Home » Public Forums » GMCnet » Stumped on brakes - hard pedal very little braking
| Stumped on brakes - hard pedal very little braking [message #225631] |
Mon, 14 October 2013 15:20  |
|
|
Been a long time since I have posted and of course looking for some advice on my brakes.
GMC has been sitting way too long, about 1 year with very little use. Went in to move it out of the shelter and brake pedal went to the floor. The front chamber of the master cyl was almost empty and I really pushed to far so I replaced the master cyl. When bleeding the brakes I found a rear brake cyl leaking so I replaced it and went on to bleed all the brakes. Brake bleeding went well and when done with the engine running the pedal was very hard to push to get much braking at all. I figured maybe the brake booster had gone bad so replaced with new sensitized version with the modified rod from Jim Bounds. Got that all in and the same problem very hard pedal very little braking. Good vacuum to the booster so that should be good to go. I have the standard OEM brake setup no modifications except for sensitized booster have been made to the system and it has always worked pretty well.
So, that is where I am at and stumped can't figure what else it might be so hopefully I can get some suggestions of my next step.
Thanks
Bob & Terry Stockholm
Xenia, OH
1976 PB
|
|
|
|
|
|
| Re: Stumped on brakes - hard pedal very little braking [message #225634 is a reply to message #225633] |
Mon, 14 October 2013 15:32  |
|
|
| biggreen wrote on Mon, 14 October 2013 16:27 |
Had the same trouble, replaced the rubber brake lines to the calipers in the front. The rubber deteriorates and plugs up the line.
|
Thanks I will look into that but they bled very good up front so not sure the lines are blocked but does make sense that I may not have much braking up front.
Bob & Terry Stockholm
Xenia, OH
1976 PB
|
|
|
|
| Re: [GMCnet] Stumped on brakes - hard pedal very little braking [message #225635 is a reply to message #225631] |
Mon, 14 October 2013 15:33 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
|
Senior Member |
|
|
Bob, you have one more component to replace. The distribution valve,
located in the drivers side wheel well. Spray all the brake lines with your
favorite penetrating oil, wire brush around the lines and spray them again.
Wait a couple of days for the penetrating oil to work. Then take a firring
wrench, which looks like a box end wrench with one hex cut away and attempt
to loosen all the brake lines. If you get a really difficult to remove one,
clamp a pair of vice grips to the outside of the fitting wrench to prevent
it from spreading enough to round off the fitting. Jim K has replacement
valves in stock. It sounds like you have a stuck spool valve inside. Do
everything you can to not round off the brake line fittings. But in the
likely event that you do, replace the lines with stainless ones. Just what
happens when you work on 40 year old brake parts.
Jim Hupy
Salem, OR
78 GMC Royale 403
On Mon, Oct 14, 2013 at 1:20 PM, Bob Stockholm <rstockholm@woh.rr.com>wrote:
>
>
> Been a long time since I have posted and of course looking for some advice
> on my brakes.
>
> GMC has been sitting way too long, about 1 year with very little use. Went
> in to move it out of the shelter and brake pedal went to the floor. The
> front chamber of the master cyl was almost empty and I really pushed to far
> so I replaced the master cyl. When bleeding the brakes I found a rear brake
> cyl leaking so I replaced it and went on to bleed all the brakes. Brake
> bleeding went well and when done with the engine running the pedal was very
> hard to push to get much braking at all. I figured maybe the brake booster
> had gone bad so replaced with new sensitized version with the modified rod
> from Jim Bounds. Got that all in and the same problem very hard pedal very
> little braking. Good vacuum to the booster so that should be good to go. I
> have the standard OEM brake setup no modifications except for sensitized
> booster have been made to the system and it has always worked pretty well.
>
> So, that is where I am at and stumped can't figure what else it might be
> so hopefully I can get some suggestions of my next step.
>
> Thanks
>
> --
> Bob & Terry Stockholm
> Xenia, OH
> 1976 PB
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
|
|
|
|
| Re: [GMCnet] Stumped on brakes - hard pedal very little braking [message #225637 is a reply to message #225635] |
Mon, 14 October 2013 15:35 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
|
Senior Member |
|
|
Should read "fitting wrench" My bad.
