Hi guys,

has anyone heard anything good/bad about installing an underdrive crank pulley in a 98' eclipse 420a engine, 2gnt?

I recently purchase a afx pulley and after reading several forums where they say it could damage the engine, i'm getting worried.


what are your thoughts on this mod?

ramie
98' eclipse rs

Bs. Where did you read that btw? Any amount of searching on this forum will prove to you that dozens of members have installed and currently run UDPs on their cars without problems. :) The only "DAMAGE" that may occur is that which YOU can cause, beating that baby into place. Some people have had to hammer theirs in...aside from damage due to that, dont hesitate to install it :thumbsup

P.S. Oh and Welcome and btw...

BANME!! :P

Easy, easy, there, edex, mon.

The turbo guys do talk about lack of balance or something, but the AFX UDP is a great mod for your 420A. It's both common and widely recommended around here.

If you really want to know what's up with your car, check out the search on this forum and search for whatever by subject. You will get all kinds of good information. This site is the source of most of the legitimate tech you will find for these cars on the web.

Originally posted by DR1665
Easy, easy, there, edex, mon.

Woah, Driggs do you think we are having another one of those Newwbie uprisings again? lmao

what?! what did i do wrong this time?!


all i want is to be one of you guys... ;(

I've heard several instances where installing an aluminum UDP can cause issues. However, NONE of them were related to a 2gnt.

On the 4.6l mustang, supposedly an aluminum UDP doesn't dampen harmonics enough. After all, it's a harmonic dampner, not ballancer. The problem caused by the high harmonics was a broken oil pump gear. Now, it's probably one of those things like crank walk, a handful of people got it, so now "EVERYONE will get it" craze.

Personally, I'm planning on installing an aluminum UPD set when I can spare the cash to order one for my 4.6l.

Yeah, thats the issue with the 4g63s. I bought one for my project Talon cuz I got a good deal on it, but after reading the issues about them decided not to put it on. The 4g63 uses the pulley as a dampener. The stock one has rubber between the inner hub and outer ring. The 420a one is just solid metal though, so a quality UDP that's been balanced will have no negative effects on reliability. They do give some noticeable gains though. I finally put the one I bought for my old 2gnt on (best friend owns it now) and it seems to have a bit more snap from the low end. Course, its hard to tell since we also did a full rebuild and put the UDP on right after the build, so I'm sure a lot of the gains were from a fresh motor :-D. Regardless, do a little searching and you'll find a lot of happy campers with the AF/X or Unorthodox pulleys.

Originally posted by Silv Blt
<snip>The 420a one is just solid metal though, so a quality UDP that's been balanced will have no negative effects on reliability.

420A crank pulleys have rubber rings between the inner hub and the outer pulley grooves. At least the five stock ones I have are that way. Were there really some that are solid?

On 420As I have read that the rubber is mainly there for lowering acoustic levels and not for harmonic dampening so I put a UDP on my 420A and am not too concerned about it. Chances are I'll blow the motor for some other reason long before I loose a bearing from accelerated wear issues related to a UDP install.

I took a really quick look. There could be a thin layer of rubber in the stock 420a pulley. The 4g63 ones definitely have a noticeable layer though and those actually wear out as the years go by making the harmonic damper a replacement item. One of the well noted 4g63 builders (I'm thinking Slowboy Racing, but I'm not sure) found very accelerated wear on a motor that they built using a UDP. They won't use them anymore and I trust their opinion. I'm sure I could get away with it for many thousands of miles, but chances are that the little bit of wear will be enhanced when I hit the 300whp mark. Since I've got a turbo on my side, I'll let it do the power making and leave the UDPs to the NA Eclipses :-) I've yet to hear of any premature wear from the 420a ones.

When everything was balanced for me, they actually asked for the udp and balanced it with the crank. I would assume any respectable shop would do the same.

Did they have to do anything to the pulley? no, but they still marked it for me so that I could install it again exactly as it was.

