Rusty master cylinder

[Matt Cup]

Went to clean behind my arch liners whilst the car was in the air and discovered my master cylinder looking a bit sorry for itself.

Is this a major cause for concern? I’ve just ordered some BH deox gel in hope that it will treat this and turn it back into some sort of metal. But I was wondering if there is anything else I can put on it before I lather it in hammerite.

It’s in a proper shitty place so it’s impossible to see the other side of it too.

 

[16v_paddy]

I can show you what the other side will look like and just like the master cylinder, the servo is another thing that I found impossible to find

 

[Matt Cup]

Ah, it’s the servo/booster not the m/c that the issue 🤦‍♂️

 

[Matt Cup]

I can show you what the other side will look like and just like the master cylinder, the servo is another thing that I found impossible to find

So yours had split completely?

 

[16v_paddy]

Here's a selection of pics from when I had to piss around with the same problem
I couldn't find a new one at all and the new parts I could find weren't the same

When I finished repainting it I filled the lip around the bottom with silicone sealant to try & stop anything like spilt brake fluid or crap from the road being able to sit inside it and rot it again

 

[16v_paddy]

So yours had split completely?

Yes, lucky for me it did it while I was changing the brake fluid rather than while driving

 

[Matt Cup]

Was it fiddly to remove?

 

[16v_paddy]

Was an absolute c**t to remove and that was with it split in half, you need to take the engine mount off & pull the engine forwards to make enough room

Probably a lot less of a c**t to do if you've got someone to help though

 

[Matt Cup]

Was an absolute c**t to remove and that was with it split in half, you need to take the engine mount off & pull the engine forwards to make enough room

Probably a lot less of a c**t to do if you've got someone to help though

I presume you have to get up under the dash too?

This is probably well beyond my skill set tbh 🙁

 

[16v_paddy]

I presume you have to get up under the dash too?

This is probably well beyond my skill set tbh 🙁

It's actually just in the foot well at the top of the brake pedal so it's not too bad, just 4 13mm nuts and a connecting rod with a split pin

 

[Beauvais Motorsport]

So glad I never have to work on a clio again 😄

From the engine side unbolt the master cylinder, pull the vacuum hose (carefully) and disconnect clutch line from gearbox. Then inside disconnect the throttle connector, brake light switch and cruise switch if you have it and remove the fasteners and pull the whole thing out from the inside.

 

[Matt Cup]

I suppose the only saving grace is that we don’t have to mess about with any ABS gubbins being a cup?

 

[Beauvais Motorsport]

Interesting seeing the inside of one. I hated that it had this play before it would move the piston.

I suppose the only saving grace is that we don’t have to mess about with any ABS gubbins being a cup?

If you just want to remove the servo you don't need to disconnect the lines from the mc so wouldn't matter either way.

 

[Matt Cup]

Interesting seeing the inside of one. I hated that it had this play before it would move the piston.


If you just want to remove the servo you don't need to disconnect the lines from the mc so wouldn't matter either way.

So lines can be left in situ on the m/c will just need to wiggle the servo out from behind it?

 

[Beauvais Motorsport]

Only pic I could find. The servo and pedal assembly comes out together from the inside.

 

[Matt Cup]

Thanks @16v_paddy and @Beauvais Motorsport for the tips, very useful for any arising future issues.

I didn’t go to the extent of taking it out, I did manage to get the majority of the rust removed with deox, hydrate 80 and a smothering of hammerite. It looks 10x better than it did at the beginning of the week,

 

[16v_paddy]

Once that's dried I'd suggest cramming a bead of silicone or something similar into the bottom lip of it just to stop anything from being able to get in there & just sit & make it rot

 

[Matt Cup]

Once that's dried I'd suggest cramming a bead of silicone or something similar into the bottom lip of it just to stop anything from being able to get in there & just sit & make it rot

Good shout. Will do that 👍