Frequently Asked Questions
Find answers to Frequently Asked Questions for First Generation Firebirds that have been asked and answered on FGF. Special thanks needs to be given to all the FGF members who took the time to respond to other member's questions.
Wheels, Brakes, and Axle - Brakes
Short answer: Bench-bleed the master cylinder first; if the pedal still sinks to the floor afterward, suspect the master cylinder itself — even a brand-new one.
Bench-bleeding the master cylinder:
- Secure the master cylinder dead level (this is very important).
- Attach a tube to each brake-line outlet and route the other end back into its own reservoir well.
- Fill each well with fresh brake fluid.
- Push the plunger (pedal pushrod) in with an appropriate tool.
- Repeat until no more bubbles appear.
- Plug the outlets and put the lid on.
If the pedal still goes to the floor: test the master cylinder by plugging the brake-line outlets and pressing the pedal; if it sinks, fluid is bypassing the internal seals. (One member’s new master was the culprit — the old one bled fine.)
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Content last modified: June 13, 2026 at 10:06 am
Short answer: The brake-system valves explained:
- Metering valve — the round cylinder next to the master cylinder; holds back front-disc pressure so the rear drums make full contact first. All 1969–70 GM disc cars have it.
- Proportioning valve — a small square inline valve under the driver’s seat (on 1969 ‘birds, on the left subframe rail) in the rear-brake line; slightly reduces rear braking on nose-heavy cars. Not all 1969–70 GM cars had it (V8/AC cars did).
- Distribution block / warning-lamp switch — all 1967+ dual systems (including 4-wheel drum) have it; the two lines from the master become three out (one rear, one to each front wheel).
- Combination valve — from 1971, GM combined the distribution block, warning switch, metering, and proportioning valves into one unit (mounted on the frame, hard to see).
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Short answer: A pedal that nearly hits the floor with a weekly need to re-bleed, plus a tiny leak that seems to come from the metering valve, can actually be the calipers — one member chased a phantom “leak” for years (the front disc section kept emptying and fluid appeared at the master) until rebuilding the disc calipers fixed it. Air was getting in through the caliper seals and pushing fluid back out the master, mimicking a leak there.
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Short answer: The pedal is pushed back up (to release the brake-light switch) by the pushrod from the booster/master — not just a spring. If the lights won’t shut off, remove the clevis pin, unthread the clevis to lengthen the rod a quarter-turn at a time, and recheck until the pedal returns far enough to release the switch.
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Short answer: If clamping the front flex lines gives a solid pedal (and the warning light then works), the problem is at the front calipers — and the master cylinder bore size is not the issue. The likely cause: the 4-piston calipers are reversed side-to-side, trapping big air pockets.
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Short answer: No — you can’t keep the drum master cylinder. Drum systems use a residual check valve (5–7 psi) to keep the wheel-cylinder cups seated; a disc/drum system only keeps that valve in the rear (drum) circuit, because residual pressure on discs would drag and overheat them. So use a disc/drum master cylinder (or a 4-wheel-disc master for 4-wheel disc), plus the proportioning/metering valves and warning-light switch appropriate to the system.
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Short answer: The calipers mount toward the rear of the car. If they’re hitting the stabilizer bar, they’re on the wrong sides — swap the caliper, backing plate, and caliper bracket left-to-right (the spindle is machined the same either side, so it doesn’t matter).
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Short answer: Rebuilding a caliper is just replacing the seals — unless the piston bore is corroded/damaged, in which case it must be re-sleeved (~$35/piston, pricey). To bleed air from behind the pistons:
- Two-person: one pumps to a firm pedal and holds; the other opens the bleeder until the pedal drops, then re-tightens; repeat until fluid runs clear.
- One-person: run a clear tube from the bleeder into a bottle with ~1/4″ of fluid (tube submerged), open the bleeder, pump 4–5 times, refill the master, repeat until clear.
- Keep the bleeder at the highest point; tapping the caliper lightly with a hammer floats bubbles toward it.
Also check the proportioning valve — one member’s was sucking air without leaking fluid, defeating many bleed attempts.
