Wednesday, July 17, 2013

Symphony of Sounds of the GT-R - Part #4 of 4

ANNOYING SOUND #4: CLICK CLICK CLICK WHEN TURNING

Ever encounter a vehicle with bad or worn out CV joints. When a full lock low speed turn is made, a horrid click-click-click sound emanates from the front wheels. This sound is very similar to what is heard from the GT-R under similar conditions i.e. full steering wheel lock turns at slow speeds e.g. pulling in and out of a parking spot or maneuvering around a parking lot. Personally this is the worst of the noises covered thus far. I can live with #1-3, but not this one. This is not the attention I want. It never seems to happen on high speed turns.

Rust on the Hubs


To re-create this noise...
Simply find an empty parking lot or similar structure, windows down, turn the GT-R steering wheel fully in one direction and perform a slow turn ~5-10 mph in the forward direction. Now perform it in reverse. Turn the steering wheel fully locked in the opposite direction and perform the same procedure - forward and reverse. In 1 up to maybe all 4 directions, you may hear a distinct click-click-click noise emanating.

The first time I heard this noise, I was certain that one of the front CV joints was gone, on account of the GT-R being a 4WD. I took it in to the dealership, the GT-R master technician double checked all drive and suspension components and found nothing awry. TechLine's suggestion was to clean the surface between the wheel and the rotor, as there is visible silver deposit from the wheel allay material on the black rotor surface and re-torque the lugs to 98ft-lb, the specification. 

Surely it went away, but to return a few weeks later. The suggestion was again to clean and re-torque to 102 ft-lb, then 104 ft-lb, each time the noise would go away for a few days. At this point, the stud holes on the alloy wheels were developing a small but distinct lip from the additional re-re-torquing of the lugs. I had enough and decided to get to the bottom of the mystery myself.
Continual Re-torquing eating away wheels 
I considered and experimented with multiple causes including but not limited to:
  • Changing out various front brake pads types Stock to MX72 to ME20 to Stock.
  • Tightening the hat bolts on the rotors.
  • Smoothing the back surface of the wheel with an orbital sander and high grit sand paper, trying it with and without lubricant.
  • Removed the little cylinder and bolt that is attached to the outside of the hub and prevents the rear wheel from being mounted to the front hub.
  • Putting high temperature brake lubricant on the back of the brake pads and on the top and bottom surfaces of the pad that slot into the calipers.
  • Making a mark on one wheel stud and always ensuring the wheel went on the same way.
  • Swapping wheels left to right, swapping from my summer set to my winter set i.e trying different wheel sets.
  • Putting a small amount of lubricant on the wheel surface that makes contact with the hub.
The Hats cannot be the reason because the rotor simply doesn't have much room to make that noise:

Ironically, everything seemed to work but only temporarily and the noise came back the only lowest common denominator was that the wheel was removed and put back. It then dawned up me that that every time the wheel is removed or any work is done floating rotors move ever so slightly. So as a paid service to my dealership, since it is not considered a warranty fix, I had GT-R master tech removed the rotors completely off the hub and realized that there was a considerable amount of rust on both the hub and rotor; the back of the rotor which looked like nooks and crannies of an english muffin. 

Rust on the Back of the Rotor
Due to all these hardened 'rust bubbles' the rotor never makes good contact with the hub even at 104ft-lb. Over time more rust develops due to the gap and causes the clicking noise. This is considerable rust, on the left rotor the rust was at least 1mm thick, which is too much for surfaces that should be flush.
Rust on the Hubs
Why is it more pronounced after a track day or the day after a wash? Simple. High temperatures and water accelerate the rust process considerably. Chemistry 101.

I asked the GTR master technician, to clean the surfaces of the hub and rotor with a wire brush wheel and put some Permatex 24125 Extreme Brake Parts Lubricant, and put everything back. The shiny show how much rust had to be removed to make the surface smooth:
Rotors Rust Cleaned Up
Front Hub Rust Cleaned & Permatex Added
This was done in back June 2012. 

The vehicle had exhibited absolutely no signs of of the click-click-click noise for about one whole year. It has been through two track events, multiple spirited driving events, multiple brake re-bedding-in, changed wheels to winter, driven through rain, snow, salt, and finally multiple car washes including pressure washer to the wheels; and finally a change to summer wheels.


Recently (May 2013), I had the tires changed on the summer wheels from Dunlop to Michelin PSS. After that, a faint clicking noise started and progressively got louder in the coming weeks. Ironically, the wheel to hub surface was already cleaned and "re-greased" by my dealership technicians when the tires were changed, and the clicking noise was still present. 


