I just bought a 34% UnderDrive crank pulley (piggyback style) off this board and am now having second guesses about installing it. I did a search and read for about an hour on it, and need to know more opinions still. One guy said that the piggyback style could cause internal engine damage because it's unbalanced. Others said their alternator charge went way low. I know I should have just bought the ASP pulley, but I've already bought this one. So anyways, will it be worth it to install it this weekend or should I just resell it...

 

In my opinion, sell it. Tried it, gave it away for a favor.

 

It will cut your voltage down a tad too much. If you dead set on keeping it though, you can order a replacement alternator pulley from ASP. I just had to order one for my 383 set up because I wen't with a 6.75" ATI damper. Down from the stock 7.5". Although I was still running around 12v, it was about 12.1 to 11.8 most of the time and didn't like that. ASP has a 1.6" alternator pulley and it's only $20.

Ken R.

 

That'd make my alternator work a little harder though right? It's got a lot of miles on it already... I'm not really set on keeping this pulley that's why I'm asking for everyone's opinion. Any opinions on the piggyback style crank pulley actually damaging the internal engine? Just wanna be safe ya know...

 

What brand? How many pulleys?

 

I think its a March Pulley, crank 34% underdrive... 1 pulley

 

I had the March piggyback on an A4 car and the charging system sucked. Its ok till it's night and your cooling fans come on. Now I have the ASP set on a M6 and have no problems.

ASP>March

 

my cooling fans come on way early as it is, so my charging system could really be screwed huh

 

Using a "piggyback" pulley will not cause internal engine damage... as long as you install it piggyback WITH the stock harmonic damper. If you leave the damper off, as a few people have done, you run the risk of premature crankshaft failure due to torsional fatigue. The problem does not result from the pulley being "unbalanced", it results from incorrect installation.

 

I've had the March 2-pulley UD on my 97SS since new--and though I've experienced mucho problems through the mod process--I do not believe any were due to the UD. And I can say that I don't believe that it has adversely affected my drivability or performance one bit, however I have never driven the car a night so perhaps there might be issues, but I doubt it.JMHO

 

I have the 23% ASP pulley that replaces the stock pulley, and I don't have any charging problems at all, it stays at 12.5-13 volts all the time, even with the a/c on max and the lights on.

 

So basically my only concern should be charging. Well then What alternator pulley do I need to order so that my battery will stay well charged. Someone mentioned the ASP 1.6" alternator pulley for $20? Does that cancel out what small gains the crank pulley will be giving me?

 

Is the pulley you have the one that comes with the March 2-pulley system?

If so, you should be good to go by getting the alternator pulley from March.

 

Thunder Racing

Part 03-121 Alternator overdrive pulley
03-4050 Crank Underdrive Pulley
03-4485 Crank Underdrive and Alt. OverDrive Pulley.

So if you have the Crank UD 03-4050 pulley, get the Alt. overdrive pulley number 03-121 ($21.00)

Do check with T racing to make sure that this is correct.JMHO

 

You also have an M6, which idles at 800rpm. A stock A4 idles at 550rpm in gear.
ASP says the charge with the 23% pulley is sufficient with an 800rpm idle.
BirdMan, wait till you put your cam in to put the pulley on. You'll have to raise the idle with that cam more than likely.
I have a 215/224/112 cam, an ASP pulley, with 850rpm idle and the charge is just fine, or get the alternator pulley.