Brake booster/master cylinder/prop valve
 

I bought this stuff new a while back and it got all rusted up and has zero miles. I plan on cleaning up the booster. but I need a new master cylinder. and also am wondering is a prop valve really needed? and if so, how would I know which to get?

truck has disc brakes up front with rear drums. does the year for the master cylinder make a difference? I believe mine is a 1" bore. but I really hate the locking metal bars on the lid

Re: Brake booster/master cylinder/prop valve
 

Prop valves are for safety as well as function once they were introduced. One can bypass them but you'll still need something to allow adjusting front & rear bias.

The fronts are usually 70% of the stopping force so something needs to be able to tune/adjust the rear. Factory prop valves are intended for factory applications (tire sizes). Once different tire sizes are used front & rear, the bias changes. Whether it's detectable or not is debatable & subjective.

Later model master cylinders will work so they don't have to be 'year model specific'. You'll want/need to use the proper bore size for the brake application. Manual brakes, power brakes, Hydraboost usually all require a different bore size. Bore size impacts pedal feel/force required. The plunger depth can also be different when using/mixing parts so you have to pay attention there as well.

My recommendation is to stick w/a kit if you aren't familiar w/this info already. Kits are usually based on a good combo of parts for a specific application.

Re: Brake booster/master cylinder/prop valve
 

I read your info on the adjustable prop valves and that's probably the way I will go. I was digging around oreillys website and found the 73 master cylinder with the same 1" bore. I bought this stuff brand new from there and have no idea what route I went the 1st time.

I also have the 2002 tahoe booster and master cylinder assembly on my parts truck I could rob, but I haven't even started looking into that

Re: Brake booster/master cylinder/prop valve
 

Food for thought...1-1/8" bore is normally for power brakes, but it seems some of these trucks did come with a 1" bore MC with PB. No idea what the difference would feel like between the 2.

Re: Brake booster/master cylinder/prop valve
 

The stuff was new a while back, and then sat outside for 20 years? :)

Re: Brake booster/master cylinder/prop valve
 

ha! just about. I put it on the truck about 7 years ago? maybe less. I never put a coating on it. I rolled the truck out the garage and I got burnt out and didn't work on it much. drove it down the street once. so I pulled everything back off to actually paint it (front frame, suspension, etc.). the booster seems fine, but the master cylinder rusted inside too where the holes are. I don't trust it.

Re: Brake booster/master cylinder/prop valve
 

the problem is this stuff I pulled off, I bought it brand new from oreillys. I just don't remember what the hell I bought back then (as in what application I told them). I'm really thinking I told them 73 c10, because that's what my pads and rotors are for

Re: Brake booster/master cylinder/prop valve
 

Re: Brake booster/master cylinder/prop valve
 

Your combination valve looks like the Bendix 411, which was stock for these trucks.

Your MC is a newer "universal" model that works for disc/drum or disc/disc applications. Will work fine on your truck.

I have no idea on the booster. Looks right tho.

Re: Brake booster/master cylinder/prop valve
 

the 72 master cylinder is listed as a 1.13 bore...I used some cheapo HF calipers and I got 1.10. so I think the 72 is spot on. I don't see anything "bendix 411" though

Re: Brake booster/master cylinder/prop valve
 

these are the brackets for the booster

Re: Brake booster/master cylinder/prop valve
 

Those are the 67-72 adapter brackets for the vacuum booster.

Re: Brake booster/master cylinder/prop valve
 

ya I'm pretty confident I went 72 booster, cylinder, and prop valve.

thanks scoti