So to continue our journey on the rolling restoration of our Stag, we decided that it was time to sort the spongy brakes that have come about in the last couple of weeks.
First we checked that we were not loosing brake fluid and as the reservoir was at the same level as it was a few months earlier when it was last checked its not a problem with it escaping anywhere!
As the pedal was soft when pressed slowly down but if then you take your foot off and then put it straight back on again and it was nice and firm its got to be air or seals in the master cylinder. We had a similar problem with our old Triumph Spitfire a few years ago and that was cured by replacing the master cylinder so a new one (reconditioned) was sourced on Saturday morning.
We had done some research friday evening on how big the job was going to be and make sure that we were going to be able to tackle this without any of our experienced folks in the club on hand for help. Having read through the manual (you must always consult the workshop manual before starting any job and always follow the instructions) and quite a few posts on the forum we decided that we were happy to do the change over (as we had previous experience of bleeding the brakes under supervision we were happy with that aspect). We did get some advice from Mick when we bought the new one that we should be able to get the master cylinder off without removing the servo unit from the car as the manual states, this is due to the lower bolt being difficult to remove – so we were going to try without and see how we got on.
So as we are talking about lots of bolts and screws that are going to go from fairly hard to loosen to ones that challenge the patience , and as we are talking about needing to bleed all the way round the car we decided to ensure that all the bleed nipples were both accessible and not seized up as well as all the bolts on the master cylinder itself were going to come undone.
A few (well quite a few) sprays of WD40 later the front nipples were freed off, rear were ok as we had refurbed them a year or so ago, and the bolts on the master cylinder to the servo and on the brake lines were also not too difficult to free off – happy days no seized screws or bolts to contend with!!
First we emptied the reservoir by bleeding the rear and front furthest from the master cylinder, not a small amount of dirt in the bottom!!
Next we removed the brake lines from the cylinder – good large piece of rag underneath to catch any fluid remaining and to then wrap the ends to keep the dirt out.
The two bolts fixing the master cylinder to the servo were removed and yes the bottom one is a bit tight to get a socket onto it but thats when small hands come in handy!!! Then the cylinder was withdrawn from the servo – now this sounds easy but as there is a spring and some seals this did require a bit of a tug, when it did release it came out a bit sharpish (bit of a shock)
New one is simply placed into the hole in the servo and secured with the same spring washers and bolts, and the brake lines attached (after taking out the red blanking plugs – these were left in until ready to attach the lines to keep any dirt from getting in)
Once connected up, its time to fill up the new reservoir with dot 4 fluid, and check the master cylinder connections for leaks.
Then the joyous task of bleeding all 4 wheels, starting with the back and furthest away from the master cylinder checking to make sure all the air is removed.
Another job tackled and completed, and more importantly much improved braking!!
PLEASE NOTE – these are NOT instructions on how to undertake this job just some pics and words of our experiences, always consult professionals when undertaking any repairs or restorations. (please refer to the disclaimer on our about page)