The front brakes are 9.5"x1" disc brakes with single piston floating calipers. The discs for 1971-1975 cars are not vented--vented rotors were added in 1976.
The rear brakes up to and including 1975 are 9"x1 1/4" drums. In 1976 the Monza/Sunbird/Starfire/Skyhawk got 9 1/2"x2" drums.
Both power- and non-power assisted brakes were available. Pre-1976 cars do not have combination/proportioning valves.
5.2 What can I do to improve my H-body's braking performance?In general:
For front brakes, you can (in order of cost):
Clyde (CJBIAGI) notes:
"One thing that I did when I swapped my spindles to install the late
Monza vented rotors was to inspect the spindle where the caliper contacts.
On one of my spindles there was some sign of wear where the spindle
contacted the caliper. What I ended up doing was to weld the area that
contacts the caliper and then grind/file the weld smooth to make up for the
wear. You want the caliper to fit snug but also want to leave a small amount
of a gap so that the caliper can slide without binding. This will
prevent any rattling of the caliper, especially if you install the new
bushing kit."
Larry (vega_man_larry) writes:
"I installed the same parts [80 h-body power brake w/comb valve] in my
Vega. It depends on what pedal
combination you have. I found that I
had to slightly enlarge the hole in actuating rod in the booster to fit
my pedal assembly. I used an
adjustable reamer to carefully open the hole until it fit my pedal
assembly. It would be easier to get the
pedal assembly from the donor but I learned that too late. I removed the
old master and installed the new
booster and master with no problem. I also installed the brace that goes
from the outboard masterlug to
the inner fenderwell. I attached the brace and used it as a drill
template (match drill). I then used a
stainless fastener combination to anchor the strut. I bolted the
proportioning valve where the manual one
was and routed the lines. I perfomed the bleeding procedure per the
manual, and had my wife pump the
brake, my daughter hold the switch on the proportioning valve, and I did
the bleeding, starting rr, then lr,
then rf and finally lf. Stops alot better but I still need to do the
S-10s."
For rear brakes, you can:
Note that the larger ('76-up) Monza rear drums are the same size as the S-10 and GM midsize cars, only with 4 lugs instead of 5, and no cooling fins (to fit in the 13" wheels). Upgrading to 5-lug rear axles is good for wheel choices but don't expect a big increase in rear braking power if you do the axle swap (however you WILL be able to keep your backing plates).
Paul (pvgatto) offers this general advice:
"Before I upgraded the brakes on my Vega, I did a lot of research on the
design of a braking SYSTEM. I
emphasize the word SYSTEM, because it all has to work together to have a
safe vehicle. There is some
great information out there on braking systems, I recommend a book
called "Brake Handbook," by Fred
Puhn.
The first thing to consider is that the automakers have a pretty good idea on how to build a car. They have been doing it for close to 100 years now. The reason that many cars brake just fine without an adjustable proportioning valve is that the CORRECT proportioning valve was designed and put in the car in the first place. As soon as the front to rear weight bias, tire sizes, spring rates, caliper piston sizes, wheel cylinder sizes, master cylinder sizes, and any other number of things are changed, the brake proportion is no longer correct.
A basic principle of fluid physics is that the larger a caliper or wheel cylinder piston, the more force will be applied. Force = P x A, where P is the hydraulic pressure in pounds per square inch and A is area of the piston in square inches. This is one of the reasons for calipers with multiple pistons. By increasing the number of pistons, the total area is increased, creating more force.
Therefore, the larger the rear wheel cylinders, the MORE apt they are to lockup, given the same pressure. The statement about increasing the MASTER CYLINDER bore size to reduce lockup on the rear brakes is more correct.
In almost all automobile applications (not trucks), the front brakes do the vast majority of the work. This is due to the weight transfer that was discussed earlier. This is also why cars are designed with front discs / rear drums or large discs in front and small discs in the rear. In my conversations with the people at Baer Racing, http://www.baer.com/ , I learned that even when they are doing a high-end system, they recommend their smallest rear disc. The only reason their customers purchase larger rear discs is for appearance.
This is starting to get a bit long-winded, so I'll get to the point. To reduce the tendency of the rear brakes to lockup before the front, here's what can be done. The easiest ideas first.
1. Adjustable proportioning valve.
2. Smaller rear wheel cylinders.
3. Larger rear master cylinder bore.
4. Larger rear tires.
5. Different weight bias.
6. Different suspension tuning.
When I installed an adjustable proportioning valve the folks at Baer Racing recommended that I remove the insides of the factory proportioning valve to keep from reducing the pressure too much. I didn't take their suggestion at first, and I found that my rear brakes were not working as well as they should. After removing the "guts" from the factory valve, I was able to get things adjusted properly."
5.3 How do I convert my car to the 5-lug pattern used by most other GM mid-size cars? (G-body, F-body, S-trucks, etc)The rear is EASY compared to the front! Simply put, you need S-10 axle shafts. Get two of GM part number 14030355 (axle shafts for a 1988 2WD S-10 pickup, 26-spline, 7.5") and replace your current shafts with these, which have the desired 5-lug pattern. NOTE: These shafts are 1/16" shorter than the Monza shafts. You may need to grind down the backing plate or machine the drum, or if you're brave, put a 1/16" spacer between the end of the shaft and the brake drum. This may not be a problem at all if you use aluminum drums. The GM part number for these aluminum drums is 1255496 (Buick Regal, Chevrolet Malibu, Olds Cutlass, Pontiac Grand Prix and Monte Carlo from 1981 to 1989). At least one person needed to remove his brake hardware to push the axle in far enough to install the C-clips in the rear end housing.
