Un­der the hood: Meth­ods dif­fer about break­ing in your brakes

Lodi News-Sentinel - - WHEELS - — Jill D. BRAD BERGHOLDT — Collin W.

I re­cently had brakes done on my Acura and was told by the ser­vice ad­vi­sor to drive gen­tly for the first hun­dred miles or so. A friend told me this is all wrong and I should have done a half dozen or more hard stops to “heat cy­cle” them be­fore nor­mal driv­ing. Who is right?

This is a con­tro­ver­sial sub­ject, as the rec­om­mended brake bed­din­gin process can vary quite a bit be­tween brake pad man­u­fac­tur­ers and shops per­form­ing the work. Other names for the process are break-in, con­di­tion­ing and bur­nish­ing. This pro­ce­dure should be per­formed when­ever new brake pads are in­stalled, new brake ro­tors are in­stalled or the ro­tors are re­fin­ished. Ide­ally, this is done by the brake in­staller prior to ve­hi­cle de­liv­ery, but it helps if the ve­hi­cle owner picks up the ball and fol­lows up with gen­tle brake use for sev­eral weeks. Suc­cess­ful bed­ding-in pro­motes smoother jud­der/noise-free brake per­for­mance over the long haul.

Ac­cord­ing to Raybestos, a ma­jor brake parts man­u­fac­turer, a proper break-in pro­ce­dure pro­vides three im­por­tant func­tions: “Phys­i­cally and ther­mally con­verts the com­po­si­tion of the pad and/or ro­tor, smooths the as­per­i­ties (rough­ness, un­even­ness) of the mat­ing sur­faces, and heat cy­cles the en­tire pad struc­ture.”

The bed­ding in process ba­si­cally in­volves trans­fer­ring a very thin layer or film of pad ma­te­rial to the ro­tor sur­face. A typ­i­cal rec­om­men­da­tion is to find an iso­lated sec­tion of road and per­form about six to 10 mod­er­ate slow-downs from 40 mph down to 10 mph, al­low­ing the brakes to cool a bit be­tween each cy­cle. Stop­ping fully isn’t rec­om­mended as the brake pads may im­print on the ro­tor, up­set­ting the even trans­fer of film. Some pad man­u­fac­tur­ers go a step fur­ther with ad­di­tional firmer stops to gen­er­ate ad­di­tional heat. Con­tin­u­ing to drive af­ter­wards for a bit to al­low a gen­tle cool-down is some­times called for, as well as avoid­ing us­ing the park­ing brake dur­ing this first phase (if ap­pro­pri­ate/safe). At­tempt­ing gen­tle brake use for the next 300 to 400 miles is also rec­om­mended to fully achieve film trans­fer, al­though if a sud­den/se­vere stop is needed, of course do so!

While do­ing a lit­tle ser­vic­ing un­der the hood I no­ticed my bat­tery was sweaty and seemed warm, al­though I had driven on and off for about an hour be­fore. I've never seen a bat­tery do this. Is it nor­mal?

This doesn't sound good! It's pos­si­ble your charg­ing sys­tem is over­do­ing things and is some­what cook­ing the bat­tery. If so, it's odd you haven't seen ei­ther an il­lu­mi­nated bat­tery or check en­gine light, but weirder things have hap­pened! An over-charge con­di­tion can be eas­ily con­firmed by ob­serv­ing bat­tery voltage, while run­ning, ei­ther from an in­stru­ment panel gauge or a volt­meter placed across the bat­tery ter­mi­nals. Most charg­ing sys­tems top out at about 14.8 volts. A read­ing no­tably higher than this does in­di­cate a prob­lem with the voltage reg­u­la­tor. This part is typ­i­cally con­tained within the al­ter­na­tor or the process is con­ducted by the PCM (pow­er­train con­trol mo­d­ule). If an over-charge con­di­tion is oc­cur­ring, it's best to get it fixed right away to pre­vent pos­si­ble bat­tery and com­po­nent dam­age! Rins­ing the bat­tery, the tray be­neath and sur­round­ing metal of any acid residue with a stream of fresh water would be a good idea as well.

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