340BHP-WRX

iTrader: (6)

Just wondered how to tighten the bolts on the power steering and alternator pulley bolts when fitting lightweight pulleys ?

FLAT ERIC

iTrader: (1)

This is a guide I did a while back.

Hints on removing/refitting the Power Steering pulley on a MY03 WRX

1. Undo the two 10mm cover fixings.
2. Lift the corner to release cover & swivel it out the way around the throttle cable.



3. Spray some "Plus Gas" or "WD40" on the shaft & nut to be soaking in.
4. Slacken the two 12mm bolts holding the alternator & turn the adjuster anti clockwise to slacken the belt enough to remove.



5. Place a short extension bar through the pulley aperture & rest it on the ledge of the pump mounting bracket.
6. Use a 19mm ring spanner to undo the pulley nut whilst bracing the extension bar against the ledge to gain leverage & stop the pulley turning.





7. Remove the nut & slide the pulley off the splined shaft..


The alternator pulley

The alternator pulley is held on by a 24mm nut but has no openings to lock it against anything. Don't be tempted to poke something inside the alternator as you will damage it. Impact air wrench is probably easiest way to loosen it.

I had a new Alternator fitted not long ago at a Subaru dealer & you can see four sets of clamp marks equally spaced around the edge of the pulley. This is where they used something to hold the pulley whist it was undone.



Fitting :- Disclaimer: This is for information only & does not claim to be complete & should not be interpreted as instructions. If in doubt seek qualified help.

Mark

340BHP-WRX

iTrader: (6)

Thanks for that mate

The alternator pulley is the one i'm most worried about now. Managed to remove it by tightening the belt right up and just shocking the nut undone.

What can I use to hold the new pulley tight enough so that it doesn't move but so that it doesn't damage the pulley itself ?

tanyatriangles

iTrader: (2)

Tried a pair of water pump pliers? If it worries you, pad them with folded paper.

340BHP-WRX

iTrader: (6)

Thought of them but didn't know if they would hold the pulley tight enough.

Anyone know how tight the bolt needs to be ?

jasongtr

iTrader: (19)

do these lightweight pulleys make much difference against the cost of them?

FLAT ERIC

iTrader: (1)

An impact wrench (electric or air) will shock it back up tight so you won't need to hold the pulley so tightly to stop it turning.

To grip it use an old bit of belt to wrap & protect the pulley then use something like a oil filter strap wrench. There are several types just get one that will open up enough to fit over the pulley.





Mark

340BHP-WRX

iTrader: (6)

I've actually got a similar oil filter strap wrench to those so maybe i'll give that a try

FLAT ERIC

iTrader: (1)

When a pulley or flywheel of a car is lightened it can have a great effect on acceleration - much more than just the weight saving as a proportion of the total vehicle weight would account for. This is because rotating components store rotational energy as well as having to be accelerated in a linear direction along with the rest of the car's mass. The faster a component rotates, the greater the amount of rotational kinetic energy that ends up being stored in it. The engine turns potential energy from fuel into kinetic energy of motion when it accelerates a vehicle. Any energy that ends up being stored in rotating components is not available to accelerate the car in a linear direction - so reducing the mass (or more properly the "moment of inertia") of these components leaves more of the engine's output to accelerate the car.

That's why people get the flywheel skimmed when they have their clutch apart. These pulleys are a simple bolt off old/bolt on new job & they don't effect the timing or anything so you just put the belts back on & tension them & away you go.

Crank pulley 550 grams. (OE pulley is 2700 grams.)

Underdrive crank pulley 350 grams.

Powersteering pulley 200 grams.

Alternator pulley 50 grams.

Power gain achieved ???

This is for just a crank pulley & does not include the lightweight powersteering & alternator pulleys. Also this pulley weighs 1400grams !!!! not 550 grams like my one.

An increase of 10 bhp and 7 lbft torque. So maybe 15 bhp with the full set?



Mark

jasongtr

iTrader: (19)

ok so now im interested but how much are these pulleys?

Granby

iTrader: (5)

Have a word with CDF Racing

jasonius

iTrader: (1)

Eric, was the dyno plot done after just doing the crank pulley (same day)..?

Impressive improvement, low down response in particular..

Makes me wonder how much difference adding a lightweight flywheel would make after seeing that..?

340BHP-WRX

iTrader: (6)

I bought my lightweight pulleys mainly for looks but if they can give that much extra power that's brilliant

Every little helps

mit

iTrader: (10)

What belts did you guys use? I searched all over, and only managed to find one that has one groove less, not ideal!

Mit

340BHP-WRX

iTrader: (6)

I bought my pulleys from CDF Racing and they told me I can still use the original belts.

Why would you need a belt with less grooves ?

mit

iTrader: (10)

The crank pulley i fitted is smaller, so i needed a smaller belt. I only fitted the belt with one less groove as i couldn't find anything else!

340BHP-WRX

iTrader: (6)

Oh right,is yours an UnderDriven pulley then ?

mit

iTrader: (10)

Yeah, my standard pulley was damaged, had been slipping around the woodruf key, so had to replace it in a hurry! I found this underdrive pulley for £22, it was well made too!

340BHP-WRX

iTrader: (6)

That's a good price

I was going to get the underdriven pulley but was told there isn't much difference over the standard size lighweight one so didn't bother.

mit

iTrader: (10)

I wasn't really after a underdrive pulley either, but the price and time was right. It's much lighter as said above, and looks nice!

FLAT ERIC

iTrader: (1)

Yes that plot was after just the crank pulley was changed. Not from my car BTW. Clutch flywheel lightening gives more of the same but be aware it can make the engine more liable to stalling when pulling away until you get used to it.

The underdrive pulley gives marginal gains & can lead to charging problems as the alternator gets less turns per turn of the crank. Ok if you do plenty of long journeys.

You are not wrong they do look good as well.



Mark

bigarf

iTrader: (67)

Mark [/QUOTE]
got the blue ones on mine from cdf racing they do smarten the engine bay up a bit.didnt realise they made that much difference to performance though.