Brake issues

[Kazza]

Hi all,

 

I've got vibration under mid/heavy braking, most pronounced when braking going down hill. I've also got a constant "rotational" noise coming from what sounds like the front left wheel (drivers side). With the wheel jacked up, I can hear a consistent "uneven" frictional sound at the same point when I rotate the wheel or rotor by hand.

 

So... I decided to Inspect the front brakes today for the first time since I got the car (45k km ago, 160k km on the dial now) and made a few observations.

 

1. Brake pads are worn down pretty low. Front (of rotor) Pads = 1/4 inch, Rear (of rotor) pads = 3/16 inch.

2. Rear of rotor pads are worn on the top and bottom edges more than the middle - see HERE.

3. Front left rear of rotor pad tapers to one end - see HERE. 

4. Rear of rotors (both sides) have a smaller "clean surface area" than front. Heavy rust band on inner and outer circumference. This coincides with the rear of rotor pads being worn down on the top and bottom edges more than middle - see HERE.

5. The wheel bearing cap has taken a beating at some point (all dented round its circumference) probably from the car being driven with the wheel not on properly. Might be a non issue but its the drivers side (where i'm suspecting the noise is) - see HERE.

 

I'm definitely going to replace the pads, but my concern is the condition of the back of the rotors and this wear pattern on the corresponding pads (observations 2 and 4) .. is this normal or are my rotors kaput?

 

Also, for point 3 - should I be concerned with anything other than the pad/rotor for this tapered wear?

 

Thanks in advance..

 

K

[Guest]

Hi all,  

I've got vibration under mid/heavy braking, most pronounced when braking going down hill. I've also got a constant "rotational" noise coming from what sounds like the front left wheel (drivers side). With the wheel jacked up, I can hear a consistent "uneven" frictional sound at the same point when I rotate the wheel or rotor by hand.

 

So... I decided to Inspect the front brakes today for the first time since I got the car (45k km ago, 160k km on the dial now) and made a few observations.

 

1. Brake pads are worn down pretty low. Front (of rotor) Pads = 1/4 inch, Rear (of rotor) pads = 3/16 inch.

2. Rear of rotor pads are worn on the top and bottom edges more than the middle - see HERE.

3. Front left rear of rotor pad tapers to one end - see HERE. 

4. Rear of rotors (both sides) have a smaller "clean surface area" than front. Heavy rust band on inner and outer circumference. This coincides with the rear of rotor pads being worn down on the top and bottom edges more than middle - see HERE.

5. The wheel bearing cap has taken a beating at some point (all dented round its circumference) probably from the car being driven with the wheel not on properly. Might be a non issue but its the drivers side (where i'm suspecting the noise is) - see HERE.

 

I'm definitely going to replace the pads, but my concern is the condition of the back of the rotors and this wear pattern on the corresponding pads (observations 2 and 4) .. is this normal or are my rotors kaput?

 

Also, for point 3 - should I be concerned with anything other than the pad/rotor for this tapered wear?

 

Thanks in advance..

 

K

 

Are the pads bigger than the disc surface?

 

Clean and lube the guide pins really well

 

Sent from my iPhone using Tapatalk

 

[Kazza]

Just now, R50JR said:

Are the pads bigger than the disc surface?

 

 

Sent from my iPhone using Tapatalk

 

No they are the same size.

[Slartibartfast]

That is an odd wear pattern, and those rotors don't look good. +1 for cleaning and greasing the slide pins while you're in there, though I'd expect more of a taper if those were the problem. Check the wheel bearing while you're in there.

[Kazza]

25 minutes ago, Slartibartfast said:

That is an odd wear pattern, and those rotors don't look good. +1 for cleaning and greasing the slide pins while you're in there, though I'd expect more of a taper if those were the problem. Check the wheel bearing while you're in there.

 

Whats the process for checking if the wheel bearing is good? I have a guide on disassembling the hub / rotors but keen to hold off on this until I order the new pads (and potentially rotors). 

 

Edit: There is no play in the rotors when yanking on them. The drivers side rotor does have a very "grainy" sound when turning it compared to the passenger side which is relatively quiet. Both are hard to turn (don't turn freely) probably cause the car is in Park though.

 

K

Edited September 21, 2019 by Kazza
add info

[Mr_Reverse]

With both front wheels off the ground, the front wheels should turn smoothly and easily. What you are describing sounds like dragging brakes and or bearing issues. If you have the pads off and the wheel still has trouble spinning, it is likely in the bearings if the CVs look ok. 

