Drivetrain: Difference between revisions
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|Active Yaw Control, or open differential | |Active Yaw Control, or open differential | ||
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| | |The open differential can have the internals from an Evo RS installed to make it an LSD. | ||
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== Gearbox == | == Manual Gearbox == | ||
Manual gearboxes while same model as used on the Lancer Evolution, have different bellhousing for the 6A13 and slightly different gear ratios. | |||
=== Common Issues === | === Common Issues === | ||
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|Replace shifter bushings with new OEM replacements or solid CNC machined aluminium | |Replace shifter bushings with new OEM replacements or solid CNC machined aluminium | ||
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== Automatic Transmission == | |||
Early W5A51 transmissions are prone to failure due to the wavesprings. | |||
Planetary gearset pins are usually welded to prevent them moving. | |||
== Transfer Case == | == Transfer Case == | ||
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|- | |- | ||
|Magna LSD | |Magna LSD | ||
|The LSD from the | |The LSD from the AWD Mitsubishi Magna or Diamante is a drop-in replacement, however you will also need the Magna inner CV joints. | ||
This LSD is a viscous LSD. | |||
|Drivers side spline as as second smaller spline to engage with the Viscous unit within the centre. | |||
Passenger side inner joint spline is shorter than the VR-4 spline. | |||
Need to put the Magna joints onto the VR-4 driveshafts + outer CV. | |||
Need to use the VR-4 diff cover on the magna diff case so mounting bolts will work with VR-4 subframe. Some others have used spacers and longer bolts. | |||
|- | |- | ||
|Evo RS centre | |Evo RS centre |
Latest revision as of 19:59, 14 May 2022
Drivetrain Overview
The VR4 drivetrain is, from the gearbox on, almost a clone of the Lancer Evolution drivetrain for the Evolution IV-VI model years.
Component | Details | Differences to Lancer Evolution | Additional Notes |
---|---|---|---|
Manual Gearbox | W5M51 gearbox | Different bellhousing
Different gear ratios |
|
Transfer Case | No LSD from factory | Evo 4 through Evo 6 are a drop-in replacement transfer case
Evo 6.5 is also a drop-in but the internals cannot be swapped with earlier cases or VR4 case Magna transfer case also fits but is same as Evo 6.5 internal dimensions
| |
Rear Differential | Active Yaw Control, or open differential | The open differential can have the internals from an Evo RS installed to make it an LSD. |
Manual Gearbox
Manual gearboxes while same model as used on the Lancer Evolution, have different bellhousing for the 6A13 and slightly different gear ratios.
Common Issues
Symptom | Cause | Solution | |
---|---|---|---|
3rd gear welds failing | No 3rd gear | Each gearset has an inner and outer ring. The welds holding the inner and outer rings together for 3rd gear are known to break on high power output applications. | Re-welding of the 3rd gear |
Shifter bushes failing | Mushy shifting or very difficult to shift into gear | The shifter bushes that connect the shifter cables to the gearbox are known to degrade and fail. | Replace shifter bushings with new OEM replacements or solid CNC machined aluminium |
Automatic Transmission
Early W5A51 transmissions are prone to failure due to the wavesprings.
Planetary gearset pins are usually welded to prevent them moving.
Transfer Case
The transfer case uses a Viscous Coupling Unit (VCU) as the means of limiting the difference in wheel speed between the front and rear wheels. This "Viscous" coupling is the reason for the "VR4" nomenclature - literally "Viscous Realtime 4WD".
Note that the center differential is an open differential located inside the gearbox housing, but the VCU provides the mechanism of applying Limited Slip capabilities.
Reliability of the transfer case is fairly high, however it is possible to strip the ring and pinion gear through severe launches and general abuse.
Front Differential
The stock front differential is an open differential, located within the transfer case.
Rear Differential
The stock rear differential depends on the VR4 sub-model and year.
Sub Model | Rear Differential type |
---|---|
Type-V | Open Differential |
Type-S | Active Yaw Control |
Issues with AYC
The stock AYC differential in the VR4 is known to fail. This has been determined to be caused by weak castings for the differential housing. Your mileage may vary, but the risk of rear differential failure is high. A stronger rear differential is practically a requirement for high power applications.
Modifications
Front Differential
The front differential located in the transfer case can be replaced by a Limited Slip Differential. This is a highly recommended modification to improve power delivery and handling.
Any Evolution 4 to 6 LSD option will fit, however the OEM LSDs are known to break some of the screws and bolts that hold the LSD assembly together.
Rear Differential
The rear differential for the VR4 can be upgraded via a few options, depending on whether your car came with an AYC rear differential or not.
Rear Diff upgrade option | Details | Notes |
---|---|---|
Super AYC | The Super AYC differential from the Evolution 8 is a drop-in replacement (no tuning or electronics required) for the stock AYC differential. Only some spacers are required for mounting to the diff carrier, which could be made from a stack of washers (although a CNC machined aluminium spacer is recommended and available from TME). | If your VR4 was supplied from factory without AYC, upgrading to AYC is infeasible as there are multiple additional components required, including the AYC computer, the AYC sensors and potentially a replacement wiring harness.
|
Magna LSD | The LSD from the AWD Mitsubishi Magna or Diamante is a drop-in replacement, however you will also need the Magna inner CV joints.
This LSD is a viscous LSD. |
Drivers side spline as as second smaller spline to engage with the Viscous unit within the centre.
Passenger side inner joint spline is shorter than the VR-4 spline. Need to put the Magna joints onto the VR-4 driveshafts + outer CV. Need to use the VR-4 diff cover on the magna diff case so mounting bolts will work with VR-4 subframe. Some others have used spacers and longer bolts. |
Evo RS centre | This is an internal modification to the stock differential housing for the open diff. |