Tag Archives: AWD

Legacy: 1989-1994 Subaru Legacy (BC/BF) GT/RS

Prior to the Legacy RS turbo, Subaru had never enjoyed the experience of distributing a genuine performance car. Of course, there had been the 4WD turbo RX and Vortex, but neither could crack 10 seconds for the 0-100km/h sprint – although they were very reliable. The RS was the gun version of the first Legacy series released in 1988 and discontinued in 1994. The RS (Rally Sport) model was aimed squarely at world rallying, with many of its components and concepts carried over to the dominating Impreza WRX.

Legacy: The BC/BF is unique in having an Air - Water intercooler with a front mounted radiator for optimal cooling. The bonnet scoop only provides cooling to the turbo. While later model legacy's have all used air to air intercoolers.
Legacy: The BC/BF is unique in having an Air – Water intercooler with a front mounted radiator for optimal cooling. The bonnet scoop only provides cooling to the turbo. While later model legacy’s have all used air to air intercoolers.

The center Viscous LSD on the MT models initially starts out with a 50/50 torque split, front and rear, and will up the ratio towards the end with more traction. The manufacturer doesn’t give a final figure, so the max split is either 65/35, or could even venture as high as 95/5, since the A/T model has a different system that is marketed at a 65/35 maximum split. A higher ratio would explain some of the handling characteristics at the limit. The rear differential is also a Viscous LSD model.

The BC/BF is unique in having an Air – Water intercooler with a front mounted radiator for optimal cooling. The bonnet scoop only provides cooling to the turbo. While later model legacy’s have all used air to air intercoolers.

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How to shift with AWD or a Manual Transmission.

How to shift with AWD or a Manual Transmission:

Where can I find good background information of transmissions? A good general reference for new people as well as a refresher for more advanced users is How Stuff Works’ Transmission Tutorial.

Where can I find good background information on differentials? A good general reference for new people as well as a refresher for more advanced users is How Stuff Works’ Differential Tutorial.

Shift: STi Shifter
Shift: STi Shifter

Is shifting different with an AWD car vs. a FWD or RWD car? One has to visualize the power transfer in a car to get a better understanding. In a FWD or RWD car, if you shift or launch the car too aggressively, the excess power is transmitted to the tire(s), which will spin. Put another way, excess power is “burned off” through tire smoke. In an AWD car, if you shift or launch the car too aggressively, the excess usually isn’t enough to overpower thetires’ grip. In this situation, the excess power must be absorbed somewhere else in the drive train. Though some drive train shock is normal, in an overload situation, excess power is transmitted to the various driveline components, which can accelerate wear and tear.

Where are the shifting differences most apparent? Starting off in first gear and the 1-2 shift are the most common causes of driveline shock. Obviously, there is reason to shift responsibly in every gear but these are the most commonly seen problematic shifting issues.

Is resting my hand on the shifter bad? From the WRX Owners Manual: “Do not drive with your hand resting on the shift lever. This may cause wear on the transmission components”. This advice should apply to every Subaru MT model. That being said, the safest course of action is to keep both hands on the wheel unless actually shifting.

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The 2008 Cusco Subaru Impreza WRX STi Super GT

Cusco's Impreza in GT300
2008 Subaru Impreza WRX STi Super GT

The Cusco team have been campaigning a heavily modified STi with a rear drive conversion as required by regulations since the late nineties and having no two-door model available at present, the Super GT committee gave a special permit for them to race with a four-door model instead of a two-door one. The rear drive conversion rule was lifted in 2006, and since then they returned to all-wheel drive with a transaxle gearbox.

GT300
The Cusco Subaru Impreza in 2008.

In 2008, Cusco’s Impreza won the first GT300 race in Sepang. It marked the first AWD car victory in Super GT/JGTC history. Even though they were having very impressive results(with 1 win and 2 podiums) that season, Cuscho announced that they would not participate in the 2009 season as they want \ The performance of Cusco was outstanding even though they were using a 4-door car, it later lead the Super GT committee to officially allow all 4-door model cars to participate the series. The Toyota Corolla Axio followed suit in 2009.

Cusco's Impreza
In 2008, Cusco’s Impreza won the first GT300 race in Sepang. It marked the first AWD car victory in Super GT/JGTC history.
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EJ257 Block info

So you bought an EJ257 block to build on the side. The seller says it’s “good” and “was running.” I mean, they can say anything, right? That is until you pull the engine block apart and the crank suffered major rod bearing damage from either oil starvation or debris from other failing components.

Here we go to look at the bore housings of the main bearings on the engine block. They look perfectly round to the eye but only measuring tools will reveal how oval they really are. Heat isn’t your friend and is the major cause in warping the bore housings. Rod bearing failure will cause excessive heat if driven on. Even brand new blocks from Subaru can be out of round.

The pictures show the honing marks after a pass on the honing machine. You can see where the color is more dull and has minimal light reflection. There was no contact there with the honing stones. You can see the dark defining line, which was where the bearing sat. Half of the bore housing number 3 (middle) didn’t make contact while honing as with bore housing number 4, which did not make any contact except where the block halves met.

What do we do now? The issue here is you’ll have bearing clearances that are too small or too large. This will cause oiling issues to areas where they most need it. Also the warped mains will not be straight. This can cause bearing to crank journal contact. So when looking at a block to buy, ask about the block’s history. If the seller has the block apart, look for yourself before purchasing. An experienced machine shop that has an align hone machine will be able to straighten the bearing housings as long as they aren’t too out of round.

EJ257 honing Marks
EJ257 honing Marks
EJ257 honing marks
EJ257 honing marks
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5spd Subaru WRX five speed manual tips and tricks

5spd Subaru WRX five speed manual tips and tricks:

So you’ve got this noise coming from your 5spd transmission. It is starting to whine when you’re on/off the throttle. The sound seems to come right from below like around the shifter area. You may be a victim of the infamous falling apart center differential!

Don’t be too worried, transmissions are a dime a dozen! You still have the option to go 6spd or another 5spd transmission with different gear ratios if you choose.

 5spd: The damage. Most times the rear cover will back out minor like this photo. Other times it will completely come off. You can see the circlip survived this incident.
5Spd: The damage. Most times the rear cover will back out minor like this photo. Other times it will completely come off. You can see the circlip survived this incident on this WRX
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How to not tow a Subaru like a idiot

If there is one thing you never do with a manual all wheel drive Subaru is tow it with car dollies without removing  the drive shaft. Really the preferred way of towing a Subaru is putting the Subaru on a flatbed or a car trailer.

 

Kind of a bad idea.
Kind of a bad idea.

 

Having the Subaru towed on the two rear wheels is asking for the all wheel drive system to die a horrible death and to leave a trail of parts and tears on the road. It’s a great way to need to install if you are lucky a new center differential or if you are unlucky your transmission will need a complete replacement.

 

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If you have to ask you can’t afford a engine swap

A simple google search would have answered this guy’s question.  LS swaps on a Subarus are known to be able to be done, but it seems like this person is more of a dreamer than a doer. Anything can be done with time, talent, and money. However, if you have to ask random people on Facebook how to do something as complex as a engine swap you might be over your head in all three areas.

 

STi Swap

 

 

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How to hydro-lock your Impreza

Sometimes not going through the gigantic puddle in a stock height Subaru Impreza 2.5RS is the smart thing to do.

This Subaru Impreza 2.5RS is now flooded and done for. Maybe a lifted 4×4 truck is what you should use if you want to go “mudding”.

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