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Short answer: The classic bolt-in front disc swap recreates a factory 1969 Firebird disc setup using GM A-body or X-body donor parts. Shopping for everything as “1969 Firebird with factory disc brakes” simplifies sourcing. Pieced together from a salvage yard it can run as little as ~$100–500; a complete kit is ~$350 used or ~$795–825 new.
Donor cars: 1969–72 A-body (Chevelle/Malibu/Monte Carlo, Cutlass/442, Skylark/GS, Tempest/LeMans/GTO/Grand Prix, F-85), 1968–74 X-body (Nova, Apollo, Ventura/GTO, Omega), or a 1969 F-body. Avoid 1973+ A-body and 1975+ X-body (redesigned spindle won’t fit) and big B-bodies/Cadillacs (spindles too tall, wrong bolt circle). Earlier cars have the pricier, rust-prone 4-piston caliper; first-gens use the “early” GM single-piston corporate caliper.
What to gather:
- From the donor: spindles, calipers (fine as cores for rebuilds), caliper brackets, rotors, master cylinder, booster (if you want power), combination/proportioning valve, and dust shields/backing plates. All but the spindles, caliper brackets, and dust shields can serve as cores. (New spindles, brackets, and shields are available from Classic Industries/NPD if needed.)
- Keep from your car: the F-body steering arms — first-gen F-bodies (and X-bodies) are rear-steer, so bolt your own drum-brake steering arms onto the donor spindles (keep left/right straight).
- Buy new: brake pads (Hawk/EBC/Performance Friction); new front flex hoses (never reuse old ones — but take the old ones along to match the ends); DOT 3 fluid (Ford HD DOT 3 is well regarded; avoid silicone); Timken inner/outer bearings, races, and seals; high-temp grease; new rotors (the originals are often unusable).
Master cylinder & proportioning valve — get these right:
- You must use a disc-brake master cylinder (the power version if you have power brakes). A drum master “works” but isn’t right — it has a residual check valve that keeps ~5–7 psi in the system (to seat drum wheel-cylinder cups), and on discs that constant pressure drags the pads, causing wear and heat.
- Never use a drum/drum proportioning valve on a disc/drum car — the wrong front/rear balance causes severe rear-wheel lockup. Use the disc combination/proportioning valve, or keep the drum warning-light/divider block and add an aftermarket adjustable proportioning valve in the rear line only.
- Valve type varies by donor year: 1969–70 A-body and the 1969 F-car used separate valves; 1971–72 A-body used a combination valve. (The 1968 V8 A/C disc Firebirds used a different separate valve.)
Booster & pedal rod: the booster is the same except for pushrod length — compare the new booster to the one on your car (the pedal-to-booster pushrod can differ ~1″), and use the correct long/short pin for your master/booster combo. A-car boosters reportedly have an “A” stamped on the firewall pushrod. A high-volume “fat boy” master (1967 Vette / 1967–68 Z28 / J52/J56) is a nice upgrade over the standard 1969 disc master.
Control arms: you do not need to change them — just take the spindle and everything attached to it (dust shield, caliper bolts, etc.). Remove the upper and lower ball joints and take everything in between.
Wheels: some 14″ wheels rub the single-piston caliper (a 14×7 Rally II clears); all 15″ clear. Disc brakes push the track out ~1/4″, so very wide/deep wheels may get tight. (Admin note: Rally II rim code “JC” was used on both disc- and drum-equipped 1968 Firebirds.)
Fitment gotchas (from a member’s detailed 1968 build with 1969 donor parts): control arms weren’t needed (swapped only as a bonus); the 1969 flex-line brackets weren’t a direct bolt-on to the 1968 subframe (locating them took guesswork); rear axle hard lines needed minor rebending for the 8.5″ 2nd-gen housing; a couple of fittings didn’t match the prop-valve ports and needed adapters or a shop-made line; and stainless lines are harder to bend/flare than mild steel. El Camino 1-piece rotors are a good direct replacement for the too-thin 2-piece originals.
