Consensus on LW crank pulley and LW flywheel?

[Compressed]

I would like to determine what everyone thinks regarding the combination of a lightweight flywheel (11ish lbs) and a lightweight crank pulley (1.25 lb). I have heard that this combination leads to some serious drivability issues. I could see this happening, I had to get used to my Exedy flywheel, but once I did drivability was no problem. I am thinking of adding a lw pulley and after researching I am unsure whether I should or not. I see lots of people who do it and I hear about a lot of people who say to avoid this combo at all costs. My car is a daily driver, but I appreciate a car that is highly tuned and do not mind making some sacrifices to deal with the potential gains this setup might provide. This is on a DOHC 2.5 if that makes any difference.

So speak up everybody and lets take this chance to settle this issue once and for all.

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[That Guy]

bump

because I've been wondering the same thing

[Kostamojen]

There isnt a consensus because not many folks have even tried. Hell, i'd let someone borrow my pulley I have on my car now if they had a lightweight flywheel to see what happens...

General some folks say either that combo is always bad, sometimes bad, or perhaps not bad at all, and a small minority say that pulleys are always bad...

I tend to think a midweight lightweight flywheel (12-13lbs) with a non-underdrive lightweight pulley would probably work fine. I tend to think the problems would start occuring with an underdrive pulley and a 9-10lbs flywheel, but I havent ever seen anyone try and report back to us on how it worked.

Try it out, and if it doesnt work sell the pulley to another local i-cluber.

[orndog]

I bought a lightweight pully, but can't help wondering why Subaru didn't just make the pulley light to begin with. What are the drawbacks? There is always a trade-off.

[Blindeye_03]

Well here is the gunnea pig...ME!

LOL, I have had a underdrive pulley for about 45k miles now, and I just added a lightweight exedy flywheel and sport clutch (I am a little over 57000 miles). The flywheel has been on for about 600 miles now.

The only 'issues' I have are at 1500rpms the car vibrates hardcore...mainly because of my sti motor and tranny mounts. And at 3100rpms there is minor vibrations. I dont know if its 'safe' to use the UDP with a light flywheel...I guess we will see, eh?

-justin

[goobie]

I've been running an Unorthodox UD LW pulley along with a 15lb flywheel for quite some time and have seen no divablility issues related to that setup. Other than the occasional clutch shudder the car works great. I think the key here is to not go crazy with the flywheel weight.

I tend to think a midweight lightweight flywheel (12-13lbs) with a non-underdrive lightweight pulley would probably work fine. I tend to think the problems would start occuring with an underdrive pulley and a 9-10lbs flywheel, but I havent ever seen anyone try and report back to us on how it worked.

I tend to agree with the above quote except I don't see what difference it would make if the Pulley was UD or not. I mean it weight we are looking at here, not the drive speed of your accessories.


Cheers,
Chad

[jeffg]

9.6# findenza
UoR pulley

no problems. no misfires.

the car does make more noise now. I am sure that I lost a lot of vibration dampening. Oh wells.

J

[Compressed]

Okay good info guys

I tend to think a midweight lightweight flywheel (12-13lbs) with a non-underdrive lightweight pulley would probably work fine. I tend to think the problems would start occuring with an underdrive pulley and a 9-10lbs flywheel, but I havent ever seen anyone try and report back to us on how it worked.

I tend to agree with this as well. I too dont think it matters if the pulley is underdriven or not though.

The only 'issues' I have are at 1500rpms the car vibrates hardcore...mainly because of my sti motor and tranny mounts. And at 3100rpms there is minor vibrations. I dont know if its 'safe' to use the UDP with a light flywheel...I guess we will see, eh?

Hmm, this makes me a little apprehensive. Your STI mounts probably exagerate this, but I want to add STI mounts too, the stock mounts let the engine flop around way too much. Did you notice a resonance around 1500 rpm before? If not did it start right after the FW install?

Lets get some more anecdotal evidence here, c'mon guys.

[Compressed]

Originally posted by jeffg
9.6# findenza
UoR pulley

no problems. no misfires.

the car does make more noise now. I am sure that I lost a lot of vibration dampening. Oh wells.

