| POOR BRAKE PEDAL HEIGHT [message #228946] |
Fri, 08 November 2013 14:36  |
hal kading
Messages: 642
Registered: February 2004
Location: Las Cruces NM
Karma: 4
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Senior Member |
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My Buskirk Stretch has 80 mm calipers on all four rear wheels, one ton calipers on the front wheels that replaced the former 80 mm calipers and a 34 mm master cylinder. Brakes have been bled multiple times and multiple ways. Clearance on the rod between the booster and the master cylinder has been checked, master cylinder has been changed and I still have excessive brake pedal travel. The excessive pedal travel seems to have started with the one ton installation, though we cannot see any reason, no retraction of the caliper pistons with brake release or other obvious reason. One ton caliper pistons appear to be approximately the same size as the 80 mm pistons. Has anyone else experienced this with the one ton installation? Any other ideas?
Hal Kading 78 Buskirk Stretch Las Cruces NM
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| Re: [GMCnet] POOR BRAKE PEDAL HEIGHT [message #228952 is a reply to message #228946] |
Fri, 08 November 2013 15:07  |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Hal, excessive travel? Does your brake pedal travel to the floor? I am
having difficulty visualizing just what you mean by "excessive travel".
There needs to be SOME free play in the upper part of the pedal travel.
Just how much is a subject of discussion. The master cylinder operating
piston(s) need to retract fully in order to uncover the reservoir bleed
back ports.
Let's start with this much info, and go from there.
Jim Hupy
Salem, Or
78 GMC Royale 403
On Nov 8, 2013 12:37 PM, "Hal Kading" <halkading@fastwave.biz> wrote:
>
>
> My Buskirk Stretch has 80 mm calipers on all four rear wheels, one ton
> calipers on the front wheels that replaced the former 80 mm calipers and a
> 34 mm master cylinder. Brakes have been bled multiple times and multiple
> ways. Clearance on the rod between the booster and the master cylinder has
> been checked, master cylinder has been changed and I still have excessive
> brake pedal travel. The excessive pedal travel seems to have started with
> the one ton installation, though we cannot see any reason, no retraction of
> the caliper pistons with brake release or other obvious reason. One ton
> caliper pistons appear to be approximately the same size as the 80 mm
> pistons. Has anyone else experienced this with the one ton installation?
> Any other ideas?
>
> Hal Kading 78 Buskirk Stretch Las Cruces NM
>
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| Re: POOR BRAKE PEDAL HEIGHT [message #228962 is a reply to message #228946] |
Fri, 08 November 2013 17:03 |
bwevers
Messages: 597
Registered: October 2010
Location: San Jose
Karma: 5
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I lost a little brake pedal when I converted to the one-ton.
The one-ton calipers are bigger and it takes more fluid
to apply the brakes (more brake pedal travel).
It also helps if I adjust the rear drum brakes to be snug.
I don't know if converting to rear disks take even more fluid.
Bleeding the brakes real good with a pressure bleeder helped a lot.
-Bill
Bill Wevers GMC49ers, GMC Western States
1975 Glenbrook - Manny Powerdrive, OneTon
455 F Block, G heads
San Jose
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| Re: POOR BRAKE PEDAL HEIGHT [message #228970 is a reply to message #228946] |
Fri, 08 November 2013 18:39 |
78 Barbi
Messages: 80
Registered: August 2004
Location: Tiverton, Ontario , Canad...
Karma: -1
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Hal Kading writes : The excessive pedal travel seems to have started with the one ton installation, though we cannot see any reason, no retraction of the caliper pistons with brake release
Hal ; you have probably already done this BUT ; I've found on just about all occasions when trying to bleed those darn 80mm calipers, (EVEN WITH A PRESSURE BLEEDER) I've had to remove them from their mounts , tip them clockwise about 35 degrees , and having a block of wood or metal between the pads , proceed to bleed them . Without fail I've got a significant amount of air out of them . Just a thought .
Cheers.......Albert
The 23 foot Birchaven
Tiverton, ON
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| Re: [GMCnet] POOR BRAKE PEDAL HEIGHT [message #228974 is a reply to message #228970] |
Fri, 08 November 2013 19:08 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Hal, it sounds to me like you still might have some air in the system. You
should have a firm pedal as soon as you use up the free play in the
linkage. Be very sure that your bleeder screws are the highest point on
each wheel caliper. If they are not, it is next to impossible to bleed all
the air from the system. Another thought comes to mind. Do you still have
the OEM combination valve? If you do, replace it with one designed for all
disc brakes, as it was intended for a combination of Disc and Drum brakes
and the internal metering is not quite right for all discs. Spongy or soft
pedal is almost always caused by air in the system. Hope this helps.
Jim Hupy
Salem, Or
78 GMC Royale 403
On Nov 8, 2013 4:39 PM, "Albert&Sheila Branscombe" <branscoa@bmts.com>
wrote:
>
>
> Hal Kading writes : The excessive pedal travel seems to have started
> with the one ton installation, though we cannot see any reason, no
> retraction of the caliper pistons with brake release
>
> Hal ; you have probably already done this BUT ; I've found on just about
> all occasions when trying to bleed those darn 80mm calipers, (EVEN WITH A
> PRESSURE BLEEDER) I've had to remove them from their mounts , tip them
> clockwise about 35 degrees , and having a block of wood or metal between
> the pads , proceed to bleed them . Without fail I've got a significant
> amount of air out of them . Just a thought .
