brake issues - The 1947 - Present Chevrolet & GMC Truck Message Board Network

white 67 · 11-18-2011, 07:26 PM

I have been trying to get the rear brakes working on the 67 i picked up last week. I have replaced the shoes, wheel cylinders, a brake line and the master cylinder. Im tring to bleed the brakes but i am not getting any pressure to the rear, there is fluid but no pressure and the rear brakes dont work at all. The only old part in the system is the proportioning valve, could it be the problem. Thanks for the help.

57larry · 11-18-2011, 07:29 PM

drum or disc on the front?

Lee H · 11-18-2011, 08:05 PM

Did you bench bleed the master before hooking up the lines?
Posted via Mobile Device

white 67 · 11-18-2011, 08:13 PM

Its drum/drum and yes i bench bled the master cylinder. Im pretty much stumped on this one.

68gmsee · 11-18-2011, 08:40 PM

After you double check by loosening the connections check the rubber brake hose on top of the rear drive axle shaft. It can collapse internally and won't allow or restricts the brake fluid from reaching the rear drums.

Only good way to check it is to remove it and look at it. You can also insure hydraulic fluid is going to the rear breaks after you remove it by placing a container to collect the fluid or by using a rubber hose that fits over the line.

white 67 · 11-18-2011, 11:49 PM

ttt.i just blew out all the lines and every thing was fine, i didnt find any blocks, still no pressure to the back.

**VetteVet** · 11-19-2011, 12:54 AM

Check your free play on the pedal rod to master cylinder. If you have none then the valve cannot return past the reservoir hole and allow more fluid to enter the pressure port for the rear lines.

Gmichael · 11-19-2011, 01:01 AM

Quote:

Originally Posted by VetteVet

Check your free play on the pedal rod to master cylinder. If you have none then the valve cannot return past the reservoir hole and allow more fluid to enter the pressure port for the rear lines.

That was my problem when I did my brakes two months ago....
Posted via Mobile Device

68gmsee · 11-19-2011, 10:05 AM

Quote:

Originally Posted by white 67

ttt.i just blew out all the lines and every thing was fine, i didnt find any blocks, still no pressure to the back.

Assuming you blew them out starting at the master cylinder then the master cylinder is defective. There is a front and rear piston internally to the master cylinder and the piston seals may be defective allowing brake fluid to be bypassed under pressure.

I had to replace couple of new defective ones a few years ago and finally went to a different auto parts store and got a different brand. Didn't have any more problems.

**michael bustamante** · 11-19-2011, 12:02 PM

Yup I once had to replace a new remanned m/c a couple of times myself.

**allchevy58** · 11-19-2011, 01:08 PM

Do the front brake bleed just fine? If so, did you adjust rear brakes before bleeding?

white 67 · 11-19-2011, 03:57 PM

Quote:

Originally Posted by allchevy58

Do the front brake bleed just fine? If so, did you adjust rear brakes before bleeding?

Yes the front bleed out fine. Im no i didnt adjust the rear yet, im not really sure what that would have to do with any thing. There is just no pressure.

I guess im going to order another master cylinder and see what happiens.

68gmsee · 11-19-2011, 04:31 PM

Quote:

Originally Posted by white 67

Yes the front bleed out fine. Im no i didnt adjust the rear yet, im not really sure what that would have to do with any thing. There is just no pressure.

I guess im going to order another master cylinder and see what happiens.

What he means is that brakes have to be adjusted before bleeding so that they make contact before you run out of braking action. When I do my brakes I always adjust them so that they lightly scrape the drums as I rotate them before I bleed them.

fastwillie 696969 · 11-19-2011, 07:02 PM

reset the PV ?

MagmaJct · 11-19-2011, 10:08 PM

I don't remember, does the front of the master cylinder operate the back brakes? Or does the front of the master cylinder operate the front brakes?

Here's why I ask: The pistons in the MC must move completely to the back (towards the firewall) when the pedal is not being depressed. This uncovers a port that allows fluid to flow into the cylinder.

If the piston is not completely returned it'll block the port and not allow any fluid to fill the cylinder. Of course, this assumed the bench bleed didn't go well and air is trapped in the cylinder.

If the hose that is connected to the MC is loosened, will fluid leak out if the pedal is pressed?

white 67 · 11-19-2011, 10:24 PM

I just checked to make sure the master cylinder was returning all the way and it is.

Fluid will come out the master cylinder if the line is loose.

