Uh-oh where does this piece go? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**Gregski** · 04-09-2015, 05:56 PM

I have no idea what this came out of or where it goes, it looks like a riffle bullet? Any guesses? It's as thick as a pencil and about 2 1/2 inches long. This is not a trick, I honestly have no idea what this is. Please help

**396ci** · 04-09-2015, 06:27 PM

that is the pin that pushes on the brake master cylinder. it goes into the rubber boot on your vacuum brake booster.

in this illustration its called the 'power brake vacuum booster push rod'

**Gregski** · 04-09-2015, 07:29 PM

thank you so much Brian, I found it now in the pictures I took when I disassembled the brake booster, thanks again

question now is, did this genius forget to put that back in or did the new master cylinder come with a new one of these (I doubt it) and how in the world are my brakes working without it?

tucsonjwt · 04-10-2015, 08:48 AM

I think I got two different ones with my new Delco booster.

**Gregski** · 04-10-2015, 09:50 AM

Quote:

Originally Posted by tucsonjwt

I think I got two different ones with my new Delco booster.

Thanks Tucsonjwt, that's interesting, in my case though I did not buy a new booster, I just cleaned and painted my old one, I just bought a brand new master cylinder and that did not come with one of these push rods

FYI: I did pop mine back in real quick, and to be honest with you it really made no difference, so I am still super puzzled on how the brakes could have worked without it, puzzled

**rgunlock** · 04-10-2015, 01:38 PM

Is the Greg perhaps a magician?

bnoon · 04-10-2015, 01:57 PM

The pin simply centers itself into the piston on the master cylinder, that's why it's got a bullet shaped nose. It's not the only part that moves forward to move the master cylinder piston, so the piston was still being pushed forward by the booster sleeve, it just wasn't being centered. It needs to be centered to minimize wear over time, so short term the brakes will still work without this centering pin.

**Gregski** · 04-10-2015, 05:55 PM

Quote:

Originally Posted by bnoon

The pin simply centers itself into the piston on the master cylinder, that's why it's got a bullet shaped nose. It's not the only part that moves forward to move the master cylinder piston, so the piston was still being pushed forward by the booster sleeve, it just wasn't being centered. It needs to be centered to minimize wear over time, so short term the brakes will still work without this centering pin.

good explanation, thank you so much

04-09-2015, 05:56 PM	#1
Gregski Post Whore Join Date: Aug 2014 Location: Sacramento, CA Posts: 10,820	Uh-oh where does this piece go? I have no idea what this came out of or where it goes, it looks like a riffle bullet? Any guesses? It's as thick as a pencil and about 2 1/2 inches long. This is not a trick, I honestly have no idea what this is. Please help Attached Images

04-09-2015, 06:27 PM	#2
396ci Senior Member Join Date: Jun 2005 Location: Modesto, CA Posts: 776	Re: Uh-oh where does this piece go? that is the pin that pushes on the brake master cylinder. it goes into the rubber boot on your vacuum brake booster. in this illustration its called the 'power brake vacuum booster push rod' Attached Images __________________ Brian XNGH ECV Chapter 58 1972 Jimmy / Blazer Project 2wd 1974 Chevy Crew Cab Shorty Last edited by 396ci; 04-09-2015 at 06:33 PM.

04-09-2015, 07:29 PM	#3
Gregski Post Whore Join Date: Aug 2014 Location: Sacramento, CA Posts: 10,820	Re: Uh-oh where does this piece go? thank you so much Brian, I found it now in the pictures I took when I disassembled the brake booster, thanks again question now is, did this genius forget to put that back in or did the new master cylinder come with a new one of these (I doubt it) and how in the world are my brakes working without it? Attached Images

04-10-2015, 08:48 AM	#4
tucsonjwt Registered User Join Date: Jul 2007 Location: Tucson, AZ Posts: 3,188	Re: Uh-oh where does this piece go? I think I got two different ones with my new Delco booster.

04-10-2015, 01:38 PM	#6
rgunlock Senior Member Join Date: Jul 2009 Location: Tomball, Texas Posts: 1,592	Re: Uh-oh where does this piece go? Is the Greg perhaps a magician? __________________ Rick 78 GMC K15 SWB, 350/NV4500/NP205/4.10s Project Hazel 71 GMC C25 350/TH400 - Project Angie 59 Chevy SWB Stepside (next in line? Not sure now ) 2001 GMC Sierra K2500

04-10-2015, 01:57 PM	#7
bnoon Registered User Join Date: Jul 2012 Location: Des Moines IA Posts: 1,250	Re: Uh-oh where does this piece go? The pin simply centers itself into the piston on the master cylinder, that's why it's got a bullet shaped nose. It's not the only part that moves forward to move the master cylinder piston, so the piston was still being pushed forward by the booster sleeve, it just wasn't being centered. It needs to be centered to minimize wear over time, so short term the brakes will still work without this centering pin. __________________ - 1981 Sierra 454, NV4500 swap - 2006 Z06, 25k miles - 1973 Nova - Project CarNova Virus on Youtube



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