Flexible pipes and a change of master cylinder

A thread on Blatchat piqued my interest a while back; a discussion on master cylinders and how, on a second hand car you could tell which cylinder is installed. The key is the colour of the cable tie around the body of the cylinder. Blue = standard. Orange = uprated.

Standard master cylinder

Standard master cylinder

I ordered uprated brakes and so double checked what had been fitted to the car at the factory. A blue cable tie looked back at me. I did what any builder would do. Swore, then fired off an email to Derek. Thank you Blatchat. Without that thread I suspect I would never have noticed.

A couple of days later and the new master cylinder arrived, and it is a thing of beauty. Much thicker in the body, thanks to the larger cylinder, and finished in a more refined manner on the outside.

Uprated at the bottom

Uprated at the bottom

Removing and fitting the master cylinder is quite easy. I undid the brake pipes, loosened the two bolts holding the cylinder in place, then took apart the pedal linkage, a simple, clever piece of engineering. Finally, I removed the two securing bolts and lifted the cylinder away.

Fitting is the reverse of removal. Guidance from Derek was that the brake pipe fittings are torqued to 10Nm and the securing bolts are at 25Nm. I found the connections for the pipes quite difficult to engage on the new cylinder as the position of the connectors is slightly different, and the pipes are bent for the standard cylinder. Once the thread was started, though, it was simple although I have a bit of re-shaping of the pipework to fit it neatly back in place.

Fitted back together, we’re ready to get on with the connections at the other end of the pipework at the front.

First I inserted the adaptor into the caliper. Two come in the pack with the pipes, I chose the one with the bullet tip, which was in the pack with the copper washer and locking nut needed at the other end of the connector. I tightened the adaptor to 10Nm as per the guide.

I loosely attached the chassis-side of the pipe to the inner pipe work, then connected up the flexible pipe to the adaptor. The printed guide that came with the car states this connection is torqued to 25Nm, and I set about this but very quickly it started to feel wrong and over-tight. I backed off immediately, but unfortunately had seized the connector on the end of the pipe. More swearing and another email to Derek and a new hose arrived next day. While waiting, I reviewed the instructions in the copy of the manual I downloaded, and that one states 10Nm for the connection I just ruined. Cue more swearing.

Once the new pipe arrived though, it went straight on. The acid test of whether I’ve got it right will be when I bleed the brakes. Fingers crossed I don’t ruin the paint with a leak.

4 thoughts on “Flexible pipes and a change of master cylinder

  1. The uprated cylinder isn’t necessary for the larger brakes and use to be ordered, if required, separately. Whilst it does shorten the pedal a little it increases the pedal force needed and isn’t always best, certainly for road use.

    Is it a standard part of uprated brakes these days?

  2. Ah, from your blog, I wondered. I specced it for my kit and, whilst it’s arguably better on track where you are pressing the pedal very hard generally and it gives better control, it does make the brakes feel a little ‘dead’ at normal pressures on n the road. IMO.

    • Where were you when I was speccing my car, Scott? 🙂
      I’m looking for feel and response. I drove a K series with a standard master cylinder before placing my order and those brakes felt very wooden. I was hoping the uprates m/c would give me more feel. I’ll report back on it when I get this thing out on the road.
      Thanks for the input though Scott, I appreciate you taking the time to contribute to the blog. Please keep following and chip in wherever you fancy.

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