 

The dust cap is looking like that because someone used pliers to remove the cap. I generally use a flat blade screwdriver or cold chisel to pop them off by putting the blade between the cap and hub and tapping lightly with a hammer to pop the cap off. 

 

From your statement about the pulsation and the pictures, I suggest replacing the rotors. While you have the hubs off, clean them out and clean and inspect the bearings for wear or damage. If questionable at all, replace the bearings and races, they are relatively inexpensive. Replace the grease seal with a new one regardless. When I repack the bearings, I also fill the void in the hub with new grease, level with the inner bearing races. Grease is cheap and having the hub full like that helps keep the bearings happy. 

The uneven wear on the pads is the result of several problems. One, the rotor surfaces are not flat and smooth. Second, you have worn abutment shims that go between the pads and the caliper torque member. Third, the caliper slides are not letting the caliper move smoothly. Pull them out, clean out the bores and clean and inspect the pins for wear and putting. If worn or have putting, good idea to replace them. It is also a good idea to replace the rubber hardware at this time. 

 

When pushing the caliper pistons back into the caliper, I like to open the bleeder valve a bit with a 1/4(6mm) hose on the end going into a bottle to catch the fluid pushed out. 2 reasons for this. First, it makes pushing the pistons home much easier. Second, when you see what comes out, you will understand why it is recommended to flush the brake hydraulics every couple of years. 

 

When lubing the caliper slides, us a good silicone based grease, petroleum grease will damage the rubber parts causing problems. For the metal on metal lube for the pads themselves, I use a molybdenum brake grease. A small amount on the pads where they contact the torque member and a thin layer between the back and the shims unless the shims have adhesive, then a thin coat between the pad and the caliper helps a lot with noise control. I also wire brush and was the caliper and torque member before lube and assembly. The cleaner it is, the easier it is to reassemble and the better the brakes work. 

 

I do this stuff professionally, and have noticed that I spend more time on the brake job than most because of the detail I put into it. However, my bosses and I have noticed that I have fewer comebacks with complaints and more satisfied customers as well. I make a bit less on the job, but I tend to get more repeat customers requesting me to work on their cars. 

 

One option you might want to look into is getting a pair of loaded calipers for your truck. That saves you a lot of work cleaning, inspecting, repairing, and lubing. Plus most come with a lifetime warranty on the caliper so if anything happens, can simply swap out. 

 

Long and involved, hope this helps. Hit me up if you need any help. Couple of tips for the wheel bearings, use an impact driver on the small lock screws for the axle nut. They are very soft and the phillip head strips easily. The impact driver will pop them loose without damage. Axle nut socket for an Isuzu Trooper or Rodeo will fit the nut. Might need to file the edges of the pins a little, but should fit. Another option I have seen is a piece of flat bar with 2, 1/4" bolts that are long enough to reach into the holes of the nut run through the bar spaced the same distance as the holes in the nut. 

[Kazza]

52 minutes ago, Mr_Reverse said:

With both front wheels off the ground, the front wheels should turn smoothly and easily. What you are describing sounds like dragging brakes and or bearing issues. If you have the pads off and the wheel still has trouble spinning, it is likely in the bearings if the CVs look ok. 

 

The dust cap is looking like that because someone used pliers to remove the cap. I generally use a flat blade screwdriver or cold chisel to pop them off by putting the blade between the cap and hub and tapping lightly with a hammer to pop the cap off. 

 

From your statement about the pulsation and the pictures, I suggest replacing the rotors. While you have the hubs off, clean them out and clean and inspect the bearings for wear or damage. If questionable at all, replace the bearings and races, they are relatively inexpensive. Replace the grease seal with a new one regardless. When I repack the bearings, I also fill the void in the hub with new grease, level with the inner bearing races. Grease is cheap and having the hub full like that helps keep the bearings happy. 

The uneven wear on the pads is the result of several problems. One, the rotor surfaces are not flat and smooth. Second, you have worn abutment shims that go between the pads and the caliper torque member. Third, the caliper slides are not letting the caliper move smoothly. Pull them out, clean out the bores and clean and inspect the pins for wear and putting. If worn or have putting, good idea to replace them. It is also a good idea to replace the rubber hardware at this time. 

