Hello everyone, I haven't posted in a while, but I do pop in time to time.

Anyway, I have a question about the brake master cylinder, and wonder if anyone has taken there's apart so I can compare please. (I think neal has a couple judging by this thread).

Essentially the story goes:

+ Feb 2006 @ 39k miles, F/OS inside edge disc was warped, so front discs changed.
+ July 2011 @ 70k miles, I noticed F/OS disc was sticking when I did a quick oil+filter change. Long shot being it released eventually, so as long as the driving didn't involve much braking, it's ok. Drove to the Alps and back - very fast round alpine hairpins to avoid using brakes.
+ End July 2011 @ 72.5k miles, rebuilt front calipers with new seals, new flexi-hoses, new discs, new pads and flushed the brake fluid system completely. Brkaes never felt better, no dragging or anything, lovely jubbly. I thought this had even sorted the warped disc issue from Feb 2006.

+July 2013 @ 87k miles - drive to screwfix with my old man so I can buy some jubilee clips to stop some exhaust heat shields rattling on my mothers car, 4 very sedate miles - no hard braking and probably didn't go above 45mph anywhere if I was lucky, park up in screwfix car park, and smell cooked brake. F N/S was stone cold and I could touch the caliper and disc etc, F O/S I couldn't even touch the wheel it was so hot. What was weird was that I didn't feel the car pull me to the right or anything. Anyway, so what I did was buy some allen keys and a G-clamp from screwfix as I was there, jacked the car up, took wheel off, undid caliper and pushed the piston back, waited for everything to cool down, and limped home using only the handbrake.

So after that, as I rewound the piston easy peasy, and I'd rebuilt them 2 years previously, I thought it unlikely it would be the calipers again, and in fairness when I rebuilt the calipers I didn't spot anything that looked bad. After lots of thinking/research and discussions, I decided it most likely to be the brake master cylinder, and that costs £267 from mazda. Anyway, I've taken the brake master cylinder apart, and can't find anything that looks odd :tink


Brake Master Cylinder by zippyonline, on Flickr

I then had another look at the master cylinder with a bit of a critical eye. Here are three pictures to show what I found:

Master Cylinder looking broadly from above, as if the reservoir was there.

P1170943 by zippyonline, on Flickr

Master cylinder reservoir joint closest to the pushrod/servo. Notice one hole which is a pinprick into the master cylinder, and the large hole which is located on the shoulder where the rubber seal/join bushing seals the feed from the reservoir.

P1170941 by zippyonline, on Flickr

And here is the master cylinder reservoir joint furthest from the pushrod/servo. Notice one hole, not on the shoulder of where the rubber seal is.

P1170940 by zippyonline, on Flickr

Given the history of the car from new and the constantly recurring F O/S sticky brake, I have a sneaking suspicion that this may be a manufacturing fault and the cause of my problems. Does anyone know which way round the pipes feed which brake? It's not the easiest thing to follow round the car given it goes through the ABS module, but i'm guessing each piston on the master cylinder feed brakes diagonally opposite corners rather than front and rear.

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So any advice gratefully received. If anyone has a master cylinder or taken one apart to compare, I'd really appreciate that too.
Thankyou very much.

So, what I've done is bought one from jap car parts that has been tested. I'll compare to see if my suspicions are confirmed or not, and report back if anyone is interested.

On both of the Subaru master cylinders I have taken apart the port closest to the flange had the pin hole as well as the fluid hole the port furthest away only had one fluid port

So it would seem yours is normal

However the sticky caliper is most probably the sliders again from what I've seen on here they tend to stick after about 2 years make sure you use a good silicone based lubricant on the sliders, Someone should be able to tell you what brand and type exactly is recommended MarcS, Stuartspel or Ernee will hopefully add the info for you

Cheers for that response.

In light of that - any advice on brake calipers that would be a simple swap, but less prone to getting sticky

Might have to start learning all about the offsets and standards etc. to what will fit.

I'm not very clued up on the BJ model of 323F so I'm not sure if there are any direct replacements,
you try and include re-greasing the sliders with your annual service

I can't see the MC causing you to have a siezed caliper, I would look at the caliper housing itself, look for any splits in the rubbers, and for corrosion under the piston seal, it gets lumpy under there, and pushes the seal onto the piston - if you check the piston and it looks clean, and the sliders are greased and free...I would drop the piston out of the caliper and check there

I don't know of anything that will bolt on to replace the mazda caliper...

Thanks for the help guys.

I just wasn't 100% sure it was the caliper again. Given the recurring of that particular wheel locking on, the fact it happened literally overnight (I know for a fact the day before it was running fine) and that the sliders were fine. I also check after any enthusiastic run for any brake heat difference between the wheels because I'm aware our cars are prone. This led me to the M/C and the symptoms I've been having matched them after ruling out sticky pistons.

Also having changed the hoses, pads and discs + rebuilt the calipers with all new rubbers and pulling the piston out etc. only 2 years ago and not really finding a lot at fault I then started looking at the rest of the brake system.
Like I said, just buying some basic tools in screwfix (lucky I was there I guess!) I pushed the piston back really easily...so I got a bit confused and wasn't 100% sure it was that.