Jim Hupy
On Mon, Oct 14, 2013 at 1:33 PM, James Hupy <jamesh1296@gmail.com> wrote:
> Bob, you have one more component to replace. The distribution valve,
> located in the drivers side wheel well. Spray all the brake lines with your
> favorite penetrating oil, wire brush around the lines and spray them again.
> Wait a couple of days for the penetrating oil to work. Then take a firring
> wrench, which looks like a box end wrench with one hex cut away and attempt
> to loosen all the brake lines. If you get a really difficult to remove one,
> clamp a pair of vice grips to the outside of the fitting wrench to prevent
> it from spreading enough to round off the fitting. Jim K has replacement
> valves in stock. It sounds like you have a stuck spool valve inside. Do
> everything you can to not round off the brake line fittings. But in the
> likely event that you do, replace the lines with stainless ones. Just what
> happens when you work on 40 year old brake parts.
> Jim Hupy
> Salem, OR
> 78 GMC Royale 403
>
>
> On Mon, Oct 14, 2013 at 1:20 PM, Bob Stockholm <rstockholm@woh.rr.com>wrote:
>
>>
>>
>> Been a long time since I have posted and of course looking for some
>> advice on my brakes.
>>
>> GMC has been sitting way too long, about 1 year with very little use.
>> Went in to move it out of the shelter and brake pedal went to the floor.
>> The front chamber of the master cyl was almost empty and I really pushed to
>> far so I replaced the master cyl. When bleeding the brakes I found a rear
>> brake cyl leaking so I replaced it and went on to bleed all the brakes.
>> Brake bleeding went well and when done with the engine running the pedal
>> was very hard to push to get much braking at all. I figured maybe the brake
>> booster had gone bad so replaced with new sensitized version with the
>> modified rod from Jim Bounds. Got that all in and the same problem very
>> hard pedal very little braking. Good vacuum to the booster so that should
>> be good to go. I have the standard OEM brake setup no modifications except
>> for sensitized booster have been made to the system and it has always
>> worked pretty well.
>>
>> So, that is where I am at and stumped can't figure what else it might be
>> so hopefully I can get some suggestions of my next step.
>>
>> Thanks
>>
>> --
>> Bob & Terry Stockholm
>> Xenia, OH
>> 1976 PB
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>>
>
>
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
|
|
|
|
| Re: [GMCnet] Stumped on brakes - hard pedal very little braking [message #225641 is a reply to message #225635] |
Mon, 14 October 2013 16:26 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
|
Senior Member |
|
|
Here's the "greatest thing since sliced bread" for removing tight flare
nuts:
http://www.amazon.com/Vise-Grip-4LW-Locking-Wrench-Cutter/dp/B00004SBBE
That's to the 4" version; 7" and 10" versions are indicated just below
under "Frequently Bought Together".
Ken H.
Americus, GA
'76 X-Birchaven w/Cad500/Howell EFI & EBL
www.gmcwipersetc.com
On Mon, Oct 14, 2013 at 4:33 PM, James Hupy <jamesh1296@gmail.com> wrote:
> Bob, you have one more component to replace. The distribution valve,
> located in the drivers side wheel well. Spray all the brake lines with your
> favorite penetrating oil, wire brush around the lines and spray them again.
> Wait a couple of days for the penetrating oil to work. Then take a firring
> wrench, which looks like a box end wrench with one hex cut away and attempt
> to loosen all the brake lines. If you get a really difficult to remove one,
> clamp a pair of vice grips to the outside of the fitting wrench to prevent
> it from spreading enough to round off the fitting. Jim K has replacement
> valves in stock. It sounds like you have a stuck spool valve inside. Do
> everything you can to not round off the brake line fittings. But in the
> likely event that you do, replace the lines with stainless ones. Just what
> happens when you work on 40 year old brake parts.
>
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
|
|
|
|
| Re: [GMCnet] Stumped on brakes - hard pedal very little braking [message #225648 is a reply to message #225641] |
Mon, 14 October 2013 17:15 |
 |
Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
|
Senior Member |
|
|
Ken,
We have a slight disagreement here.
