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Old 12-05-2008, 05:15 AM   #1
bereda
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Default are light weight pulleys and underdrive worth it

i found some on ebay but will the set seriously give me some more ???

heres a set i found

http://cgi.ebay.com/ebaymotors/UNDER...Q5fAccessories


and what should i look for spec wise ( weight, diameter,etc.)

i have an 04 rs

and whats a over drive pulley what advantages over under drive?

http://cgi.ebay.com/ebaymotors/OBX-O...Q5fAccessories
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Old 12-05-2008, 05:20 AM   #2
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You may not see any power differences but them being lighter makes it easier for them to spin. So you may make a difference but you prob wont notice it
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Old 12-05-2008, 06:25 AM   #3
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many people stay away from underdriven pulley,i guess they're bad for the engine!@##@!
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Old 12-05-2008, 10:43 AM   #4
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worth it.
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Old 12-05-2008, 10:44 AM   #5
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They spin faster so they actually help the engine rev faster. They kinda ¨free¨ the engine of some weight. The problem with the underdriven is they are smaller so you have to change your belts. Another thing is, they reduce the amount of power on the power steering and the alternator, so it might be wise to stay with the lightweight. Good luck
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Old 12-05-2008, 12:00 PM   #6
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Quote:
Originally Posted by bereda View Post
and whats a over drive pulley what advantages over under drive?
I have never heard of overdrive pulleys. I do not understand any advantage it would have 'over' under drive pulleys. It says they have been dyno proven. Honestly, I believe the buyer meant to say underdrive pulleys.
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Old 12-05-2008, 12:17 PM   #7
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anytime you remove rotating mass it's good....up to a certain point. The engine needs some rotational inertia in order to get going. but yes, a LW pulley will make your engine seem peppier since it is no longer using its' power to spin mass.
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Old 12-05-2008, 03:18 PM   #8
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Less rotating mass can be good, as long as your gearing isnt too close together. Lack of inertia can make your revs drop below the power band if you dont feel like shifting fast all of the time
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Old 12-05-2008, 03:36 PM   #9
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get cobb or perrin. same size as stock, just a lot lighter. you don't have to change your belts or anything.
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Old 12-05-2008, 03:53 PM   #10
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my cobb pulley really helped me to enjoy my subaru . its like night and day. just make sure you have the car in a nice strong gear like 5th when you crack that bolt.
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Old 12-05-2008, 04:37 PM   #11
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maybe someone can comment on this, I was talking to my local shop here... and they advised against the LW pulley stating that they cause problems with the balance of the crank.....

I am really interested in one.. but want to be sure they is not going to be a problem.

Thanks
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Old 12-05-2008, 04:40 PM   #12
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if you search hard enough on here you'll find a letter from subaru stating that a pulley is a pulley. furthermore the subaru crank pulley is just that it is not a harmonic balancer.

you will be fine just buy a good quality pulley, stock sized , like cobb or perin or kartboys
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Old 12-06-2008, 02:23 AM   #13
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Quote:
Originally Posted by watchunglava View Post
my cobb pulley really helped me to enjoy my subaru . its like night and day. just make sure you have the car in a nice strong gear like 5th when you crack that bolt.
5th and have someone stand on the brakes too.
Quote:
Originally Posted by watchunglava View Post
if you search hard enough on here you'll find a letter from subaru stating that a pulley is a pulley. furthermore the subaru crank pulley is just that it is not a harmonic balancer.
+10 for truth.
Quote:
you will be fine just buy a good quality pulley, stock sized , like cobb or perin or kartboys
I'm partial to the agency power, but most of them are within a few tenths of a pound anyway.
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Old 12-06-2008, 04:47 AM   #14
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so whats the lightest and best priced? and is there a full light weight pulley kit? to change every pulley to light weight
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Old 12-06-2008, 05:07 AM   #15
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Quote:
Originally Posted by It Hertz View Post
maybe someone can comment on this, I was talking to my local shop here... and they advised against the LW pulley stating that they cause problems with the balance of the crank.....

