Underdrive pulleys [ merged 1/6/07]

[larryd]

Worth it or not? I'm thinking of going with the AEM tru-power pulley kit. Anyone used them?

 

[oldman]

like what??? mine seperated and i had no clue what happened

Squeelling belts-lifter like tick-clunking noise- 2 snapped alternator belts- complete seperation.

 

[heavypedalmuzic]

i had the underdrive crank pulley for a year or so and it totally killed my voltage. ofcourse i have a sound system in the car and that may have worsened the problem but after changing back the stock crank pulley my voltage improved significantly. i also have a friend that after adding the underdrive pulley had bearing failure 3 times and since he's removed the underdrive pulley the car has been running for a while and the problem has not re-occured. could be coincidence but in my opinion these underdrive pulleys look good but arent really worth it.

 

[MitzMadness]

Thats why you need a dampened pulley so you don't have bearings go bad. If you have voltage problems, considering better alternator, battery, grounding kit.

 

[killab443]

I was considering an underdrive pulley for my 92 gst. ITs a 6 bolt. I have heard some talk that they can stress bearings in the motor because typically the motor is balanced with it. Now can it harm or risk the life of my engine? Also I know it will rev a little quicker but how much hp can I actually expect from this bolt on.

 

[killab443]

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&item=7971439333&category=38656

heres the link

 

[slider85]

I've had my Unorthodox Crank Pulley on for about 5000Kms so far and no problems. Some people have said that they can cause engine failure but I don't believe a lot of it. And, the engine doesn't seem to rev faster but it does have more power now at the lower end.

 

[doug]

Any HP gains from this will be negligible, but I personally think it's a good mod because it eliminates the possibility of the two-piece OEM pulley separating and causing engine damage.

I've been using a one-piece pulley for almost three years.

 

[speedy13]

Hey doug.how's the bov problem going?The reason they say is bad,is because that rubber peice Dampens harmfull vibrations from the motor to the crackshaft,and can cause premature problems in your engine.This does not apply to the 420a because it is internally balanced cranckshaft,but the 4g63 isn't.I personally would'nt risk it.this is used on race cars because the don't really care about some premature engine problems,since they tear down and rebuild engines on a constant basis.

 

[doug]

BOV problem remains.

I'm with slider on this one; I don't believe a lot of the lore surrounding the non-dampened pulley issue.

 

[Attack Eagle]

IT's an nvh thing...

IMHO


the thin circle of rubber they use in the pulley is MUCH less than the rubber belts you use on it. there are no vibrations getting INTO the crank from the pulley or accesories, but the two piece does quieten belt noise.

pro's: won't separate, the a/c doesn't make you seasick as it kicks in and out while running down the freeway...

Con's: maybe there is a reason other than NVH... maybe not... you will never see more than 13.4-13.5 volts out of the alternator again... and will be down near 12.5-12.7 at night with a full accesory load. You can't order stock belts... I use a 377 gatorback... it's the ONLY one that fits and holds.
ANd finally I don't know that they have timing marks...

 

[Defiant]

http://www.dsmtuners.com/forums/showthread.php?t=2580

IT's an nvh thing...

Harmonic balancers are not for noise/vibration/harshness. It's crank windup.

the thin circle of rubber they use in the pulley is MUCH less than the rubber belts you use on it. there are no vibrations getting INTO the crank from the pulley or accesories, but the two piece does quieten belt noise.

The rubber isn't what's doing the work. It's the weight the rubber is bonding to the hub, and how it interacts with flex of the crank. The harmonic balancer isn't for forces nor noises getting "into" the crank, but for forces generated at the crank by the torque generated by they pistons/rods.

Con's: maybe there is a reason other than NVH...

NVH isn't the "why" to start with. Even the balance shafts aren't for NVH- they're for cancelling the primary drawback of a large-displacement inline 4, which is large secondary imbalance in the basic design.

ANd finally I don't know that they have timing marks...

They do.

You may drive forever without an harmonic balancer, and have no trouble at all (as the flood of following posts will try to attest). Or, there may be trouble:

 

[zyrusp]

whats going on dsmers? my question is concerning the AF/X UDP. i was just woundering if the oem belt will work with it or not. if it does not, can you guys hook me up with some info on what i should use? thanks.

 

[Dracas]

Yeah, I used the OEM bolt on mine.

 

[eclipse13]

I am using the belt that came with the UDP. I don't know how you are using the stock belt. The new pulley is smaller, so the new belt should also be smaller.

 

[speedy13]

yeah,AFX sends em with belts.THe pulley is ALOT smaller then the stock one so i don't see how a stock belt would work,but hey if it worked for him, fine.If not you can check Unorthodox site for reference or call up howell and theyll tell you the gates or gatorback equivalent.

 

[bullettdsm]

Yeah, I used the OEM bolt on mine.

Check the spelling. belt vs bolt. I also used Howell kit. Sent correct belts with it.
MB

 

[speedy13]

oops sorry.Yeah I used the stock bolt too.

 

[eclipse13]

I used a new OEM bolt

 

[kobykris]

Totally agree. To me, the reason to use a one-piece pulley is because it's just that-- one piece. It won't separate on you at some random, probably inopportune, moment.

Mine had no warning signs. I had accually looked at in not 4 months ago and it was just fine. No play.

Then last weekend at the track, it separated and tossed the alternator belt on me. No good.

I'm looking to replace it with a solid unit.

 

[Forces32psi]

KOBYKRIS i have tried to email you many times stating that i got your payment and i emailed you lastnight telling you that i mailed the pulley and a belt for it so you wouldnt have to go spend $14 on one and im guessing the emails arent going thru??? i get a meail from paypal today saying that i havent contacted you or anything.. my wife sent parts out yesterday and your pulley was w/ thsoe parts.. she didnt say anything about overnighting it, im guessing it just went w/ regular mail it was through the post office i have the receipt saying that postage was paid on it etc to your zip code... call me.......... 816-522-5861 steven

 

[Morel]

I was able to get my hands on an underdrive pulley (a lightweight aluminum one) but it doesn't come with the directions. I can put it on myself, but I donno what size belts get put on. Are they they stock sizes, or do I have to get a new size..

Anyone able to help?

Thanks in advanced!

 

[Talon ESI-T]

For the power steering you want a 48-50" belt, I have used a 48" since I couldnt find a 50" in stock anywhere. I cant remember what size for the alternator but I would venture to say 2" smaller, stock is 35.5".

In Gatorback belts the last 4 digits are your length of belt. 0480 would be 48.0", 0505 would be 50.5 " and so on. The first 3 numbers are also coding for belt design. For example # 4050510 is broken down like this: 4=I am not sure, maybe number of ply in construction, 05=# of ribs and 0510 is 51.0" belt

Stock sizes are:
Alt: 4040355.....SO
4 ply
04 ribs
035.5" long

P/S: 4050510....SO
4 ply
05 ribs
051.0" long

You will be safe with a 48" belt for the power steering Gatorback number 4050480 and if you have an autozone near you, this belt will be in stock

For your Alternator, try the stock belt and see if you can adjust the Alt out to fit, otherwise the next size smaller that autozone carries is 31.5......thats a big difference but it might fit. P/N 4040315

Terry

 

[Morel]

I thought it was a serpintine belt..

 

[Talon ESI-T]

Come on buddy, look at your once in a while. You have 2 serpentine belts

 

[Morel]

OK thanks man.

and BTW, I did look, I actually replaced it a few years ago and I just didn't remember noticing 2 belts (I was in the parking lot of a Autozone at the time.. so I didn't have a chance to really take my time).