**allchevy58** · 11-19-2011, 11:16 PM

68gmsee explained it, if shoes don't make contact to drums, pressure will not build up in brake lines to rear brakes.

68gmsee · 11-19-2011, 11:21 PM

Forgot to add re. adjusting brakes before bleeding...

The only way you will get pressure in the brake system is if there's resistance by the shoes contacting the drums. Otherwise there's very little pressure.

MagmaJct: On the stock units the front is front brake and rear is rear breaks.

add again.. Just saw allchevy's post above.

white 67 · 11-22-2011, 11:00 PM

Just wanted to update everyone on the fix. I replaced the master cylinder with a new one, not reman from napa and bled the brake again and now every thing is working great. Thanks for the help, the old truck is one step closer to going for a drive.

slikside · 11-23-2011, 08:08 PM

Good info for future. Subscribed

68gmsee · 11-24-2011, 12:29 AM

Fantastic.. Glad you got it going.

**allchevy58** · 11-24-2011, 01:12 AM

Glad to hear you got it working properly.

11-18-2011, 07:26 PM	#1
white 67 Registered User Join Date: Oct 2009 Location: coupeville ,washington Posts: 348	brake issues I have been trying to get the rear brakes working on the 67 i picked up last week. I have replaced the shoes, wheel cylinders, a brake line and the master cylinder. Im tring to bleed the brakes but i am not getting any pressure to the rear, there is fluid but no pressure and the rear brakes dont work at all. The only old part in the system is the proportioning valve, could it be the problem. Thanks for the help.

11-18-2011, 07:29 PM	#2
57larry Registered User Join Date: Nov 2007 Location: Indianapolis Posts: 1,161	Re: brake issues drum or disc on the front?

11-18-2011, 08:05 PM	#3
Lee H Registered User Join Date: Jun 2010 Location: Upland Ca Posts: 4,147	Re: brake issues Did you bench bleed the master before hooking up the lines? Posted via Mobile Device __________________ 1972 C10 SWB, Air, PS, PB, 350/350THM. Second owner. 1965 Corvette roadster, 44K miles, 327/365 SHP, 4 speed, side exhaust, knockoffs, teak, second owner (bought in 1970), Have ALL numbers matching components. My frame off restoration thread: http://67-72chevytrucks.com/vboard/s...d.php?t=556703

11-18-2011, 08:13 PM	#4
white 67 Registered User Join Date: Oct 2009 Location: coupeville ,washington Posts: 348	Re: brake issues Its drum/drum and yes i bench bled the master cylinder. Im pretty much stumped on this one.

11-18-2011, 08:40 PM	#5
68gmsee Active Member Join Date: Jul 2007 Location: Centrally located between Houston, Austin and Waco. BCS area. Posts: 7,947	Re: brake issues After you double check by loosening the connections check the rubber brake hose on top of the rear drive axle shaft. It can collapse internally and won't allow or restricts the brake fluid from reaching the rear drums. Only good way to check it is to remove it and look at it. You can also insure hydraulic fluid is going to the rear breaks after you remove it by placing a container to collect the fluid or by using a rubber hose that fits over the line.

11-18-2011, 11:49 PM	#6
white 67 Registered User Join Date: Oct 2009 Location: coupeville ,washington Posts: 348	Re: brake issues ttt.i just blew out all the lines and every thing was fine, i didnt find any blocks, still no pressure to the back.

11-19-2011, 12:54 AM	#7
VetteVet Msgt USAF Ret Join Date: Jan 2005 Location: Kalamazoo, Michigan Posts: 8,718	Re: brake issues Check your free play on the pedal rod to master cylinder. If you have none then the valve cannot return past the reservoir hole and allow more fluid to enter the pressure port for the rear lines. __________________ VetteVet metallic green 67 stepside 74 corvette convertible 1965 Harley sportster 1995 Harley wide glide Growing old is hell, but it beats the alternative.

