BRAKES

7. This setup uses several combos of Calipers on the back bogey, one would be using the Cadillac 70mm with the mechanical parking brake or the 70mm calipers from the front of the coach or from the 1984 BOP cars. By the way BOP means Buick/Oldsmobile/Pontiac. An 80MM is used on the middle bogey and is the same unit that was used on the front brakes.

The disk brakes could be the Cadillac Eldo system, Harrison brake system, TSM or others

As for master cylinders the stock unit will work with most applications. The installations with the larger slave cylinders and calipers would benefit from the use of a Chevy P-30 master cylinder that has more volume.

This list is by all means is not complete and many other parts have been used to modify and update the GMC's braking systems.'

THIRD BRAKE LIGHT	HYDROBOOST CONVERSION
SUMMARY CONFIGURATIONS	OEM BRAKES REBUILD	PRESSURE BLEEDER	BUILDING A BLEEDER
80 mm UPGRADE PARTS	DOING THE 80mm UPGRADE	BRAKE ERROR LIGHT FUNCTION	Stainless Brake Lines
MASTER CYLINDER CONFIGS	ENHANCED BOOSTER	DISK MASTER CYL	SINKING PEDDLE
Disk Brake Differences	Cadilliac Rear Disk Brakes	PARKING BRAKE PULLEYS'	Brake Analysis

	FRONT	REAR
1	70MM calipers	drums with asbestos shoes with standard 15/16" slave cylinders
2	80MM calipers	drums with asbestos shoes with standard 15/16" slave cylinders
3	70MM calipers	drums with Carbon Metallic shoes
4	80MM calipers	drums with Carbon Metallic shoes with 1 1/8" slave on middle bogey/15/16"slave on the back
5	70MM calipers	drums with asbestos shoes on the rear bogey with 15/16" slaves, Disk brakes with asbestos or carbon metallic pads on the middle bogey
6	80MM calipers	drums with asbestos shoes on the rear bogey with 15/16" slaves, Disk brakes with asbestos or carbon metallic pads on the middle bogey
7	80MM calipers	Disk brake package installed on both rear bogeys with asbestos or carbon metallic pads

You need to understand what you need before you start. Most people that have done the cad rear brake conversion do not use the cad calipers with the emergency brake feature. It has a tendency not to release and the rear brake stays locked. The base set up is the 80MM
calipers on the front and middle bogey and the 70MM on the rear. The 70mm are the same unit that the front uses as stock. As for an
emergency brake some use a line lock valve that you set when you push down on the brakes. I recommend the carbon metalic pads on all
locations
http://www.gmcmotorhome.com/commodore/front_brake/index.html

If you decide that you what to use the cad rear calipers with the brake lever you must find and old set to use as a trade in because you need
the spring and arm assembly to hitch up the cable. The rebuilt units do not come with the spring and arm assembly and they are difficult to
buy. Take a good look at all the pictures. J.R. Wright
*************************

Ken Henderson

HYDROBOOST BRAKE CONVERSION

The biggest problem doing the installation seems to be the necessity for modifying the actuator (pedal & cross-shaft). The Hydroboost extends much farther into the cockpit than does the OEM booster. That calls for moving the cross-shaft aft (where the OEM dash interferes), and/or extending the bellcrank. And the HB must be mounted lower on the firewall to make room for the MC to clear the front "hood". GMCwiperman kenH

A diesel PS reservoir is desireable because it's got a second fluid return line, but it's not essential; most have no trouble with a tee in the single return.

The P-30 MC fits just fine on the HB but it may have to mounted a little lower that the OEM would require since its reservoir is taller. ORSIT Ken H.

I had the HB custom made for me, there are at least 10 or 12 ways to build one up, depending on the application and how much stopping power is needed. Too lengthly to explain here, but you need a large power piston and the small reaction piston to give you the pressure with the least amount of pedal pressure to do the job right for the MH. The one off the Astro van is NOT the one you want on the MH, it is not set up correctly for the MH. I did a Power Point at one of the GMCMI conventions on my installation.

You can view some pics here;
http://www.gmcmhphotos.com/photos/showphoto.php?photo=20252
----------------------------
Make sure you have a good power steering pump, as that is necessary to furnish the needed hydraulic pressure for the Hydro-boost. The OEM Saginaw P2 pump for the MH will be OK, you can test the output pressure by the instructions in the MH manual. Pressure from the pump is supplied to the hydroboost, and then on to the PS unit. I would recommend two returns on the pump canister, as you do not want to have interference with the return fluid on the spool valves. The early to mid 80's vehicles with the 350 Diesel had these, if you have a good pump, just switch the canister to your good unit, or braze a return nipple on the canister you have.

