| [GMCnet] What IS Best vacuum Pump [message #94684] |
Thu, 05 August 2010 07:05  |
Arthur Mansfield
Messages: 290
Registered: April 2010
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I have tried everything to get my brakes to work better except going to rear disks. I cannot lock up my brakes so I was thinking I might try adding vacuum pump to see if that is my problem. The cam I have has a little lower vacuum than a stock cam. New front and rear brakes. 2 inch shoes on the middle brakes. New master cylinder and booster. My tow brakes help me stop better than I can without the tow. Any ideas as what to try without going to disks in the rear.
Art & Doris
76 EL
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| Re: [GMCnet] What IS Best vacuum Pump [message #94689 is a reply to message #94684] |
Thu, 05 August 2010 08:32  |
C Boyd
Messages: 2629
Registered: April 2006
Karma: 18
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| Arthur Mansfield wrote on Thu, 05 August 2010 08:05 |
I have tried everything to get my brakes to work better except going to rear disks. I cannot lock up my brakes so I was thinking I might try adding vacuum pump to see if that is my problem. The cam I have has a little lower vacuum than a stock cam. New front and rear brakes. 2 inch shoes on the middle brakes. New master cylinder and booster. My tow brakes help me stop better than I can without the tow. Any ideas as what to try without going to disks in the rear.
Art & Doris
76 EL
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Sir: when trying to find a brakeing issue I try to start with a test drive. I have a laser thermometer to shoot the drums and rotors to check temp. I would try a few fairly hard stops from hiway speeds then stop in a parking lot and check temps (wright them down to compare). I found on mine that the front calipers were not working very well even with new lines and pads. I also found the rears were not adjusted equally. I replaced the front calipers and adjusted the rears. It helped me.....
Good Luck....
C. Boyd
76 Crestmont
East Tennessee
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| Re: [GMCnet] What IS Best vacuum Pump [message #94706 is a reply to message #94684] |
Thu, 05 August 2010 10:05 |
Bob de Kruyff
Messages: 4260
Registered: January 2004
Location: Chandler, AZ
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| Arthur Mansfield wrote on Thu, 05 August 2010 06:05 |
I have tried everything to get my brakes to work better except going to rear disks. I cannot lock up my brakes so I was thinking I might try adding vacuum pump to see if that is my problem. The cam I have has a little lower vacuum than a stock cam. New front and rear brakes. 2 inch shoes on the middle brakes. New master cylinder and booster. My tow brakes help me stop better than I can without the tow. Any ideas as what to try without going to disks in the rear.
Art & Doris
76 EL
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Assuming the check valve on the booster is OK, your booster quite likely will have a higher vacuum than what you will read via a gage on your engine. For example, when you decelerate, you should see high vacuum and your booster should stabilize at that higher level--at least for the first stop. So I doubt a vacuum pump will help for that reason, but it does have other advantages.
Bob de Kruyff
78 Eleganza
Chandler, AZ
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| Re: [GMCnet] What IS Best vacuum Pump [message #94708 is a reply to message #94693] |
Thu, 05 August 2010 10:15 |
Terry Skinner
Messages: 379
Registered: January 2004
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Been a few years back but there were a few GMCs running around with
thermocouples mounted on the spindles to check temperatures on the
brakes and bearings. I just figured the maybe it was too much
information so never tried it...........Terry
On Thu, Aug 5, 2010 at 7:46 AM, Arthur Mansfield <1104agm@gmail.com> wrote:
> CharIes
>
> I replaced the calipers, brake lines, rotors in front when I had the front bearing replaced. I adjusted the rear brakes shoes several times. I have checked the temperature every time I stop and the mid are generally the hotest. I guess I need to get a away to read the temperatures instead of just checking. What do you use to read the temperatures?
