Frozen caliper

Tom Lins

Tom Lins

New member
Dec 30, 2005
939
0
1
Elkton, FL
Brought the GMC over to our house from the storage location last week (HOA will not allow me to park it here) and discovered that one of the brakes
was sticking.
I figured the easiest way to tell which wheel was sticking was to check the temps of the brakes at each wheel.
It took me some time to locate my temp gun and when I started checking 5 out of six drums/calipers were around 110 degrees but the right front disc
was close to 600
The rotor appears to be ok
I decided to replace the caliper and hose on both sides since Murphy lives next door. The cost to just go to 80mm calipers was not much of a
difference so I am going that way.

The parts got here yesterday (thank you JimK) but now I am trying to figure out what casting marks I need to grind down, does anyone have a picture?
Are ther any gotcha's I should watchout for?

--
Tom Lins
Elkton, FL
77 GM Rear Twin, Dry Bath, 455
Manuals on DVD
http://www.bdub.net/tomlins/
 
I do not to have a picture. I'll go look for one in a minute. Set the caliper down on it's back (hose entrance end). Now look at the piston. I
should be up looking at you. Then look at the circular casting around the piston. You will see that the outside of the casting has a bump about 1/2"
by 1/2 inch. There is no apparent reason for this bump to be there but that is what you want to grind off. I'll go look for a picture.

Ken B
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
 
Also, mount the caliper to the knuckle, using the slide pins, without pads
installed. Slide the caliper all the way in- and out-board to be sure
there's no interference between the caliper and the knuckle. Some slight
grinding of the knuckle may even be necessary for clearance. These days,
this precaution (from Dave Lenzi at Tucson and before) is applicable to
both standard and 80 mm calipers.

Ken H.

> I found it. Look here:
> http://gmcmotorhome.com/commodore/front_brake/index.html
>
>
> --
> Ken Burton - N9KB
> 76 Palm Beach
> Hebron, Indiana
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
Check the front Rubber brake hose as it probaly collaped and not letting
the pressure return.

On Sat, Apr 21, 2018 at 9:16 AM, Ken Henderson
wrote:

> Also, mount the caliper to the knuckle, using the slide pins, without pads
> installed. Slide the caliper all the way in- and out-board to be sure
> there's no interference between the caliper and the knuckle. Some slight
> grinding of the knuckle may even be necessary for clearance. These days,
> this precaution (from Dave Lenzi at Tucson and before) is applicable to
> both standard and 80 mm calipers.
>
> Ken H.
>

>
> > I found it. Look here:
> > http://gmcmotorhome.com/commodore/front_brake/index.html
> >
> >
> > --
> > Ken Burton - N9KB
> > 76 Palm Beach
> > Hebron, Indiana
> >
> > _______________________________________________
> > GMCnet mailing list
> > Unsubscribe or Change List Options:
> > http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
> >
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

--
Jim Kanomata
Applied/GMC, Newark,CA
jimk
http://www.appliedgmc.com
1-800-752-7502
 
That wasn't really a complete description of Dave's caution: He especially
mentioned interference of the inner pads with the caliper itself,
especially the SS tabs which wrap around the pad from the
anti-rattle/squeal pads on the back. He's found those binding also. Says
newer PF 052-20 pads have the SS backers riveted rather than tab-mounted.

Ken H.

On Sat, Apr 21, 2018 at 12:16 PM, Ken Henderson
wrote:

> Also, mount the caliper to the knuckle, using the slide pins, without pads
> installed. Slide the caliper all the way in- and out-board to be sure
> there's no interference between the caliper and the knuckle. Some slight
> grinding of the knuckle may even be necessary for clearance. These days,
> this precaution (from Dave Lenzi at Tucson and before) is applicable to
> both standard and 80 mm calipers.
>
> Ken H.
>
>
 
> Check the front Rubber brake hose as it probaly collaped and not letting
> the pressure return.
>
> On Sat, Apr 21, 2018 at 9:16 AM, Ken Henderson

>
> > Also, mount the caliper to the knuckle, using the slide pins, without pads
> > installed. Slide the caliper all the way in- and out-board to be sure
> > there's no interference between the caliper and the knuckle. Some slight
> > grinding of the knuckle may even be necessary for clearance. These days,
> > this precaution (from Dave Lenzi at Tucson and before) is applicable to
> > both standard and 80 mm calipers.
> >
> > Ken H.
> >

> >
> >> I found it. Look here:
> >> http://gmcmotorhome.com/commodore/front_brake/index.html
> >>
> >>
> >> --
> >> Ken Burton - N9KB
> >> 76 Palm Beach
> >> Hebron, Indiana
> >>
> >> _______________________________________________
> >> GMCnet mailing list
> >> Unsubscribe or Change List Options:
> >> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
> >>
> > _______________________________________________
> > GMCnet mailing list
> > Unsubscribe or Change List Options:
> > http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
> >
>
>
>
> --
> Jim Kanomata
> Applied/GMC, Newark,CA
> jimk
> http://www.appliedgmc.com
> 1-800-752-7502
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org

Jim
I figured that could be an issue since the 78 we had previously had the problem with three of the hoses.
Is there a way to determine which hose goes to which side?
The banjo ends are a little different on each one but it is not obvious to me anyway which goes on which side?
One hose has a BQ stamped into the metal at each end and the other has nothing?

