Brake bleeding--new MC and rear disks

[Larry Davick]

Is it verboten to use any thread sealer on a bleeder fitting?
--
Larry Davick
A Mystery Machine
1976(ish) Palm Beach
Fremont, Ca
Howell EFI + EBL + Electronic Dizzy

 

[jerry burt]

> Is it verboten to use any thread sealer on a bleeder fitting?

The seat is what seals on the bleeder valve. Putting any sealer on the threads isn't going to work.
--
Patti & Jerry Burt Fresno, CA.
73 Gmc 26' Canyon Lands
77 Palm Beach - Parts Coach
Members: FMCA - GMCMI - GMCWS
A truly happy person is one who can enjoy the scenery on a detour.

 

[mark sawyer]

I assume you tried checking the bleeder and the seats for debris or any sort of defect that would allow fluid to escape....

If you have and that's not the issue, another option is they do make these conical copper washer like things that actually fit in the tapper on the
brake fitting, though I've never actually used them on a bleeder, I have used them on brake lines, and I'd imagine they would work the same way on a
bleeder....

Backstory on the conical washers is a while back I'd bought some stainless braided brake lines from Goodridge, and I had leak issues... Called their
customer service and they went and sent me a set of these washers and they solved the issue....

They look similar to this:

http://www.aektechnology.com/airdrome/AEK_Conical_1114.pdf
--
Mark S. '73 Painted Desert,
Manny 1 Ton Front End,
Howell Injection,
Leigh Harrison 4bag and Rear Brakes,
Fort Worth, TX

 

[Jim Hupy]

One trick that people use while bleeding the brakes is to use silicone
based grease on the bleeder screws liberally and screw them into the
caliper. This prevents air from leaking in from the atmosphere and
appearing in the clear bleeder tube as air coming from inside the system.
Several GMCers use this trick successfully. I have never found the need to
do so.
Jim Hupy
Salem, Or

On Fri, Sep 13, 2019, 11:48 AM Jerry Burt via Gmclist <

> > Is it verboten to use any thread sealer on a bleeder fitting?
>
> The seat is what seals on the bleeder valve. Putting any sealer on the
> threads isn't going to work.
> --
> Patti & Jerry Burt Fresno, CA.
> 73 Gmc 26' Canyon Lands
> 77 Palm Beach - Parts Coach
> Members: FMCA - GMCMI - GMCWS
> A truly happy person is one who can enjoy the scenery on a detour.
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

 

[Ken B]

I have used teflon tape on the threaded part of the bleeders for years. This accomplishes 2 things. The do not seep air when vacuum bleeding and 5
or 10 years from now when you want to bleed them again they are not rusted in place. I have also used anti-seize on the threads.

I consider it a requirement to put the rubber caps on the bleeder screws when I am finished bleeding.

If you do not have them you can buy just the caps on ebay.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana

 

[Matt Colie]

Rick,

Well, KenB already said what I think is a most important thing in brake maintenance.

But, I will add that in my lengthy and lack-luster experience in passcar brakes, I have had two bad bleeder screws. Both had a visible mark on the
sealing face. One I took back and the other I just took the screw out of the old cylinder.

One time that I had a weeper like yours, I went and retightened it 3 or 4 times with a 1/4 drive socket on a long extension and a T-handle so there
was minimal side load. That seemed to get it.

Good Luck

Matt
--
Matt & Mary Colie - '73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan
OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Twixt A2 and Detroit

 

[Rdenney]

In the end, I replaced the bleeder screws in two calipers with new ones
from NAPA. I used Teflon tape on the threads to make them easier to loosen,
and so far no leaks.

I got it all buttoned up today and took the coach for a drive. The coach
tracks straight as an arrow, now that I have tight bogie bushings.
Everything seemed to work as it should.

The coach stops, and it does so reliably. Lots of pedal travel, though.
When I rent a car, which I do often given my travel schedule, the brakes on
those econoboxes are quite sudden and responsive. My Expedition brakes feel
sluggish on the way home from the airport. That coach braking feels more
sluggish than the Expedition by about the same amount. I’m sure hoping the
break-in of the new brakes will make them a bit grippier and more
responsive, and increase ultimate braking power. But it’s been on jack
stands for five weeks and I don’t trust my memory of how the brakes behaved
before. They did always require high pedal effort.

