being stuck in calipers and may well be stuck on an angle, have had this a couple of times. Also slider pins could be seized which stop the calipers from its normal movement. These should be greased on pad replacement.
I got pads from local motor factor for £20, I wouldn't spend a lot on the rear pads as front do most of the work and because of the problems we get on these rear calipers.
What I honestly can't understand is why I never had any of these problems with any of my rover 800 cars. The set up is identical and my mk1 vitesse was nearly 20 years old when I broke it for parts and the original factory rear calipers were working great, the same with my 825 sterling coupe vey strange.

 

I managed to release the handbrake cable, but I misread how it all fits together, so that doesn't actually help. DAMN!

I also have a hot-running offside front caliper now. It's not binding much, but it's enough to generate significant heat (and smell).

 

Bullet Bitten
I've just ordered new calipers all round (£125 inc rear pads) plus a vacuum brake bleeding kit (£15).

Hopefully, not money wasted, but we shall see!

 

That's a good price, where are they from?

 

Section 3.8 of the mot manual explains it all. It seems that the parking brake must hold on a 16% gradient.

 

Yes, a 16% gradient being a 1:6 hill.

@TalkingCars : I followed the link supplied by deebee.

I still haven't gotten round to this as awaiting extra bits. I was expecting the calipers to come complete with bracket and slide pins, copper washers etc. SILLY ME!

It's not a problem on the front, as the slide pins are fine, but they are well seized at the back. That is going to be one hell of a game, I think.

Re: Limiting brake fluid loss
If I remove the filler cap, place some foam over the top and weight it down, that should limit leakage should it not? I assume there are no other breather points by which air can get in. I know this is a bodge, but I'd prefer not to clamp the hoses.

 

Don't use foam, use cling film or I always used a bit of plastic bag before cling film was invented - showing my age now !!!

 

First rear caliper now replaced. Pedal seems long, but probably no more so than before. (I made sure the pad slotted into the piston correctly, so it's not that). Now that I know how, hopefully the second one will go more smoothly.

Bleeding was interesting - I used the vacuum device I bought, but I think gravity did most of the work. Suction doesn't really work unless the thread of the bleed nipple is airtight. I tried PTFE tape, but that wasn't an overwhelming success either.

Working without a clamp was far too messy for my liking, so I'm planing to make my own which should be gentle.

Does anyone know what the capacity of the whole brake system is? The only figure I've found simply said 1 litre, but that seems rather imprecise.

 

Apply grease to the bleed nipple. It helps with vacuum bleeding and also when you come to undo it in a couple of years time too! Capacity of the brake systme is probably less than a liter, but thats why I tend to buy when I'm doing a fluid change and I've not run out.

 

Both rear calipers sorted now. Weather permitting, I'll do the fronts tomorrow.

The handbrake cable was a nightmare to release, but my home-made hose clamp was a great success - yippee!

The brake pedal still seems soft, but I turned the car around without any dramas, and I'm planning to completely replace the fluid anyway, so it's not a major concern yet.

If nothing else, I've learned a great deal so far - so thanks for all the help and advice. (Should also thank YouTube and EricTheCarGuy.)

 

I decided to leave the nearside front caliper for now, but have otherwise finished and have fully bled all the air out (I think). Unfortunately, the brake pedal still seems soft. I'm inclined to think it's just the new pads bedding in (front and rear) but I'd appreciate thoughts on the subject.

The rear pads came with silicone shims on the back. It did occur to me that these may be compressing, leading to a small degree of additional sponginess, but this seems unlikely.

I also read somewhere that if new calipers return more than the old, this can result in slack, which would make sense in my case, since at least one caliper was binding, if not two.

When the engine is off, the pedal feels normal (i.e. hard) so it's unlikely there's a major problem. But it's MOT time again, and I'd be extremely annoyed if it failed again!