--
Tom Lins
Elkton, FL
77 GM Rear Twin, Dry Bath, 455
Manuals on DVD
http://www.bdub.net/tomlins/
 
> Also, mount the caliper to the knuckle, using the slide pins, without pads
> installed. Slide the caliper all the way in- and out-board to be sure
> there's no interference between the caliper and the knuckle. Some slight
> grinding of the knuckle may even be necessary for clearance. These days,
> this precaution (from Dave Lenzi at Tucson and before) is applicable to
> both standard and 80 mm calipers.
>
> Ken H.
>

>
> > I found it. Look here:
> > http://gmcmotorhome.com/commodore/front_brake/index.html
> >
> >
> > --
> > Ken Burton - N9KB
> > 76 Palm Beach
> > Hebron, Indiana
> >
> > _______________________________________________
> > GMCnet mailing list
> > Unsubscribe or Change List Options:
> > http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
> >
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org

Ken

Thanks that is good to be aware of.

--
Tom Lins
Elkton, FL
77 GM Rear Twin, Dry Bath, 455
Manuals on DVD
http://www.bdub.net/tomlins/
 
> That wasn't really a complete description of Dave's caution: He especially
> mentioned interference of the inner pads with the caliper itself,
> especially the SS tabs which wrap around the pad from the
> anti-rattle/squeal pads on the back. He's found those binding also. Says
> newer PF 052-20 pads have the SS backers riveted rather than tab-mounted.
>
> Ken H.
>
> On Sat, Apr 21, 2018 at 12:16 PM, Ken Henderson

>
> > Also, mount the caliper to the knuckle, using the slide pins, without pads
> > installed. Slide the caliper all the way in- and out-board to be sure
> > there's no interference between the caliper and the knuckle. Some slight
> > grinding of the knuckle may even be necessary for clearance. These days,
> > this precaution (from Dave Lenzi at Tucson and before) is applicable to
> > both standard and 80 mm calipers.
> >
> > Ken H.
> >
> >
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org

Ken
I am glad you said something about mounting the calipers and trying to slide them it looks like I have to take about 1/8 inch off.
I am going to split it one half of that off each part.
Thanks for the heads-up.


--
Tom Lins
Elkton, FL
77 GM Rear Twin, Dry Bath, 455
Manuals on DVD
http://www.bdub.net/tomlins/
 
> > I found it. Look here:
> > http://gmcmotorhome.com/commodore/front_brake/index.html
>
>
> Wow completely forgot about those pictures and instructions from Arch, it has been literally a decade. Thank you Ken

Do not feel bad. I forgot about them too. I just went looking for a picture for you and stumbled across them.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
 
> Brought the GMC over to our house from the storage location last week (HOA will not allow me to park it here) and discovered that one of the
> brakes was sticking.
> I figured the easiest way to tell which wheel was sticking was to check the temps of the brakes at each wheel.
> It took me some time to locate my temp gun and when I started checking 5 out of six drums/calipers were around 110 degrees but the right front
> disc was close to 600
> The rotor appears to be ok
> I decided to replace the caliper and hose on both sides since Murphy lives next door. The cost to just go to 80mm calipers was not much of a
> difference so I am going that way.
>
> The parts got here yesterday (thank you JimK) but now I am trying to figure out what casting marks I need to grind down, does anyone have a
> picture?
> Are ther any gotcha's I should watchout for?

Does anyone know what the torque spec is for the banjo bolt on the rear of the 80mm caliper?
--
Tom Lins
Elkton, FL
77 GM Rear Twin, Dry Bath, 455
Manuals on DVD
http://www.bdub.net/tomlins/
 
Tom,

http://www.hoseandfittings.com/banjo-torque/

Regards,
Rob M.
The Pedantic Mechanic
Sydney, Australia
AUS '75 Avion - The Blue Streak TZE365V100428
USA '75 Avion - Double Trouble TZE365V100426
USA '77 Kingsley - TZE 267V100808


-----Original Message-----
From: Gmclist [mailto:gmclist-bounces] On Behalf Of Tom Lins
Sent: Sunday, April 22, 2018 12:19 PM
To: gmclist
Subject: Re: [GMCnet] Frozen caliper

Does anyone know what the torque spec is for the banjo bolt on the rear of the 80mm caliper?
--
Tom Lins
Elkton, FL
77 GM Rear Twin, Dry Bath, 455
Manuals on DVD
http://www.bdub.net/tomlins/

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