Rick “not knowing what to expect” Denney

On Sat, Sep 14, 2019 at 10:52 AM Matt Colie via Gmclist <

> Rick,
>
> Well, KenB already said what I think is a most important thing in brake
> maintenance.
>
> But, I will add that in my lengthy and lack-luster experience in passcar
> brakes, I have had two bad bleeder screws. Both had a visible mark on the
> sealing face. One I took back and the other I just took the screw out of
> the old cylinder.
>
> One time that I had a weeper like yours, I went and retightened it 3 or 4
> times with a 1/4 drive socket on a long extension and a T-handle so there
> was minimal side load. That seemed to get it.
>
> Good Luck
>
> Matt
> --
> Matt & Mary Colie - '73 Glacier 23 - Members GMCMI, GMCGL, GMCES
> Electronically Controlled Quiet Engine Cooling Fan
> OE Rear Drum Brakes with Applied Control Arms
> SE Michigan - Twixt A2 and Detroit
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
--
'73 X-Glacier 230 "Jaws"
Northern Virginia
Offlist email: rick at rickdenney dot com

 

[sean kidd]

Richard, one last note, I was instructed to reverse reservoirs when I did my rear discs. Original rear port on MC was to go on front Port on P-30 MC
and vice versa.
--
Sean and Stephanie
73 Ex-CanyonLands 26' #317 "Oliver"
Hubler 1-Ton, Quad-Bags, Rear Disc, Reaction Arms, P.Huber TBs, 3.70:1 LSD Honda 6500 inverter gen.

Colonial Travelers

 

[Rdenney]

Which brings to mind my thinking this morning.

I’m noting a lot of pedal travel. The pads are in contact, and remain so
even with a test spin of the freshly mounted wheel. I did not explicitly
measure the runout, but it did not seem excessive. A little runout is
necessary to keep the pads from wearing and making constant heat in any
case.

That said, I’m using the stock MC, because its smaller piston results in
lower pedal effort. But it requires greater travel to move the same amount
of fluid. I’m wondering if the stock MC is a little too small, in terms of
volume moved over the pedal range, for six disk brakes. (I already know the
reservoirs are too small, and have to check fluid level routinely as the
pads wear.)

I may need the P30 to reduce pedal travel, and the sensitized booster to
restore the lower pedal effort lost to the larger piston, at least for
routine braking.

But I’m not going to think about this again until the current brakes are
fully broken in, so I can see where I am.

Rick “reversing the lines is just a matter of reservoir capacity, right?”
Denney

On Sun, Sep 15, 2019 at 8:48 AM Sean Kidd via Gmclist <

> Richard, one last note, I was instructed to reverse reservoirs when I did
> my rear discs. Original rear port on MC was to go on front Port on P-30 MC
> and vice versa.
>
--
'73 X-Glacier 230 "Jaws"
Northern Virginia
Offlist email: rick at rickdenney dot com

 

[Rdenney]

By the way, I just ordered a set of Performance Friction pads for the rear
disks.

Rick “thinking it might help” Denney

> Which brings to mind my thinking this morning.
>
> I’m noting a lot of pedal travel. The pads are in contact, and remain so
> even with a test spin of the freshly mounted wheel. I did not explicitly
> measure the runout, but it did not seem excessive. A little runout is
> necessary to keep the pads from wearing and making constant heat in any
> case.
>
> That said, I’m using the stock MC, because its smaller piston results in
> lower pedal effort. But it requires greater travel to move the same amount
> of fluid. I’m wondering if the stock MC is a little too small, in terms of
> volume moved over the pedal range, for six disk brakes. (I already know the
> reservoirs are too small, and have to check fluid level routinely as the
> pads wear.)
>
> I may need the P30 to reduce pedal travel, and the sensitized booster to
> restore the lower pedal effort lost to the larger piston, at least for
> routine braking.
>
> But I’m not going to think about this again until the current brakes are
> fully broken in, so I can see where I am.
>
> Rick “reversing the lines is just a matter of reservoir capacity, right?”
> Denney
>
> On Sun, Sep 15, 2019 at 8:48 AM Sean Kidd via Gmclist <

>
>> Richard, one last note, I was instructed to reverse reservoirs when I did
>> my rear discs. Original rear port on MC was to go on front Port on P-30 MC
>> and vice versa.
>>
> --
> '73 X-Glacier 230 "Jaws"
> Northern Virginia
> Offlist email: rick at rickdenney dot com
>
--
'73 X-Glacier 230 "Jaws"
Northern Virginia
Offlist email: rick at rickdenney dot com

 

[emerystora]

Yes, the original master cylinder does not provide enough volume for six wheel disk brakes, especially if you have switched to 80m front calipers.
However, the P30 master cylinder give less pressure to the calipers. There are a lot of different P30 master cylinders. I would suggest the use of the GM 14009146 master cylinder which corresponds to an AC/Delco 174-834.
This also crosses to Wagner F103239, Bendix 11641, EIS E150063 and a CarQuest 20-2234. I don't have the NAPA cross.
This is a 34 mm piston bore (approx. 1-21/64”).