I worked with Tim at Precision Rebuilders in St Clair, MO to build up my unit.
http://www.precisionrebuilders.com/tech_support.html

This is what I have in my unit;
Input (reaction) rod size= .545"
Power piston diameter= 1.56"
Lever ratio of .72 to 1
Accumulator volume= 3.0 cu in
Use the shortest pedal rod you can get.

The unit comes into the cockpit area further than the vacumnn booster, approx 1-5/8" more, but that was no problem for me with a custom made dash. You can do the math on changing the pedal ratio, I changed mine from the 4 to 1 to 5.5 to 1.

Make sure all your braking components are in excellent shape, as, if done correctly, there will be increased brake hydraulic pressures. BOBD
------------------------------
A couple of weeks ago I tore down a Hydroboost just for curiosity. Pictures are at
http://www.gmcmhphotos.com/photos/showgallery.php?cat=5009 if you're
curious also. Ken Henderson
-------------------------------
A note of caution, it may be necessary to replace all brake lines. The Powermaster (and Hydroboost) delivers considerably more line pressure to the system than the stock MC and vacuum booster, so your lines must be in excellent condition. Failure to replace rusted or otherwise compromised lines could result in lines bursting under pressure, possibly when you need them the most. JWID Larry :)

As most all of us have changed the master cylinder, you would have a spare lid. I braised on a nipple to feed fluid under pressure from a can. You don't need much pressure. If you have too much, the top will leak. I have that top to loan , if anyone wants to use it. Dean Hanson

This note came through over the GMCnet and no one commented. Yet it is one of the great ideas of the year. GMCs are known to be difficult to bleed the brakes. The combination of Gravity and Brake Peddle seem to be the most successful but requires a lot of patience and is a two person job. Pressure bleeding has been used for years by manufacturing and truck and brake shops. The problem is getting the proper equipment. This is a low cost way to build your own Pressure Brake bleeding system. The really keen part of this tool, is the siphon to return the fluid to normal level after filling.

This is especially useful when you want to flush all the fluid in the whole system. It takes a lot of fluid and a lot pumping if you are using the brake peddle.

I would add only one feature. There used to be a kit that was called Easy Bleed. He used a spare tire (could be one of those Mickey Mouse skinny spares) for the air source. This has the advantage of a large volume of air at a constant pressure that you can set with your air compressor. The tire will have enough air to do the whole rig. Gene
---------------
One advantage of pressure bleeding is that master cylinders often seem to have a tendency to fail soon after brakes are bled bny pumping the pedal. That is due to people pushing them all the way down to the floor when opening the bleeder valves. This allows a portion of the master cylinder seals to ride farther down into the bore than they normally would. Sometimes there is surface residue on the bores in this area that can scuff the seals and then they will subsequently begin to leak.

If one is going to bleed by having someone pump the brake pedal, it is a good practice to put a 3/4" board on the floorboard under the pedal so that the pedal can never go all the way to the floor. Emery

Color of the fluid is Blue, so that as you bleed, when it turns to blue, you know that the old stuff has passed out. Building the Bleeder was the hardest part of the project.....my old hoses came off easy....lucky me!! Larry :-)

        2 ea    Banjo bolt, p/n 313940, $1.99
        1 ea    Caliper, left side, p/n 90185, $12.99 + core charge ($17.00)
        1 ea     right side, p/n 90184, price same as above
        4 ea     Caliper mounting bolt, p/n H5004, $1.29
        1 ea     Brake pad set, p/n 1534, $37.99 (these are Performance Friction carbon metallic pads)
        1 ea     Flexible hose, left side, p/n 77320, $24.99,Wagner F110424,NAPA 38563-702
        1 ea     right side, p/n 77421, price same as above,Wagner F110425,NAPA 36954-726
                For the brake hoses, try Raybestos # BH38563 & BH36954. You will need two
                5/8 national fine jam nuts to attach the hoses to the bracket at the frame.
                You will have to slightly alter and move the bracket that is in the middle
                of the hose. The steel tube end that fastens to the caliper will have to be
                bent a little to clear the upper ball joint.Denny
        2 ea     bracket clip, p/n H1457, $1.29
        2 ea     jam nut (don't have AutoZone number for this)
        2 ea     bolt and nut, ss, ¼ x 1" (not an AutoZone item)

One of the benefits of going with an 80 mm caliper is it applies, I'm told, approximately 1000 psi more braking force vs. original caliper. The difference is noticeable.