| Item | Cost |
|---|---|
| Used parts (rotors [unusable], calipers [cores], brackets, control arms, hose brackets) | $180.00 |
| Calipers x2 (Bendix rebuilds) | $30.00 |
| Beadblasting | $50.00 |
| Rebuilt master & booster (incl. plating) | $125.00 |
| Stainless brake lines (front, rear, axle) | $239.00 |
| Braided stainless flex lines (front & rear) | $70.00 |
| Front brake pads (Performance Friction) | $24.00 |
| Front wheel bearings & seals | $30.00 |
| Fabricate new LH hardline | $15.00 |
| Misc. flared-nut adapters | $12.00 |
| 1-piece front rotors (Bendix) | $90.00 |
| Proportioning valve (Master Power) | $125.00 |
| Combined total | $990.00 |
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Bulletin 68-I-37 — Pontiac Motor Division Dealer Service Information Bulletin, Section 5, dated January 31, 1968. Attention: Service Manager.
Subject: 1968 Tempest Rear Brake Drums.
Short answer: Some early-production 1968 Tempests were built with Kelsey-Hayes rear brake drums stamped “F” instead of the specified “KH” identification. Future drums will use the combined code “KH-F.” All three codes (“KH,” “F,” or “KH-F”) represent acceptable Kelsey-Hayes drums — a variation between right and left drums is not a concern.
Pontiac Engineering has advised that certain early-production Tempests were built using Kelsey-Hayes rear brake drums coded with identification letter “F”, rather than the specified identification “KH”.
Future Tempest rear drums manufactured by Kelsey-Hayes will incorporate the code letters “KH-F” as an optional identification.
Since Kelsey-Hayes drums with any one of these codes (“KH”, “F”, or “KH-F”) are installed in production, there should be no cause for concern regarding the variation of code between right and left rear drums.
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Bulletin 68-I-47 — Pontiac Motor Division Dealer Service Information Bulletin, Section 5, dated February 28, 1968. Attention: Service Manager.
Subject: Complaints of Low Brake Pedal.
Short answer: Many low brake pedal complaints on power-brake-equipped vehicles are psychological in nature — the depressed floor area directly below the pedal is a design feature. Pedal height should be measured as described below; pedal height must not be adjusted, and if it does not meet specification, a full brake system inspection per the 1968 Pontiac Service Manual is required.
The area of the floorboard located directly below the brake pedal is depressed by design, allowing full travel of the brake pedal in the fully applied position and permitting the driver to pivot his foot from the accelerator to the brake with no appreciable raising of the foot (see the scan below, Fig. 1).
Correct method to check brake pedal height (see the scan below, Fig. 2): With the pedal in the fully released position, measure from the lower (inner) edge of the pedal pad to the raised area of the floor. The distance should be 2½″. This measurement may vary slightly depending on the amount of compression applied to the carpet and jute.
It is important that no attempt be made to adjust pedal height.
The specification requires that the brake pedal clevis (which connects the pedal arm to the pushrod) be torqued at the clevis stop nut to 90 lb-in. This applies to all 1968 applications.
If pedal height does not meet specifications, perform a thorough check of the brake pedal and associated parts (mounting bracket, clevis adjustment, etc.) and perform repairs as outlined in the 1968 Pontiac Service Manual.
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Bulletin 68-I-50 — Pontiac Motor Division Dealer Service Information Bulletin, Section 5, dated March 19, 1968. Attention: Service Manager.
Subject: Brake Drum Turning — Front Hub and Drum Assemblies.
Short answer: When turning a front brake drum on a lathe, the drum must be torqued securely to the hub using five flat washers and five stud nuts torqued to 35 lb. ft., eliminating any movement between drum and hub during the turning operation.
When turning a front brake drum, install five flat washers and five stud nuts on the wheel studs and torque to 35 lb. ft. This mounting procedure eliminates any possibility of movement between the drum and hub during the turning operation.
See the figure in the original bulletin for the proper method of mounting the front hub and drum assembly on a drum lathe.
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Bulletin 68-I-69 — Pontiac Motor Division Dealer Service Information Bulletin, Section 5, dated May 13, 1968. Attention: Service Manager.
Subject: Service Procedures — New Type 1968 Tempest and Firebird Front Brake Drums — Limited Production.