If you install a 34mm master cylinder then the brace will no longer fit on the front of the mounting lugs and you will have to bend it so that it fits between the booster and the master cylinder. That means that you will need a longer push rod.
You can grind your own or you can purchase an adjustable one. I recommend 0.015 inches (3.8mm) clearance between the end of the push rod and the piston.

You will encounter another problem with using the 34mm master cylinder. It will not seal properly against the rubber seal on the face of the booster and you will get a vacuum leak there. Dave Lenzi provided a small “collar” to me that would take up the gap and seal it properly.

When I recently removed the 4 rear calipers and disks and put on Dave Lenzi’s rear brake double piston caliper and larger disk on the mid axle I switched to the original master cylinder and even though I have no braking on the rear axle I have excellent braking now. Much better than with the 4 smaller rear disks. I will be installing Dave’s hydraulic parking brake on the caliper. It already has the mounts on it.

Emery Stora
77 Kingsley
Frederick, CO

>
> Which brings to mind my thinking this morning.
>
> I’m noting a lot of pedal travel. The pads are in contact, and remain so
> even with a test spin of the freshly mounted wheel. I did not explicitly
> measure the runout, but it did not seem excessive. A little runout is
> necessary to keep the pads from wearing and making constant heat in any
> case.
>
> That said, I’m using the stock MC, because its smaller piston results in
> lower pedal effort. But it requires greater travel to move the same amount
> of fluid. I’m wondering if the stock MC is a little too small, in terms of
> volume moved over the pedal range, for six disk brakes. (I already know the
> reservoirs are too small, and have to check fluid level routinely as the
> pads wear.)
>
> I may need the P30 to reduce pedal travel, and the sensitized booster to
> restore the lower pedal effort lost to the larger piston, at least for
> routine braking.
>
> But I’m not going to think about this again until the current brakes are
> fully broken in, so I can see where I am.
>
> Rick “reversing the lines is just a matter of reservoir capacity, right?”
> Denney
>
> On Sun, Sep 15, 2019 at 8:48 AM Sean Kidd via Gmclist <

>
>> Richard, one last note, I was instructed to reverse reservoirs when I did
>> my rear discs. Original rear port on MC was to go on front Port on P-30 MC
>> and vice versa.
>>
> --
> '73 X-Glacier 230 "Jaws"
> Northern Virginia
> Offlist email: rick at rickdenney dot com
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org

 

[Rdenney]

After all of yesterday’s second-guessing, I drove the coach home this
afternoon—about 40 miles. Within five miles, I’d forgotten about the
brakes. They just work, and I got used to the pedal travel and feel in no
time. I’ll check on maximum braking when they are really broken in.

Nothing got too hot (though the brakes were hot, which they have to be if
they are working). If I was having a bearing problem after installing the
reaction rods, the ends of the spindles would be hot; they weren’t.

But what had me smiling was that the coach drove more nimbly than my
Expedition. It tracked straight, never needed more than a single light hand
in the wheel, and didn’t change directions without permission. I am so glad
not to have wobbly shopping cart caster wheels any more.

Rick “the coach is now Redhead-driveable” Denney

> Both me and the Redhead’s uncle hope so.
>
--
'73 X-Glacier 230 "Jaws"
Northern Virginia
Offlist email: rick at rickdenney dot com

 

[LarryW]

> By the way, I just ordered a set of Performance Friction pads for the rear
> disks.
>
> Rick "thinking it might help" Denney

Rick, keep in mind that the performance friction pads take some work to break in. You will need to scratch the hell out of the rotors to give the pads
a surface to break in. Then do progressively harder stops. The first time you hit the brakes with the new PF pads, you will be shocked at how LITTLE
brakes you have. But keep at it and brakes will come back better than before. Just what I noticed with the PF pads. Follow the break-in procedure that
comes with the pads.
--
Larry
78 Royale w/500 Caddy
Menomonie, WI.

