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-   -   Perrin Lightweight Crank Pulley (http://legacygt.com/forums/showthread.php?t=21423)

PhilT 10-28-2005 08:47 PM

Perrin Lightweight Crank Pulley
 
I decided this was quite a cheap and easy mod, one that I could handle fairly easily, and from what I have read gives a reasonable return on the investment, but more of that later.

The instructions that came with the pulley were reasonable, although I found the "Vacation Pics" far more useful, definately worth looking at before starting.

After removing the engine cover, and front air intake section, it was very easy to slacken the belts off and remove them. I don't have access to a belt tension measurement device, so what I did was to measure the deflection on the longest run of each belt with a good press of my thumb, and use that as a reference. Make sure you slacken the belts right off and don't try to pry them the last little bit.

Now for the painful part: with the car in 5th gear and the handbrake tight on, use a 22mm socket on the pulley centre bolt and with the longest lever you can find pull as hard as you can. The first time I tried this my hand slipped and took the skin off the back of my hand, so after cleaning up and this time wearing gloves, I puilled even harder and the bolt cracked loose. Take the bolt out, and with both hands slide the pulley off, don't try to pry from one side as you can crack the plastic engine cover behind it. As you slide it off, keep an eye out for the shaft key, which may or may not fall out, it didn't for me though.

Clean the end of the shaft up with a clean lint free rag, if you look inside you can see the timing belt. Slide the new pulley onto the shaft, taking note where the keyway is for alignment. Put a drop of oil on the bolt threads and on the underside of the bolt head. Then tighten up finger loosely. This part confused me, as the Perrin instructions stated the tightening torque should be 90 ft-lbs, but the manual states 132 ft-lbs. I know there is s difference in the material, but I can't understand why the big difference, maybe someone can point it out ?

Anyway, going by the manual, I went to 130. I wouldn't advise doing this without a torque wrench, as 130 is very tight, and it would be hard to try and guess.

Replace the belts and tighten until you have the same deflection as before. replace the belt cover, the engine cover and the intake. Then go drive !

My first impressions are that the engine seems to rev quicker now, the gas pedal seems more sensitive. Of course this might be because I've read that this should happen, but it does feel that way. The local track is closed for the winter now, so I can't prove any performance improvement, but my butt is happy !

LittleBlueGT 10-28-2005 09:13 PM

Nice write-up. Thanks.

Any drive-ability diff?

Is it easier to stall the car starting out. Will my wife notice?

PhilT 10-28-2005 09:19 PM

Quote:

Originally Posted by LittleBlueGT
Nice write-up. Thanks.

Any drive-ability diff?

Is it easier to stall the car starting out. Will my wife notice?

No change in driveability, just seems to rev quicker. No reason to stall it at all, it doesn't feel any different setting off, just when you floor it the needle climbs faster.

No way she will notice, mine hasn't noticed any change from stock even though I'm at AP stg.1.
I just drive accordingly when she is in the car.

firedawgs 10-28-2005 09:19 PM

I just installed my Perrin crank pulley last weekend. The biggest difference is that I have a 5EAT. With the AT trans there is no way to stop the flywheel except for one, that I found. I took off the intercooler; which was easy. There is a rubber plug almost directly straight down from the intercooler. There I ended up using two screw drivers place in the flywheel to stop the mass movement. The biggest problem in taking off the stock crank pulley is the mass muscle to loosen it up. It took all of me and my ass to loosen the stock crank pulley bolt, while a buddy was holding the screwdrivers in place. Once it was loose the rest of the job is "cake".

Reinstalling the belts was done by eye and feel. Luckily I had a buddy (dv8ingvector with me) that has a LGT. So I went and checked his stock belt tension by hand and tighten my own belt. Checked and double checked, then I was good to go.

As far as I am on modding I can not tell you if the pulley alone did anything, but I have seen dyno prof that it does something. That is why I chose to do mine.

PhilT and myself, MT and AT will show you enough for the non mechanical mind to accomplish this simple but effect mod.

If anyone needs help, PM me and I will help you through this. "Cake"

firedawgs......Sean

eL GaTo 10-29-2005 04:56 PM

PhilT.........the reason Perrin recommended 90 ft-lbs is because of the aluminum. As we all know, this metal is a lot softer than the stock steel. :icon_neut

PhilT 10-29-2005 05:26 PM

I agree that aluminium is weaker than steel in tension and shear stresses, but this in is compression where there is not a great deal of difference.

I would be interested in anyone who has a Cobb or other LWP, what they recommend.

eL GaTo 10-29-2005 07:39 PM

Quote:

Originally Posted by PhilT
I agree that aluminium is weaker than steel in tension and shear stresses, but this in is compression where there is not a great deal of difference.

I would be interested in anyone who has a Cobb or other LWP, what they recommend.

I have an "Unorthodox Racing" stock diameter pulley. Recommended torque was at least 90 ft-lbs.

mudfoot 10-29-2005 08:20 PM

I torqued mine to 94lbs... The vacation pics say 130.. but that heavy ass stock one can take that torque... i figured 4 more lbs wouldnt kill it. I guess they say 90 because its light weight... I have the Perrin pulley

jim1969 11-12-2005 09:26 AM

do you need to change any belts with the perrin pulley? I know you do with the unorthodox powersteering and crank pullies.

eL GaTo 11-12-2005 09:39 AM

Quote:

Originally Posted by jim1969
do you need to change any belts with the perrin pulley? I know you do with the unorthodox powersteering and crank pullies.

With stock size pulley, you do not need to change belts. With "under drive" pulley.....meaning smaller in diameter than stock, you need to change belts.

jim1969 11-12-2005 09:44 AM

yes that's usually true but unorthodox required new a new belt for the lightened pulleys and 2 belts I believe for the underdriven ones. something about the design of the pulley. http://www.legacygt.com/forums/showp...4&postcount=23

eL GaTo 11-12-2005 11:07 AM

Quote:

Originally Posted by jim1969
yes that's usually true but unorthodox required new a new belt for the lightened pulleys and 2 belts I believe for the underdriven ones. something about the design of the pulley. http://www.legacygt.com/forums/showp...4&postcount=23

I have Unothodox Racing "stock" size lightened crank pulley only. It does not require new belts. Even if you have the set of lightened pulleys as long as all the diameters of the pulleys are the same as stock then you do not need new belts. The grooves on the pulleys are the same as the stock belt grooves.

jim1969 11-12-2005 02:32 PM

I think the belt is required if you got the power steering pulley. How do you like the unorthodox pully?

eL GaTo 11-12-2005 03:26 PM

Quote:

Originally Posted by jim1969
I think the belt is required if you got the power steering pulley. How do you like the unorthodox pully?

I do not know exactly what you have or what you are getting, but I do have just the lightened crank stock size pulley. The stock belt is re-used.

You really can't go wrong with the popular brand names. The UR is well made and they have been around for a while.

blkwag 11-14-2005 06:34 PM

If I'm not mistaking that the harmonick ballencer is located on the pully. So threre for would the have pre mature wear?


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