As usual the solution was to clean the wheel, re-lubricate and torque to 104ft-lb. I could pay for a time-based service to ask for hub re-greasing, but instead I decided it will make for a great DIY as I estimate al least 50% of GT-R owners probably have this issue.


So here it is:


DIY - HOW TO ELIMINATE THE HORRID CLICK CLICK CLICK NOISE FOR A VERY LONG TIME

STEP 1: Preparation and Tools


You will need the following tools for the job:

- Jack, Jack Stand, Chucks, etc.
- Hammer and Punch
- 3/8" Ratchet and 2 1/2" extension, 10mm, 12mm and 13mm socket
- 10mm HEX 1/2" drive with 1/2" Torque Wrench
- 2"-3" 1/2" drive extension and Lug Nut Socket
- 2 to 2 1/2 Ft Bungee Cord
- Permatex 24125 Ceramic Extreme Brake Parts Lubricant
- Cordless Drill with 2" Wire Cup Brush
- Small Screwdriver
- Fine Grit sandpaper
- 2-3 Cans of Brake Parts Cleaner
- Rags
Tools for the Job

STEP 2: Removal and Marking of the Wheels


- Put some chucks on the back wheel

- Loosen the lug nuts on one front wheel 
- Jack up the side of the car
- Remove the wheel.
- One of the five studs, there is a black mark. I always make sure to place the wheel on the same stud by using the valve stem to match the stud with the black mark. See picture below.
Anatomy & Removal
STEP 3: Removal of the Pad Pins, Tie Rods & Brake Pads.

- Using a Punch remove the two pad pins from the caliper by hammering them inwards.

- Remove the Cross Springs from the tie rods.
- Unbolt the tie rods from the back and slide them outwards.
- Slightly press the brake pads against the pistons, wiggle them to loosen them i.e. away from the rotor and then slide them out of the caliper. Wiggling them slightly pushes the caliper pistons in. Mark which one is the inner and outer pad respectively, they should go back the same way.
- Next, slide the rubber grommets  that hold the ABS Sensor out of the bracket as shown by #1 &; #2 in the picture below.
- Separate the 2 brackets, by removing bolt marked #3. This may cause the entire bracket to bend, avoid that. you may need a few drops of penetrating oil on that bolt #3, then work it out slowly.
- Remove the bolts holding the bracket to the suspension arm marked #4 & #5 below.
Removing The Brackets

STEP 4: Removal of Brake Calipers (without draining the brake fluid)


This is the trick to making the whole procedure easy. The service manual will state that all brake fluid must be drained but who has time for that.  We are not going to do that. Instead, we already unbolted the bracket that holds the brake fluid lines.

- Get the bungee cord and carefully slide it through the middle part of the caliper and then loop it around the suspension arm and connect it to itself. The bungee cord cannot be too short long, cannot be too weak or too tight. The objective is to keep the caliper (and therefore the lines) as close to the original position of the vehicle as possible. See below.

Install Bungee and Note reference of rotor position on hub
- Next loosen (not remove) the 3 bolts - 2x 10mm Hex bolts and the other bolt holding the caliper.
- Now Remove the bolts in the order shown 1, 2 & 3 completely. 
Caliper Removal Bolts
The Caliper should be able to hang freely, off the rotor and the rotor should be able to be removed very easily off the hub as shown below. 
Important: Note the relative position of the rotor on the hub, use the stud with a black mark & steel cylinder bolt on the rotor for reference (or if you have removed it then use the hole). As you can see most of the old Permatex from a year ago has melted or been washed off, hence the clicking has started again.


Rotor Removed.