Although there was some degree of controversy on this subject a number of months back, you may want to consider going to a larger master cylinder if making the switch to larger the calipers. If so, it's available from
Autozone, p/n 10166, $53.43, and does require an ~ 0.010" longer brake rod (p/n GM 5469384)(between master cylinder and brake booster) as well as a modified mounting bracket. If you need further details on this
modification, let me know. Paul Bartz

The brake light that comes on in the lower right of the round Gauge Cluster (fuel gauge at top) is not parking brake related but it is truly a brake warning light and should not be ignored. It is triggered by the proportional valve located on the left frame behind and above the driver's side front wheel. The proportional valve has brake lines going into it from the master cylinder and out to the front and rear calipers and wheel cylinders. There is an internal sliding valve that should normally be centered. If the pressure is lower in the front brake circuit the valve slide forward and the switch grounds the wire coming into the top of it. The same thing happens when the back brake circuit has lower pressure. Marlene -- try pulling the wire clip off the top of the proportional valve (turn on your key) and with it disconnected the brake light should go out. When you ground it to the frame or other ground it should light. It may be that you've got a short in the wire somewhere or you might actually have a brake problem. A sticking wheel cylinder could cause this. A faulty proportional valve could also be the problem. Internal leak in the master cylinder or just air in the system somewhere. If you have never replaced the front hoses you should try that first. They have a history of collapsing internally. This could cause a higher pressure in the front brake circuit and trigger the light. Bleed the master cylinder and then all the wheel lines.
Emery Stora

---------------------------
Leigh Harrison
- uses a huge rotor on the center axle(15 inch<?>) which requires a
backspacer to move the rotor inboard
- complete "bolt-on" kit
- all components cad plated
- Expensive(quality costs)
- Requires P30 master cylinder

TSM
- Less expensive
- Works with original master cylinder
- Not really a "bolt-on" - if you don't get the optional braided rear
hoses you must come up with an acceptable way to plumb the calipers
and the braided hoses are not that great either.
- Currently limits you to a 60mm caliper
-----------
I suggest that you look at Bill Harvey's write up on the GMC Western States web site:
http://www.gmcws.org/tech.htm#2

Heinz points out that there was nothing wrong with the TSM system but since the Harrison system uses larger calipers he wanted to try them. One of the big differences is cost.

I have had the TSM system in for about 2 years now and am very pleased with it. I have towed my CJ-7 Jeep (over 4000 pounds of tow weight) up and down many mountain grades and the disk brakes perform extremely well. I don't have an aux. braking system on my toad and I had experienced brake fade and vapor lock with the drum brake system even while using the asbestos brake shoes that I had bought from Cinnabar and I also had to adjust the brakes frequently due to shoe wear, but I have had absolutely no problems once I switched to the disk brakes.

When I installed the disks I had a hard time bleeding the rear brakes. It turned out to be a capacity problem with the master cylinder. The four calipers just take a lot more fluid than four stock wheel cylinders. My solution was to put on a larger master cylinder as shown on my PhotoPoint site:
http://albums.photopoint.com/j/AlbumList?u=209754
After installing the larger master cylinder they rears bled easily.

Cost was definitely a factor in my decision to use the TSM brake system. I used their Cadillac rear calipers with the parking brake levers since I wanted to use my stock parking brake lever. This is a slightly smaller caliper than the mid axle ones but they seem more than adequate for stopping the GMC even when pulling a heavy toad. I modified the parking brake cable system to use pulleys instead of the wire guides that cause a lot of drag on the cable. If anyone needs details on those mods, let me know.