Short answer: A new separable front hub-and-drum assembly is being installed on a limited run of 1968 Tempest and Firebird models. Unlike standard units, the drum can be removed separately from the hub; the alignment index mark on the drum web must line up with the hole in the hub on reassembly. Approximately 10,000 sets are being installed at each plant.
Affected Vehicles
| Plant | Vehicle | V.I. Number |
|---|---|---|
| Pontiac, Michigan | Tempest | P268122 (8-Cyl.) / P612794 (6-Cyl.) |
| Lordstown | Firebird | 0154610 (8-Cyl.) / 0611614 (6-Cyl.) |
Brake Drum Turning or Replacement
Hub Bolt Replacement
- Remove the hub bolt(s) with a press or hammer. These bolts are not peened into the hub. Use care not to damage the wheel mounting surface on the hub flange.
- Install new serrated bolt into the hole in the hub. Tap lightly with a hammer to start bolt serrations into the hole, making sure that the bolt is square with the hub flange.
- Press bolt into the flange until the head is fully seated against the hub flange (see Fig. 2).
Front Hub Bearing Replacement
The procedure for replacing front bearings and races is the same as that shown in Section 3, page 3-5, of the 1968 Pontiac Service Manual.
Parts Information
| Description | Part No. | Group No. |
|---|---|---|
| Drum | 3853799 [M-CX] | 5.809 |
| Hub Assembly | 3887867 [Z-CX] | 6.307 |
| Front Hub Bolt | 3851677 [Z-CX] | 5.812 |
Reference:
- 1968 Pontiac Service Manual Section 3 Page 3-5
Content last modified: June 13, 2026 at 10:06 am
Bulletin 68-I-Special — Pontiac Motor Division Dealer Service Information Bulletin, Section 5, dated November 22, 1967. Attention: Service Manager.
Subject: Warranty Policy Clarification for Brake Drum Turning.
Short answer: This bulletin establishes uniform warranty policy for brake drum turning: grooves under .020″ deep need not be turned; out-of-round drums should be turned a maximum of .010″ per side before replacement; hard spots need not be removed unless raised. Always measure drum diameter and eccentricity before cutting.
This bulletin establishes a uniform policy to be adhered to when making adjustments under warranty for brake drum turning. Measuring the brake drum — both for total diameter and eccentricity — is essential before any turning. Reference is made to previous bulletin 67-T-22, covering the procedure to correct brake shudder. Many drums have been cut beyond specifications because they had been previously cut and no measurement was made.
The following policies will apply when turning brake drums:
- Scored Drums — Grooves less than .020″ deep will not affect brake operation, and drums should not be turned for this condition.
- Out-of-Round Drums — Determine if shudder is caused by front or rear drums (use parking brake to make determination). Turn both front (or rear) drums the same amount, but in no case take more than a .010″ cut (.020″ diameter). If the problem is not corrected after taking a .010″ cut, replace the drum.
- Drums with Hard Spots — Drums containing hard (dark) spots indicate overheating. These spots, unless raised, do not affect brake operation and need not be removed. When turning drums with hard spots for a brake shudder complaint, use a cutting tool specifically manufactured to remove hard spots.
Content last modified: June 13, 2026 at 10:06 am
Short answer: Yes — you can convert to front discs and keep 14″ Rallys. The roadworthy choice is the 1969 Firebird/Camaro single-piston system (shared with 1969–72 A-bodies and 1969–~74 Nova X-bodies); most 14×6 and 14×7 Rally II wheels clear it (a couple of wheel codes are noted incompatible — ask the group for the specifics).
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Short answer: GM’s own names are inconsistent, which is why this valve has several. The rear valve on the frame rail of V8/AC cars is called both “rear brake pressure proportioning valve” (parts book) and “rear brake pressure regulator” (illustrations catalog); tech textbooks call it the “proportioning” valve.
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Short answer: The “round piece” under the master cylinder is the metering valve (front) — it holds off the front discs until the rear drums engage. A separate proportioning valve (rectangular, on the frame rail under the driver’s seat) was fitted only to 1967–69 V8 + A/C + disc cars to limit rear pressure and prevent the nose-heavy car’s rear wheels from locking.
