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Brake Job Myth Busting


3/9/2010

Six myths could be holding your customers back from performing the best brake job.
 
By Andrew Markel
Editor, Brake & Front End Magazine


1. All pads are created equal
One of the greatest myths out there is that some customers will not use the full potential of a brake pad due to their driving style or commute. This is false, because the one time the customer needs to use the full potential of the pad, the performance will not be measured in dollars and cents, but inches and feet.

What standards should your customers use when selecting replacement brake pads? Try them for yourself! Set aside some time when the shop is not busy or on a weekend to try out the brands of brake pads your customers install. Perform at least four emergency stops from 55 mph to a dead stop back to back. Let your right foot be the judge.

2.  The more lube, the less noise
Basting a set of pads or caliper slides in lubricant, no matter how expensive they are, will not solve a noise issue for an extended period of time. Why? Because the excess lubricant can melt or some chemicals can flash off. The melting lubricant can find its way on to the pads causing a judder problem and longer stopping distances.

Excessive lube also can attract debris and dirt. As the lube hardens over time, it turns to a concrete-like substance that causes slides and calipers to stick. If excessive lubricant finds its way onto the caliper piston’s boot, the lubricant will attract metal particles that can destroy the rubber.

Shims need only a small amount of lubricant. Some floating one-piece and two-piece shims require only a small amount of lubricant between the surfaces of the shim and pad. There is no need to coat the entire back of a brake pad with a lubricant.

For the caliper anchor pins, a silicone-based brake grease should be used. It must be compatible with all rubber compounds including nitrile, Teflon, nylon and other synthetic rubbers.

For the shims, abutment clips and slides, a synthetic-based boundary-type lubricant that has a high-solids content and typically contains a variety of friction-reducing ingredients, such as molybdenum disulfide (moly or MOS2) and graphite, should be used.

3. Shims are not required
One of the greatest mistakes made is not installing shims on a new set of pads. On new vehicles, the shims are designed along with the caliper and pads. Shims are not a last minute “add-on” to make sure the pads fit. Instead, they are a critical part making sure the brakes operate sufficiently and quietly.

More and more OEMs and aftermarket brake pad manufacturers are using single and two-piece shims that clip on to the front in-board and outboard pads. This design creates a “boundary layer,”  preventing vibrations from being transmitted to the caliper and knuckle. They can also prevent heat from being transmitted to the piston. Shims should always be replaced.

4. All rotors are the same
A rotor can fit on a vehicle and still not be the right rotor for the vehicle or driver. The wrong rotor that fits may develop runout, BTV and DTV sooner than a quality rotor. Also, low-quality  rotors may have compromises in the structure and metallurgy that may make sense to the wallet, but not the driver.

5. New rotors need to be machined
New rotors are supposed to be finished to specifications and ready to install out of the box. There should be no reason to give them a “clean up” cut. If they do need a cut, you need to find a different rotor supplier.

A recent Babcox survey found that 35 percent of our readers are still machining brand new rotors before they install the rotors on their customers’ vehicles. Machining new rotors shortens rotor life. It may also leave a rougher finish on the rotors than the factory finish.

The manufacturing tolerances  on most new rotors average about 0.001 inches or less, with a maximum upper limit of 0.004 inches. Some cars are unusually sensitive to rotor runout. As little as 0.0015 inches of runout on these cars may produce noticeable pedal pulsations.

6. Repair information isn’t needed for a brake job
All brake systems may look the same after a while, but it is the unseen that can hurt and cause a comeback. It might be as simple as a torque specification for a caliper bracket or as complex as a disarm procedure for an ABS system. Technicians need to have access to current repair information. Information can pay for itself by saving time and preventing a comeback.
  Previous Comments
avatar   Braker Braker   star   4/11/2010   10:53 AM

I just tell people that I wouldn't put the bottom dollar pads on my ex girlfriends car.



avatar   Chris   star   3/27/2010   3:28 PM

I tell them simply that the rotor is no good, and I won't cut it for them. Had one guy tell me I didn't know what I was doing, so I said, "Oh, I didn't know you could cut rotors. Come on back here, show me how." Boy, he got mad, but I convinced him to buy new rotos.



avatar   Will   star   3/24/2010   1:22 PM

Sad to say this Ed, but those are the people that do end up having or causing an accident. You hear it on TV: "My brakes failed and I couldn't stop". Tell the family of the people hurt or killed you shortcut on a brake job.



avatar   Ed   star   3/22/2010   1:51 PM

I actually called a customer out on that once before. It was a VW Passat, old man brings in two rotors to be turned, well below machine spec, even below discard spec. I inform him of this, he says "BS", that I am just making numbers up. After going back and forth for a few minutes, I finally crack and tell him that I pray for his family or whoever was going to drive this vehicle, because he intended to murder them. That shut him up.



