Technical Guides - MK4 Jetta GLI

Engine

1.8T Timing Belt Replacement

ADVANCED · 4-6 hours

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Complete timing belt kit installation with water pump, tensioner, and idler. Step-by-step with alignment marks.

PROCEDURE

Remove engine covers, serpentine belt, and accessories for access
Set engine to TDC on cylinder 1 — verify cam and crank alignment marks
Remove upper and lower timing covers (10mm bolts)
Mark belt rotation direction if reusing (not recommended)
Loosen tensioner and remove old belt, tensioner, idler, and water pump
Install new water pump with fresh O-ring (15 Nm)
Install new tensioner (25 Nm) and idler roller
Route new belt: crank → water pump → tensioner → exhaust cam → intake cam → idler
Set tensioner to proper tension using alignment tab/tool
Rotate engine 2 full revolutions by hand — re-verify all alignment marks
Reinstall covers, accessories, and serpentine belt

PARTS NEEDED

06B 109 119 B — Timing belt (Continental/Gates)
06A 121 012 G — Water pump (Graf or Hepu)
06D 109 243 C — Belt tensioner (INA/SKF)
06B 109 244 — Idler roller
Coolant (G12/G13) for refill

This is an interference engine — belt failure = bent valves. Follow VW service interval (every 75,000 miles or 5 years).

Always replace water pump with timing belt — labor is the same, and WP failure causes belt failure.

AWP Full Torque Specs OEM Parts Catalog Engine Reference

K04 Turbo Upgrade Guide

ADVANCED · 8-12 hours

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Upgrading from K03s to K04 turbo with supporting modifications, tuning, and fueling requirements.

PROCEDURE

Flash K04 software (APR, Unitronic, or Eurodyne) before hardware install
Remove front bumper and intercooler for turbo access
Disconnect oil feed/return lines, coolant lines, exhaust downpipe, and intake piping
Remove exhaust manifold heat shield and turbo-to-manifold nuts (3× 13mm)
Remove K03s turbo assembly
Transfer oil feed banjo fitting (use new crush washers)
Install K04 turbo with new gasket to exhaust manifold (25 Nm)
Reconnect oil feed (new banjo bolt + restrictor), oil return, and coolant lines
Install upgraded front-mount intercooler (FMIC) with piping
Install 3" downpipe (catted or test pipe)
Upgrade diverter valve to 710N if not already done
Install upgraded injectors (550cc minimum) and fuel pump if targeting 300+ WHP
Start engine, check for boost leaks with VCDS boost test
Verify tune is loading proper boost targets via VCDS logging

PARTS NEEDED

K04-001 or K04-023 turbo
K04 exhaust manifold (or K03/K04 hybrid setup)
Front-mount intercooler kit
3" stainless downpipe
710N diverter valve (06A 145 710 N)
New oil feed line with crush washers
Upgraded injectors (550cc+ for 300 WHP target)
ECU tune (K04 file required)

Do NOT run K04 hardware without a K04-specific tune. The stock tune cannot control the larger turbo properly and will cause overboosting.

AWP Engine Specs Camshaft Upgrades All Engine Codes

1.8T Camshaft & Head Upgrade Reference

REFERENCE · VIEW FULL GUIDE →

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AWP Engine - Complete Technical Specifications

REFERENCE · VIEW FULL GUIDE →

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Brakes

312mm Big Brake Upgrade

INTERMEDIATE · 3-4 hours

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Upgrading from 288mm to 312mm front brakes using Audi TT/R32 carrier brackets with MK4 calipers.

PROCEDURE

Raise vehicle and remove front wheels
Remove caliper (2× 13mm guide pin bolts — 25 Nm) and hang with wire
Remove caliper bracket (2× 18mm bolts — 115 Nm)
Remove 288mm rotor (may need persuasion — tap with rubber mallet)
Install 312mm Audi TT carrier bracket to knuckle (115 Nm)
Install 312mm rotor (clean hub mating surface first)
Reinstall MK4 caliper with new pads onto 312mm carrier
Torque guide pin bolts to 25 Nm
Verify pad clearance — should be 1-2mm each side
Bleed brakes if lines were disconnected
Bed pads: 10 stops from 40 mph with moderate pressure, then 5 stops from 60 mph

PARTS NEEDED

8N0 615 125 / 126 — Audi TT 312mm carrier brackets (L/R)
1J0 615 301 M — 312mm front rotors (or Zimmermann equivalent)
Brake pads (Hawk HPS, EBC Redstuff, or Textar OEM)
Brake hardware clips (new recommended)

312mm rotors require minimum 15" wheels. Stock 15" steel wheels will NOT clear — verify wheel clearance before ordering.