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Short answer: The round metering valve under the master cylinder can fail (leaking, or sucking air) — one member went through four rebuilt units. Members who bypassed it reported the pedal felt firmer and they couldn’t tell a difference in normal street driving (on dry pavement). There’s a safety/originality debate, though — the engineers fitted it for a reason.
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Short answer: Clean them up and brush on POR-15 (a rust-killing coating that bonds to bare metal and acts as primer + color — comes in black, gray, silver), then a clear coat. Two coats plus clear looks great.
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Short answer: Replacement boosters often have the wrong pedal-rod length (e.g., 7.75″ vs the correct ~5.75″ for a 1969). One member’s fix: a section of thick-wall tubing sized to the rod’s OD — cut the rod ~2″ from the end, set the master/rod-end at the correct length with the tube joining them, mark, and weld both ends — which let him fit a smaller-diameter ’84 Z28 booster/master (clears the valve covers nicely).
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Short answer: The booster was cadmium plated — a silver with a slight gold hue (“yellow cad”), not as yellow as some other GM boosters (Jim Mattison discusses the correct color in the magazine articles on his 1967). The spray-can “cadmium” paints are only a look, take 5–6 cans and several steps, and don’t match real plating.
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Short answer: If the master cylinder is bolted directly to the firewall, it’s manual. If it’s bolted to a saucer-shaped vacuum booster with a hose running to the top of the engine, it’s power.
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Short answer: A car that pulls or fishtails under hard braking, with all brake parts already replaced, usually comes down to the front drum brakes being out of adjustment (they’re not self-adjusting in front on 1967–69 and aren’t forgiving) — or a front-end issue.
- Diagnose in an empty lot: brake hard and note which way it pulls / which wheel locks. Use the parking brake (rear/drum only) to check if the rears are the issue. Pump the pedal first — if it stops straighter, there’s air in the system.
- Manually adjust the front drums (and check the “self-adjusting” rears anyway). A veteran trick after a drum rebuild: drive while braking firmly and repeatedly to seat the shoes.
- Also check the spindle ball-joint tapers (can wear out-of-round) and upper control-arm bushings (cause erratic steering). Finish with a proper 4-wheel alignment.
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Short answer: A 2nd-gen F-body rear (the 8.5″ 10-bolt) drops into a first-gen and is stronger, cheaper, and more available than the first-gen 8.2″ — but you must relocate the spring perches, match the transmission/U-joint type, set pinion angle, and shorten the driveshaft.
- Width: measured overall only ~1/4″ wider (1/8″ per side) — not the “1–2 inches” often claimed.
- Multi vs mono leaf: 1968–81 are multi-leaf; a 1967 mono-leaf car needs its old perches reused or a multi-leaf conversion.
- Spring perches: the 2nd-gen perches sit ~2¾” farther out, are ~1/2″ taller (lowers the car that much), and (unlike first-gen) have no built-in angle — so cut them off and weld on first-gen perches, ideally setting the angle with the car’s weight on the springs. Set pinion angle carefully.
- U-joint/driveshaft: match the donor to your trans (350 vs 400 use different U-joint sizes; may need a big/little U-joint); the 2nd-gen sits ~1″ longer axle-to-U-joint, so shorten/replace the driveshaft (and refresh U-joints + trans output seal while you’re there).
- Brakes: parts are essentially the same — order them as the donor year (e.g., 1977); use the donor backing plates/drums; but get brake lines for your original first-gen year so routing matches, and move the rear-cover-bolt line bracket over before installing.
- Also: replace cheap seals (local parts store, ~$1–2), check bearings, recalibrate the speedo for the new ratio, and pull the gas tank as a precaution (especially when changing springs — you’ll likely torch the old bolts).
Parts to have ready:
- Rear end: seals, bearings (optional), brake lines & parts, new posi tag, gear oil + limited-slip additive, cover gasket, backing-plate bolts/nuts.
- Swap: U-bolts & nuts, T-bolts & nuts, upper/lower spring pads, trans output-shaft seal.
- New springs: front eye bushings, front bracket bolts & clip nuts (Ames carries both), eye bushing bolt/nut, shackles/bolts/nuts, rear shackle bushings.
- Gas tank: straps, attaching-bolt kit, tank-to-body anti-squeak kit.
