Suburban brakes poor performance

Its been awhile... -replaced combination valve per service bulletin -adjusted rears per Ben's (From another board) recommendations and found things dragging on brake release so...
-replaced callipers/disc/pads (were due) from NAPA left rears alone... -loaded the whole caboodle(6+gear) went skiing... -no brake drag noted on brake release but wow!!! brakes work like never before, confidence inspiring, could have stopped on a dime from 100 Km/h going Down hill! Parts required were -1 1/16 dia wheel cylinders (OEM 1")to improve rear capacity (installed previously) -combination valve for slight improvement to bias fr/r -front callipers/discs/pads Hopefully We'll benefit from longer front pad life as the rears will share more of the overall braking. (my goal from the outset) Respectfully shared Rolf
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RE/

What year is the vehicle?
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PeteCresswell

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'93 K1500
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I have a 98 1500UT here and no service bulletin. What's the deal with the combination valve? How difficult to replace? What kind of cost? I have too much front brake wear, gone through too many pads and actually cooked a set of front rotors in 35,000 miles. Local repair shop seems to love getting me to spend more money every time I'm in...don't really trust them.

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First try adjusting the rear brakes so that the shoes have "light drag" whilst turning the wheel(s). The adjusters though automatic don't work as designed. You'll have to re-adjust 3K-5K miles. I searched: Alldata.com NHTSA.com And found the reference #99-05-24-001a refering to brakes pulling/front pad wear but no details though . Lost my copy of details (Hard Drive/OS failure) Dealer may print copy for you. Combination valve PNs vary depending on year/ABS module installed. Mine cost $85 cdn Dealer only item( favour from friend) GM parts direct lists less but shipping will bump Price. Have not heard of 1500UT typo? Rolf

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Caliper TSB
Tech - Brake Lead/Pull and Frt Brake Wear (Repl. Frt Brake Pads, Rr Brake Shoes) #99-05-24-001A Brake Lead/Pull and Front Brake Wear (Replace Front Brake Pads And/Or Rear Brake Shoes) 1992-1999 Chevrolet and GMC C/K Cab Chassis, Crew Cab, and Pickup Models with Power Brakes (RPO JB8) 1992-99 Chevrolet and GMC C/K Suburban Models with 8600# GVW (RPO C6P) 1996-2000 Chevrolet and GMC G Vans with Power Brakes (RPO JD7 & JB8) and GVW's of 7,700# up to 9,500# (RPO's C3F, C6P, & E23) This bulletin is being revised to update information in the Models Section and Correction Information. Please discard Corporate Bulletin Number 99-05-24-001 (Section 5 -- Brakes). Condition Some owners may comment about the vehicle leading or pulling to either side while applying the brakes, and premature front brake wear, especially vehicles that have been used to tow a heavy load. Cause The condition may be caused by wearing of the front brake material. Improvements to the above conditions can be gained through brake material modifications. On the Suburban models, the best performance from this new brake material can be achieved with replacing the brake combination valve. Correction Replace the rear brake shoes with P/N 18029651. THIS FIX DOES NOT APPLY TO THE 13 x 2 1/2 BRAKE, DURASTOPT P/N 18029650, OR ANY OTHER SIZE. On Suburban models, a brake combination valve must be replaced. ALL OTHER MODELS (C/K, G Van), NO BRAKE COMBINATION VALVE CHANGE IS REQUIRED. Refer to the Drum Brakes or Hydraulic Brakes subsection of the appropriate Service Manual. For G2/G3 Series Vans only (with GVW's of 7,700# up to 9,500# -- RPOs C3F, C6P, E23) also replace the front brakes pads with P/N 12471685. Refer to the Disc Brake subsection of the appropriate Service Manual. Important The new front brake pad material has been selected for improved wear characteristics. Some customers may experience increased brake noise from this brake pad and should be advised that some squeal is a characteristic of this particular material. Important If you encounter disc brakes that are extremely worn on the inboard side, with very little wear to the outboard side, verify the clearance between the caliper and the steering knuckle bracket stops. MEASURE THE CLEARANCES INDIVIDUALLY AND ADD THE CLEARANCES TOGETHER FOR TOTAL CLEARANCE BEFORE REMOVING THE CALIPER. If the caliper (total clearance) to the steering knuckle stops is under 0.26 mm (0.010 in), correct this by filing metal off at the steering knuckle stops in order to obtain a total clearance of 0.26 to 0.60 mm (0.010 to 0.024 in). DO NOT FILE METAL OFF OF THE CALIPER. Refer to the Disc Brake subsection of the appropriate Service Manual for additional information on this procedure. Parts Information Part Number Description Qty 18029651 (17452R Canada) Shoe Kit, RR Drum Brk (13 x 3.5 in.) 1 12471685 Pad Kit, Frt Disc Brk 1 15650150 (92-94 Suburbans) Valve Asm., Brake Comb. 1 12548265 (95 and Newer Suburbans) Valve Kit, Brake Comb. 1
Parts are currently available from GMSPO. Warranty Information For vehicles repaired under warranty, use: Labor Operation Description Labor Time H0257 Shoes and Linings, Drum Brake - R&R or Replace (Rear) Use published labor operation time H0042 Pads, Disc Brake - R&R or Replace (Front) 1.0 hr* H0780 Valve, Brake Combination - Replace Use published labor operation time *This time is updated from the current Labor Time Guide. The next issue will contain this change
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