Diy: Replacing Pads And Rotors On D2/g4/attkd Etc 8 Piston Brakes

[Duncan]

I recently changed the rotors on the stagea, it runs the 8 piston D2 brakes (which are currently available on an excellent Group Buy for $1700 http://www.skylinesaustralia.com/forums/topic/413182-big-brake-group-buy/)

Warning:

Changing Brake bits is dead serious. As in, if you get it wrong, you can be dead. Go carefully, double check everything, and don’t start this job unless you are confident you have everything to finish it properly.

Parts and Supplies:

A set of pads (~$300)

A pair of rings (~$400)

Brake cleaner (probably 2 cans at about $10ea)

Rags

Tools you will need:

A jack

At least 1 car stand (2 is much easier!)

Something to remove the wheel nuts (generally 17, 19 or 21mm socket). I had an electric rattle gun which is great

Gloves are a real smart idea, especially if you want to go to work the next day with all digits intact

Hey Key set (edit to add sizes). Preferably ones that mount on 1/2" breaker bar or ratchet. You will not get the bolts undone with an ikea hex key, you will end up wrecking something.

10mm ring spanner or socket

Torque wrench (highly recommended, but not essential)

Rattle gun electric or air (not essential, but a lot easier!)

Catch tray is a good idea depending on the work surface

Steps:

1. Identify a supervisor for the job. This can be someone with a deckchair and beers, a nagging spouse, a little voice in your own head, etc. I had DogZilla fill the role.

2. Check the fluid level in your master cylinder under the bonnet. If it is at MAX, and the pads and rotors are very worn, remove some! If you don't you will have brake fluid spill out and wreck the paint in your engine bay

3. If you don’t have a rattle gun, you need to loosen the wheel nuts before you jack the car up. Undo the wheel nuts ½ turn before you start. If you don’t have a rattle gun and don’t read this, you’ve got a frustrating job ahead.

4. Jack the car up at the front on level ground, and support it safely on chassis stands, chock the rear wheels to stop it rolling. Give it a wobble, make sure it doesn’t fall off. If you are not sure where or how to jack the car up search around for the DIY on that, it is important to get right

5. Take the wheels off. Marvel at the tasteless colour of the calipers

6. Remove the pins holding pad in with a hex key. Keep the pins, bushes and spring together.

7. Slide the pads out of the caliper. As you do, if you lever them sideways you can push those 4 little pistons on each side back in until they are flush with the caliper. There are tools and lots of other ways to do it, but the pads are large (so harder to push sideways) and already in your hand.

8. Put an oil tray under the hub, and give the calipers a good clean with brake cleaner and a rag.

9. Undo the hey bolts that bolt the caliper to the adapter. You should need a big breaker bar, because it should be tight. Never use a ratchet to undo a tight bolt, you can break them. If you can't budge the bolt, get a longer bar (or put something like a jack handle over the breaker bar). If that still doesn’t work you can tap the bar with a hammer with moderate but not excessive force - make sure you hit it straight on and that the hex key is on absolutely straight. If you round off the bolt you have just made the job bloody hard. You can also remove them where the adapter bolts to the hub, but the caliper to adapter bolts are sooooooo much easier. This is one of the great things about this caliper design.

10. Take the caliper off and rest or cable tie it to the hub or upright. Never let it hang by the brake line. Clean the back of the caliper!

11. Slide the rotor off the hub/studs

12. Find some bench space, and undo the nuts and bolts that hold the ring onto the centre of the rotor. Tedious, there are 12 per side! I was lucky enough to have the rattle gun again, if you are doing it by hand it is hard work and will take a while. Unless you have bought new ones, you need to keep and re-use all the nuts and bolts

11. Clean the centres, the nuts and the bolts. Give the old rings to the scrap metal guy. How is your supervisor going? DogZilla wasn't too concerned yet, looks like I might be able to crack a beer without him seeing

12. Get the new rings, make sure the vanes inside run the same way as the one you just removed. The slots on the disc may have changed, some go forward, some go backwards, it's not relevant. The cooling comes from air going in the centre of the disc and being pumped out by the vanes inside the disc as they turn.