I personally believe that the Vice-Grip (X)LW, 4,7&10 beat sliced bread and are right up there with canned beer.
Not only are those the greatest things for flare nuts that some bozo has blown the corners off (since they don't need the corners, it doesn't matter to them), but all those times when the screw head is on one side and the nut is on the other, you can lock one on one side and deal with the other to get your butt out of that problem.
So, if you are working on 40 year old brake lines, get a 4. Then you will soon figure out that you should have just bought the set.
No, I don't own stock in Irwin Tools, but if I could, I would.
Matt
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
|
|
|
|
| Re: Stumped on brakes - hard pedal very little braking [message #225653 is a reply to message #225631] |
Mon, 14 October 2013 18:10 |
|
Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
|
Senior Member |
|
|
| stkhlm wrote on Mon, 14 October 2013 16:20 |
Been a long time since I have posted and of course looking for some advice on my brakes.
GMC has been sitting way too long, about 1 year with very little use. Went in to move it out of the shelter and brake pedal went to the floor. The front chamber of the master cyl was almost empty and I really pushed to far so I replaced the master cyl. When bleeding the brakes I found a rear brake cyl leaking so I replaced it and went on to bleed all the brakes. Brake bleeding went well and when done with the engine running the pedal was very hard to push to get much braking at all. I figured maybe the brake booster had gone bad so replaced with new sensitized version with the modified rod from Jim Bounds. Got that all in and the same problem very hard pedal very little braking. Good vacuum to the booster so that should be good to go. I have the standard OEM brake setup no modifications except for sensitized booster have been made to the system and it has always worked pretty well.
So, that is where I am at and stumped can't figure what else it might be so hopefully I can get some suggestions of my next step.
Thanks
|
Bob,
Try a diagnostic for me..
The master cylinder is the common part in the problem and it is new or rebuilt and therefore suspect. I'm going to guess that you bench bleed it before installing it.
Have someone lean on the pedal and crack the lines at the master cylinder. If the pedal goes down, reset and try the other. Do the front one first, if the floating piston isn't, that will tell you right away.
If that yields no valuable information, do the same thing with the lines down at the proportioning valve (I know it isn't but that's what I will always think of it as). Just crack the lines out to the brakes, you have proved the master cylinder is doing what it should already.
Hopefully you now know which end to look at.
You have got to let us know what you find.
Matt
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
|
|
|
|
| Re: Stumped on brakes - hard pedal very little braking [message #225656 is a reply to message #225653] |
Mon, 14 October 2013 18:42 |
|
|
[/quote]
Bob,
Try a diagnostic for me..
The master cylinder is the common part in the problem and it is new or rebuilt and therefore suspect. I'm going to guess that you bench bleed it before installing it.
Have someone lean on the pedal and crack the lines at the master cylinder. If the pedal goes down, reset and try the other. Do the front one first, if the floating piston isn't, that will tell you right away.
If that yields no valuable information, do the same thing with the lines down at the proportioning valve (I know it isn't but that's what I will always think of it as). Just crack the lines out to the brakes, you have proved the master cylinder is doing what it should already.
Hopefully you now know which end to look at.
You have got to let us know what you find.
Matt [/quote
Matt,
Thanks for the suggestions and I will try it out and let everyone know. I am out of town for the next two weeks so it will take awhile before I get back to it.
thanks again.
Bob & Terry Stockholm
Xenia, OH
1976 PB
|
|
|
|
|
|
| Re: [GMCnet] Stumped on brakes - hard pedal very little braking [message #225661 is a reply to message #225648] |
Mon, 14 October 2013 18:53 |
MikeT
Messages: 225
Registered: November 2009
Location: Marine City, Michigan
Karma: 0
|
Senior Member |
|
|
Ken/Matt,
I sure wish I had known about those vice grips before I ruined my brake lines and had to replace with all stainless. Thanks for the tip on the tool as I'm about to start working brakes on my brothers coach.
Do you have any other tool tips? Seems I've had to replace multiple parts on mine in the past because of self inflicted wounds and don't want to make same mistake twice.
Thanks and keep the tips coming.