11-19-2011, 12:02 PM	#10
michael bustamante Senior Member Join Date: Sep 2007 Location: Albuquerque NM Posts: 7,862	Re: brake issues Yup I once had to replace a new remanned m/c a couple of times myself. __________________ 1967custom

11-19-2011, 01:08 PM	#11
allchevy58 Senior Member Join Date: Aug 2011 Location: Reno, Nv. Posts: 1,440	Re: brake issues Do the front brake bleed just fine? If so, did you adjust rear brakes before bleeding? __________________ 1927 Willy's Knight 24,000 original miles, 1958 Impala 283/Powerglide, 1971 Monte Carlo 350/350, 1972 GMC K2500 350/350, 1976 Chev. K10 350/350, 2006 GMC Sierra 2500HD LBZ Duramax/Allison, 2006 Chev. Silverado K3500 LBZ Duramax/Allison

11-19-2011, 07:02 PM	#14
fastwillie 696969 ~Rest In Peace~ Join Date: May 2005 Location: CALIFORNIA NOR CAL Posts: 9,707	Re: brake issues reset the PV ? __________________ is it fast ? it has a lighting bolt donut? B___H please, I can remove 90% of your so called "beauty" with a kleenex

11-19-2011, 10:08 PM	#15
MagmaJct Registered User Join Date: May 2008 Location: Mesa, AZ Posts: 281	Re: brake issues I don't remember, does the front of the master cylinder operate the back brakes? Or does the front of the master cylinder operate the front brakes? Here's why I ask: The pistons in the MC must move completely to the back (towards the firewall) when the pedal is not being depressed. This uncovers a port that allows fluid to flow into the cylinder. If the piston is not completely returned it'll block the port and not allow any fluid to fill the cylinder. Of course, this assumed the bench bleed didn't go well and air is trapped in the cylinder. If the hose that is connected to the MC is loosened, will fluid leak out if the pedal is pressed? __________________ I own 3 classic vehicles. 1971 LWB C10 Deluxe. 1974 VW Super Beetle. 1971 VW Fastback. The C10 and the Super Beetle run, the Fastback is just not there yet! Please visit my Super Beetle and Fastback profile on TheSamba.

11-19-2011, 10:24 PM	#16
white 67 Registered User Join Date: Oct 2009 Location: coupeville ,washington Posts: 348	Re: brake issues I just checked to make sure the master cylinder was returning all the way and it is. Fluid will come out the master cylinder if the line is loose.

11-19-2011, 11:16 PM	#17
allchevy58 Senior Member Join Date: Aug 2011 Location: Reno, Nv. Posts: 1,440	Re: brake issues 68gmsee explained it, if shoes don't make contact to drums, pressure will not build up in brake lines to rear brakes. __________________ 1927 Willy's Knight 24,000 original miles, 1958 Impala 283/Powerglide, 1971 Monte Carlo 350/350, 1972 GMC K2500 350/350, 1976 Chev. K10 350/350, 2006 GMC Sierra 2500HD LBZ Duramax/Allison, 2006 Chev. Silverado K3500 LBZ Duramax/Allison

11-19-2011, 11:21 PM	#18
68gmsee Active Member Join Date: Jul 2007 Location: Centrally located between Houston, Austin and Waco. BCS area. Posts: 7,947	Re: brake issues Forgot to add re. adjusting brakes before bleeding... The only way you will get pressure in the brake system is if there's resistance by the shoes contacting the drums. Otherwise there's very little pressure. MagmaJct: On the stock units the front is front brake and rear is rear breaks. add again.. Just saw allchevy's post above.

11-22-2011, 11:00 PM	#19
white 67 Registered User Join Date: Oct 2009 Location: coupeville ,washington Posts: 348	Re: brake issues Just wanted to update everyone on the fix. I replaced the master cylinder with a new one, not reman from napa and bled the brake again and now every thing is working great. Thanks for the help, the old truck is one step closer to going for a drive.



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11-23-2011, 08:08 PM	#20
slikside Registered User Join Date: Jun 2010 Location: San Diego Co. Posts: 1,179	Re: brake issues Good info for future. Subscribed

11-24-2011, 12:29 AM	#21
68gmsee Active Member Join Date: Jul 2007 Location: Centrally located between Houston, Austin and Waco. BCS area. Posts: 7,947	Re: brake issues Fantastic.. Glad you got it going.

11-24-2011, 01:12 AM	#22
allchevy58 Senior Member Join Date: Aug 2011 Location: Reno, Nv. Posts: 1,440	Re: brake issues Glad to hear you got it working properly. __________________ 1927 Willy's Knight 24,000 original miles, 1958 Impala 283/Powerglide, 1971 Monte Carlo 350/350, 1972 GMC K2500 350/350, 1976 Chev. K10 350/350, 2006 GMC Sierra 2500HD LBZ Duramax/Allison, 2006 Chev. Silverado K3500 LBZ Duramax/Allison

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