Jim Anstett has done an excellent job on getting the stock drum system to work about as well as it can, but I just feel that the advantages of disk brakes are really great. Easy to check the pad thickness just by looking at them without disassembling anything, very easy to quickly replace the pads when needed, no need to periodically adjust the rear brakes, and no fade or vapor lock due to the cooling running inherent in the design of disk brakes. It is no accident that manufacturers install all wheel disk brakes on modern, high tech vehicles.Emery Stora
---------------------------------
76-78 Eldorado rear disk brakes
Another alternative is the "roll your own" using 76-78 Eldorado rear disk brakes.
OEM.....
-------------------------------------------------------------

Front brakes
        Front Calipers OEM (not over size)
        Brake Pads      Carbon Metallic (Performance Friction Co) P/N 0524 (about $40)
        New Hoses       ????? Long Toronado (2) BH36675
        Rotors can be obtained from Cinnabar for $125 each 1-800-720-2227

Rear Brakes
        Mid Axle Cyl    1 1/16" Wagner F79767
        Rear Axle Cyl   15/16"   Wagner F51081 OEM Size
2 sets Brake Shoes     Asbestos Only   GM #8020290/Delco -- BUY FROM GATEWAY--
        Springs                         #171-500

DISK BRAKE RETROFIT
-------------------------------------------------------------

   P-30 master cylinder
      Autozone, p/n 101668, $53.43, and does require an ~ 0.010" longer brake rod
      (p/n GM 5469384)(between master cylinder and brake booster) as well as a
      modified mounting bracket.
   or
      Wagner P/n F79821      $60

        2 ea Banjo bolt,                  p/n 313935, $1.89
        1 ea Caliper, left side,          p/n 90185 , $12.99 + core charge($17.00)
        1 ea Caliper, right side,         p/n 90184 , price same as above
        4 ea Caliper, mounting bolt,      p/n H5002 , $3.39
        1 ea Brake pad set,               p/n 1534 , $37.99 (these are Performance Friction carbon metallic pads)
        1 ea Flexible hose, left side,    p/n 77320 , $24.99
        1 ea Flexible hose, right side,   p/n 77421 , price same as above
        2 ea Flexible hose, bracket clip, p/n H1457 , $1.29
        2 ea Flexible hose, jam nut (don't have AutoZone number for this)
        2 ea bolt and nut, SS, ¼ x 1" (not an AutoZone item)

.... 76-78 Cadillac El Dorado rear wheel backing plates ....
   One option for converting to rear disc brakes is using 76-78 Cadillac El Dorado rear wheel backing plates
   as the basis to mount the caliper's and elimination of the dust shield on the backing plate is required,
   as well as a slight notching of the backing plate to clear the swing arm. The backing plate mounting bolt
   holes do not need to be enlarged or moved. Machining is only required to allow the backing plate to fit over
   the axle shaft by enlarging the center hole (2.250" with a 45 degree by 1/16" chamfer on the back side).

                       *** CAUTION ***
   *** The Front Bogie Backing plates NEED to be strengthened/Reinforced. ***
   *** Especially if 80mm calipers are used. Lots of torque here. ***
   The back bogie can use the stock plates/calipers w/parking brake.

The rotor requires locating and drilling three new holes (same size as existing) for the mounting bolts.

   Additional parts, from Autozone rear disc brakes on the rear wheels are:
      2 ea Banjo bolt,                      p/n 313940,   $1.99
      1 ea Caliper, left front rear axle,   p/n 90185,    $12.99 + core charge ($17.00)
      1 ea Caliper, right front rear axle, p/n 90184,    $12.99 + core charge ($17.00)
      1 ea Caliper, left rear rear axle,    p/n 90557,    $73.94 + core charge ($70.00)
      1 ea Caliper, right rear rear axle,   p/n 90553,    $73.94 + core charge ($70.00)
      1 ea caliper bolt                     p/n H5004 @ $1.29
      8 ea mounting bolt,                   p/n H5002,    $3.39
      1 ea Brake pad set (front rear axle), p/n 0524,     $26.99 (these are Performance Friction carbon metallic pads)
      1 ea Brake pad set (rear rear axle), p/n 25265,    $6.49 (these are not Performance Friction carbon metallic pads)
      4 ea Flexible hose,                   p/n 77226,    $9.99
      2 ea bracket, left side               p/n 3757443, $8.20
      2 ea bracket, right side,             p/n 10257203, $8.20
      4 ea bracket clip,                    p/n H1457,    $1.29
      4 ea jam nut (don't have AutoZone number for this)
      4 ea Brake line, 3/16 x 20",          p/n H320,     $2.49

Emergency Brake...
McMaster-Carr (http://www.mcmaster.com/) pulleys.
P/N 3099T52 and they sell for $5.36 Total shipping was $2.17.
CBWoods