Mike Thomas
Marine City, MI
77 ex Palm Beach
|
|
|
|
| Re: Stumped on brakes - hard pedal very little braking [message #225662 is a reply to message #225631] |
Mon, 14 October 2013 18:56 |
lqqkatjon
Messages: 2324
Registered: October 2010
Location: St. Cloud, MN
Karma: 5
|
Senior Member |
|
|
I pieced my brakes over the last three years. they would work for a while, then had issues.
my first attemempt at getting the brakes to work, I started out with rebuilt master, new booster, new hoses. all seemed good.
about a year later, brakes went bad again, like I had no booster.
after unsuccessful bleeding(with power bleeder), I changed the proportioning valve. and all was good.
now once more this summer brake pedal went hard. like booster quit again. after unsuccessful bleeding:
I first changed to a new raybestos master cylinder. no help, then I went with both front brake calipers, and pads. as it turned out, brake calipers were my issue this time. hanging up, or just not working correctly.
brakes seem now better then ever.
FYI, calipers, brakes and master cylinder, total in parts for the last replacement was less then $100. and took me about 2 hours to do that job including bleeding. Pretty easy and simple thing to replace to assure that front end is braking properly. Not sure why my cheapness kicked in when I put the new hoses on when I first got the GMC, and I didn't replace those parts then.
Jon Roche
75 palm beach
EBL EFI, manny headers, Micro Level, rebuilt most of coach now.
St. Cloud, MN
http://lqqkatjon.blogspot.com/
|
|
|
|
| Re: [GMCnet] Stumped on brakes - hard pedal very little braking [message #225668 is a reply to message #225648] |
Mon, 14 October 2013 19:19 |
Jim Miller
Messages: 501
Registered: March 2008
Karma: 10
|
Senior Member |
|
|
On Oct 14, 2013, at 6:15 PM, Matt Colie wrote:
> I personally believe that the Vice-Grip (X)LW, 4,7&10 beat sliced bread and are right up there with canned beer.
Canned beer? When you were at our rally i would have traded your Vice-Grip LW set for some of my home-made draught beer! You haven't had a beer until you've had a Miller's beer.
On topic: I had a similar problem to what Bob reported - hard pedal, terrible braking effectiveness. I went through a similar process: new master cylinder, install sensitized booster, vacuum checks, electric vacuum pump etc. (My hoses, calipers and wheel cylinders were already relatively new). Finally I took out my (also relatively new) pads of unknown origin and replaced them with the EBC yellows. Big difference but still not great.
The remaining part of my system that has not been changed is the distribution valve as James Hupy suggested. I have a new one in hand but have not yet installed it.
The sensitized booster did not come with a transfer rod; I used the rod out of the original. What sort of modified rod does Jim B have? I'm starting to wonder if mine might not be correct for application; I am strongly considering making the measurement gauge and then fabricating a new rod if necessary.
--Jim Miller
1977 Eleganza II
1977 Royale
Hamilton, OH
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
Jim Miller
1977 Eleganza II
1977 Royale
Hamilton, OH
|
|
|
|
|
|
| Re: [GMCnet] Stumped on brakes - hard pedal very little braking [message #225702 is a reply to message #225634] |
Tue, 15 October 2013 06:52 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
|
Senior Member |
|
|
Also, be sure the calipers are free to move side to side and the pistons are free in the bore.
--johnny
'76 23' transmode norris
--------------------------------------------
On Mon, 10/14/13, Bob Stockholm <rstockholm@woh.rr.com> wrote:
Subject: Re: [GMCnet] Stumped on brakes - hard pedal very little braking
To: gmclist@temp.gmcnet.org
Date: Monday, October 14, 2013, 8:32 PM
biggreen wrote on Mon, 14 October 2013 16:27
> Had the same trouble, replaced the rubber brake lines
to the calipers in the front. The rubber deteriorates
and plugs up the line.
Thanks I will look into that but they bled very good up
front so not sure the lines are blocked but does make sense
that I may not have much braking up front.