avatar   Will   star   3/22/2010   7:34 AM

Yeah Gabe I love it. When did your kids vehicles warrant cheap junk? I had a 1975 C-10 and I used mid grade pads until I started towing race cars for my friends. I understand MONEY and being young, but safety shouldn't be put on the back burner. What happens to those cheap pads when you have to make an aggressive stop? They usually come apart. The cheap set did on the 1974 Duster I had.



avatar   Gabe   star   3/19/2010   2:49 PM

Will-HA HA HA Don't you love that! "Yep it my daughter's car so just get me the cheapest pad you got!" Am I backwards in thinking that is messed up!? So she may be in high school and she may have a beater turd! But really! The cheap crap for your daughter?



avatar   Will   star   3/18/2010   9:58 AM

I love it when people/shops say "Send me the cheapest pads you have". Nothing better than listening to them whine about noise and pulsation later on. Upsell your customer by explaining differences. Some people are dead set on cheap crap though. I tell them cheap is fine..if you're fixing to sell. I wouldn't want a $15.00 pad on my wifes Durango especially since she drives our kids to school.....



avatar   negator   star   3/17/2010   12:48 PM

"hard pads are noisy."

"send me something soft."

. . . when can we dispel this myth?




avatar   Tad   star   3/17/2010   12:57 AM

Most street-oriented ceramics are softer than semi-metallics. They're quiet though and easier on rotors, and they work well on cars designed to use them. SM's are aggressive and tend to chew up rotors faster, but they stop better because of it. They also dissipate heat very well. Ceramics don't dissipate heat as well, which can cause the rotors on a car designed for SM's to run hotter than they're designed to (hot spots), and can leave pad material 'glued' to the rotor surface. More importantly, they can fade quicker than SM's.



Basically, use the OE recommended material. Altering the pad compound can have unexpected results sometimes. Fortunately for me, Wagner matches OE compounds, and I also have a good selection of OE import pads to complement my brake lineup.




avatar   Gabe   star   3/16/2010   2:43 PM

I am more curious about the myths my customers spew from their mouths. Like..Don't buy ceramics they chew up rotors! Or I need special rotors for ceramic pads. Although I remember reading an article on here about how ceramics bonding material actually has more give than semi metallics.



avatar   Andrew Markel, Editor, Brake & Front End   star   3/15/2010   8:55 PM

Will, you are right about the TQ pads and no lube. I have seen some techs put lube on the outside of the piston boot. Telling technicians about brakes is tough, it is even tougher to get them to read any thing that is written on a slip of paper. Just try telling them about bedding procedures after the pads are installed!



avatar   Will   star   3/15/2010   1:45 PM

#2 I have a shop guy that insist on lubing up pads on every car he does. We sell Wagner TQ to him 98% of the time. I included the Wagner "Do not Lube" sheet from the website. He insist that it is necessary everytime. #6 Mess up a new cars brake system and see how much money floats out of your pockets and your "Reliable and Honest" status suffers. #1 Never assume pads are equal...EVER! Doom awaits the counterpro or shop owner that claims this. These are the same people that say all Small Block Chevy's are the same! Do the research or don't sell them. Dealer pads sometimes are the only option. Check your paper catalog when in doubt (Chrysler Corp SRT 8 equipped vehicles)w/ Brembo system. Be smart and learn the ins and outs by asking for tech classes to better serve your clients.



avatar   Andrew Markel, Editor, Brake & Front End   star   3/12/2010   10:28 PM

Tad,

You are right, .004" is huge, but on some vehicles it is within spec due to the brake system design, but it might lead to thickness variation down the road. Nissan is considering lowering their runout spec to .0005 on some of its vehicles. Most shops do not have a dial indicator that can even measure this!

Great method for selling premium rotors! But, even if customer buys a "super-duper" premium rotor and they install it on a hub flange with runout, it will still have runout (maybe a little bit less than the economy rotor). Maybe it could be a new sales method to sell more wheel bearings.




avatar   Tad   star   3/10/2010   1:14 AM

#5 is not true all of the time, especially when considering economy rotors. That .004" runout is over spec for many vehicles. A lot of vehicles are specifying .001" maximum runout. That .004" runout can turn into hot spots or thickness variation down the road, each of which can result in pad pulsation.

This is one of the points I use to sell premium rotors to retail customers. Most retail customers have no way to check rotor runout, so they have to rely on what comes out of the box. Better to rely on the more expensive rotor with lower runout tolerance from the factory than the cheap rotor that could be +/- .004" and cause pedal pulsation down the road.




avatar   Tad   star   3/10/2010   1:14 AM

#5 is not true all of the time, especially when considering economy rotors. That .004" runout is over spec for many vehicles. A lot of vehicles are specifying .001" maximum runout. That .004" runout can turn into hot spots or thickness variation down the road, each of which can result in pad pulsation.

This is one of the points I use to sell premium rotors to retail customers. Most retail customers have no way to check rotor runout, so they have to rely on what comes out of the box. Better to rely on the more expensive rotor with lower runout tolerance from the factory than the cheap rotor that could be +/- .004" and cause pedal pulsation down the road.


















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