They are upgrading the fronts, necessitating the larger 17" wheels. The rears are going to drums instead of the current discs.
This applies only to the 1500 series trucks and likely tahoes burbs (1500). That article ommitted that info.
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Bosch, GM Bolster Truck Brakes
Joint project reduces pedal pressure, distance for stopping of 2005 Sierra and Chevrolet Silverado
The Detroit News
By Ed Garsten
May 25, 2004
MILFORD — Hoping to overcome negative consumer feedback and improve a key product amid stiff new competition, General Motors Corp. and brake supplier Robert Bosch AG have teamed up to develop a new braking system for the 2005 GMC Sierra and Chevrolet Silverado pickup trucks.
The new brakes will allow drivers to stop or slow more quickly while applying less pressure on the pedal.
The Silverado and Sierra are two of GM’s best-selling and profitable vehicles but are squaring off in the U.S. marketplace with the all-new Ford F-150 and Nissan Titan, as well as the Dodge Ram.
With the new brakes, the amount of time needed to stop has been reduced by two seconds and stopping distance has been cut by 85 feet, using just the front brakes.
In recent J.D. Power and Associates quality studies, customers complained that it took too much effort to depress the brake pedal, that the pedals felt mushy or soft and that the brakes just didn’t have enough stopping power.
“People said when they first touched the brakes they felt nothing,” said Ken Hamann, director of brake systems for GM.
Bosch was given responsibility for developing the new system when it was awarded the contract in 2002, said Tom Brennan, Bosch engineering manager.
Working with two or three lower-tier suppliers, Bosch improved the stiffness in the front brake calipers to reduce pedal travel — the distance a driver must depress the pedal before braking begins — changed boosters and redistributed power between the front and rear brakes.
“We did more with the front and a little less with the rear for overall better brake distribution and balance,” Brennan said.
Despite the improvements, the system will not cost more to install because the federal government has dropped requirements for certain brake control components, said Terry Woychowski, GM’s chief engineer for full-size trucks.
In a new J.D. Power initial quality study released earlier this month, customers reported a high number of problems with the brakes on the Silverado and Sierra.
“Compared to the segment, they’re having more quality issues in those areas than those of their competitors,” said Carolyn Picard, senior general manager at J.D. Power.
Across the industry, the average number of braking problems per 100 vehicles for light duty pickup trucks was 7.5. The Silverado had 10.5 problems per 100 models, and the Sierra had 12.6 problems per 100. In comparison, the Ford F-150 Heritage and Lightning models topped the list with just 2.9 problems per hundred vehicles, the Dodge Ram had 4.8. The new Nissan Titan was last with 16.5 problems per 100 models tracked.
The study included eight different brake-related problems ranging from noise to pull to inadequate stopping power.
In equipping the 2005 Sierra and Silverado with the improved brake system, GM should be given credit for recognizing and fixing the problem, Picard said.
GM measures overall braking comfort and performance on a scale — from zero to 100 — it calls its brake feel index. The automaker estimates the brake feel index will improve to 84 in the 2005 Silverado and Sierra crew cab models, up from 62 points on 2004 models, according to Hamann.
In comparison, the brake feel index for the 2004 Ford F-150 super crew is 76 points, 62 points for the 2004 Dodge Ram quad cab, 71 points for the 2004 Titan crew cab and 59 points for the 2004 Toyota Tundra, according to GM.
The improvements to the brakes in the Silverado and Sierra include a new master cylinder that helps reduce pedal travel, along with larger front rotors and larger rear brake drums, Woychowski said.
“They feel more natural,” he said.
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The 2500HD's and 3500's have great brakes. Discs front and rear. This will not be changing. GM way overengineered the brakes on these trucks to stop any complaints of porr braking feel.
I've seen the specs on GM buypower for the 05 HD's.. Tires are the 16" variety, so I am assuming that the wheels will also be 16"