13. Bolt the ring to the centre with those clean shiney bolts. I used a little wd40 because there was a bit of light rust after 5 years of abuse, even smarter would be replacing the bolts (but not essential, especially for road use). Doing the nuts up properly is important, I strongly recommend using a torque wrench. Too loose and the bolt may come undone, too tight (much more likely with little bolts) and it may strip or snap (and you may not notice). Either way, your rings and centres would not be bolted together properly which could lead to an unpleasant surprise when you stomp the brakes one day. The correct torque for a high tensile M6 bolt is 8-10NM (7-8ft/lb) according to my friends at Nissan. Always have a clean bolt, lightly oiled, when you use a torque wrench.

12. Clean the new rings. This is super ultra totally important - they are coated in an oil to stop them rusting which will immediately stuff the pads if it is not removed before use. Your supervisor should check this.

12. Clean the hub, the surface where the rotor is held against. Do I keep mentioning cleaning? Brake dust in between surfaces is the biggest cause of squeally brakes, if you do this right you won't have the problem. If you don't you can try all sorts of tricks until you get the shits and blame the pads. Even my race car's pads don't squeal (mostly!)

13. Slide the disc over the wheel studs, hold it in place with 1 wheel nut. This keeps it nicely aligned making it much easier to get the pads in. Is your supervisor keeping an eye on things?

14. Clean the caliper bolts. Refit the caliper over the disc and bolt in place on the adapter. Tighten in correctly (I don't have the correct torque handy, if someone can confirm the bolt's diameter I can update this, either 10 or 12mm).

15. Slide the pads in. I don't think you can get these around the wrong way...but check anyway! If they are not sliding in, it is because the pistons have not been pushed back flush into the caliper. They sit right into the caliper, if they are not in far enough you will not be able to get the pins and spring back in

16. Clean the pins, bushes and spring. Slide one pin in, fit the spring and hold it down, then fit the other pin. You only need to get one or 2 turns on the bolt to hold it in place for now.

17. Tighten the 2 pins into the caliper. Everything (pins, spring, pads) should be snug and not move.

18. You may decide to bleed the brakes as well now, it is a convenient time if it needs doing. You should bleed the system every year for good/racing fluid, and every 2 years for normal stuff. You'll have to find another DIY if you want to do this.

18. Put a small smear of grease on the wheel studs, give the disc a final clean to make sure there is no oil or grease, and then put the wheel back on. Tighten the wheel nuts to 110nm.

19. Jack the car up, remove the stands and lower the car carefully. Did you get all the tools and oil tray out first? Did you do both sides?

20. Check the brake master cylinder under the bonnet. Now that you have new pads and discs, you should fill it to MAX.

21. Get in the car and pump the brake pedal until it is solid. If it is not solid, or worse it sinks slowly to the floor, you have a leak or fluid problem. Find it and fix it before you do anything! You will probably forget or ignore this step, and then have the absolute shit scared out of you on the first stop....nothing stops the heart like a brake pedal that sinks to the floor without doing anything.

Bedding in the pads and rotors.

From here on this is personal opinion built on experience only. If the instructions with the pad say do something else, it would be safer to do something else.

You have to bed in the pads to remove a factory coating, and to evenly deposit the new pad material on the rotor. If you don't do it properly the coating can smear around and the pads will never work properly.

Bedding in pads is aggressive, and hard to do on a public street. These instructions apply to a private road only, be careful if you don't have one!

1. First, head out slowly and stomp the brakes. If the car doesn't stop, you have a problem.

2. Put the driver's window down, and make sure your nose works. Then, accelerate to 100-120 and hit the brakes hard. If you have ABS feel free to trigger it, if not you should brake as hard as you can without locking the brakes. Slow to 10-20klm/h but don't come to a halt (if you do, you can leave hot spots on the rotors that can warp them)

3. Repeat until the brakes are damn hot. In a normal car with normal pads this is generally on 2-4 big stops. In a car with these brakes it can take a lot longer, in my case it took 8-10 stops to get them hot. Be careful if there are other cars around, this is a really erratic type of driving!

