|Replacing the discs and pads|
|Fitting braided steel front brake hoses|
|Fitting new disc retaining screws|
|Changing the brake fluid|
|Replacing the discs and pads|
|I've always wanted to uprate the brakes on a car I own but never actually got round to it. Although my current pads and discs aren't particularly worn, I decided to replace them. I chose the Turbogroove discs and Greenstuff pads by British brake company, EBC. When braking hard, a thin layer of hot gas is created between the pads and the disc surface, this layer of gas can reduce brake efficiency. The grooves in the disc allow this gas to escape allowing better pad/disc contact. The grooves also prevent the pads glazing which causes brake fade when the brakes are hot. Greenstuff pads are fast road pads, they are designed for normal cars and hot hatches and give better bite with lower levels of dust so your alloys don't get as mucky . Apologies to anyone who's noticed that two of the following pic's are taken 10,000 miles after I did the original guide. I realised two pic's were missing and added them when I did the slide pin pic's.|
|Before you begin, look at the section at the top of the Oil and filter page. It shows the correct jacking and support points for the K12 Micra.|
|Tools you'll need: 13, 15, 18 and 19 mm sockets, 15 mm spanner, large philips screwdriver, torque wrench, can of brake cleaner, copper grease.|
|[A] After removing the wheel, start by freeing the caliper assembly. Hold each slide pin with a 15mm spanner and use a 13mm spanner to remove the bolt.|
|[B] Lift the caliper assembly off the brakepad retaining assembly and place a pad retractor in the gap (if you don't have a pad retractor, a piece of wood or a book work just as well). Failure to do this can lead to the piston falling out which will almost certainly lead to expensive replacement.|
|[C] Being careful not to damage or stress the brake hose, hang the caliper from the suspension out of the way. I used a luggage bungee but a piece of wire will do the job.|
|[D] The brake pads can now be pulled out of the retaining clips and put to one side. If the clips are very rusty or mucky, remove them and give them a good wire brushing before refitting them.|
Remove the two 18mm bolts on the rear of the brake pad retaining assembly then remove it and put it somewhere safe. If your disc still has the disc retaining screws (I don't bother), remove them and remove the old disc.
|[E] You are left with the bare hub and steering knuckle assembly. With all these bits removed, it's a good time to visually check all the various suspension components.|
|[F] Now clean the whole hub face area with tissue and lots of brake cleaner. The whole hub face should be spotless.|
|[G] You can now put the new disc on the hub. If you have the retaining screws, refit them now. I don't so a good tip at this stage is to put a couple of the wheel bolts back in to stop the disc slipping off the hub.|
|[H] Brake discs are made of cast iron which is very fragile. Most brake discs say on the packet not to use the disc if it's been dropped.|
EBC discs are galvanised so don't need any protection but normal brake discs have an oily coating. If your new discs do have an oily coating, use plenty of brake cleaner spray to remove it.
|[I] Carefully smear some copper grease on the tabs at each end of each pad and clip them back into the carrier.|
|[J] Put the retainer back over the disc and put the two 18mm bolts back in behind it and torque them up to 45ft/lbs. To make putting the caliper back on easier, squeeze the pads together so that they are touching the disc.|
|[K] Now smear copper grease carefully over the backs of the pads making sure none goes anyone near the disc or pad surface. This should ensure that the brakes don't yowl or squeal when you apply them.|
Update: I've just fitted Green Stuff pads to my new diesel and the pads now come with a pad of anti-squeal material stuck on all 4 pads so copper grease wasn't necessary.