J

Good to hear! What kind of mileage are you at and how long have you had this combo?

Also everyone else who posts, list your mileage so we can get some kind evidence regarding longevity with this combination. Thanks.

[jeffg]

I have like 38,XXX on my car and the UoR pulley has been on since like 3000 miles. The flywheel has only been in since March. so maybe like 1200 miles total for the combo.

J

[Blindeye_03]

Originally posted by Compressed
Okay good info guys



I tend to agree with this as well. I too dont think it matters if the pulley is underdriven or not though.



Hmm, this makes me a little apprehensive. Your STI mounts probably exagerate this, but I want to add STI mounts too, the stock mounts let the engine flop around way too much. Did you notice a resonance around 1500 rpm before? If not did it start right after the FW install?

Lets get some more anecdotal evidence here, c'mon guys.

Yea it did it before @ 1500 rpms, just not as bad as now...as an above poster said I am sure I got rid of some dampening. Oh well, the car is just farking amazing now! .

-justin

[Kostamojen]

Well I think im having alternator as well as power steering pump issues due to my underdrive pulley, but I dont really care cause I want my engine to explode and I paid an insanely cheap price for my pulley If I had a choice and had to buy a new pulley from a vendor i'd go for the stock size pulley to reduce the risk of accessory driveline issues, especially paired with a lightweight flywheel... But since we have folks here running UD + rather light flywheels it might not be that big of a deal afterall

[orndog]

Originally posted by orndog
I bought a lightweight pully, but can't help wondering why Subaru didn't just make the pulley light to begin with. What are the drawbacks? There is always a trade-off.

I quoted myself Does anybody know the answer to this?

[Compressed]

I bought a lightweight pully, but can't help wondering why Subaru didn't just make the pulley light to begin with. What are the drawbacks? There is always a trade-off.

Subaru didn't put a LW pulley in for a couple reasons.

1st, is that a heavier pulley has more momentum when moving, having more momentum in the system makes the car easier much easier to get moving. You can almost think of it as stored power, it takes more power to move a heavier pulley, but it is also more resistant to forces acting on it to slow it down (starting from a stop).

2nd, Harmonics. The stock pulley has a harmonic balancer built into it, this is dampen any destructive forces that may occur in the engine. Since our engines are horizontally opposed and fully balanced from the factory this feature may or may not be needed. Do a search on this, there is lots of controversy regarding this subject, most people are camped one way or another. There does seem to be a fairly large sample size of people using LW pulleys that are not damped, with good results, i.e. without significant crank bearing wear or premature engine failure.


note: I simplified this greatly and obviously the physics behind this is much more complex.

[orndog]

Being an earth and space science major, I understand the physics of it. I was in the third camp - the one that thought since our flat fours were naturally balanced there was no harmonic balancer needed. Now I'm wondering whether or not to install this 140 dollar pulley I have sitting on a shelf (makes a nice art-deco piece either way ).

[goobie]

2nd, Harmonics. The stock pulley has a harmonic balancer built into it, this is dampen any destructive forces that may occur in the engine. Since our engines are horizontally opposed and fully balanced from the factory this feature may or may not be needed. Do a search on this, there is lots of controversy regarding this subject, most people are camped one way or another. There does seem to be a fairly large sample size of people using LW pulleys that are not damped, with good results, i.e. without significant crank bearing wear or premature engine failure.

I've thought about this one long and hard for quite some time. While the rubber balancer may be designed to dampen forces destructive to engine internals, I really think the main reason for all that rubber being there is simply to reduce the noise caused by the A/C compressor. Did anyone notice how much louder your A/C was after a LW pulley install? I know mine is at least twice as loud, if not more.

Chad

[Kostamojen]

Ya, mine is louder too (the A/C), but my '95 didnt even have any of that rubber stuff on the stock crank pulley...

[Compressed]

Well I don't mind a car that has an edge to it, so I think that I am going to order a MrJosh pulley and see how I like it. I have the exedy flywheel which I believe is 13lbs, its not ultralight so it should be okay with the light pulley. Hopefully the lightened combination will not create any issues. I think that it will make the low gears quite fun. The car is really good already actually, alas it could use more thrust. After this I will be thinking about some headers. And STI mounts, fuel control, morettes, chassis stiffening, Sparco Torinos.......