 

When pushing the caliper pistons back into the caliper, I like to open the bleeder valve a bit with a 1/4(6mm) hose on the end going into a bottle to catch the fluid pushed out. 2 reasons for this. First, it makes pushing the pistons home much easier. Second, when you see what comes out, you will understand why it is recommended to flush the brake hydraulics every couple of years. 

 

When lubing the caliper slides, us a good silicone based grease, petroleum grease will damage the rubber parts causing problems. For the metal on metal lube for the pads themselves, I use a molybdenum brake grease. A small amount on the pads where they contact the torque member and a thin layer between the back and the shims unless the shims have adhesive, then a thin coat between the pad and the caliper helps a lot with noise control. I also wire brush and was the caliper and torque member before lube and assembly. The cleaner it is, the easier it is to reassemble and the better the brakes work. 

 

I do this stuff professionally, and have noticed that I spend more time on the brake job than most because of the detail I put into it. However, my bosses and I have noticed that I have fewer comebacks with complaints and more satisfied customers as well. I make a bit less on the job, but I tend to get more repeat customers requesting me to work on their cars. 

 

One option you might want to look into is getting a pair of loaded calipers for your truck. That saves you a lot of work cleaning, inspecting, repairing, and lubing. Plus most come with a lifetime warranty on the caliper so if anything happens, can simply swap out. 

 

Long and involved, hope this helps. Hit me up if you need any help. Couple of tips for the wheel bearings, use an impact driver on the small lock screws for the axle nut. They are very soft and the phillip head strips easily. The impact driver will pop them loose without damage. Axle nut socket for an Isuzu Trooper or Rodeo will fit the nut. Might need to file the edges of the pins a little, but should fit. Another option I have seen is a piece of flat bar with 2, 1/4" bolts that are long enough to reach into the holes of the nut run through the bar spaced the same distance as the holes in the nut. 

 

 

Lots of help @Mr_Reverse thanks a bunch. I've already put the wheels back on so didn't get a chance to inspect the CV's visually. The car doesn't make any noises or give weird feedback at full lock though. Well I guess I'm going to crack on with replacing the rotors, pads and servicing the calipers and wheel bearings as per your instructions above.

 

I'm in Canada, can't find any of the loaded caliper kits online. I think I'll just go with the rotor/pad kit. My budget isn't very high. I'm between the Powerstop KOE2279 and the EBC S1KF1313, can't decide, they are in the same price range. Any thoughts here?

 

Otherwise, yes I will hit you up if I run into any snags. 

 

Thnx again!

[colinnwn]

I was having some trouble with brake shimmy starting quickly, not immediately but within 5k miles, after a brake job. So far I've bought new rotors at every brake job, I've never skipped or machined them.

It would probably be good to get even new rotors machined once mounted on the hub.

I've always done a half hearted wipe down of the rotors with brake cleaner and figured any remaining would quickly burn off.

I read a brake technical article that Sai you should get every bit of oil off new rotors by washing them with soap and water, then brake cleaner, then don't contaminate them getting them on.

Oil left on can oxidize and embed into the metal changing the coefficient of friction and the rapid but tiny changes in deceleration as the pads wipe across the rotor can cause shimmy.

So that's what I did and I'm at 15k miles I think and just starting to feel some subtle shimmy.

But I also towed a 3k trailer a little before I got the electric brakes installed, and I think the new shimmy started after a couple hard stops due to people cutting on on me and slowing down.

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[Mr_Reverse]

Both the EBC and Powerstop are good. I don't really think there is a "better" between the two of them. 

 

Never tried getting loaded calipers online, they are offered at local auto parts stores since there is a core on the calipers. 

[RainGoat]

For the metal on metal lube for the pads themselves, I use a molybdenum brake grease. A small amount on the pads where they contact the torque member and a thin layer between the back and the shims unless the shims have adhesive, then a thin coat between the pad and the caliper helps a lot with noise control.

Great write up! Pretty much my process but I have a question regarding the metal on metal contact. I’ve typically used the silicone brake grease that I use on my pins for this - mainly because it’s convenient since I already have it out. Doing my wife’s MDX recently, I noticed the Power Stop brake pads came with a silicone grease - though it was much more viscous & tacky than my silicone grease. I’ve also heard of using Anti-Seize on these metal-metal contacts though I’ve worried about the temps. I have molybdenum grease that I use on my trailer ball hitch (but it is a synthetic designed for calipers, CV joints, etc). I would be interested in your input on these 3 different lubrications as you clearly have alot of experience & have dedicated a fair amount of thought to the process.  

