Category Archives: Upgrade Work

Apikol Differential Bushing Blowout

A change in sound when accelerating led me on a search to find out what was going on.  Snooping around beneath the S4 revealed this:

Apikol B5 S4 Transmission Mount
Apikol B5 S4 Rear Differential Mount

Found it!  Fortunately Apikol sells just the bushings for the mount so I ordered a pair to replace the failed parts.

Apikol Differential Mount Bushing
Apikol Differential Mount Bushing

It turns out that there are two versions of this bushing so I needed to order both since I did not know at the time which version I have.  I’ve documented the part number in case this happens again.

Apikol Differential Mount Bushing
Apikol Differential Mount Bushing

Frankenturbo F21v3 Swap Complete

Starting on New Years Day I am taking advantage of some extra free time to get ready to swap the Frankenturbo F21s into the S4.

FrankenTurbo F21 version 3 Audi B5 S4 turbocharger
FrankenTurbo F21 version 3
S4 Engine Pull Preparation
S4 Engine Pull Preparation

The S4 sits on a set of dollies so it can move about the garage easily for positioning.  The car is at an angle in the garage when the engine hoist removes the engine.

S4 Engine Pull Preparations
S4 Engine Pull Preparations

Spending Friday evening removing the engine.

S4 engine out
S4 engine out

Saturday is turbo swap day.  This took a bit longer than usual on account of the Mamba wastegate bracket on the passenger side being too big.

Mamba Wastegate Bracket
Mamba Wastegate Bracket

Some cutting and filing of the bracket is done so that it will fit in place because the unmodified bracket contacts the cylinder head and/or starter.

Mamba Wastegate Bracket Modified
Mamba Wastegate Bracket Modified

On go the new F21s.

Frankenturbo F21v3 Driver Side
Frankenturbo F21v3 Driver Side
Frankenturbo F21v3 Passenger Side
Frankenturbo F21v3 Passenger Side

Before installing the engine the wastegate preload is set to 12 psi.  The setup is using the Yellow springs from the Mamba collection of springs.

Mamba Spring Preload Chart
Mamba Spring Preload Chart

Finally on Sunday the engine is installed.

B5 S4 Engine Install with FT21 v3 turbochargers
B5 S4 Engine Install with FT21 v3 turbochargers

Hi Ho Silver

Today marked the departure of the Silver B5 S4 that I’ve been working on for close to four months.

B5 S4 drives off
B5 S4 drives off

The car arrived nearly stock and left as a K04 charged Stage 3 car .

Midwest Turbo Connection B5 S4 K04
Midwest Turbo K04 Turbocharger

During the time here there was a long list of upgrades and maintenance performed on the car.

ComponentAdditional Parts/ProceduresPercent Complete
Fuel pump100%
Fuel filter100%
Brake Fluid Flush100%
Tie rod ends100%
JHM front axlesGaskets, axle bolts100%
Regrease front axles100%
Front brake lines100%
Brake Pad Wear Sensor Plugs100%
Front adjustable UCAUsed Fixed UCA100%
Front LCA100%
Front rotors and pads100%
Front wheel bearings & hubsDelayed
Front coil overs100%
Front swaybar endlinks100%
Front swaybar bushing/brackets100%
Rear rotors and pads100%
Rear coil overs100%
034 rear sway100%
Rear swaybar end links100%
Rear wheel bearingsAxle Bolt RemovalDelayed
Rear brake lines100%
Rear differential mount100%
Rear differential fluid100%
EngineVCG (Drv)100%
VCG (Pax)100%
Camshaft End Caps100%
Camshaft Seals100%
Camshaft Chain Tensioner Gaskets100%
Rear Main Seal100%
Timing Belt100%
Water Pump / Thermostat100%
Coolant Hardpipe O-rings100%
PS Fluid100%
Replace Snub Mount/Cage100%
Swap Alternators100%
Tune ECU software50%
Engine Oil Flush100%
Modify Airbox100%
Modify Brake Booster Hose100%
Install New Auxiliary Coolant Pump100%
Intake Manifold
New Intake Manifold Gaskets100%
Swap Fuel injectors100%
034 Spider Hose100%
Exhaust Manifold
New Exhaust Manifold Gaskets100%
New Exhaust Manifold Nuts100%
Remove stock brackets/rivets100%
Relocate AC Condenser100%
Trim Radiator Support100%
Check & Set Preload to 8 psi100%
Trim Turbocharger Inlets100%
PB5 Wastegate Line Kit100%
Paragon Oil Lines100%
Coolant Lines100%
Clean Oil Return Lines100%
Install Turbos100%
Replace Slave cylinder100%
Replace Clutch100%
Bleed Clutch/Slave Cylinder100%
Replace Throwout Bearing100%
Shift Rebuild Kit100%
Replace Flywheel100%
Regrease driveshaft joint100%
Driveshaft gasket100%
Transmission Fluid Change100%
Low Temp Thermo SWX 021 919 369 / O-Ring N 903 168 02100%
Repaired Instruments LCD100%
Assemble & Install Dual Exhaust100%

I never got to the wheel bearings as the driver side rear axle bolt proved to be very stuck and I concluded that a shop with an impact wrench would be the most likely place to get it removed.

Silver B5 S4 Stuck Axle Bolt
Silver B5 S4 Stuck Axle Bolt

Tuning was on the third revision, with the remainder to be carried out by the S4s owner when it was driven away.

B5 S4 Engine
B5 S4 Engine

In the meantime a backlog of turbochargers has grown in the corner of my garage.

BorgWarner RS6 - FrankenTurbo F21 - TiAL 605
BorgWarner RS6 – FrankenTurbo F21 – TiAL 605

Between the turbochargers and completing this engine build,

Istook Engine Clean Up
Engine Cleanup

and trying out the Mamba Wastegates, I have a number of options for future projects to tackle.

Mamba Billet Wastegates for the Audi B5 S4
Mamba Billet Wastegates for the Audi B5 S4