Brakes on a UAZ work hard. Heavy axles, tall tires, mud, water and long descents punish weak links. A clean, adjusted and well-bled system turns a wandering van into a confident tool. Ignore it and you get pull, fade and long‑pedal panic on mountain roads.
What you’re working with
Typical UAZ layouts use a vacuum booster, single or tandem master cylinder, front discs with rear drums on newer Hunter and Patriot, and drums all round on many Bukhanka Classics. Expect hard steel lines along the frame and three flexible hoses that age out. Rear brakes use manual adjusters. Some trucks have a load‑sensing proportioning valve on the rear axle.
Russian shop tip: Before chasing gremlins, verify basics. Fresh DOT 4 fluid, healthy booster vacuum hose, tight wheel bearings, free slider pins, correct rear shoe adjustment, intact shrouds and shields. Most “mystery” problems vanish once these are right.
Maintenance rhythm that works
- Every month or after deep mud/water: quick visual, pad/shoe thickness, wet backs on drums (wheel‑cylinder leaks), torn dust boots, stone damage on lines and hoses.
- Every 10,000 km: clean and lube caliper sliders, de‑glaze pads/shoes, check rotor runout and drum condition, inspect and adjust rear shoes, check handbrake cables for corrosion and freeze.
- Every 12 months or 20,000 km: full fluid flush with DOT 4 (avoid DOT 5 silicone). Replace any hose older than 8–10 years.
- Before expeditions: replace marginal hoses, carry spares, torque‑check everything, and bleed until fluid runs perfectly clear.
Symptom guide you can trust
- Soft or sinking pedal at a stop: internal leak at the master cylinder or air trapped at a high point. Slow sink under steady pressure points to master seals.
- Spongy pedal that improves with pumping: air in system, swollen hoses, or rear shoes way out of adjustment.
- Pulls to one side: sticking front caliper, seized sliders, contaminated pads, or a collapsed flex hose acting as a one‑way valve.
- Vibration while braking: warped rotor, out‑of‑round drum, uneven pad material transfer, or loose wheel bearings.
- Hard pedal with poor braking: vacuum booster issue, vacuum leak, or blocked check valve. With engine running, a hiss as you press the pedal = leak.
- Overheats/fade on descents: dragging caliper, shoes too tight, glazed friction, or contaminated/boiling fluid.
Russian shop tip: If bleeding never clears a spongy feel, crack the line at the highest junction or proportioning valve and bleed there. Air pockets love high spots.
Rear drum brakes: setup that actually works
- Remove drums; clean with brake cleaner; inspect for grooves and heat checks.
- Replace any damp wheel cylinder immediately—don’t “wait and see.”
- Lightly sand shoes to break glaze. De‑rust backing‑plate pads and add a tiny smear of high‑temp brake grease where shoe backs ride.
- Free the star adjusters. Heat and penetrating oil if needed; anti‑seize the threads.
- Refit and adjust until the wheel just kisses the shoes, then back off to a light, even drag both sides.
- Re‑check after a short drive as shoes seat.
Russian shop tip: Rear shoe misadjustment causes long pedal more often than air. Adjust first, then bleed.
Front discs: checks that save weekends
- Pull slider pins; clean and grease with proper caliper grease. Seized sliders are the number one cause of pull.
- Verify pistons push back smoothly with a clamp. Grit under a dust boot = rebuild time.
- Check pad ears/backing plates for rust‑jacking that wedges pads in the bracket. Wire‑brush bracket lands; apply a thin film of brake grease.
- Use a 6‑point bleeder wrench; keep two spare bleeders in the tool roll.
- Don’t hammer wheel nuts with a rattle gun—uneven torque can print pad material and mimic “warped rotors.”
Bleeding order, fluid and hose reality
Start at the wheel furthest from the master and move closer (on most LHD: RR → LR → RF → LF). If your system is diagonally split, follow that layout.
- Clear bottle with submerged hose so you can see bubbles.
- Keep reservoir topped up; final pass with slow strokes to avoid foaming.
- Finish with an overnight firm‑pedal test; any drop means air or a leak.
- Fluid compatibility: DOT 3, DOT 4 and DOT 5.1 (glycol) can mix. Do not mix DOT 5 (silicone). If DOT 5 ever went in, plan a full strip/rebuild.
- Moisture & boil: old fluid boils. If pedal lengthens on descents but recovers when cool, you boiled the fluid—flush now.
- Hoses: old rubber swells internally and acts like a one‑way valve. If a wheel drags or releases slowly, suspect the hose. Replace flex lines as a set.
- Hot‑bleed: do a short drive, then bleed warm—micro‑bubbles move easier.
- ABS Patriots: some air pockets live in the modulator; a scan‑tool “ABS bleed” may be required.
Russian shop tip: Zip‑tie the pedal down overnight, then do a gentle final bleed in the morning. It helps micro‑bubbles migrate.