STEP 5: Removal & Cleaning or Rotors, Hubs, Calipers, Pads, Studs & Wheels

- Clean off the hub (old grease)with brake parts cleaner and a Rag
- Now Using a Using the Cordless Drill and cup brush clean the hub surface thoroughly by running the brush on each stud. Then clean the surface once again with some brake parts cleaner. Be sure to clean the threads of the studs with the rag and cleaner.
Cleaning Wheel Hub
- Clean the back & front surfaces of the rotor that make contact with the hub and wheel with the brush. Then clean with brake parts cleaner, make sure to get the inner surface of big hole in the center of the the rotor that slots into the hub. Now would also be a good time to also use a small screw driver to unplug any clogged cross-drilled holes of the rotor.
Cleaning Rotors
- Feel free to clean the brake dust on the calipers, inside the grooves of the calipers that are usually hard to get to with the wheels on, but be sure to NOT move the calipers must as undue stress on the brake lines is to be avoided. Also do NOT spray brake parts cleaner onto the calipers directly to avoid having the cleaner make any contact with the 6 rubber seals of the caliper pistons. Now would also be a good time to make sure all seal are in good working order. One of them was showing signs of slight wear. Not too worried as they are dust boots.
Clean Rotors, Examine Seals
- The back, top and bottom surfaces of the brake pad backing plate can be cleaned too. Do not spray any cleaner on the actual pad material.
- The wheel surface with a fine grit sand paper lightly, clean any lubricant and dirt from the stud holes in the wheel as you want to prevent that from depositing on the studs when reinstalling. Use brake parts cleaner and rag to wipe off everything.
- It is worth cleaning the threads inside the lugs too with brake cleaner. Basically the threads of the lugs, studs and wheel holes should not have any lubricant present.
Clean Wheel Inner Surface.
STEP 6: Re-Installation of the Rotor

- Put a layer of Permatex compound on the hubfirst, be sure to cover the round center part of the hub, but be sure to NOT to put any on the stud threads, if some does get on, clean with a rag damped with brake parts cleaner. (
See the picture a few paragraphs above to see the quantity) Useing a finger is best to spread it evenly rather than the brush.
- Put a thin layer of Permatex on the inside of the rotor, be sure not to get any in the stud holes of the rotor. 
Permatex on inside of rotor
- Put the rotor back onto the hub in the same position that it was removed using the bolt & cylinder (or bolt hole) and black marked stud as a reference.

STEP 7: Re-Installation of the Calipers


- Put the longer 10mm HEX bolt on the top hole of the caliper, the shorter one at the bottom. Then the center one. In that order. Tighten in the same order to 74ft-lb for the top and bottom Hex bolts an 18 ft-lb for the center bolt.

- This is a little tricky as the bungee will have moved to the top of the caliper, unhook the bungee cords and work the hooks out without damaging any piston seals. This might require some stretching wiggling.

STEP 8: Re-Installation of the Pads, Retaining Parts


- Put a very light layer Permatex on the thin top and bottom surfaces of the pad i.e. the surfaces that slide into the caliper. Put a very light layer of permatex along the backing plate of the pad that makes contact with the 3 pistons. This may help with somewhat with squealing sound. See below. Make sure no Permatex comes onto the pad surface.

- Slide the pads back into the caliper in the same position that that came out from i.e. inner and outer ones as marked before. You may have to wiggle the rotor to get the pads back as we did not compress the pistons back. Be careful not to let the pads catch on the pistons when sliding them back.
Note not to press any one piston in or all or them in considerably as this may cause brake fluid to overflow in the reservoir.
Permatex on Pads
- After cleaning the tie rods, insert them back in. Outside to inside. Attach the bolts and torque to 22 ft-lb.
- You may choose to put a slight amount of Permatex on the center part of the tie rods where the cross springs attach to the tie rods.
- Snap the cross spring(s) back onto the tie rods, if only one then it goes on the bottom with the arrow pointing down.
- Insert the Pad pins, one at a time from the inside of the calipers: through the inner pad, through the cross spring, through the outer pad and finally through the caliper hole. Hammer gently from the inside without damaging the calipers until the pins are all the way secure.
- Tighten the bracket bolts that were removed in Step 3 in the reverse order 5 --> 4 --> 3
- Return the ABS sensor cable grommets which were removed in step #3 back # 2 --> 1.


STEP 9: Re-Installation of the Wheel


- Apply a very light layer of permatex on the inner surface of the wheel/rim that makes contact with the hub, ensuring that none of it goes into the wheel hole studs. If it does clean it out.
- Re-Install the wheel in the same position as it was removed using the stud with the black mark as a reference point. For my GT-R the marked stud always coincides with the valve stem.
- Torque the wheel lugs in an alternating pattern  1 --> 3 --> 5 --> 2 --> 4. Or in other words skipping a lug until you come all the way around, they need to go to 98 ft-lb. I prefer to do this while the wheel is still up in the air. It is a little tricky as I have to hold one of the spokes with 1 hand and the torque wrench with the other.

STEP 10: Testing

- Repeat the Procedure Steps 1-9 for the other side.
- Test by performing the turning procedure highlighted on the top of the topic by performing full lock turns in each direction.

I can't provide any guarantees, but personal experience has shown that this is the been the only fix that has lasted the longest time without the issue coming up again in a short time.

When you start hearing little rocks and debris being kicked up and hitting the wheel well instead of the horrid clicking noise, hopefully it will bring a smile to your face too.