1. Why are you posting brake issues in "Engine Performance + Maintenance"?
2. "NBS" and "OBS" are vague and ambiguous terms.
3. JB3 and JB5 brakes have the ****** leading-trailing shoe rear brakes. It's uncommon to find them properly adjusted, and therefor they rarely work properly.
4.
Replacing a Quick-Takeup master cylinder with a non-Quick-Takeup master is a FRIGGIN' DISASTER. You will LOSE hydraulic advantage, and you FAIL to supply the low-drag calipers with a "gush" of low-pressure fluid to push the pistons up to the rotor. GM put STEPPED-BORE master cylinders on these vehicles FOR A REASON.
Photo 1. Note HUGE rear piston, and stepped-casting. JB3 has a 1" nominal bore with 32 or 36 mm (I forget which) rear low-pressure piston. JB5 & (I think) 6 have a 1 1/8 nominal bore with 40 mm rear, low-pressure piston.
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Some doofus removes a correct-but-failed master cylinder, installs an incorrect but working master, and thinks he's accomplished something. Then he tells other folks who also don't comprehend the concept of low-drag calipers and high-volume (stepped) master cylinder bores, and they make the SAME MISTAKE.
The JB3, JB5, and (I think) JB6 (well, xx3, xx5, and xx6) brake systems use low-drag front calipers, and NEED the quick-takeup (step-bore) master cylinder.[/
1. I dint exactly know which category to post it too. Suspension???? If you are an admin feel free to move the post for me
2. If u spend even 5 minutes on at least one GM truck forum you will learn very quickly what a nbs and obs is. Seems to me you must live under a rock because your probably also the only person on this post who doesn’t understand these terms
3. Previous owner who I am friends with blew the rear end and replaced the whole rear axle with a BRAND NEW unit not junkyard/reman and the NEW rear brakes were properly adjusted bled etc by a certified mechanic I know personally with 20+ years experience.
4. I will not argue with you on the exact sciences on brakes bc quite frankly it’s not my strong suit. I’m an electrician not a brake expert. If this new MC is supposedly so bad and shouldn’t work blah blah blah then PLEASE TELL MY WHY IT WORKS A LOT BETTER FOR ME. All I know is the brakes work a lot better than factory brakes it had. If it works for me and helps me drive more safely for myself and others on the road then I’m all for it. When GM designed these brakes, we still used cassette tapes. This ain’t the 90s anymore get with the program. People used to also design paint with lead in it but them realized there was a better way. Same can be said for the nbs swap. I saw an opportunity to improve MY truck and figured I’d share to maybe help other OBS enthusiasts improve their old tired 20 year old trucks too. I can’t tell other folks how it will help them but it helped me TREMENDOUSLY. In the 2 weeks I’ve drove wit it I have had ZERO issues. My truck brakes a whole hell of a lot better and my other braking components are In good shape as well. I don’t get on this site but maybe once every other week or so but when I got on tonight and read your post I felt obligated to reply. If you have a difference in opinion you could haverespectfully replied to me instead of pretending to be a keyboard gangster. So have fun with your raggedy 20 year old squishy brakes and claim it’s supposed to be like that because “it was designed for it”. Me and the rest of the “doofuses” with“NBS” master cylinders are happy with our firm brakes. I’ll log back on in a week or two hopefullyyou have a more respectful response. Have fun trying stomping on thst marshmallow in themiddle of your floorboard when you have to startbraking 100 yards from a stop sign going 60