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Short answer: When freshening a junkyard 1969 disc setup for a 1968: vacuum-test the booster (if it leaks, use it as a core); use the master cylinder and calipers as core exchanges for reliable rebuilt/new parts; replace the flex hoses (old ones fail when you need them most); and replace pitted/rusted caliper pins/bolts (parts-store “HELP!” line).
- Cleaning: have brackets and spindles hot-tanked/bead-blasted, then paint (POR-15 works well). The booster’s correct finish is silver cadmium (Eastwood sells a cad-look kit; most cheap rebuilds are painted black, or pay extra to have one plated).
- Rotors: the original 2-piece rotors (the ones with the groove) are hard to find and costly; 1-piece replacements (1969–72 Nova/Chevelle/LeMans/Omega/Ventura/Skylark) work fine. Have rotors checked for warpage/thickness — if good, just clean them (many shops turn to minimum thickness, so they can’t be turned again).
- Valve: stock proportioning valves are non-adjustable — use the disc unit from the donor or buy new (Master Power). Two types exist: one with separate front-line outlets, and one that relies on a second small valve to split the single front line.
- Inspect ball joints and front-end parts (and the rear brakes) while you’re in there.
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Short answer: For a safety upgrade, the 1969 F-body single-piston front-disc setup is the practical choice (the correct-for-1968 4-piston system is more work than needed; 4-wheel discs are nice but unnecessary). Get the master cylinder, booster, and valves from a 1969 Firebird/Camaro, and the disc spindles from the same car or a 1969–72 A-body (Chevelle, Skylark, GS, LeMans, Tempest, GTO, Cutlass, F-85, 442) — A-body spindles are the same, just bolt your Firebird steering arm onto them.
- Donors: 1969 F-body; 1969–72 A-body; pre-1974 X-body (Nova/Apollo/Omega/Ventura); Grand Prix and 1970–72 Monte Carlo. Try to get the whole system: spindles, brake lines, bracket, master cylinder, and booster with valve.
- Valves: 1969–70 GM disc cars used separate metering, proportioning, and warning-light pieces; from 1971 GM combined them into one “combination valve” on the frame rail. Some 1969 V8/AC cars had an extra rear proportioning valve on the left frame rail under the driver’s seat.
One member’s build: 1969 used parts (calipers as cores, El Camino 1-piece rotors replacing the too-thin 2-piece originals), braided stainless hoses, Performance Friction pads, stainless lines, rebuilt master/booster (replated silver cad — the correct Pontiac finish). Trickier spots: rear axle hard lines needed rebending for the 8.5″ housing; some line fittings didn’t match prop-valve ports (adapters/shop-made line); the 1969 flex-line brackets weren’t a direct bolt-on to the 1968 subframe.
| Item | Cost |
|---|---|
| Used parts (rotors [unusable], calipers [cores], brackets, control arms, hose brackets) | $180.00 |
| Calipers x2 (Bendix rebuilds) | $30.00 |
| Beadblasting | $50.00 |
| Rebuilt master & booster (incl. plating) | $125.00 |
| Stainless brake lines (front, rear, axle) | $239.00 |
| Braided stainless flex lines | $70.00 |
| Front pads (Performance Friction) | $24.00 |
| Front wheel bearings & seals | $30.00 |
| Fabricate new LH hardline | $15.00 |
| Misc. flared-nut adapters | $12.00 |
| 1-piece front rotors (Bendix) | $90.00 |
| Proportioning valve (Master Power) | $125.00 |
| Combined total | $990.00 |
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Content last modified: June 13, 2026 at 10:06 am
Short answer: Yes — on a 1968 with power brakes the booster vacuum line runs through a small clamped bracket attached to the throttle-cable bracket (as on 1967s), and members confirm this appears original. The pre-formed hose attaches at about the 9 o’clock position on the booster (the valve points toward the right side of the car, not straight up).
Any proposed updates, changes, pictures, and/or corrections, please use our comment section below (may need to click on permalink to access comments feature). Information is subject to change and offered as is without any warranties or guarantees. Please review our Term's Of Use for more information.
Content last modified: June 13, 2026 at 10:06 am
Content last modified: June 9, 2026 at 7:10 am
