underdrive pulleys?
Thread Starter
TECH Enthusiast
Joined: May 2006
Posts: 631
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From: Metairie, LA
underdive pulleys I'm looking for mods to do for under $500. I already have the bolt ons for my 02 z28 a4. Electric fans and water pumps is too expensive, at least for new stuff. March dampener, ac, and accessory pulleys are at thunder racing for $230. Any feedback? Is this installable at home with basic tools(no airguns or hydraulic lifts)? Is there a web site with install instructions? What sort of hp gains could I expect to see?
I replied to this on cz28 as well but ill say it on here a swell
you need a pulley puller and you can do it in your driveway. if you have nothing else to do you might as well, you will pick up a little bit but not much
you need a pulley puller and you can do it in your driveway. if you have nothing else to do you might as well, you will pick up a little bit but not much
swapping the crank pulley is a great mod.....the car will definitely rev up more freely than it did before, especially on the top end. probably one of the only mods that you will actually be able to detect with the SOTP meter. just do it!
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Thread Starter
TECH Enthusiast
Joined: May 2006
Posts: 631
Likes: 0
From: Metairie, LA
will my stock damper be ok with underdrive pulleys, or will I need an upgrade to reduce crankshaft torsional vibration? Aftermarket dampers are expensive, and I'm looking for a relatively cheap mod. A broken crankshaft or any other of the problems crankshaft vibration can cause is not cheap either. What kind of hp gains will I see with an ATI damper, for example? Thunder racings sells them with a 10% ud serpentine pulley for around$450. btw does a higher % mean more underdriving, and how does this equate to hp? Also, what is sfi approved and how important is it. March has cheaper ud crank pulley,belts, and balancer bolt sets, but they don't have any mention of sfi approval. ASP does, but their more expensive. I should've asked these things to start the thread. Sorry, I'm trying to research and learn as I go. 
Last edited by maro z28 #2; Jul 2, 2006 at 02:17 AM.
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Nothing needed exceot pulley, new belt, and tools. To be exact, 24mm or 15/16 socket, half inch drive breaker bar, pulley puller from auto zone and a rubber mallet to get the new pulley started back on. and of course, jacks and jack stands. Good luck, well worth it
please be aware that taking the march OFF is a bitch....if you ever have to do a cam swap or whatnot...i have the march, GREAT product, GREAT price, just letting you know
Go for it, you will also need a longer bolt to install it....I have a longer threded rod and nut if you need it...
Go for it, you will also need a longer bolt to install it....I have a longer threded rod and nut if you need it...
You don't need a longer bolt!!! Definitely don't need, that's what rubber mallet is for, to get pulley on far enough to use stock bolt. Longer bolt helps, but un needed, and definitely not a good thing to break bolt off in crankshaft, so i say tap it then use stock bolt.
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Joined: Jun 2003
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From: Los Angeles, CA
you need a pulley puller which you can rent
as well as a torque wrench which can measure..
i forget.. either 150 or 250.. i think 250ft/lbs
the large one!
if you have an automatic
you might want a flywheel locker
there are other methods around this
i will not get into..
you'll need a new belt, too.
make sure to get one that is 25% underdrive
as well as a torque wrench which can measure..
i forget.. either 150 or 250.. i think 250ft/lbs
the large one!
if you have an automatic
you might want a flywheel locker
there are other methods around this
i will not get into..
you'll need a new belt, too.
make sure to get one that is 25% underdrive