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Guest Message by DevFuse

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UnOrthodox Underdrive Pulley Install

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26 replies to this topic

#1 Guest_Legacy777_*

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Posted 04 June 2001 - 10:43 PM

Well I did this about 3 weeks ago. I had some money burning a hole in my pocket, and wanted to give this thing a try. My biggest concern was about dimming lights at idle. I have a friend with an impreza, who's lights dim pretty bad. Turns out it's really not too noticable. I notice it cause I'm a little anal ;) but normal person most likely would not notice it. I also have an Optima Yellow top battery, that may help a little. But I think the Legacy charging system may be a little more beefy then the impreza, or his alternator is poop...hehe.

First thing I did was take out the radiator fans, not too hard. Next took the belts off, the pulley tensioners on these motors are quite ingenious. Then came the second biggest pain in the rump roast in the project. Loosening the bolt for the main pulley and getting it off. I had noone to help me, stuck a BIG screw driver down the little access hole on the auto tranny, and tried to hold the two while not poppin my shoulder out...;) I finally get the bolt off. Then the stupid pulley wouldn't come off. I bang on the inside of it with a small hammer for a while, finally got that off, after strugglin for a while. Cleaned the shaft, of course the stock pulley slides on and off alot easier now.

The biggest pain in the rump roast was getting the Underdrive pulley to fit. The key way did not fit. I'm pretty sure the main thing, was that it was not tall enough. I ended up filing the key way deeper, and slightly wider so it would fit on. I got it on almost all the way, maybe a mm or 2 that I didn't just push on with my hands. Then I just cranked it down the rest of the way with the bolt. The subie mechanic I talked to recommended 110 ft/lbs of torque on that bolt, as well as lock titing the threads. Reassembled in reverse order, the belts they sent fit perfectly. They were the gates Unorthodox recommended. I got my pulley from SPO Motorsports. They had probably one of the better prices.

Now you're probably askin, so was it worth the $190. Well I've put close to 1000 miles on it in the past few weeks, to and from school a bunch of times, and up to Toronto :) .

The biggest thing I notice is an increase in fuel economy. I have gone up 4-5 mpg on average, per tank of gas, even the way I drive ;) . I went from around 20-21 mpg to 25-26 mpg or more, depending on type of driving conditions, and my lead foot. I would get 100 miles to half tank, I get 130+ Again big thing to remember is with my driving habits. It also feels more peppy, pretty much through entire rpm range. Other thing I've noticed is that it likes to drive faster....Like my car LOVES 90+ mph. The engine is in it's nice torque/hp range, 3000 rpm or more, and it seems to go faster, easier....uh oh...not good for me. HAHA.

Overall if I save 5-6 mpg per tank, I'll get my money's worth eventually, so it will have paid for itself. All and all, if you got the money, and it's burnin a hole in your pocket, and you don't know what to buy, this would make a nice addition ;) If you have moderate mechanicing skills, you should be able to do this mod.

Now for the pictures :)

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#2 Guest_ShawnW_*

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Posted 04 June 2001 - 11:32 PM

Again Pretty darn cool Josh!

You have been such an asset to this forum, especially to me as I havent had my 90 Legacy a long time but have benefitted from your help more than a couple of times!

Might do that mod, if I ever find a job.


#3 Guest_MailmanX_*

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Posted 04 June 2001 - 11:56 PM

What! No job? Check with ReMarcAble. I think he has a lead on a job that pays $50,000 per month, working part time from your home, while losing weight, curing cancer and solving world peace. It might be nice in a pinch until you find a real job!

P.S. - Josh, you da man!

#4 Guest_subeman90_*

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Posted 05 June 2001 - 05:04 AM

WOW that kind of increase in the MPG is awesome. Hey Josh does your A/C work? If not you should lose that belt too. Less load again.....

Did you buy that kit from Teague? Even if you didn't that is a heck of a plug for a product he sells.


#5 Guest_meep424_*

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Posted 05 June 2001 - 05:20 AM


Are you totally serious about the MPG gain? That's HUGE! I commute 400 miles per week, and a gain like that would pay for the pulley in just a few months.

(Note, it took un-lockable hubs, insulating the entire air intake, synthetic motor, gearbox, tranny and diff lube, and new driving habits to get our truck from 18 to 22 mpg, so I see a 1-part solution for 5+ mpg and get really interested...)

Question: Is the stock pulley considered a harmonic balancer in these cars? I know that in some vehicles such as BMWs, you don't want anything with less rotational weight to replace the stock pulley b/c it's designed to counteract rotational vibration (think twisted tuning fork) that otherwise tears the crank apart over time.

Has anyone seen whether the subee motors are OK with changes in the pulley weight? If they say it's Ok-- I think I'm going to have to play "follower" to this example...


#6 Guest_Huckster_*

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Posted 05 June 2001 - 05:39 AM

I don't think the small weight reduction, will afect the boxer style engine as much as it would a V engine, in the V-engine there is a lot more vibration to quell, not so in the boxer syle in the Subarus, Of course it might weigh the same, as it gains power from its smaller diameter, not by weighing less.
my 2 cents,

#7 Guest_Legacy777_*

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Posted 05 June 2001 - 09:13 AM

Matt: Yah my A/C works, I'm goin to leave that on, I'll be goin down to tennesse to start work in July, so I'll probably want it ;) By kit you mean pulley and belts right? I got the pulley and belts from SPO. I believe teague's has the same kit available. I think his prices were a little more, which is why I bought it from SPO.