[mcu81]

I see your reasoning for #1, but by reducing all the rotational mass i have with my motor, it attacks redline so fast its scary, i have the gfb pulley kit(lightened, and underdriven) and i have a exedy flywheel. I have had both on my wrx for 15,000 or so. I do believe that by doing this, it will shorten the life on the motor as well, but not by much.
-mikey

Originally posted by Compressed


Subaru didn't put a LW pulley in for a couple reasons.

1st, is that a heavier pulley has more momentum when moving, having more momentum in the system makes the car easier much easier to get moving. You can almost think of it as stored power, it takes more power to move a heavier pulley, but it is also more resistant to forces acting on it to slow it down (starting from a stop).

2nd, Harmonics. The stock pulley has a harmonic balancer built into it, this is dampen any destructive forces that may occur in the engine. Since our engines are horizontally opposed and fully balanced from the factory this feature may or may not be needed. Do a search on this, there is lots of controversy regarding this subject, most people are camped one way or another. There does seem to be a fairly large sample size of people using LW pulleys that are not damped, with good results, i.e. without significant crank bearing wear or premature engine failure.


note: I simplified this greatly and obviously the physics behind this is much more complex.

[joefocker20]

I have the Exedy 13lb clutch and Mr Josh's pulley, the combo has been on for approximately 3000 miles and I've had no problems at all. I also have my AC belt disconnected too.

[Compressed]

I've now added a lightweight pulley and have driven it for about a week, so I wanted to post my experience for the archives. To recap I have an Exedy flywheel and Mr.Josh pulley. This combination is very liveable, in fact I think it is bit better for low speed, low rpm 1st or 2nd gear creeping, not sure why maybe I'm just used to the lightweight flywheel more now. Anyway starting from a stop is no big deal, I might have to use a little more gas but not much to get going.

The benefits.
The car revs noticeably quicker, heel toeing is even better now, the throttle blip required now does not take as long, hello late braking . One caveat is that with the a/c on I need to to shift quicker to ensure I will be in the right rpm range as the revs can drop pretty quick with the parasitic a/c compressor going.

Power, I can feel a little more in the low gears and while wringing out the bigger gears too. Partial throttle power has definitely increased, this is very nice while cruising on the highway when needing to pass, and definitely is nice while in slow moving traffic, the car starts to pull at lower rpms.

[goobie]

One caveat is that with the a/c on I need to to shift quicker to ensure I will be in the right rpm range as the revs can drop pretty quick with the parasitic a/c compressor going.

Yeah no kidding hey? Same with me. When the A/C is on you've got be really on your game with the shifting in order to make it smooth!

[joefocker20]

Originally posted by Compressed
Well I don't mind a car that has an edge to it, so I think that I am going to order a MrJosh pulley and see how I like it. I have the exedy flywheel which I believe is 13lbs, its not ultralight so it should be okay with the light pulley. Hopefully the lightened combination will not create any issues. I think that it will make the low gears quite fun. The car is really good already actually, alas it could use more thrust. After this I will be thinking about some headers. And STI mounts, fuel control, morettes, chassis stiffening, Sparco Torinos.......

The best performance mod that I've done to my RS is relegating it to daily driver status and buying an 87 RX-7 turbo for a toy. It was faster than my fairly modded RS when it was stock, and by adding a 3" turboback, removing smog/AC/PS, and bolting a HPI cone filter to the AFM, it probably picked up about 80HP.

[Andrew Bacon]

Originally posted by joefocker20
I have the Exedy 13lb clutch and Mr Josh's pulley, the combo has been on for approximately 3000 miles and I've had no problems at all. I also have my AC belt disconnected too.

How much loss is there really when the A/C clutch is open?
I mean, isn't it pretty much just another idler pulley when the A/C is off?

I got to get the LW pulley/flywheel combo, and a new clutch is in my near future- The stocker is showing it's age nowadays.