The front is trickier. Pick your poison:
Tony (Tonyhallo) says:
"The following information is my findings while installing 1981 Monte Carlo
spindles on a 1971 Vega. I have not installed the calipers yet because I
have a long way to go and the brakes will be one of the last areas to address.
Ball joint clarification: The ball joint holes in the spindle are too big for stock Monza or Vega ball joints.
Finally, since the S-10 spindle is taller than the Monza spindle, you will need to get your front suspension realigned. If you have trouble getting the alignment set as you want it, you can use Dobi adjuster cams that give you more adjustability.
NOTE: If you have a '75 or older car, consider upgrading to an S-10 master cylinder to go with the S-10 brakes, or else you might have problems! However, the S-10 master won't fit in the H-body booster.
About the conversion, birdman8099 asked:
"Anyone had any problems with their centerlink rubbing on the passenger side tierod
link after S-10 conversion? Mine rubs the tie rod [on the idler arm side].
This is I'm sure, because the S-10 spindles have longer tierod arms. It only rubs at
one point from lock to lock and thats right when the Pitman is lined up with the
steering box with the front wheels straight. You can't feel it in the steering wheel
but it rubs enough to cause the tierod to deflect a slight amount. I used my die grinder to
take off about a 16th of an inch off the centerlink to get it to go by without hitting
but its still damed close."
Clyde (CJBIAGI) replied: "I have not done this conversion but since you say that it is the idler arm side that rubs, I seem to remember that when I changed my idler arm that there was an adjustment that you could do by turning the arm while holding the part that bolts to the frame that would effectively raises or lowers that end of the idler arm and centerlink. The objective is to have the centerlink level on both ends, you don't want one end higher than the other or it could screw up your geometry. This may be a possible reason why your centerlink is rubbing. If you just bolted the idler arm on the way it came out of the box without performing this adjustment this might be what's causing your rubbing. I seem to remember that there were some instructions that came with my idler arm, but then it's been a while since I have done this."
Roger (ks_skyhawk) adds about alignment:
"When you get all the weight and parts on the car, set the car on a smooth and level floor, to its normal
ride height without the wheels installed. Support the lower control arms, and set the alignment cams to
the middle position. Then use a carpenter's framing square on the floor and against the brake rotors.
How flat the rotors are against the square will give the best idea of how easily it will align. Mine required
moving the upper ball joint out at the top to rid myself of the excessive negative camber. ( -1.8 on Right
and -.8 on the Left )"
Robert (twelve_second_vega) adds these thoughts:
"Fitting the S-10 ball Joint to the Monza/Vega Control Arms isn't that
difficult, as "Denisst78" has proven with his
skillful use of a Milling Machine. On the Upper Control Arm, I have
noticed something that I wanted to share with
the club. The Seat Area will easily accomodate an S-10 Ball Joint, but
it (Ball Joint) should be rotated slightly to give
its attaching hardware the best possible contact with the Control Arm
Seat. Additionally, opening the hole in the
Control arm is a touchy Subject indeed. Since the mounting hole in the
Vega/Monza (Other "H"-Body) Control Arms
is already near the outer edge of the arm, the only safe action, in my
opinion, is to move the centreline of the Upper
Ball Joint Approximatley .150" Inboard. This will create a Negative
Camber condition on a suspension system that is
know to have limited adjustability. I think one could offset the problem
with Moog's "Problem Solver" Offset Upper
Control Arm Bushing Kits, but this doesn't seem like the best way to
attack the probelm. Also, approximately how
much variation in Camber will result from moving the Upper Ball Joint
Inboard .150". I prefer to set my front ends
at 1/4 degree Positive Camber for Street Use. My concern is lack of
adequate adjustability and accelerated tire wear
in an exclusively street-driven vehicle."
Clyde (CJBIAGI) adds more about brake hydraulics:
"80's Malibu, S-10, & Camaro( & others) use the same caliper piston, &
kit as the H-body w/vented rotors, so if you do
change to malibu/S-10 spindles/rotors you don't need to change master or
p-valve(unless you have solid rotors). Then
just use all for 76-80 parts."
Yes, why else would this question be here? :) The Honda booster is smaller and offers better pedal feel. See the details in the Tech Tips section of HBOA Online (http://www.inwave.com/~bacchus/HBOA). A custom bracket needs to be built.
5.6 What wheel sizes came stock with H-bodies?
Some things that have worked for people:
Street tires:
Some things that have worked for people:
Street tires:
Drag tires:
Ones with the correct 4 x 4" bolt pattern are scarce.
Ones with 4 x 100mm bolt patterns can be forced to work, but it's not recommended. However they're much easier to find since this pattern is used by many imports.
Some manufacturers that still make 4 x 4" wheels: Revolution, Panasport, Lite Speed, Monocoque, and Keizer. These companies make lightweight racing wheels in many sizes. They are built for racing and as such are probably more expensive and less attractive than typical "street" rims.
Also, Centerline makes the AutoDrags in 4 x 4". Jeg's sells them:
184-065351-440, 15x7, 3 5/16 backspace, about $95
184-065703-440, 15x3 1/2, 1 1/2 backspace, about $125
Wagner (check your local parts store) part #f76641
5.11 How do I convert manual to power brakes or vice-versa?First get the brake booster, master cylinder, and combination valve. If you have a parts car, you might also want to grab the brake lines and pedal assembly.
On the brake pedal, the master cylinder pin can attach in one of two places. For manual brakes, it attaches to the larger hole on top; for power brakes, it attaches to the smaller hole on bottom.
5.12 Where can I refill or replace my spare tire inflator?The inflator part number is 9590679 the list price is $48.75. It can still be ordered from a dealer.
Some places will still refill them (with Nitrogen)--try places that refill fire extinguishers.