Meep: Yeah I'm serious about the MPG. It may be on the higher side or lower side of what I said, depending on type of driving, and whether I feel like speedin or not...hehe. The only other thing I did was put in a new knock sensor around the same time. My old one was not bad, I just had fiddled with the wiring with Gary's hesitation fix, and didn't like the results so I put everything back. I didnt' feel like leavin the wires jimmy rigged, plus I heard the new knock sensors were better. I don't really know. I can't say I notice any difference in the area where the over sensitive knock sensor would cause hesitation. Plus I don't think that would change mpg that much.

The stock pulley is to my knowledge a harmonic balancer type thingy for the boxer engine. However it is no way like a harmonic balancer on a V-8 or something. As Huckster said the boxer engine's design is inherantly less vibration prone. So getting rid of the heavy stock pulley shouldn't be a problem. Mine really hasn't seemed to have any problems. Only thing I notice is that there is a slightly different tone or noise when idling. Almost like normal lifter noise, but just different tone or something. Idling may be the only area where it may not be perfectly smooth. Especially when fans are on. However my car never idled super smooth.

Other thing I didnt' mention is when I first used the A/C after I installed the pulley, the idle oscilated up and down a little bit, but then was fine after a while. I guess the computer relearned what it had to do to get the car to idle right with this pulley or what not. I don't have any problems with it now.

I don't want to make fabulous claims that everyone will see the mileage increase I did, but I am just reporting what I see and experience. I do think it is a good modification for the boxer engines, because they are more stable and have less vibrations.

If anyone has any more questions about the install, or pulley, etc. Don't hesitate to ask

#8 Guest_czo79_*

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Posted 05 June 2001 - 10:18 AM

Apparently subarus do not have harmonic dampers, or at least the crank pulley doesn't act as one. I guess it does act as a torsional damper, but the reduced diameter and weight of the UOR pulley reduces acc. loads on the crank, so it isn't a problem. If people want to know more about these they should check out the tech notes on them at SPO motorsports. Hey josh, if I remember correctly you run quite a stereo...any problems with that? Do you have capacitors (sp?) for your amp(s)? People should also be careful when torqueing the UOR pulleys. I believe the stock pulley is rated for 110-130 ft/lbs, but I think UOR says there pulleys should only be torque to 90 ft/lbs. I remember someone on the I-club bending theirs torquing it to fact. spec. Thanks for the info josh, since i gotta do my belts anyway, I think i am going to try and put one of these on next week.
97 Legacy GT

#9 Guest_Legacy777_*

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Posted 05 June 2001 - 10:27 AM

Yeah I've got a pretty hefty stereo that can max out my alternator amperage if it wanted to. I really haven't had any problems with the electrical stuff, stereo, lights, etc. That was one of my biggest concerns with doin this mod. But it has turned out to not be much of an issue. I do have the Optima Yellow top battery, which I think helps, and yes I do have a 1 farad capacitor for my sub amp. That may be a little overkill, ;) oh well.

I guess now that you mentioned it, because the UOR pulley is alumnium it could use a little less torquing. I really don't know if 20 lbs of torque would do that though. I didn't have any problems with mine.

#10 Guest_meep424_*

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Posted 05 June 2001 - 11:19 AM


Thanks for the info. I read the SPO notes too, and for the most part they address the question of torsional dampening, etc., but they also caveat most of their statements in "does not use a harmonic balancer *in the traditional sense*". That still leaves the possibility of "untraditional" balancing-- so there's still a hole there; so I dropped them an e-m to see what they say.

Pretty interesting stuff-- actually, I suspect the ru's would have less of a problem than others b/c the crank is so short. It'd be a bigger problem in a straight six, or as y'all mentioned, in an 8.

Hey I'll let you know if SPO says anything interesting.

Y'all are great. This is a cool forum. Thanks for the opportunity to talk tech.


#11 Guest_Commuter_*

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Posted 11 June 2001 - 05:41 PM

The following is from SPO's website info on the UnOrthodox pulley.

"Weight loss is the most critical factor in HP production, each lb. of mass taken off the crank/eccentric shaft is worth approximately 2.7 HP and the figure increases with forced induction, nitrous, VTEC and increased RPM's. Only 15-20% of the gains seen from our pulleys comes from the underdriving. We achieve the maximum gain for each application/model by the singular use or combination of reduced diameter ("underdriving") and weight loss versus the OEM crank pulley/s. This principle allows us to maximize the HP gain without causing any adverse effects in the general function of the vehicle."

As you can see, most of the gain comes from reduced weight, not from from the smaller diameter.

Some time back, I thought I read of a pulley which was a reduced weight version, but maintained the same diameter. (This would eliminate the new belts, concerns of dimming lights, etc.) Upon searching, I was unable to turn up such an animal.