|[L] This is least fun part of the job. Put a load of tissues around the brake reservoir neck and remove the cap. Using the brake pad spreader you need to force the piston back into the caliper far enough so that the caliper fits over the pads and disc. The new pads and discs will be much thicker so pushing the piston back in a long way can cause brake fluid to overflow the reservoir. The tissues will absorb any spillage.|
|[M] Holding the 15mm flats on the slide pins, do the two 13mm bolts that retain the caliper up to 20ft/lbs torque.|
|Once you've done both sides, refit the brake fluid reservoir cap and put both the wheels back on the car. The wheel bolts are 19mm and Nissan say to torque them up to 77 ft/lbs.|
|[N] With the new pads and discs fitted, I took the car for a 10 minute drive. I didn't do any hard braking as the discs and pads need to bed in. I generally took it easy with the braking and did some left foot braking from 80mph to 60mph on the dual carriage way leaving a few minutes between goes to allow everything to cool down. Greenstuff pads have an abrasive bedding-in compound on and although the discs and pads are nowhere near bedded in, I was extremely impressed. Sharp controlled braking with no noise except perhaps a slightly rough pedal feel which will probably disappear when the bedding in compound wears off. Overall, well worth doing .|
|Fitting braided steel front brake hoses|
|This is another job I always wanted to try. I ordered a set of stainless braided brake hoses from British company HEL for around £30 and decided to give it a go. WARNING: Be extremely careful when doing this job - brake fluid WILL get everywhere and it WILL strip any paint it touches. I had a catering sized roll of tissues to hand and ended up going back into the house and washing my hands every 10 minutes to keep then brake fluid free. A great tip when doing this job is to give all the nuts, bolts and fittings a thorough spraying with proper penetrating oil half an hour before you start work.|
|[A] The first thing to do is remove the clip that holds the middle of the hose to the suspension strut. These clips get pretty crudded up and I found a hammer and punch the best way to get it off.|
|[B] With a bit of a wiggle, the hose should come free of the bracket.|
|[C] Next thing to do is loosen the union nut that attaches the solid brake line to the brake hose. The service manual says it requires a 10mm flare spanner but it actually requires an 11mm one. The part of the hose it screws into is shaped so it's trapped by the bracket which means you don't need to hold it with anything while you loosen the union nut. Once it's loose, remove the clip that holds the hose to the bracket. This bit is a swine and takes some ingenuity to remove! I ended up using the middle section of a very small spanner wedged between the fitting on the end of the hose and the lip of the clip.|
|[D] Now use a 12mm socket to remove the bolt that holds the banjo fitting to the caliper. Once the banjo is off, you see a sort of scaly crud around the hole, scrape this all off so the area around the hole is completely clean and flat. I found the edge of a 50p perfect for the job. This ensures a fluid-tight fit when you attach the banjo on the new hose. The caliper looks dark in the pic because I soaked all the connections in penetrating oil before I started.|
The hose assembly can now be removed. Remove the copper washer that will be stuck to the caliper.
|[E] Put a copper washer on one of the new banjo bolts, place it into the banjo and add the second copper washer so the banjo if sandwiched between the washers. Screw the banjo into the caliper making sure the banjo is orientated the same as the original one. The tightening torque is 14ft/lbs according to Nissan but the hose manufacturer says 14-20ft/lbs in the instructions.|
|[F] Fit the plastic block on the new hose into the retaining plate on the strut and refit the clip, tapping it on with a hammer works perfectly.|
Now, holding the 17mm nut on the end of the hose with a spanner, screw the union nut in to the new hose and tighten to 14ft/lbs or as close as you can guess.
|[G] Lift the nut on the end of the new hose so that the groove in it is above the retaining plate and refit the clip, again a hammer is a good tool for this.|
|[H] If everything has gone well, this is what you should end up with. Give everything a good clean with some tissues, the brake fluid gets everywhere.|
|[I] I didn't have a spare person to act as pedal pumper so I thought I'd risk £20 on a Gunson Eezibleed kit. You fit the lid that matches your brake fluid reservoir to the short clear hose with the supplied brass nuts and fibre washers and tighten it onto your reservoir. Fill the bottle at least half full of clean DOT4 brake fluid and screw it tightly into the cap.|
|[J] For the compressed air supply, I used the space saver wheel. I dropped the pressure in the space saver to exactly 15 psi (in hindsight, I may try 18psi next time), connected the black pipe and was pleasantly surprised nothing exploded. It was then just a case of putting the supplied hose over the bleed nipple with the other end in an empty coffee cup and loosening the nipple. When all the air bubbles stop, tighten up the bleed nipple and the job's done.|
A good tip here is to give the caliper a few light clonks with a hammer to dislodge any bubbles stuck in it.
