Reconditioning front brake callipers

 

(If you have reconditioned callipers before - you'll find this article boring)

For some time now, whilst driving, I had feeling that the brakes needed looking at.  I have previously fitted braided flexible hoses and these have sharpened up the feel no end and impressed the hell out of the MOT inspector.

 

Now I could feel the car twitch to one side as I began to apply the brakes and sometimes, they squealed for a while after I had braked.  The other clue was that the front wheels were getting incredible black from brake dust, despite me cleaning them fairly regularly.  My diagnosis - sticking brake callipers.

 

I thought about some shiny new ones, these are still available as the Girling Type 14 Mk3 calliper was used on lots of cars.  Rimmer Brothers list them under the Dolomite at 80.00 outright or 63.00 reconditioned.  Although the shiny parts were attractive, being a cheapskate, I opted for a repair kit from Rimmer's - Dolomite Part No. 520957 - 13.00 - that's more like it.  Ordered early on Friday morning and it arrived on Saturday morning in the post - one genuine Lucas Girling repair kit.

 

I checked the Haynes manual and found that for once it was quite helpful, but seemed to show the calliper in one piece all  the time, I know from past experience that getting the pistons out can be very difficult like this.  I also chatted with another Marina owner (Chris Kirman) and he suggested that once I had got them off the car that I should split the callipers as it makes the job easier - good advice.

 

Preparation - I sealed the brake fluid by putting some cling film under the cap on the brake master cylinder, to stop it draining down when I stripped of the callipers.  Not having done a Marina calliper before, I decided to do one side a time to avoid the car being off the road too long if I hit any problems.  So I started on the nearside one.  Off with the wheel, disconnect the little brake pipe that runs from the calliper to the bracket on the suspension leg and undo the two big bolts that hold the calliper to the bracket - 5 minutes - hey presto.

 

The calliper was very mucky (road dirt and brake pad dust) and oily from the brake fluid in the back of the calliper spilling all over the place, so I washed it all down with Gunk and then cleaned it with white spirit.

 

Holding the calliper in my trusty Workmate, I undid the four bolts that hold the two halves of the calliper together, be careful as you open it as there is an 'O' ring in there and the repair kit doesn't have a new one.  This is the seal around the hole that allows the brake fluid to move to the outside calliper.  You can see it in the shot below, sitting on the calliper half on the right.

 

The next job is to pull out the pistons from their housings, they are a close fit (a) to avoid brake fluid losses, (b) so that they run true in the calliper bore, (c) minimise the rubber seal, (d) to make it difficult for the home mechanic to remove them so that they send them to a specialist.

 

Firstly strip off the wire circlip and the dust cover (new ones in the kit), this exposes a lip at the top of the piston.

 

I found the easiest way to remove the piston is to clamp the calliper half in a vice and get two large tyre levers or flat head screwdrivers.  Position your levers on opposite sides of the piston with the blades under the lip.  Apply equal pressure so that the piston comes straight up, if you apply more pressure to one or other side, then the piston will jam in the bore.

 

Of course if you have access to an airline, you can rig something that will seal into the passageway and pop them out with a blast of compressed air.

With the pistons out , you may have something like this.  You can see the groove in the calliper, this is where the new rubber seal goes, you can also see some marks on the cylinder wall, there were similar marks on the pistons.  These are caused by the piston sticking in the bore and were the cause of the snatching and squealing that I had experienced.  The piston and bore are precision pieces so need to be treated v carefully.

 

I washed out all the passageways with white spirit and pushed a pipe cleaner through them.  I then cleaned up both parts with a piece of 90 gram printer paper, using no abrasives, but soaked in a little white spirit.  What you don't want is anything that will make the piston or calliper even slightly oval.  Five minutes on each piston and calliper brought them up well.  If the piston is badly scored, then they are available new from Rimmer's or from brake specialists, I saw some at an auto jumble for 1.00 each. 

OK so now the rebuild, the first job is to lubricate everything.  There is a special red grease available for hydraulic parts, useful on clutches also, it is specially formulated not to degrade rubber parts.  I bought a tin for a fiver at an autojumble, but there is enough there for me to do a set of callipers every day for the rest of my life.  You can also by little tubes, for about 1.50 (sorry for the blurry shot).

 

First grease up anywhere where the rebuild kit will touch, then insert the rubber seal into the groove in the calliper.  Now you need to squeeze the piston into the calliper, so that it fits inside the new seal.  To do this requires more than hand pressure and you need to keep it parallel to the calliper walls.  I used a woodworking G clamp and gently wound it in about half way - perfect.

Next comes the outer dust seal and circlip.  Fit the inner edge onto the piston first and then push the piston home until it is flush with the calliper face.  Then it's is easy to fit the outer edge over the calliper lip.

 

Now the difficult part - the wire circlip holds the outer edge onto the calliper, you have to open up the circlip to fit it and and at the same time avoid nicking the very thin dust seal.  I found that fitting one end and holding it with my thumb and then chasing the circlip around the calliper with a fine flat headed screwdriver did the job.  Push it home so that it sinks into the calliper groove trapping the rubber seal all the way round.  Repeat the process on the other calliper half.

 

Next find that O ring, use some of the red grease to stick it into its' recess in the outside calliper.  Lay the outer calliper on its back and hold the inner calliper (with the mounting lugs) over it.  Drop in the bolts and line everything up.  Carefully lower the inner half down, making sure that you don't dislodge the O ring.  Bolt the two halves together and you are done!

I just refitted my callipers, but if you wanted to, at this stage you could mask up and spray the complete calliper a pretty colour with one of the coloured calliper paints available from Halfords etc.