--
Bob & Terry Stockholm
Xenia, OH
1976 PB
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
|
|
|
|
|
|
| Re: [GMCnet] Stumped on brakes - hard pedal very little braking [message #225827 is a reply to message #225656] |
Wed, 16 October 2013 10:43 |
Jim Bounds
Messages: 842
Registered: January 2004
Karma: 0
|
Senior Member |
|
|
A hard pedal with little braking point me to the booster. Pinch off the vacuum line going to the booster and see if anything changes. Also listen carefully at the pedal, see if you can hear any vacuum leak.
Jim Bounds
----------------------
________________________________
From: Bob Stockholm <rstockholm@woh.rr.com>
To: gmclist@temp.gmcnet.org
Sent: Monday, October 14, 2013 7:42 PM
Subject: Re: Stumped on brakes - hard pedal very little braking
[/quote]
Bob,
Try a diagnostic for me..
The master cylinder is the common part in the problem and it is new or rebuilt and therefore suspect. I'm going to guess that you bench bleed it before installing it.
Have someone lean on the pedal and crack the lines at the master cylinder. If the pedal goes down, reset and try the other. Do the front one first, if the floating piston isn't, that will tell you right away.
If that yields no valuable information, do the same thing with the lines down at the proportioning valve (I know it isn't but that's what I will always think of it as). Just crack the lines out to the brakes, you have proved the master cylinder is doing what it should already.
Hopefully you now know which end to look at.
You have got to let us know what you find.
Matt [/quote
Matt,
Thanks for the suggestions and I will try it out and let everyone know. I am out of town for the next two weeks so it will take awhile before I get back to it.
thanks again.
--
Bob & Terry Stockholm
Xenia, OH
1976 PB
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
|
|
|
|
| Re: [GMCnet] Stumped on brakes - hard pedal very little braking [message #225872 is a reply to message #225827] |
Wed, 16 October 2013 17:49 |
Jim Miller
Messages: 501
Registered: March 2008
Karma: 10
|
Senior Member |
|
|
On Oct 16, 2013, at 11:43 AM, Jim Bounds wrote:
> A hard pedal with little braking point me to the booster. Pinch off the vacuum line going to the booster and see if anything changes. Also listen carefully at the pedal, see if you can hear any vacuum leak.
Hi Jim,
Does the sensitized booster use a different transfer rod than the OEM booster? Installing a new sensitized unit and MC made very little difference in my hard-pedal-but-ineffective-braking problem. The new booster did not come with a transfer rod so I used my old one.
Thanks,
Jim
--Jim Miller
1977 Eleganza II
1977 Royale
Hamilton, OH
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
Jim Miller
1977 Eleganza II
1977 Royale
Hamilton, OH
|
|
|
|
|
|
| Re: [GMCnet] Stumped on brakes - hard pedal very little braking [message #225879 is a reply to message #225872] |
Wed, 16 October 2013 18:51 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
|
Senior Member |
|
|
Yes, between the different years, and boosters, and master cylinders there
is a very good chance that your pushrod is not the correct length. Ken
Henderson posted pictures and instructions on how to build a low cost gage
from two pieces of tubing that will measure the available space between the
MC and Boosters. Critcal measurement.
Jim Hupy
Salem, Or
78 GMC Royale 403
On Oct 16, 2013 3:49 PM, "Jim Miller" <gmcnet@jcmco.com> wrote:
> On Oct 16, 2013, at 11:43 AM, Jim Bounds wrote:
>
> > A hard pedal with little braking point me to the booster. Pinch off the
> vacuum line going to the booster and see if anything changes. Also listen
> carefully at the pedal, see if you can hear any vacuum leak.
>
> Hi Jim,
>
> Does the sensitized booster use a different transfer rod than the OEM
> booster? Installing a new sensitized unit and MC made very little
> difference in my hard-pedal-but-ineffective-braking problem. The new
> booster did not come with a transfer rod so I used my old one.
>
> Thanks,
> Jim
> --Jim Miller
> 1977 Eleganza II
> 1977 Royale
> Hamilton, OH
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
|
|
|
|
Goto Forum:
Current Time: Sat Sep 21 18:34:29 CDT 2024
Total time taken to generate the page: 0.01267 seconds
|
GMCforum
Search
Help
Register
Login
Home