4. You can tell the brakes are hot because of the distinctive brake burning smell. If you see smoke, you have probably gone too far (but no big deal). If you never smell the brakes...keep trying, brake harder and leave less time between stops.

5. It is important that you don't stop while the brakes are hot; and when they have got hot you need to drive 3-5 min with no or only very light braking to let them cool down (eg idle around the block a few times).

Once you have done this, the brakes should be quiet, effective and smooth for years of abuse

[Victory]

Good write up Duncan.

I have first hand experience with not tightening up caliper bolts to the correct torque. We recently installed a complete GTR cradle in our GTS-T and only tightened up the caliper bolts without using the torque wrench. On a test run around the block the car developed an unusual noise in the rear end that we traced to the caliper bolts working themselves loose and allowing the calipers to move with application of the brakes.

[simpletool]

GREAT write-up but aren't wheel nuts meant to go on dry? (ie. no grease on wheel studs) then 100-110Nm.

[Duncan]

I agree Charles....is sounds over-cautious but there are some things it is worth checking with a torque wrench, especially if you don't work with bolts all the time. If you do, you pretty quickly get a feel for it...but then why would you be reading a DIY??

Daniel...this is just my experience, and I'm no mechanic. However, I've been lightly greasing wheel studs on all my cars including the race car for years. It guarantees they will come off nicely when you next need them to. I've never lost a properly torqued wheel nut on a greased wheel stud, and I've never had a broken stud, even after years of racing.

[MrStabby]

You only need 75% of the torque if you lube the thread to get the correct bolt tension. The shop manual will specify if you should lube it (eg it says to use engine oil on flywheel bolts) and of course it specifies the torque assuming you have done so. So 110Nm on a lubed thread produces about the same tension in the stud as 147Nm on a dry thread. I would have assumed the 110Nm was for a dry thread, but cant be bothered checking....

[Carbon 34]

Changing the rotors can I ask why they didn't look that bad?

Any decent street pads for those , low dust kind lol , I have a set to put on still after removing the writing on the calliper and the colour , redone in metallic blue candy with Nissan logo ( it's stock lol)

Have you been picked on by the man for those , im worried since they're not legal according to A to B in Sydney? And really don't need a defect for 4k worth of safety improving brakes haha

a note

Remove the fluid cap on the master cyl while installing pads( use care not to get crap in it while off ) or you risk pushing rust into the bore where rust didn't exist resulting in a failure of the cylinder bore from scratches , or blowing the internal seal between the pedal and piston

This is by pushing new pads into calliper , not a issue if you change it often but watch the seals still

as described above brake fluid eats paint promptly so use care it will overflow easy , water , lots of it to clean off pronto , do not wipe it , that makes the problem worse , once clean you can wipe, brake cleaner eats some rubber and paint too so use care

Recheck the lug bolts after a few km , alloy nuts fall off after heated and cooled a few times if they didn't get tightned enough

I use the gold non seize grease on bolts and never issue ,a tiny drop is enough

Your caliper slides should have a drop too , just a tiny amount then wipe it down leaving a film only

Edited December 26, 2012 by Carbon 34

[tricstar]

yeah those rotors look ok..

I have K-sport 8-pots, same as D-2, what replacement rotors did you use and where did you get them $$??

[Duncan]

Yeah the rotors probably could have lasted a bit longer but I bought them all together (little cheaper) and did them all together (little faster). They have lasted very well considering the abuse.

Retail for the discs is $599 and pads $269 at just jap.

Thanks Carbon 34 for the extra tips too. And no I haven't had legality issues but then my car looks like a boring volvo....on what basis were you told they were not OK? Generally an upgrade is fine although I guess you could be asked to get an engineering cert for them?

BTW I agree, a good rule of thumb is to use 75% of the specified (dry) torque if you are greasing a bolt.