|When I finished, before I put the wheels back on, I cleaned all the new fittings with tissues to make any potential leaks visible. I then started the engine and gave the brake pedal a few good sustained presses. There were no signs of leaks so I put the wheels back on and took it for a spin. The brakes worked (always a relief) and it may be psychosomatic but I thought the pedal felt a bit firmer . |
100 miles later update: Having put a few miles on the car I noticed the overfilled brake fluid reservoir (from the Eezibleed kit) has dropped to it's normal level. Perhaps it's internal air or something burping out of the system or some other reason, I just don't know, but I am convinced now that this is a better upgrade than the pads and discs. When you apply the brakes, it feels like you are much more directly connected to what's going on and the brake response is much stronger and more immediate - an excellent upgrade!
|Fitting new disc retaining screws|
|I finally decided that having no disc retaining screws is a pain; you have to align the hub holes with the brake disc holes and then try and align the holes in the alloy - not fun. Nissan were fairly hopeless when I asked bout them but then, weirdly, a new guy on the Micra Sports Club mentioned as his first post that Renault sold them over the counter and gave the part number! I went in and bought three, two to use and a spare for the toolkit.|
|[A] The first thing to do is absolutely slather the screw in copper grease. These screws are notorious, on all cars, for rusting into their holes and being a right pain to get out. Don't crank the screw in as hard as you can but just snug it up nicely.|
|[B] Once the screw is in, smear copper grease all over the head so it well protected. To prevent corrosion in the Torx opening, put a blob of copper grease on the end of your T40 Torx driver and splodge it in. Next time the discs need to come off, you should have no difficulty removing them .|
|Changing the brake fluid|
|It's said that you should change your brake fluid every two years because it absorbs water. I recently found out that K12s can be prone to ABS pump failure costing £1,600 to repair and, as my car is of unknown provenance and three years old, I decided on a full fluid change. I used a Gunson Eezibleed kit so didn't need a second person to help out. According to the ESM, the bleed order is:|
|Left rear ---> Right front ---> Right rear ---> Left front|
|Because this job doesn't involve fighting with the car or me going underneath it I didn't use axle stands and relied on the jack. If you're unsure of your jack or are of a more sensible disposition than I am, use axle stands!|
|[A] Start by emptying the brake fluid resevoir as well as you can, I used a turkey baster that cost 75p from Wilkinsons.|
Now fill the Eezibleed bottle with new DOT 4 fluid to about an inch from the top and attach it to the resevoir. Don't attach the airline to the tyre yet but make sure you drop the pressure in the tyre you're using to below 20 PSI before you do.
|[B] The rear brake nipples are an unusual size. You will need a 7mm spanner, one where the ring end is slightly angled. I picked one up from Halfrauds for about £4.|
|[C] Attach the pressure hose on the Eezibleed to your pressure source carefully and confirm everything is fluid-tight.|
Attach a short length of plastic tube to the bleed nipple and loosen it with the 7mm spanner. Because of the awkward design, it is hard to open the bleed nipple much so place a jar under the tube and let the fluid trickle out until about 200-250ml of fluid has come out. Nip up the bleed nipple and remove the plastic tube. Refit the rubber nipple cover and the wheel and move on to the next corner.
|[D] You will need to refill the Eezibleed bottle between corners. Let the pressure off the pressure source as slowly as you can as the fluid can foam up if you do it too quickly and don't put the plastic tube down anywhere dirty - I used shop towels.|
|[E] The bleed nipples on the front brake calipers are a more conventional 8 mm.|
|[F] Loosen the brake nipple on the caliper and, again, let about 220-250 ml of fluid drain out. Nip up the bleed nipple and remove the plastic tube. Refit the rubber nipple cover and the wheel and move on to the next corner.|
|[G] Once you've done all 4 corners you need to remove the Eezibleed kit. The kit leaves the master cylinder completely full so wrap LOADS of tissues around it before removing the lid to absorb the fluid that leaks out. Use the turkey baster to lower the level in the master cylinder to the 'Max' mark and refit the resevoir cap securely.|
When you start the car, pump the pedal a few times to make sure it feels nice and firm and enjoy your rejuvenated brakes .