Originally posted by Chamuko
When everything was balanced for me, they actually asked for the udp and balanced it with the crank. I would assume any respectable shop would do the same. Did they have to do anything to the pulley? no, but they still marked it for me so that I could install it again exactly as it was.

The UPD is nod keyed, there's really nothing to balance it to, and the UDP should be neutral balanced anyway.

Some engines use the crank pulley/harmonic damper and even flywwheel to balance the engine. Ours does not, it is pretty well balanced from the factory. I've been running one UDP or another for a goo 85,000 miles with no signs of trouble.

Exile Racing Technologies
http://www.exileracing.com
Go that way, really fast, if something gets in your way... turn. I was too lazy to do it myself.

Like Mike said, the pulley on the 420a has no dampening affect (unlike the 4g63). Whether you are turbo or not has no effect on the function of the pulley. Now, if you were to put on an UNbalanced pulley (like you may get cheap of E-bay) this will cause harm to the engine. The AF/X by virtually all accounts has no problem with balance and you can use it with confidence that it will not harm your engine ( I have used it on my engine before and after the rebuild). The 4g63 pulley is a totally different design.

MB

I figured I thrown in my 2 cents to add to this thread...

Ive had a UDP on my 420a for a year now. I have eaten up 5 Alt belts, always on the sides. I figured I had it too far in and too far out. Ive tried to remedy moving the opposite way and it still did it. So now I have a Alt belt thats missing a rib and is fine the way it is, Im not bothering anymore.

Im def putting the stock pulley back on when I swap my heads soon.

food for thought

Hey David,
Is that an AF/X UDP?

MB

Originally posted by DJ420a
I figured I thrown in my 2 cents to add to this thread... Ive had a UDP on my 420a for a year now. I have eaten up 5 Alt belts, always on the sides. I figured I had it too far in and too far out. Ive tried to remedy moving the opposite way and it still did it. So now I have a Alt belt thats missing a rib and is fine the way it is, Im not bothering anymore. Im def putting the stock pulley back on when I swap my heads soon. food for thought

If everything is not perfectly in line you will eat up belts. I had the same problem the first say month or so I had my UDP, but the stock pulley will do it also... Happened to me. IF theverything is not in alignment then yes it will shred the belts, but ever since I had everything re-aligned, about 4 months ago, I have not had a single problem since

I know that, I just thought it was a nice thing for them to do. They marked it for me, Its now marked.

Our engines are nicely balanced, hence no balance shafts.

Very true... That is a nice thing to do also

This is an old thread, but Im bumping this up instead of making a new one. At least I searched, right?

One of my relatives got me an UDP for christmas and I have yet to put it on. As far as I know its a no name brand, but it looks like it was machined very nicely. Is there any way I can find out if its balanced?

Also, its good to finally find some information PROVING that an UDP on a 420A will not do things such as "snap the crank in half", as Ive heard on other sites like DSMtalk. I had figured a little piece of hard rubber was not stopping my crank from self-destructing.

does it have marks where it was balanced? you can always take it to a machine shop for balancing as well, if you are that concerned about it...

First off make sure the diameters are concentric. You can use a 6'' dial caliper to check wall thickness and step depths. The like dimensions should be dead on.

The most important tolerance for concentricity is from the I.D. (bore) to the belt surface diameter.. The depth of the I.D. is also important to assure alignment to the p/s a/c pullies.

Of course squareness counts for alot too. My God though. There can't be anything THAT crappy out there is there?

A part is only as good as the tooling used to make it. I'd go with a name brand if possible.

I've been running a Bomex UDP on my 420a for almost 3 years now with no issues. The only thing I could see is that your alt is underdriven at idle and would cause dimming issues if you had a big booming stereo. Other than that, its a great mod. It reduces rotating mass--its a huge difference in weight from the stock pulley. You should free up some ponies.

I had issues with my stock pulley tossing belts--I believe it had something to do with how it was pressed on the crank snout--it must have been out of alignment just enough to toss them...

Haven't had that issue with the UDP though.