The other thing is, the brakes have clearly not been working evenly left and right if you look at the discs - which are only a couple of years old. But, I never felt the car pull to one side in any way.
I think I'll get some braided lines, some brake rebuild kits, flush the system and give the car another chance.

If this sorts the brakes, I might carry on and fix the arch rust properly and maybe carry on a bit with removing weight (and I'll start my well overdue blog too). If it doesn't sort it - I think it might be scooby time


I felt it was more it wasn't returning (so the piston was moving back and forwards fine, the sliders were nice and slidey), as in the fluid wasn't bringing the piston back to a sensible off the brake position.

I know what you mean, but you only have 2 channels on the MC, front and rear...which should mean you'd have the problem on both wheels...er...I think
Thinking about it...you do have DSC - which means the car has the ability to brake any individual wheel to keep you shiny side up...maybe that is at fault somehow???

My BJ didn't pull to one side with a pretty badly siezed front caliper...the 6 on the other hand, with a very siezed one, was quite scary braking at speed!!! I wonder if the DSC was working on the beej to help out?

I don't have dsc, only tsc, which doesn't use the brakes (I don't think), I know it annoyingly kills engine power to stop you spinning the wheels up (as opposed to letting you feather the throttle yourself).

I'm fairly sure the 2 M/C channels are Diagonal opposite corners, as front and rear is a bit antiquated and you could loose a lot of braking if you lost the front line, and left and right only would put you in a spin.

Ah sorry chap, I thought you had a sport

not sure...never really thought about it...but I do remember reading it somewhere, might have been for the BG

Turns out the master cylinder is fine, comparing to another that I ordered hastily before the weekend as the one from jap parts wasn't materialising and was hoping to get it back on the the road. And compared to advice here...anyway the one I oreder from jap parts 8 days ago got onto a courier about 2 hours before I phoned them to cancel it, so I missed that - Nevermind, I can send it back I suppose

So, as the general consensus on the tinterweb in general is that sticky pistons is due to
1. crap in the lines - can be mitigated by regular bleeding.
2. Crappy seals/broken seals on the caliper
3. flexi hoses acting as one way valves.
4. Sliders sticking

So I have ordered some caliper rebuild kits for the front (I have some in my garage for the rears, and new discs and pads and flexi lines for them), some new pistons just in case, but will change them anyway, and for the £2 it costs for a new nipple, a pair of them too just in case.

Also ordered new anti-rattle kits and some braided brake lines.

I'm half tempted to get some caliper paint too - I'm taking everything off and apart anyway...

So that's where I'm at.

I plan to now bleed the brakes and grease the sliders at the same time I change the oil (every 5k - yes I know I don't need to do it that often, but I do)

Get yourself a shot blaster

and don't forget to clean the area in the caliper 'underneath' the piston seal

I had a similar problem on my focus, it only affected one caliper. It turned out to be a flexi hose. According to the owner of brakes international, it was caused by using a hose clamp. Apparently this weakens the inner lining of the flexi pipe, and can cause "flaps" inside the pipe which can operate a bit like a one way valve. After changing the offending flexi, I never had that problem again.

We cut the pipe in half (length ways) and sure enough there were signs of damage to the inner walls of the pipe, some of which had started to cause the flaps Ray was talking about.

Awesome advice and information!!
Thanks for sharing!

Glad we have braided lines that you cant clamp!

Cheers for that info..

When I rebuilt the calipers last time, I also changed the flexi hoses, so I was rather hoping they'd still be alright 2 years later (hence my fannying about with other parts of the system).

If this doesn't fix the problem, I've only got the ABS bit of the system left to check

I might have impulse bought some caliper paint too - not a lot more work to tart it up a bit


Also looking around the t'internet a bit, seems like most cars have these sort of issues, I guess due to the design of sliding calipers. I've had this problem on one of my bicycles (I've got a half decent fleet, with some high end hydraulic brakes, circa £600 for front + rear on the race MTB), and this was a cheap set of brakes. I guess everything is made to a budget

So here's what I ended up doing (Master Cylinder also got rebuilt and flushed through and cleaned as it was apart anyway).


323-BrakesRefurb by zippyonline, on Flickr

Calipers wire brushed down, sprayed with caliper paint, new seals, new pistons, new nipples etc. new pad fitting kit, goodridge braided lines, fully flushed and bled. Lovely

Will get round to the rears eventually too.

Only just noticed this thread:)
When i first got my sport the only real problem with the car was the brakes,just ask marc s how bad they were

I ended up buying two used MC,the first one was the wrong one as it was the non sport,so i got another one and popped up to marcs and got it fitted and spent about 2 hours bleeding the system.It sorted the problem for a while but eventually the brakes were completely gone,my foot went all the way to the floor,was some scary shit

Took the car to a garage again,calipers were fine and so was the MC.Turned out there was loads of air in the system,even tho marc had bleed them somehow air was still getting in.They bleed the system again and i have had no problems since.And that was over a year ago.I still have two MC up stairs in storage.You never know