A very simple and inexpensive improvement to
the brake cable system did improve the holding power of my brakes. I replaced the
hooks that hold the cable where it passes through the frame (both sides) with heavy
duty pulleys bolted to the clips that the hooks were attached to. I un-did the
connection on both sides where the cable attaches to the "U" near the rear wheels,
passed the cable through the pulley and bolted the cable back in place ----- just
enough cable to still make the connection. This eliminates a lot of the friction in the
emergency brake system. My coach now holds on my driveway and all of you who have
visited will agree that it is STEEP. If any one is interested I have a source for
the "perfect" pulley ($12 for the pair). Gary

1) The "special pulleys" are special only in the sense that they fit and are rugged.
The ones I used came from a logging supply store and were marked "Block Division,
Wichta Falls, Tx, 525#". They are 3" from the center of the mounting eye to the extremity
of the pulley wheel -- just the right size to mount on the existing bracket.
They are galvanized laminated construction. Now available from Scott

2) The OEM installation of the brake cable had a hook rod on the interior of the passenger
side frame to route the cable away from the OEM muffler. I have a new muffler system and
this rod is not needed so I removed it. If you need to keep the rod in order to clear the muffler
then a third pulley can be hung on the rod if it is shortened a few inches. This will eliminate friction at this point.

3) I think that the "emergency brake" should be more properly called a "parking brake".
Mine does hold on a fairly steep incline but I have no trouble overpowering it with my 455
and I sure would hate to have to depend on it to stop in an emergency situation.

If your parts supplier can not get a Wagner, then he can cross reference to local brand. Don't get stuck with a rebuilt one, not worth taking home & small difference if bought Right. This is a perfect fit for all '73 thru '78. It's best to bleed the master cylinder on the bench before
installation. Better chance of getting all the air out of the fluid. My Wagner has been on my coach for approximately 9 years w/o any problems. Coach stops good with OEM brakes & with Brake Guard.
-----------------------
The part # for the new master cylinder for standard brakes is (MC39075) (NAPA #39705 ). That is a Raybestos number and bolts right on. I sell them for $65 no exchange, they are new. You can use your old one as a wheel chock!Jim Bounds

----------------------
Sinking Pedal Syndrome
I have not experienced the "Sinking Pedal Syndrome" but have heard of
several GMCers that have. It's not a bad master cylinder typically, but
a bad procedure of bleeding the air out of the master cylinder before
installation (extensive bench bleeding required). What happens when the
air is not completely removed from the master cylinder is that the air
will slip past the piston in the master cylinder & the pedal will slowly
go to the floor. After master cylinder removal & an extensive bench
bleeding, all is well without exchange of the master cylinder.
I always have done "Bench Bleeding" of a master prior to installation &
therefore never seen this Syndrome. Next time try to get all the bubbles
(even the tiny ones) out of the master cylinder prior to installation &
you will find gone is the Syndrome.
The procedure to determine if you have the "Sinking Pedal Syndrome" is to
start the engine (Vacuum Booster operating) & press hard on the brake
pedal for 60 seconds or so & if the pedal starts to slowly sink then you
have it.
Power of the "Net" illustrated again !!!!. Duane Simmons
------------------

I had reported earlier that my Cinnabar master cylinder with less than 10,000
miles on it failed here in Florida. Jim Bounds had a brake mechanic look at
it and they indicated that the GMC original master cylinder just didn't have
enough capacity to handle the four wheel calipers that I had put on with the
StreetRod disk brake kits. They felt that most of my braking was from the
front brakes (80 mm calipers).

My thanks to several who posted that I should use the P-30 chassis master
cylinder which has a 1-1/4" bore. I was told that Leigh Harrison uses this
cylinder with his brake kits. The mechanic tried this and still wasn't
satisfied with the amount of pedal.

It was from a 72-76 P-30 and was a 1-5/16" bore. This gives it about 10% greater volume from the same stroke (or 10% less stroke to get the same volume as the stock GMC 1-1/4" bore master cylinder. Pictures and info on my PhotoPoint site: http://albums.photopoint.com/j/AlbumList?u=209754

It is a CarQuest 20-1583 (under $40) or they have a new one for more $$$. Several different master cylnders were used on P-30s over the years. This one was used on the 1972-76 P-30 with 15" drums which used 4"wide brake shoes.

I've got over 12,000 miles on it now and it has been very satisfactory even with the 80 mm front Calipers and the 4 disc brake calipers on the rear.

