What's this bracket for. 72 Cheyenne

[Originalthor]

Good evening all. Just wondering if anybody has an idea on what this bracket is for?

[kwmech]

Brake booster/master to firewall

[Originalthor]

Deadly thanks. That's kinda what I thought it was but this is his new system which I'm kinda iffy on and the brakes don't work worth a crap

['68OrangeSunshine]

Could it be a Fleetside Rear Fender Brace?
Not sure of the length from the pic.

[mr.mud1]

as said,it's likely the brace from the firewall to the back of the booster on the left side.probably not the reason for the brakes not working well but the booster is on 180 degrees off,the plastic valve in the booster that goes to manifold vacuum should be on the engine side of the booster

[FirstOwner69]

As stated above. However, I don't believe they were used on all 67-72 years. Maybe only the disc brake years? Can anyone confirm this?

[Steeveedee]

Is it 1/2T or 3/4T? My truck came OE with drums; I added disc brakes. It does not have that bracket.

[FirstOwner69]

Originally Posted by Steeveedee

Is it 1/2T or 3/4T? My truck came OE with drums; I added disc brakes. It does not have that bracket.

My truck is a '69 3/4 ton. When I bought it new, it did not have power brakes. The sale was contingent upon the installation of power brakes. The truck has never had this brace. So, I'm not positive if it would have had the brace if the brakes were factory installed. I bought, but haven't installed, a complete power brake setup from a 1972 which included the brace shown in my picture. Later, as I was junk yarding I then noticed some trucks had braces, and it seemed that all were 71s or 72s.

[LockDoc]

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Booster brace. There are usually two of them, the round one and larger "U" shaped one.

Here are some threads with pictures.

https://67-72chevytrucks.com/vboard/...d.php?t=816814

https://67-72chevytrucks.com/vboard/...d.php?t=653806

https://www.67-72chevytrucks.com/vbo...d.php?t=676183

LockDoc
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[FirstOwner69]

Originally Posted by LockDoc

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Booster brace. There are usually two of them, the round one and larger "U" shaped one.

Here are some threads with pictures.

https://67-72chevytrucks.com/vboard/...d.php?t=816814

https://67-72chevytrucks.com/vboard/...d.php?t=653806

https://www.67-72chevytrucks.com/vbo...d.php?t=676183

LockDoc
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Interesting that I contributed to two of those threads.

Although the evidence seems to indicate these were only used on disc brake trucks, I still don't see anything saying definitively that this is the case. Maybe I'm just beating a dead horse.

[LockDoc]

Originally Posted by FirstOwner69

Interesting that I contributed to two of those threads.

Although the evidence seems to indicate these were only used on disc brake trucks, I still don't see anything saying definitively that this is the case. Maybe I'm just beating a dead horse.

I would just say, if a person feels more comfortable using them, or sees any movement in the assembly when a helper applies the brakes, use them. Otherwise don't worry about it.....

LockDoc

[Originalthor]

Thanks for the brace info saved alot of head scratching. But now I'm scratching my head on this brake install. Does this look all good to you guys? Doesn't seam like there's power brakes. I'm going to rotate the booster so the vacuum port is on the top tonight and see if that helps. The lines look ok but the slope of the master kinda worries me. I did not do the initial install. Watched a view videos last night but really couldn't find one with the same booster master combo. Now it does have a pretty hefty cam in the motor so wondering if I'm not getting enough vacuum for it. Thanks again

[mr.mud1]

couple things,here's what the original proportioning valve looks like.i don't know if you have a what should be a factory type replacement or one of these hot rod set-ups you can buy?it looks like a power disc brake set-up i put on a friend's 34 plymouth a few years ago when i installed a new mustang 2 suspension?notice on the factory set-up,the forward line goes to the rear port on the proportioning valve and the rear line goes to the forward port,your's does not.certainly a wild cam will effect vacuum.have you put a vacuum gauge on the engine to see how much vacuum it has?as far as the tilt down for the master cylinder,that shouldn't be.i don't know if it's even possible to put the bracket on upside down but is the mount bracketry between the booster and firewall,right way up?


i just checked my truck,the master cylinder isn't level either but doesn't look as downhill as yours,may just be the picture?.i also looked at my brackets between the booster and firewall.i doubt you can install them upside down but your's look different than mine?any chance they are not for this truck?might throw off the stroke for the rod going into the master cylinder if they're not correct?let us know what you find.

[Originalthor]

Yes the lines to the valve has really got me thinking. One video has them reversed like yours and another video has them like they are now.

I also seen on a video that there are two different valves aswell one for front disc and rear disc and one for disc and rear drum setups. Going to check that out aswell.

I don't know if I rotate the booster it will tilt it up any but who knows and also going to check vacuum tonight. I want to see 9hg right?

Unfortunately I got zero instructions or part numbers on what was ordered.

[mr.mud1]

Yes sir,proportioning valves are specific for different set-ups.turning the booster around I don't expect will level the master cylinder,that flange on the rear of the booster is likely flat,but it should be turned anyway.the front chamber on the master cylinder supplies the rear brakes,the line from the rear of the prop valve is rear brakes on a factory set-up.9 inches of vacuum isn't much.the motor in my truck that I just built and fired up for the first time,has over 20 inches of vacuum. Make sure you are hooked up to full time manifold vacuum,not ported vacuum with your gauge and the booster. Take care,Greg

[54blackhornet]

Contact Wes on this site, hopefully he can help you out. He builds boosters for these vehicles.

[68 P.O.S.]

Is this a C-10? C-10s are plumbed to the combination valve the way yours is. You seem to have the right booster and master cylinder as well. I would replace that combo valve, those brass one are known for leaking out of the front metering valve part. Something like this would be a good replacement https://www.summitracing.com/parts/sum-g3906

As far as vacuum for your brakes, you need a vac can to supplement your low vac for the brake booster. Or switch to hydroboost, but thats not a simple, or cheap fix. https://www.summitracing.com/parts/sum-g1464

[custom10nut]

Originally Posted by FirstOwner69

As stated above. However, I don't believe they were used on all 67-72 years. Maybe only the disc brake years? Can anyone confirm this?

I believe you’re correct.
I upgraded my 4 Wheel drum brakes with a PB setup from another 70, and it doesn’t have that brace,
I have another complete unit from a 71 (disc/drum), and it has this brace.
My guess is that it’s to firm up the system to compensate for the increased braking force.