| Re: [GMCnet] Bleeding Brakes... [message #95899] |
Sun, 15 August 2010 07:51  |
Gary Casey
Messages: 448
Registered: September 2009
Karma: 0
|
Senior Member |
|
|
Oops, I should have read the post from Bob before my previous post. My
description of function is correct, but as to whether the GMC has only the
hold-off function or has a true proportioning valve, I don't know.
Gary Casey
""Kelvin, it is truly a proportioning valve. The disc brakes on the front and
the drums on the rear have different initial pressure requirements and
different volumes required. These things have control orfices that are
carefully engineered and are different for each vehicle they are used on. I
can look up the specifics on that particular valve but suffice it to say you
"" no this is not the case here. In the GMC this is only a hold off valve not a
proportioning valve which looks very similar. You really need to do some
homework on this issue!
--
Bob de Kruyff
_______________________________________________
GMCnet mailing list
List Information and Subscription Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
|
|
|
|
|
|
| Re: [GMCnet] Bleeding Brakes... [message #95907 is a reply to message #95903] |
Sun, 15 August 2010 09:51  |
 |
USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
|
Senior Member |
|
|
Art,
Double Trouble also has a COMPLETELY rebuilt brake system and I could not
lockup the rears.
As noted in my email "TA DA - Mechanicals Done" I installed a sensitized
booster from Jim B and now I can.
Regards,
Rob M.
USAussie
-----Original Message-----
From: gmclist-bounces@temp.gmcnet.org
[mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of Arthur Mansfield
Sent: Sunday, August 15, 2010 10:42 AM
To: gmclist@temp.gmcnet.org
Subject: Re: [GMCnet] Bleeding Brakes...
I have new brakes all the round (2 inch on fwd rear and my third brake
booster and second master cylinder) and bleed my brakes but my braking power
is very very poor. I adjust the rear brakes. So could my problem be the
valve that has been discussed. I had to make a quick stop and with both
feet on the brake pedal and pulling up on the steering wheel for leverage, I
did not even lock up the rear wheel. What can I do next?
Art & Doris
76 EL
On Aug 15, 2010, at 6:51 AM, Gary Casey wrote:
_______________________________________________
GMCnet mailing list
List Information and Subscription Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
|
|
|
|
| Re: [GMCnet] Bleeding Brakes... [message #95911 is a reply to message #95903] |
Sun, 15 August 2010 11:01 |
Dennis S
Messages: 3046
Registered: November 2005
Karma: 2
|
Senior Member |
|
|
Art,
There has been discussion in the past regarding the 2 inch rear brake shoes -- the question being, while it increases swept are it reduces the pressure against the drum thereby reducing the clamping result.
Jim Moore spent quite a lot of time "improving" his brakes -- and reported that only when he returned to a stock system did he have the best result. Of course now there is the new reaction arm system and such.
Lots of variables and lots of different solutions.
I plan to remain with a stock set-up but if the booster fails I "may" consider the sensitized booster, although I have never considered the pedal force required on my 23 ft to be high.
Dennis
Dennis Sexton
73 PD 230
Germantown, TN
USA
-----Original Message-----
From: Arthur Mansfield <1104agm@gmail.com>
To: gmclist@temp.gmcnet.org
Sent: Sun, Aug 15, 2010 9:42 am
Subject: Re: [GMCnet] Bleeding Brakes...
I have new brakes all the round (2 inch on fwd rear and my third brake booster
nd second master cylinder) and bleed my brakes but my braking power is very
ery poor. I adjust the rear brakes. So could my problem be the valve that has
een discussed. I had to make a quick stop and with both feet on the brake
edal and pulling up on the steering wheel for leverage, I did not even lock up
he rear wheel. What can I do next?
Art & Doris
6 EL
n Aug 15, 2010, at 6:51 AM, Gary Casey wrote:
> Oops, I should have read the post from Bob before my previous post. My
description of function is correct, but as to whether the GMC has only the
hold-off function or has a true proportioning valve, I don't know.
Gary Casey
""Kelvin, it is truly a proportioning valve. The disc brakes on the front and
the drums on the rear have different initial pressure requirements and
different volumes required. These things have control orfices that are
carefully engineered and are different for each vehicle they are used on. I
can look up the specifics on that particular valve but suffice it to say you
"" no this is not the case here. In the GMC this is only a hold off valve not
proportioning valve which looks very similar. You really need to do some
homework on this issue!