I do a lot of "commuting". If I gained just a couple of mpg, I could pay for this thing inside of a year. Warrants a closer look... I'd like to hear of other people's experience.


#12 Guest_Legacy777_*

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Posted 11 June 2001 - 05:47 PM

Commuter, JC Sports was the one offering the same dia pulley, but lighter. I'm not sure if they still are.

#13 Guest_LostWater_*

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Posted 13 June 2001 - 06:43 PM

Isn't this the same idea as drilling your flywheel or at least lightening it to make more hp? Paeco offers that service and It sounds like their are even more ways to reduce rotating weight.



#14 Guest_Legacy777_*

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Posted 13 June 2001 - 10:16 PM

yes this is similar to lightened flywheel, or drillin it. Not sure which one would give you the most benefits though

#15 Guest_PaganQWA_*

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Posted 14 June 2001 - 08:10 AM

it doesnt matter if you drill it or lathe it; its the overall weight reduction that gives you faster revs and more HP. I would suggest getting it lathed so that it is balanced when they are done.

Its kind of a pain in the rump roast to drill exactly oposite holes into the flywheel so that you do not offset the weight balance.

#16 Guest_czo79_*

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Posted 14 June 2001 - 08:45 AM

I have heard it said that drilled flywheels are not as good as purpose built flywheels because (as someone hinted) they are more likely to be off balance, as well as they make it easier to contaminate your clutch disk w/ oil if you have any seapage from your rear main seal...Don't know if its really true though. When I put an exedy clutch in my car I inquired w/ mike sheilds at SPD about a lightened flywheel and he said:

"The belt drive of the cams is sensitive to the rotational mass of the engine, so one ought to stay above 18 pounds to insure reliability. The WRC Prodrive rally cars do run light flywheel and clutch assemblies, but they modify the pulley arrangement and use a Kevlar ($$) belt."

I personally was unable to find a flywheel that wieghed more than 15 or 16 pounds if i remembercorrectly.
I was also wondering...I know that a lightened flywheel (i guess obviously) doesn't increase horsepower when measured at the crank, but what about horsepower at the wheels? I know it allows the engine to rev faster and increases acceleration times, and allows one to shift faster...
97 Legacy 2.5 GT

#17 Guest_PaganQWA_*

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Posted 14 June 2001 - 08:57 AM

The fact that your dropping pounds of weight will give you HP but since your dropping rotating mass you might loose some torque or at least the low end.

All the old gen buggers :lol: that have done it say they rev like a banshee and have more power through the whole power curve.

I have yet to hear anyone say theirs flew apart at 7k RPMs so as longas you dont take to much off your fine. I dont know the weight of these newer fly wheels. With the H6 Subaru noticed they had to drop some pounds off the flywheel to get some response out of the engine (the XT6's ER37 engine has a lighter fly wheel then the EA 82's; and I would bet the newer H6's have lighter flywheels then the EJ22 and other newer engines) So maybe the new H6's fly wheel would be an upgrade to other newer Subaru engines? SOmething to look into...

#18 Guest_Legacy777_*

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Posted 14 June 2001 - 10:12 AM

Not to get techincal on ya, but the H6 does not have a fly wheel. It is only available with an auto, so the torque converter acts as a rotational damper "flywheel" to give/take energy when needed to ensure a smooth steady engine speed, etc. I don't remember the exact config of the torque converter setup, I just had a class about all that **** too. If someone is REALLY interested I can go look it up and get the specific names.

#19 Guest_PaganQWA_*

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Posted 14 June 2001 - 10:45 AM

Thats lame the never offerd a manual :( all that power wasted on a auto tranny!

Well forget swaping flywheels! :lol:

#20 Guest_Commuter_*

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Posted 14 July 2001 - 12:33 PM


Did the Unorthodox pulley have timing marks on it?

If not, does it even matter these days?

Just wondering.


#21 Guest_Legacy777_*

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Posted 14 July 2001 - 06:47 PM

Yeah it had a little hash mark, but it doesn't matter anyway cause you can't set it. The main reason I THINK it has a timing mark is if you're rebuilding an engine, you can check the timing to make sure it's near or where it should be. But even then, the computer should do all that.

#22 Guest_Legacy777_*

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Posted 22 July 2001 - 10:12 AM


#23 Guest_Ryan Power_*

Guest_Ryan Power_*
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Posted 22 July 2001 - 12:57 PM

Question for Legacy777: In your first post, you said that your lights dim at idle (so do mine)... my question is, since you went with a smaller diameter wheel, don't they dim even more then before?
Also, looks like you bumped the thread. ;)

#24 Guest_SmashPDX_*

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Posted 22 July 2001 - 03:08 PM

Somebody remind me to archive this thread when it putters out... thanks Josh for putting this up :)

#25 Guest_Legacy777_*

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Posted 22 July 2001 - 04:42 PM

no prob smash

No I really don't have any more dimming than I did before. I have an Optima deep cycle battery in though, so that could help. But for my car, no the lights don't dim any more then they did. Right now the most noticable thing is A/C sucks even more then it did before...hahaha....I need to get it recharged I think, at the very least.

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