 

[Jim Hupy]

I installed a quadra-bag system along with a Chuck Algur reaction arm and 6
wheel disc brakes with Cadillac calipers on the rear/rear, for a customer
that lived in the West hills of Portland, Oregon. He drove his coach down
Canyon Blvd every Sunday morning.
After I installed the systems, he complained of a soft pedal and
excessive pedal travel. He brought the coach back to me to check out, as he
thought it should have a firmer pedal. So, I replaced the P-30 m.c. with a
stock one along with a sensitized booster, and installed 80 mm calipers on
stock rotors with sticky yellow ceramic front pads. I re-bled the system,
and returned the coach to him. He called after a couple of weeks, and said
that he thought the pedal should be firmer. I told him to drive it some
more to further break-in the discs and pads.
Some time passed, and no more calls from him. Then, one Sunday morning
while out for his weekly drive, a Honda ran into a center divider after
cutting in front of him without enough clearance, spun out, and came to
rest across both lanes directly in front of him. He said some expletives
and panic stopped his coach, knowing that if he were driving the stock
brakes that he was going to T-bone the Honda on the drivers door. Much to
his suprise, the coach stopped 10 feet short of contact. He pulled over and
called me and thanked me profusely for the disc conversion. So, I know
those systems work, but differently than what we are used to.
Jim Hupy
Salem, Oregon

On Sun, Sep 15, 2019, 3:06 PM Richard Denney via Gmclist <

> After all of yesterday’s second-guessing, I drove the coach home this
> afternoon—about 40 miles. Within five miles, I’d forgotten about the
> brakes. They just work, and I got used to the pedal travel and feel in no
> time. I’ll check on maximum braking when they are really broken in.
>
> Nothing got too hot (though the brakes were hot, which they have to be if
> they are working). If I was having a bearing problem after installing the
> reaction rods, the ends of the spindles would be hot; they weren’t.
>
> But what had me smiling was that the coach drove more nimbly than my
> Expedition. It tracked straight, never needed more than a single light hand
> in the wheel, and didn’t change directions without permission. I am so glad
> not to have wobbly shopping cart caster wheels any more.
>
> Rick “the coach is now Redhead-driveable” Denney
>
>
>

>
> > Both me and the Redhead’s uncle hope so.
> >
> --
> '73 X-Glacier 230 "Jaws"
> Northern Virginia
> Offlist email: rick at rickdenney dot com
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

 

[Larry Davick]

I’m aspiring to a redhead ready coach so my Mrs could drive comfortably.

Congrats and happy camping!

Larry Davick
A Mystery Machine
Fremont Ca

 

[johnny]

My coach has a fairly long pedal travel, but when it hits the brakes, it is solid and above the floor... and has no sponginess and stops properly (It
ain't my Soul, but it ain't awful).
The idea that one needs a bit of runout to back the pads up is false. The seal in the caliper is square, not round. It displaces slightly outward
when brakes are applied, and retracts the pad a few thousandths when the pressure in the caliper is relieved. When Mac's supported an F Production
Spridget driven by our inspector, we used a tool post grinder and a jig to get the rotors completely even all the way around, and got them to
basically no runouit on the car. Do this and drive the car and the difference is noticeable on brake application. Worth a few tenths of a second
around Road Atlanta - a noticeable advantage in class racing.

--johnny
--
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

 

[Jim Hupy]

Absolutely imperative that the rotor runout be kept to a minimum. "0"
degrees is the goal. Absolutely, positively, no more than .010". Turn them
on the rig if removing them and realigning them on the hubs doesn't help.
GMC hubs are massive and somewhat crudely executed. Some are unacceptably
out of spec.
Jim Hupy
Salem, Oregon

On Mon, Sep 16, 2019, 6:14 AM Johnny Bridges via Gmclist <

> My coach has a fairly long pedal travel, but when it hits the brakes, it
> is solid and above the floor... and has no sponginess and stops properly (It
> ain't my Soul, but it ain't awful).
> The idea that one needs a bit of runout to back the pads up is false. The
> seal in the caliper is square, not round. It displaces slightly outward
> when brakes are applied, and retracts the pad a few thousandths when the
> pressure in the caliper is relieved. When Mac's supported an F Production
> Spridget driven by our inspector, we used a tool post grinder and a jig to
> get the rotors completely even all the way around, and got them to
> basically no runouit on the car. Do this and drive the car and the
> difference is noticeable on brake application. Worth a few tenths of a
> second
> around Road Atlanta - a noticeable advantage in class racing.
>
> --johnny
> --
> 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
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

 

[jim kanomata1]

It is standard to have the longer stroke when one has the 6 disc system.
Shops that have experience installing them will tell you that it works
better after you run it in.
We know lot about that system as we sell all type of system and personally
use them on my coach.