OEM Parts Catalog Transmission Reference

Brake Fluid Flush Procedure

BEGINNER · 45 minutes

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Proper bleeding sequence and fluid specs for ABS-equipped MK4. Pressure and gravity bleed methods.

PROCEDURE

Use DOT 4 fluid (ATE Typ 200 or Motul RBF 600 for track use)
MK4 bleeding sequence: RR → LR → RF → LF (farthest to nearest)
Open bleed nipple (10 Nm to close), pump pedal 3-4 times, hold
Open nipple, close when pedal hits floor
Repeat until fluid runs clear (no bubbles)
Top off reservoir between each corner
Final pedal should be firm at 1/3 travel

PARTS NEEDED

DOT 4 brake fluid (1 liter minimum)
11mm bleed wrench
Clear tubing and catch bottle

Suspension

Coilover Installation Guide

INTERMEDIATE · 4-5 hours

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Step-by-step coilover installation for MK4 platform. Front strut and rear shock replacement with alignment notes.

PROCEDURE

Measure and record stock ride height at all 4 corners
Front: Remove 3× top mount nuts (not center nut yet)
Remove pinch bolt at knuckle (70 Nm + 90° for reinstall)
Spread knuckle slightly, remove strut assembly
Compress spring with tool if removing from stock strut
Install coilover — set initial height per manufacturer spec
Torque top mount: 20 Nm (3× nuts), pinch bolt: 70 Nm + 90°
Rear: Remove trunk trim for top mount access
Remove lower shock bolt (100 Nm for reinstall)
Remove top mount nut (60 Nm for reinstall)
Install rear coilover/spring assembly
Set ride height — typical starting point: 25-30mm drop front, 20-25mm rear
Get professional alignment within 50 miles — spec: -1.5° front camber, 0 toe

PARTS NEEDED

Coilover set (Bilstein B14, KW V1/V2, or BC Racing BR)
New top mount bearings (if not included)
New pinch bolts (TTY — replace if stock)

Always get alignment after lowering. Incorrect camber/toe will destroy tires and create unsafe handling.

OEM Parts Catalog

Audi TT Spindle Upgrade

ADVANCED · 6-8 hours

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Install TT 8N spindles for improved steering geometry, 312mm brake clearance, and better camber curve.

PROCEDURE

Remove front wheels, calipers, rotors, and ABS sensors
Press out ball joint from knuckle (ball joint press required)
Remove tie rod end nut (65 Nm) and separate with puller
Remove axle nut (290 Nm — with wheel on ground or air gun)
Remove pinch bolt and separate strut from knuckle
Remove knuckle/spindle assembly with wheel bearing
Press wheel bearing into TT spindle (or have machine shop do it)
Install TT spindle — reverse of removal
Reinstall ball joint: 50 Nm + 90°
Reinstall pinch bolt: 70 Nm + 90°
Torque axle nut: 290 Nm + additional 90° (TTY — new nut required)
Professional alignment mandatory

PARTS NEEDED

8N0 407 257 / 258 — Audi TT spindles (L/R)
New wheel bearings (FAG or SKF)
New axle nuts (TTY — single use)
New pinch bolts (recommended)
New ball joint pinch bolts

Wheel bearing press required — this is not a hammer job. Improper installation will destroy the bearing.

Transmission

Clutch Replacement Guide

ADVANCED · 6-10 hours

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Single and dual-mass flywheel clutch installation for 02M 6-speed and 02J 5-speed transmissions.