--
Bob de Kruyff
_______________________________________________
GMCnet mailing list
List Information and Subscription Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
_______________________________________________
MCnet mailing list
ist Information and Subscription Options:
ttp://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
_______________________________________________
GMCnet mailing list
List Information and Subscription Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
Dennis S
73 Painted Desert 230
Memphis TN Metro
|
|
|
|
| Re: [GMCnet] Bleeding Brakes... [message #95914 is a reply to message #95911] |
Sun, 15 August 2010 11:06 |
Dennis S
Messages: 3046
Registered: November 2005
Karma: 2
|
Senior Member |
|
|
Correcfting my previous post..
That should read "while it increases the swept area does it reduce the pressure against the drum thereby reducing the clamping result...."
Dennis Sexton
73 PD 230
Germantown, TN
USA
-----Original Message-----
From: dennisfsexton@aol.com
To: gmclist@temp.gmcnet.org
Sent: Sun, Aug 15, 2010 11:01 am
Subject: Re: [GMCnet] Bleeding Brakes...
rt,
There has been discussion in the past regarding the 2 inch rear brake shoes --
he question being, while it increases swept are it reduces the pressure against
he drum thereby reducing the clamping result.
Jim Moore spent quite a lot of time "improving" his brakes -- and reported that
nly when he returned to a stock system did he have the best result. Of course
ow there is the new reaction arm system and such.
Lots of variables and lots of different solutions.
I plan to remain with a stock set-up but if the booster fails I "may" consider
he sensitized booster, although I have never considered the pedal force
equired on my 23 ft to be high.
Dennis
ennis Sexton
3 PD 230
ermantown, TN
SA
-----Original Message-----
rom: Arthur Mansfield <1104agm@gmail.com>
o: gmclist@temp.gmcnet.org
ent: Sun, Aug 15, 2010 9:42 am
ubject: Re: [GMCnet] Bleeding Brakes...
have new brakes all the round (2 inch on fwd rear and my third brake booster
d second master cylinder) and bleed my brakes but my braking power is very
ry poor. I adjust the rear brakes. So could my problem be the valve that has
en discussed. I had to make a quick stop and with both feet on the brake
dal and pulling up on the steering wheel for leverage, I did not even lock up
e rear wheel. What can I do next?
rt & Doris
EL
Aug 15, 2010, at 6:51 AM, Gary Casey wrote:
Oops, I should have read the post from Bob before my previous post. My
description of function is correct, but as to whether the GMC has only the
hold-off function or has a true proportioning valve, I don't know.
Gary Casey
""Kelvin, it is truly a proportioning valve. The disc brakes on the front and
the drums on the rear have different initial pressure requirements and
different volumes required. These things have control orfices that are
carefully engineered and are different for each vehicle they are used on. I
can look up the specifics on that particular valve but suffice it to say you
"" no this is not the case here. In the GMC this is only a hold off valve not
proportioning valve which looks very similar. You really need to do some
homework on this issue!
--
Bob de Kruyff
_______________________________________________
GMCnet mailing list
List Information and Subscription Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
______________________________________________
Cnet mailing list
st Information and Subscription Options:
tp://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
_______________________________________________
MCnet mailing list
ist Information and Subscription Options:
ttp://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
_______________________________________________
GMCnet mailing list
List Information and Subscription Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
Dennis S
73 Painted Desert 230
Memphis TN Metro
|
|
|
|
| Re: [GMCnet] Bleeding Brakes... [message #95930 is a reply to message #95914] |
Sun, 15 August 2010 14:18 |
fred v
Messages: 999
Registered: April 2006
Location: pensacola, fl.
Karma: 0
|
Senior Member |
|
|
| Dennis S wrote on Sun, 15 August 2010 11:06 |
Correcfting my previous post..
That should read "while it increases the swept area does it reduce the pressure against the drum thereby reducing the clamping result...."
Dennis Sexton
73 PD 230
Germantown, TN
USA
|
the way i understand it is that the same fluid pressure is spread out over more square inches of brake shoe thereby resulting in the same amount of brake effort. so it only makes your shoes last longer.
i got a good improvement in my brakes by going to the 80MM caliper and 1 1/16" wheel cyl. on the center wheels. brakes are not too bad now.
Fred V
'77 Royale RB 455
P'cola, Fl
|
|
|
|
GMCforum
Search
Help
Register
Login
Home
