WARPED MYTH

4 Wheel & Off Road - - NUTS & BOLTS -

Q I have a 2003 GMC 3500 sin­gle-wheel truck that I use to haul a pretty big toy hauler. I’ve weighed the whole thing and it’s heavy, but I’m within the weight rat­ing of the truck. I live up in the moun­tains in Colorado, and I keep go­ing through brakes on the truck. I’ve tried sev­eral different brands and qual­ity lev­els of brake pads, but I’ve warped mul­ti­ple sets of ro­tors. I con­sider my­self a con­ser­va­tive driver, and I even down­shift on the grades to use en­gine brak­ing, but it doesn’t seem to help. I get that I’m prob­a­bly right at the edge of what the brake sys­tem was de­signed to do and can ex­pect to be re­plac­ing brakes more of­ten than a flat­lander, but it gets re­ally ex­pen­sive when you’re re­plac­ing them ev­ery year and af­ter prac­ti­cally ev­ery big trip. Is there an up­graded ro­tor or even a bet­ter brake sys­tem avail­able for my truck?

MARK F. Via nuts@4wor.com

A We were re­cently schooled on warped ro­tors from some friends over at Baer Brakes (baer.com). First off, it’s ex­ceed­ingly rare to ac­tu­ally warp a ro­tor. In­stead, the cause of the shud­der you feel through the pedal is an un­even buildup of brake pad ma­te­rial on the ro­tor it­self.

Here’s how it works. Mod­ern as­bestos­free and non­metal­lic brake pads con­tain different resins in ad­di­tion to the ac­tual brake ma­te­rial it­self. Some of these resins and ma­te­ri­als trans­fer them­selves to the ro­tor face so that there will be ad­her­ent (sticky) brak­ing in ad­di­tion to abra­sive brak­ing. In a nut­shell, when a brake sys­tem is prop­erly bed­ded in, there’s a thin layer of pad ma­te­rial on the ro­tors. When you use the brakes hard, such as when com­ing down a steep grade, the heat buildup causes these resins to loosen. When you stop the ve­hi­cle com­pletely, such as at a red light at the bot­tom of an off-ramp af­ter that steep hill, you ac­tu­ally make an im­print of the brake pad on the ro­tor, cre­at­ing a high spot. By the time you get gas or

stop for lunch (or what­ever) the ro­tors have had a chance to cool off, but that high spot is still there. As lit­tle as 0.0004 inch can be felt through the pedal, and 0.001 inch can be down­right an­noy­ing. Re­peated use just leaves more ma­te­rial on the high spots, mak­ing the shud­der worse.

Now that you un­der­stand what’s go­ing on, here’s what you can do to help com­bat it. If caught early, you can of­ten elim­i­nate the shud­der by rebed­ding the brakes. To do this, find a safe area where you can make a se­ries of hard slow­downs from 50 mph to about 10 mph. Don’t come to a full stop. Do­ing this sev­eral times will heat up the ma­te­rial on the ro­tors and help smear it evenly on the face of the ro­tors again. Then drive around for a lit­tle while with­out stop­ping much to let the brakes cool off.

An­other thing you can do is avoid be­ing on the brakes with the ve­hi­cle stopped when you know the brakes are hot. Shift it into Park while you wait for the light to turn at the bot­tom of the off ramp and take your foot off the brakes. This helps avoid leav­ing a foot­print of the pad on the ro­tor.

Buy the best-qual­ity brake pads you can af­ford and stick with rep­utable name brands if pos­si­ble. For heavy ap­pli­ca­tions such as yours, a semimetal­lic pad is a good choice be­cause they rely more on abra­sive brak­ing than ad­her­ent brak­ing, and they have a higher op­er­at­ing tem­per­a­ture. When nec­es­sary, don’t skimp on re­place­ment ro­tors even though it might hurt your wal­let. There are also some bolt-on af­ter­mar­ket up­grades out there for your truck that don’t re­quire wheel changes. EBC Brakes (ebcbrakes.com) of­fers both pads and ro­tors for your truck.

Lastly, you might con­sider do­ing what you can to sup­ple­ment the fac­tory brake sys­tem by mak­ing sure the brake sys­tem on the toy hauler is in tip­top shape. If you have a diesel, it might not be a bad idea to in­stall an ex­haust brake on the truck. Sev­eral ver­sions are avail­able in the af­ter­mar­ket, and they sub­stan­tially im­prove over­all brak­ing per­for­mance, not to men­tion tak­ing a lot of strain off of the stock brakes.

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