PROCEDURE

Drain transmission fluid
Remove axles (30mm axle nuts — 290 Nm, TTY)
Support engine from above with support bar
Remove subframe bolts and lower subframe (if needed for clearance)
Remove starter motor
Remove transmission-to-engine bolts (varies: M10 = 45 Nm, M12 = 60 Nm)
Support transmission with jack, slide back and lower
Remove pressure plate bolts in star pattern (gradually — 22 Nm)
Remove clutch disc and pressure plate
Inspect flywheel — resurface or replace if scored/cracked
If converting DMF to SMF: remove dual-mass flywheel, install SMF + new bolts
Flywheel bolts: 60 Nm + 90° (TTY — always replace)
Install new clutch disc (align with alignment tool)
Install pressure plate — torque in star pattern: 22 Nm
Install new throw-out bearing and pilot bearing
Reinstall transmission — align input shaft carefully
Refill transmission fluid (02M: 75W-90 GL-4, 2.3L)

PARTS NEEDED

Clutch kit (Sachs OEM, Southbend Stage 2/3, or DXD)
Throw-out bearing (always replace)
Pilot bearing (always replace)
Flywheel bolts (TTY — always replace)
Rear main seal (replace if any leakage)
Transmission fluid (G 052 171 A2 or Motul Gear 300 75W-90)
New axle nuts (TTY — always replace)

If converting from dual-mass flywheel (DMF) to single-mass (SMF), expect increased gear rattle at idle. This is normal and not harmful. SMF conversions are recommended for any car making over 300 ft-lbs of torque.

Transmission Reference OEM Parts Catalog Engine Reference

Short Shifter Installation

BEGINNER · 1-2 hours

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Installing aftermarket short shift kits and adjusting cable linkage. Covers Diesel Geek, B&M, and 42DD options.

PROCEDURE

Remove shift boot and trim from center console
Disconnect shift cables at transmission end (2× clips)
Remove OEM shift mechanism (4× bolts under console)
Install short shifter assembly per kit instructions
Reconnect shift cables — adjust cable lengths at transmission
Verify all gears engage smoothly including reverse
Reinstall trim and boot

PARTS NEEDED

Short shift kit (Diesel Geek Sigma, 42DD, or B&M)
New shift cable bushings (recommended — Torque Solution poly)

Hardware Reference

Stretch Bolt (TTY) Identification Guide

REFERENCE · N/A

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How to identify torque-to-yield fasteners, why they cannot be reused, and replacement sources.

VW uses torque-to-yield (TTY) fasteners extensively in the MK4 platform. These bolts are designed to stretch during installation and cannot be reliably re-torqued. Common TTY bolts include: head bolts (40 Nm + 60° + 60°), main cap bolts (30 Nm + 90°), rod bolts (30 Nm + 90°), flywheel bolts (60 Nm + 90°), front axle nuts (290 Nm + 90°), control arm bolts (70 Nm + 90°), strut pinch bolts (70 Nm + 90°), and ball joint bolts (50 Nm + 90°). Always replace with new TTY bolts or upgrade to ARP where available.

QUICK REFERENCE

COMMON TORQUE SPECS

FRONT SUSPENSION

Strut pinch bolts	70 Nm + 90°
Strut top mount nuts	20 Nm
Control arm bolts	70 Nm + 90°
Ball joint to knuckle	50 Nm + 90°
Tie rod end nut	65 Nm
Sway bar end link	50 Nm
Sway bar clamp	25 Nm
Subframe bolts	100 Nm + 90°
Axle nut	290 Nm + 90° (TTY)

REAR SUSPENSION

Shock top mount	60 Nm
Shock lower bolt	100 Nm
Trailing arm front	70 Nm + 90°
Trailing arm rear	100 Nm + 90°
Wheel bearing nut	175 Nm
Sway bar end link	20 Nm
Rear axle beam bolts	70 Nm + 90°

BRAKES

Caliper bracket bolts	115 Nm
Caliper guide pins	25 Nm
Brake hose banjo	30 Nm
Wheel bolts (M14×1.5)	120 Nm
Bleed nipple	10 Nm
Brake line flare nuts	14 Nm

ENGINE (1.8T AWP)

Head bolts (OEM TTY)	40 Nm + 60° + 60°
Head studs (ARP)	75 ft-lbs
Rod bolts (OEM TTY)	30 Nm + 90°
Main cap bolts	30 Nm + 90°
Timing belt tensioner	25 Nm
Water pump	15 Nm
Oil drain plug	30 Nm
Spark plugs	25 Nm
Turbo to manifold	25 Nm
Exhaust manifold	25 Nm

Always verify specs with factory service manual. Stretch bolts (TTY) require replacement after removal. See our complete AWP torque spec reference for additional data.

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