On Mon, Sep 16, 2019 at 8:33 AM James Hupy via Gmclist <

> Absolutely imperative that the rotor runout be kept to a minimum. "0"
> degrees is the goal. Absolutely, positively, no more than .010". Turn them
> on the rig if removing them and realigning them on the hubs doesn't help.
> GMC hubs are massive and somewhat crudely executed. Some are unacceptably
> out of spec.
> Jim Hupy
> Salem, Oregon
>
> On Mon, Sep 16, 2019, 6:14 AM Johnny Bridges via Gmclist <

>
> > My coach has a fairly long pedal travel, but when it hits the brakes, it
> > is solid and above the floor... and has no sponginess and stops properly
> (It
> > ain't my Soul, but it ain't awful).
> > The idea that one needs a bit of runout to back the pads up is false.
> The
> > seal in the caliper is square, not round. It displaces slightly outward
> > when brakes are applied, and retracts the pad a few thousandths when the
> > pressure in the caliper is relieved. When Mac's supported an F
> Production
> > Spridget driven by our inspector, we used a tool post grinder and a jig
> to
> > get the rotors completely even all the way around, and got them to
> > basically no runouit on the car. Do this and drive the car and the
> > difference is noticeable on brake application. Worth a few tenths of a
> > second
> > around Road Atlanta - a noticeable advantage in class racing.
> >
> > --johnny
> > --
> > 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
> >
> >
> > _______________________________________________
> > 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

 

[Rdenney]

Thanks all for the final reassurances. The feel is different but it’s easy
to get used to it. I’ll test emergency stoping once the pads are broken in.

Now, to that bleeder seep. The bleeder on one of the calipers is still
seeping enough to wet my finger, but not enough to drip. A new bleeder
screw didn’t resolve it, which I sort-of expected though for two bucks it
was an experiment worth trying. That also eliminated the possibility of
dirt in the bleeder seat.

Is replacing the caliper the only alternative? I’m thinking that’s all I
can do—the caliper side of the bleeder seat must be the problem. I bought
the brake/reaction-rod kit nearly two years ago, and it came with Centric
calipers, so I think I’ll get a replacement from NAPA, which seems to have
a better reputation among the commonly available choices.

Maybe when I have the wheels off again I’ll measure runout with my dial
indicator. Maybe not.

Rick “whose projects never seem to get finished” Denney

On Mon, Sep 16, 2019 at 11:50 AM Jim Kanomata via Gmclist <

> It is standard to have the longer stroke when one has the 6 disc system.
> Shops that have experience installing them will tell you that it works
> better after you run it in.
> We know lot about that system as we sell all type of system and personally
> use them on my coach.
>
--
'73 X-Glacier 230 "Jaws"
Northern Virginia
Offlist email: rick at rickdenney dot com

 

[emerystora]

You should try using one of the small conical copper washers that go between the casting seat and the bleeder screw. It will deform to take up the imperfections in the casting to allow sealing.

Emery Stora
77 Kingsley
Frederick CO

>
> Thanks all for the final reassurances. The feel is different but it’s easy
> to get used to it. I’ll test emergency stoping once the pads are broken in.
>
> Now, to that bleeder seep. The bleeder on one of the calipers is still
> seeping enough to wet my finger, but not enough to drip. A new bleeder
> screw didn’t resolve it, which I sort-of expected though for two bucks it
> was an experiment worth trying. That also eliminated the possibility of
> dirt in the bleeder seat.
>
> Is replacing the caliper the only alternative? I’m thinking that’s all I
> can do—the caliper side of the bleeder seat must be the problem. I bought
> the brake/reaction-rod kit nearly two years ago, and it came with Centric
> calipers, so I think I’ll get a replacement from NAPA, which seems to have
> a better reputation among the commonly available choices.
>
> Maybe when I have the wheels off again I’ll measure runout with my dial
> indicator. Maybe not.
>
> Rick “whose projects never seem to get finished” Denney
>
> On Mon, Sep 16, 2019 at 11:50 AM Jim Kanomata via Gmclist <

>
>> It is standard to have the longer stroke when one has the 6 disc system.
>> Shops that have experience installing them will tell you that it works
>> better after you run it in.
>> We know lot about that system as we sell all type of system and personally
>> use them on my coach.
>>
> --
> '73 X-Glacier 230 "Jaws"
> Northern Virginia
> Offlist email: rick at rickdenney dot com
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org