 

[Guest]

50 minutes ago, RainGoat said:

Great write up! Pretty much my process but I have a question regarding the metal on metal contact. I’ve typically used the silicone brake grease that I use on my pins for this - mainly because it’s convenient since I already have it out. Doing my wife’s MDX recently, I noticed the Power Stop brake pads came with a silicone grease - though it was much more viscous & tacky than my silicone grease. I’ve also heard of using Anti-Seize on these metal-metal contacts though I’ve worried about the temps. I have molybdenum grease that I use on my trailer ball hitch (but it is a synthetic designed for calipers, CV joints, etc). I would be interested in your input on these 3 different lubrications as you clearly have alot of experience & have dedicated a fair amount of thought to the process.  

 

Copper anti seize works great for that

[Mr_Reverse]

The anti-sieze does work, but doesn't work well as a lubrication. The silicone works well as a lube, but doesn't handle the pressures as well as the moly. I do very light applications of grease since with the brakes, less is more. 

With the slip on rotors and drums, I do use a light coating of anti-sieze on the hub between the rotor/drum and hub flange. It helps prevent rust and squeels, and makes it easier to separate in the future  for servicing. 

On this subject, I also don't put anti-sieze on the lugs, or any lube really. I have had more problems lugs that had it applied than with the ones that are simply kept clean and properly torqued. If I pull a lug that is a little stiff, I will take an extra couple of minutes and dress the threads with thread chasers. Nissan's use a fine thread that is easier to damage and the anti-sieze will cause galling due to clogging the threads and causing over torque when tightening the lugs. 

 

[Slartibartfast]

I picked up a bottle of dedicated brake lube a while back. Purple synthetic schmoo with ceramic solids. Seems to work pretty well.

[Mr_Reverse]

I have a bottle of that too. Seemed to work ok. It seems to work pretty well on my Sig Sauer pistol slides when mixed with a little oil to thin it out a bit, but I still didn't trust it enough to use on the caliper slides. Kinda pricey too. 

[Slartibartfast]

Not the cheapest for sure, but I go through it pretty slowly, so, eh. Haven't had any trouble with it on my caliper slides.

[adamzan]

If it is this stuff, it is very good. https://www.amazon.ca/Permatex-24125-Ceramic-Extreme-Lubricant/dp/B0018PSASU/ref=asc_df_B0018PSASU/?tag=googleshopc0c-20&linkCode=df0&hvadid=293019627565&hvpos=1o2&hvnetw=g&hvrand=1965653352532573737&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9000662&hvtargid=pla-571820984777&psc=1

 

Those rotors are toast and the pads are wearing like that because of the ridges in the rotors. Replace rotors and pads.

[adamzan]

On 9/22/2019 at 11:13 PM, Mr_Reverse said:

The anti-sieze does work, but doesn't work well as a lubrication. The silicone works well as a lube, but doesn't handle the pressures as well as the moly. I do very light applications of grease since with the brakes, less is more. 

With the slip on rotors and drums, I do use a light coating of anti-sieze on the hub between the rotor/drum and hub flange. It helps prevent rust and squeels, and makes it easier to separate in the future  for servicing. 

On this subject, I also don't put anti-sieze on the lugs, or any lube really. I have had more problems lugs that had it applied than with the ones that are simply kept clean and properly torqued. If I pull a lug that is a little stiff, I will take an extra couple of minutes and dress the threads with thread chasers. Nissan's use a fine thread that is easier to damage and the anti-sieze will cause galling due to clogging the threads and causing over torque when tightening the lugs. 

 

I've never used anti seize on things like lugs or spark plugs. I just clean the threads and maybe a couple of drops of ATF so things spin smoothly... Never an issue in 14 years of pathy ownership.

[Mr_Reverse]

Haven't needed anti-sieze on spark plugs in many years. Back before they started nickel plating the plug bases, they were just plain mild steel. When the plain steel plugs were screwed into the aluminum heads, over time the metal mis match would cause the plugs be very difficult to remove. A light coat of anti-sieze prevented the problem. 

Modern plugs have the nickel plating that does the same thing so anti-sieze is not needed or recommended any more.

 

With the lugs, the practice seems to have started in rust regions. Problem is, the use of it on lugs tends to cause over torquing that deforms the threads, and the finer threads are damaged easier and less tolerant of damage. Add the fact that people tend to over apply just makes it worse.

[adamzan]

Exactly. My old 94 pathy had it on the lugs from the previous owner. It took me forever to get rid of it all.