>
> Art & Doris
> 76 EL
>
> On Aug 5, 2010, at 7:32 AM, Charles Boyd wrote
>>
>> Arthur Mansfield wrote on Thu, 05 August 2010 08:05
>>> I have tried everything to get my brakes to work better except going to rear disks. I cannot lock up my brakes so I was thinking I might try adding vacuum pump to see if that is my problem. The cam I have has a little lower vacuum than a stock cam. New front and rear brakes. 2 inch shoes on the middle brakes. New master cylinder and booster. My tow brakes help me stop better than I can without the tow. Any ideas as what to try without going to disks in the rear.
>>>
>>> Art & Doris
>>> 76 EL
>>> _______________________________________________
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>>
>>
>>
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>>
>> Sir: when trying to find a brakeing issue I try to start with a test drive. I have a laser thermometer to shoot the drums and rotors to check temp. I would try a few fairly hard stops from hiway speeds then stop in a parking lot and check temps (wright them down to compare). I found on mine that the front calipers were not working very well even with new lines and pads. I also found the rears were not adjusted equally. I replaced the front calipers and adjusted the rears. It helped me.....
>> Good Luck....
>> --
>> C. Boyd
>> 76 Crestmont by Midas
>> East Tennessee
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--
Terry Skinner
253-686-2624
Roy. Washington
'76 GMC
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| Re: [GMCnet] What IS Best vacuum Pump [message #94888 is a reply to message #94886] |
Fri, 06 August 2010 19:24 |
James Hupy
Messages: 6806
Registered: May 2010
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Before you go to the trouble of replacing your drum brakes, make sure that
you have ALL the air out of the brake lines. Use a power bleeder if
possible. Those mityvac hand held vacuum pumps often times leave residual
air in the tandem hoses between the two rear wheels. Also adjust your drum
brakes manually, don't rely on the self adjusters to do it. If your brake
pedal feels the least little bit mushy or soft, that is a good indicator
that you have air in the system. I still have the nearly stock system in my
78 Royale, and I can lock the tires without both feet on the pedal. I am
using semi metallic brakes all around instead of organic linings, and have a
P-30 Chev master cylinder. If you have a very heavy coach or tow with it
then you could consider discs on the back.
Jim Hupy
Salem, Or
78 Royale 403
On Fri, Aug 6, 2010 at 4:32 PM, Arthur Mansfield <1104agm@gmail.com> wrote:
> Your right I am getting older and weaker but I can still lock up the wheels
> on my old 69 Falcon without a booster. I have thought of getting a
> sensitized booster or going to hyroboost like my small 79 Lincoln has. I
> have a full set up for power booster on the floor of my shop. I just do not
> know what I should do next. I hear on the net that others lock up the
> brakes without going to disks on the back. I had to make a quick stop on my
> last trip and had both feet on the brakes pulling up on the steering wheel
> and they did not lock up or even feel close to locking up.
>
> Art & Doris
> 76 EL
> On Aug 5, 2010, at 7:58 PM, Phil Swanson wrote:
>
> >
> >
> > Make sure that new booster is sensitized. Your leg might be getting
> weaker. Something we don't like to admit.
> >
> > Phil Swanson
> > 77GMCPB
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| Re: [GMCnet] What IS Best vacuum Pump [message #94904 is a reply to message #94684] |
Fri, 06 August 2010 22:22 |
Richard Brown
Messages: 281
Registered: May 2009
Karma: 1
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I was having the same problem on mine until the booster finally failed. The
vacuum seal behind the MC came apart on mine & didn't do the MC any good,
either. I installed a sensitized booster from Jim B (didn't have to return the
old one)& a new MC, front lines, and calipers bought locally. I'll test them
when the weather cools enough to put the radiator back in & crank it up. Chances
are your old booster's going away on you a little at a time like mine did.
Boosters aren't cheap, but I like stopping when I push the brake pedal. I don't
have but 1 leg to push it anyway, so a sensitized booster made more sense to me.
Richard & Carol Brown
PO Box 941
Lindale, TX. 75771
1974 GMC Eleganza SE (DILLIGAF)
wings77sporty@sbcglobal.net
(903)881-0192
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Richard & Carol Brown
1974 Eleganza SE
1174 Hickory Hills Dr.
Murchison, TX. 75778
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