>
> Cheers.......Albert
> The 23 foot Birchaven
> Tiverton, ON
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
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| Re: [GMCnet] POOR BRAKE PEDAL HEIGHT [message #228977 is a reply to message #228974] |
Fri, 08 November 2013 19:23 |
sgltrac
Messages: 2797
Registered: April 2011
Karma: 1
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Just went through that with The Pig. It was as Jim H said. Little bit of trapped air and a stock combination valve. New combo valve from Jim K for all disc and re bled removing a couple of calipers with bleed valves in poor location on two rear calipers.
Todd Sullivan
Sully
77 royale
Seattle
> On Nov 8, 2013, at 5:08 PM, James Hupy <jamesh1296@gmail.com> wrote:
>
> Hal, it sounds to me like you still might have some air in the system. You
> should have a firm pedal as soon as you use up the free play in the
> linkage. Be very sure that your bleeder screws are the highest point on
> each wheel caliper. If they are not, it is next to impossible to bleed all
> the air from the system. Another thought comes to mind. Do you still have
> the OEM combination valve? If you do, replace it with one designed for all
> disc brakes, as it was intended for a combination of Disc and Drum brakes
> and the internal metering is not quite right for all discs. Spongy or soft
> pedal is almost always caused by air in the system. Hope this helps.
> Jim Hupy
> Salem, Or
> 78 GMC Royale 403
> On Nov 8, 2013 4:39 PM, "Albert&Sheila Branscombe" <branscoa@bmts.com>
> wrote:
>
>>
>>
>> Hal Kading writes : The excessive pedal travel seems to have started
>> with the one ton installation, though we cannot see any reason, no
>> retraction of the caliper pistons with brake release
>>
>> Hal ; you have probably already done this BUT ; I've found on just about
>> all occasions when trying to bleed those darn 80mm calipers, (EVEN WITH A
>> PRESSURE BLEEDER) I've had to remove them from their mounts , tip them
>> clockwise about 35 degrees , and having a block of wood or metal between
>> the pads , proceed to bleed them . Without fail I've got a significant
>> amount of air out of them . Just a thought .
>>
>> Cheers.......Albert
>> The 23 foot Birchaven
>> Tiverton, ON
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
> _______________________________________________
> GMCnet mailing list
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Sully
77 Royale basket case.
Future motorhome land speed record holder(bucket list)
Seattle, Wa.
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| Re: POOR BRAKE PEDAL HEIGHT [message #228999 is a reply to message #228946] |
Fri, 08 November 2013 21:32 |
kerry pinkerton
Messages: 2565
Registered: July 2012
Location: Harvest, Al
Karma: 15
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Just had an email dialog with a guy who had installed disc brakes, bled them and had good pedal until he started the engine. The brake pedal would then go to the floor. I said it sounded like air in the lines and after some investigation it was determined that he had two calipers on the wrong side and the bleeders were pointed down.
Not suggesting that is your problem Hal but it does sound like air in the system...somewhere.
Kerry Pinkerton - North Alabama
Had 5 over the years. Currently have a '06 Fleetwood Discovery 39L
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| Re: POOR BRAKE PEDAL HEIGHT [message #230705 is a reply to message #230700] |
Thu, 21 November 2013 16:37 |
Bob de Kruyff
Messages: 4260
Registered: January 2004
Location: Chandler, AZ
Karma: 1
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Senior Member |
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| hal kading wrote on Thu, 21 November 2013 15:16 |
Well, bled all the brakes again. Found a little air in one of the rear calipers with a little improvement in pedal height. Pedal free play is about 1/8". We measured perpendicular from the center of the top to bottom of the pedal face to the floor as follows:
1. Brakes off - 5 3/4"
2. Brakes on without vacuum assist - 3"
3. Brakes on with vacuum assist - 2"
4. Brakes on with vacuum assist and pumped up - 2 3/8"
This is with 1 ton calipers on front and all 80 mm calipers on rear. Does anyone else have pedal travel measurements?
We think we need a larger master cylinder piston than the 34 mm. Anyone know of one that will fit?
Hal Kading 78 Buskirk Las Cruces NM
|
Gene F has a list of master cylinders with bore diameters on his site.
Bob de Kruyff
78 Eleganza
Chandler, AZ
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| Re: [GMCnet] POOR BRAKE PEDAL HEIGHT [message #230714 is a reply to message #230700] |
Thu, 21 November 2013 17:51 |
Mr ERFisher
Messages: 7117
Registered: August 2005
Karma: 2
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Senior Member |
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Could reduce the rear calipers to 50mm
Pickup 1inch peddle and 1000 lb pressure with smaller MC
Gene
FREE WIFI @ Mickey D
On Nov 21, 2013, at 2:16 PM, Hal Kading <halkading@fastwave.biz> wrote:
>
>
> Well, bled all the brakes again. Found a little air in one of the rear calipers with a little improvement in pedal height. Pedal free play is about 1/8". We measured perpendicular from the center of the top to bottom of the pedal face to the floor as follows:
>
> 1. Brakes off - 5 3/4"
>
> 2. Brakes on without vacuum assist - 3"
>
> 3. Brakes on with vacuum assist - 2"
>
> 4. Brakes on with vacuum assist and pumped up - 2 3/8"
>
> This is with 1 ton calipers on front and all 80 mm calipers on rear. Does anyone else have pedal travel measurements?
>
> We think we need a larger master cylinder piston than the 34 mm. Anyone know of one that will fit?
>
> Hal Kading 78 Buskirk Las Cruces NM
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
_______________________________________________
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