I am really interested in one.. but want to be sure they is not going to be a problem.

Thanks
It has been said that the stock crank pulley has rubber inserts in it to help dampen engine vibrations. I have even seen pictures of it. Is it needed? That I'm not sure of. I am contemplating this mod as well, but it's hard to say if it can hurt components over time. There is a lot of speculation on the internet, and even those that are "informed" can still be wrong.

If you plan to do it, do it right - go lightweight not underdriven and choose a good brand name.
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Old 12-06-2008, 06:03 AM   #16
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^^
Subaru crank pulleys don't have harmonic dampers though
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Old 12-06-2008, 03:38 PM   #17
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Quote:
Originally Posted by bereda View Post
so whats the lightest and best priced? and is there a full light weight pulley kit? to change every pulley to light weight
I haven't found any lighter than the Agency Power, which is 1.0lbs. I ordered mine from RalliTek, and they seem to have a different picture on their website, but you get the right part.
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Old 12-06-2008, 04:40 PM   #18
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Light weight and under driven pulleys will not do any harm to much of any thing. IMO they are far more bling than bang for your buck.

-Yes you may experience minor Power Steering differences. If you are using your PS to it limits. like turning the wheels while not moving
-Yes you may experience some power fluctuation if you have some serious amps or ridiculed head light setup.

You will have more noticeable changes/problems with a Light Weight Flywheel than a Pulley Set
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Old 12-06-2008, 04:43 PM   #19
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I've been running an old JC Sports UD pulley for years and years......It hasn't done anything to hurt any of the motors that have been in my car. I've read more about botched installs of pulleys than anything else.

Cutting the weight is most important, and underdriving the accessories is an added benefit if you choose to go that route.

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Old 12-06-2008, 04:54 PM   #20
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I've got the gruppe-s pulley currently. A little heavier than the perring that I had previously. But either way, they both reduce the rotational mass. Both are stock diameter. For those who don't think they help...switch back to the oem 5lb. (ftl) It sounds like the underdriven pulleys don't bother those who have previously posted.

Storm, do you notice any downfalls to the UD pulley?
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Old 12-06-2008, 07:36 PM   #21
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i take that this will improve my low end torque??? also has anyone notice better mpg???
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Old 12-06-2008, 07:55 PM   #22
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It does make a little bit of difference for low/mid-end but as far as better mileage, nope..
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Old 12-06-2008, 11:20 PM   #23
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I have a LW flywheel, so I took my Perrin off. But I did notice a slight difference, even with my old auto snotbox.

This has been discussed many times, as far as engine balancer goes. You might have more risk of your "balancer" failing because of the rubber degrading than any damage done by a LW pulley (correctly installed of course).

Just stick with stock diameter and LW, no under driven. The one under driven I bought off ebay was light, but the ridges in the pulley are not machined correctly. They have a plateu instead of a ridge.
............. _
Like this: / \ instead of this: /\

Using this for a long enough time would more than likely damage your belts.



~Josh~

Last edited by ballitch; 12-06-2008 at 11:29 PM.
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Old 12-07-2008, 11:25 AM   #24
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No problems with my underdriven pulley. My GFs bone stock Corolla lights dimmed at idle much-much more than mine ever do. I've gone through the big amplified stereo phase of my life as well, and never had any issues at all with the UD pulley. I run a 9.5lb flywheel too.......It's all pure bullcrap. I will say that I'm also not stupid enough to have every electrical system on the car at max current draw at the same time while idling....so that may be a big reason why I don't have problems and others seem to. Turn off the defroster and big rally lights, turn down the music and cut the blower fan down a couple notches.......

Ballitch: Take a close look at the inside of your belt. That flat portion of the pulley rib is there for a reason.

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Old 06-12-2009, 06:17 PM   #25
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stick with the stock sized pullye...you will kill your alternator with a underdrive
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