Advanced checks most people skip
- Master pushrod free play: Too long and the compensation port stays closed; brakes drag when hot. Quick test: after a short drive with dragging brakes, crack a front bleeder—if pressure blasts out and wheels free, the pushrod is misadjusted.
- Wheel‑bearing play → pad knock‑back: Loose front bearings push pads away on corners/rough tracks, giving a long first pedal then a good second. Set bearings before chasing air.
- Bleeder location sanity check: Caliper/wheel cylinder on the wrong side puts the bleeder at the bottom. You’ll never purge air. Bleeders must be at the top.
- Rear axle oil vs brake fluid: Wet drum could be brake fluid (slick, evaporates) or axle oil (strong smell, persists). Axle oil = leaking hub seal; cleaning shoes won’t fix it.
- Rotor/drum limits: Don’t machine beyond spec. Thin rotors warp easier; oversize drums may need shoes arced to match or you’ll never get a firm pedal.
Off‑road, water and load
- After river crossings, lightly drag brakes to dry them. Drums can hold water and grab hard on the first stop.
- Deep mud eats seals—plan a post‑trip inspection of dust boots, wheel cylinders and sliders.
- Long descents in low range: rely on engine braking; don’t ride the pedal. If you smell resin, stop and cool with transmission in gear and wheels chocked.
- A loaded Bukhanka works the rear drums harder. If fitted, ensure the load‑sensing proportioning valve linkage moves freely and is set to factory ride height.
Russian shop tip: If you must pressure‑wash mud, don’t blast directly into dust boots and caliper seals—you’ll inject water past them.
Reliability upgrades that are worth it
- Quality hoses: fresh rubber or braided lines reduce expansion and improve feel.
- Pads/shoes: choose reputable friction. Cheap linings glaze fast and fade when hot; on heavy vans, a decent semi‑metallic or low‑metallic pad works best.
- Heat management: intact splash shields keep grit off seals and out of drums.
- Hardware kits: new springs/hold‑downs for rear drums stop chatter and uneven wear.
- Hard lines: CuNiFer (copper‑nickel) lines flare easily, resist salt and don’t seize like steel.
- Real fluid: DOT 4 from a sealed bottle only. Discard opened bottles after a month.
Noise, fade and stability
- Glaze = no bite: If brakes squeal or feel wooden, lightly de‑glaze pads/shoes and rotors/drums.
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Bedding‑in procedure:
- 10 gentle stops from ~60 → 20 km/h, then cool 5 minutes,
- followed by 4–5 firmer stops. Don’t sit on the pedal while stationary; roll slightly to avoid hot‑spot printing.
Vacuum booster checks
- With engine off, pump pedal until hard. Start engine: pedal should drop slightly—if not, suspect the booster or one‑way check valve.
- Verify strong vacuum supply and intact hose; cracked hoses mimic a failing booster.
Winter specifics
- Use grille covers in extreme cold to stabilize temps; both mechanical and electric fan setups benefit.
- Handbrake cables freeze—lube sheath ends pre‑winter and route away from spray.
Russian roadside fixes (safety‑critical, limp‑home only)
- Isolate a leak: Use a proper line clamp on a flex hose, or screw a spare flare plug into a leaking hard‑line port at a junction block. You’ll have reduced braking—drive slowly.
- Failed booster: Pull and cap the vacuum hose. Pedal goes hard but consistent; you can reach a shop.
- Temporary flare: Carry a mini flaring tool, M10x1 nuts and unions. A short pre‑flared “patch line” can bypass a rusty section.
- Stuck adjuster: Heat + oil + patience. Forcing the star through the shoe web ruins it.
- Stripped drum screws: Use the two M8 jacking holes to push the drum off—don’t hammer bearings.
- Stripped bleeder: Carry a spare bleeder screw of the correct thread. Tape one to the jack handle.
Tools that save hours
- Brake spoon and spring pliers for drums
- 8/10/11 mm flare‑nut wrenches
- Hand vacuum/pressure bleeder
- Dial indicator for hub/drum/rotor runout
- Mini tube cutter + compact flaring kit
- Caliper pin kit + high‑temp caliper grease
Parts to carry on expeditions
- One front flex hose and the rear axle hose
- One short pre‑flared hard line with M10x1 fittings and a few unions
- Two bleeder screws + copper washers
- Small bottle of DOT 4 in a zip bag
- Rear wheel‑cylinder rebuild kit or spare cylinder
- One caliper slider‑pin kit
- Hand vacuum pump or compact one‑man bleeder
Russian shop tip: Label spares in clear bags. In the rain, in a ditch, you won’t guess thread sizes correctly.
Final road‑test routine after any brake work
- Low‑speed straight‑line stops—no pull, no clunks.
- Medium stops to seat pads/shoes, then a cooling run.
- One hard stop from highway speed—should be straight and confident, no steering shake.
- Re‑check wheel temps by hand (carefully). One hot corner = dragging issue.
- Next morning, firm‑pedal hold for 30 seconds. Any slow sink means air or a master‑cylinder problem.