They made a push rod pin that was just a little longer than the stock one.
When I get home I plan to remove it and measure it and will let everyone know
the length. The other thing that they had to do was to put a washer on the
left hinge of the driver's front access door so that the door would clear the
bail wire on the master cylinder when the door was closed. I believe that I
can bend the bail slightly so that the door hinge shim can be eliminated;
however, it is out so little now that one wouldn't notice it unless it were
to be pointed out.

The result is that the brakes, which I thought were great before, are now
really great. I've got about 2-1/2" of pedal left (bottom of pedal to floor)
when I push hard on the brake pedal, whereas before I had less than an inch.
I am also using a Lamy sensitized booster which allows the pedal to go lower
due to the increased pressure of the booster.

I was told that the GM (Cinnabar) (Bendix) master cylinder plunger was
bottoming out within the master cylinder and scuffing the bottom edge of the
piston seal and that mine had failed due to this scuffing.

I suggest that any of you who have put rear disk brake kits onto watch your
master cylinders for possible failure and be prepared to put on a larger
master cylinder before you have problems. I doubt that mine was an
abnormality because I had tried two new NAPA master cylinders before buying
the Cinnabar one and on both the pedal slowly sunk to the floor and the red
light would come on. The Cinnabar one had lower pedal than before the disk
brakes were installed but it did not sink all the way to the floor. When
installing the kit I thought that it was not bled properly and my wire and I
literally spend hours bleeding and rebleeding the brakes. When the Cinnabar
master cylinder was put on they firmed up right away and when the CarQuest
one was installed the mechanic said that there was no bleeding problem right
from the start.EMERY

If either set of brakes (front or rear in our case) springs a leak, the corresponding chamber empties, and that piston "bottoms out". If it is the primary piston, it moves down until it physically touches the secondary piston, and now pressure is applied directly to the secondary piston. If it is the secondary chamber that empties, the secondary piston bottoms at the end of the cylinder bore, and pressure builds up between the two pistons in the primary chamber. In either case, THEORETICALLY you still have the remaining half of the brakes. (In fact, the DOT required manufacturers to install a brake warning light to remind the poor befuddled driver that a failure had occurred, since this system worked so well we might not notice the problem otherwise!)

HOWEVER, in the real world it doesn't work that well. Usually the problem is brakes which are out of adjustment, have a little air trapped in lines or cylinders, or spongy hoses, etc. Any/all of these things cause a low pedal. When one of the sets of brakes fails, you lose about 2/3 of the pedal travel before its piston "bottoms out". If the remaining brakes are a bit low/spongy, then the pedal hits the floor before the remaining brakes fully apply. (Your case.) Sometimes pumping the pedal will bring it up enough to work, but the GMC is hard to pump effectively. Also, the GMC brake system works hard even if it's all there, so any failure is more dramatic than in your car.

BTW, the warning light/proportioning valve has little or nothing to do with all this, except as another place to trap air bubbles, or as as a potential leak between front and rear systems which might circumvent the intended separation.
-------------------

Performance Friction # 524 (0052.10) and #6144 (0614.3) both fit our calipers and the 80 mm.calipersDenny Allen

Front brakes
        Front Calipers OEM (not over size)
        Brake Pads      Carbon Metelic (Performance Friction Co)
        Pad P/N         0524 (about $40)
        New Hoses       ????? Long Toronado (2)
BH 36675 is the correct Raybestos number for our coaches. Other numbers are Wagner F86578, Autozone 88498, Carquest or EIS# SP5363. These also fit 70-78 Toronados. If the parts guy asks "which side?" the answer is the right side. The Toronado left hand side ones are to short for our coaches.

        Rotors can be obtained from Cinnabar for $125 each 1-800-720-2227
Rear Brakes
       Mid Axle Cyl    1 1/16" Wagner F79767
        Rear Axle Cyl   15/16" Wagner F51081 OEM Size
2 sets Brake Shoes     Asbestos Only GM #8020290/Delco -- BUY FROM

John Evans 2455eva@pce.net he has the carbon met shoes,
he also has front pads if you do not have a Autozone, no cores needed

The proportional valve is available at GM Dealers under part#1236004. I just got one last month.
They might have to order it. As for bleeding I pulled the valve out not in. The real question is that do you have air in the master cylinder and if you do then you will not get any fluid to the rear brakes.JR

MASTER CYLINDER
-------------
In doing my brakes a few years ago I ran into the poor to very poor and bad "STAR" adjusters on the rear brakes. This coach is made to be self adjusting when you back up. Of course the self-adjusters will not work properly or at all if the "STAR" is not in servicable condition. chuck