Power brake conversion problem - The 1947 - Present Chevrolet & GMC Truck Message Board Network

ChopperDr · 12-02-2010, 05:50 PM

I just rolled my 68 LWB out of the shop. I converted to power disc brakes. Pedal is good, stopped good, but a scraping, grinding noise from the rear drum? I didnt mess with the rear any farther than bleeding the brakes after the conversion to the new mc/booster.A fresh rear hose was also installed.

I called CPP, who supplied the booster, they had no idea why it would operate fine before the conversion, and scrape now. The tech there suggested I readjust the rear pads. I was so stoked that I had a high firm pedal when I fired it up, now I'm bummed I have to trouble shoot this noise.

Any ideas?

Chopster

entourageguy · 12-02-2010, 10:40 PM

Did you pull the drum off to look inside? You said you replaced a hose for the rear. Is it possible the rears were not even working before and with the new hose they now work but maybe with little or no friction material left on the shoe?

spike38 · 12-02-2010, 11:41 PM

Quote:

Originally Posted by entourageguy

Did you pull the drum off to look inside? You said you replaced a hose for the rear. Is it possible the rears were not even working before and with the new hose they now work but maybe with little or no friction material left on the shoe?

Spike

C10longwb · 12-03-2010, 12:37 AM

Yeah just pull it and check it if you replace stuff do it 1 side at a time so you can refernce the other side but there real simple I just advise you to get the spring plyers made to doing drums makes it alot easier a new hardware kit is very enexpsensive but just sounds like something draging a little another quick idea is maybe Jack your truck up and spin the rears and see if you can get it to make the sound you may get a beter perspective on what it is by that
Posted via Mobile Device

ChopperDr · 12-03-2010, 09:32 AM

Good suggestions. I'll pull the drum this morning.

I also need to check on the emergency brake. I didn't say before, but I also just put 1.5" blocks in back so the air bag could run at a little higher pressure at ride height. I think there is a possibility the brake cable could be hanging up. We'll see.

Chopzilla

ChopperDr · 12-03-2010, 02:31 PM

I'm an idiot. The center support bearing was scraping on itself. It is a little worn, has about a quarter of an inch play in it. I knocked out the rivets on the mount and moved the mount up to the higher set of holes and adjusted the bearing so it wouldn't rub on itself.

The brakes work really well. Now we need to get in for an alignment.

Chop

12-02-2010, 05:50 PM	#1
ChopperDr Registered User Join Date: Feb 2008 Location: WA Posts: 189	Power brake conversion problem I just rolled my 68 LWB out of the shop. I converted to power disc brakes. Pedal is good, stopped good, but a scraping, grinding noise from the rear drum? I didnt mess with the rear any farther than bleeding the brakes after the conversion to the new mc/booster.A fresh rear hose was also installed. I called CPP, who supplied the booster, they had no idea why it would operate fine before the conversion, and scrape now. The tech there suggested I readjust the rear pads. I was so stoked that I had a high firm pedal when I fired it up, now I'm bummed I have to trouble shoot this noise. Any ideas? Chopster

12-02-2010, 10:40 PM	#2
entourageguy Yellow truck club Join Date: Apr 2006 Location: Barrie Ontario Posts: 2,080	Re: Power brake conversion problem Did you pull the drum off to look inside? You said you replaced a hose for the rear. Is it possible the rears were not even working before and with the new hose they now work but maybe with little or no friction material left on the shoe? __________________ ................................................................ Brian ...... My hub garage address http://www.hubgarage.com/mygarage/59apache I gue$$ everything has it'$ price ALL GONE NOW *59 Chev Apache* *PRAISE THE LOWERED* 350 700r lokar shifter power MII front end, shockwaves tilt, 4 wheel discs 4-link and bags 10 bolt limited

12-03-2010, 12:37 AM	#4
C10longwb Registered User Join Date: Oct 2010 Location: Texas Posts: 40	Re: Power brake conversion problem Yeah just pull it and check it if you replace stuff do it 1 side at a time so you can refernce the other side but there real simple I just advise you to get the spring plyers made to doing drums makes it alot easier a new hardware kit is very enexpsensive but just sounds like something draging a little another quick idea is maybe Jack your truck up and spin the rears and see if you can get it to make the sound you may get a beter perspective on what it is by that Posted via Mobile Device

12-03-2010, 09:32 AM	#5
ChopperDr Registered User Join Date: Feb 2008 Location: WA Posts: 189	Re: Power brake conversion problem Good suggestions. I'll pull the drum this morning. I also need to check on the emergency brake. I didn't say before, but I also just put 1.5" blocks in back so the air bag could run at a little higher pressure at ride height. I think there is a possibility the brake cable could be hanging up. We'll see. Chopzilla

12-03-2010, 02:31 PM	#6
ChopperDr Registered User Join Date: Feb 2008 Location: WA Posts: 189	Re: Power brake conversion problem I'm an idiot. The center support bearing was scraping on itself. It is a little worn, has about a quarter of an inch play in it. I knocked out the rivets on the mount and moved the mount up to the higher set of holes and adjusted the bearing so it wouldn't rub on itself. The brakes work really well. Now we need to get in for an alignment. Chop



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