the_camo_snake

So I put under drive pulleys on my car and a friend told me I need to piggy back the old crank pulley on the new one because it had a dampner on it. I read that the 4v motors are internally balanced and the only thing the pulley did was dampen vibration a bit. he said my motor will go to hell quick without it piggy backed but I have never heard this before with pulley swaps. Can anyone shed some light on this for me?

pcs

piggy back udp sux, i would not run them. the dampener looses its effectiveness if the it separated by a sandwich style pulley. if you really want udp's you might want to consider the ones that have a different crank pulley and do not require you to piggy back your o.e. dampener. a long time ago when i first got my gt i did some before and after runs with udp, about 1 hp difference.

the_camo_snake

I already put the underdrives pulleys on and have been driving with them. So i just am wondering if im gonna screw my motor up. I got MAC pulleys and if that helps any.

the_camo_snake

bump.

OzzDOA

You need the damper on there. You run the risk of busting your oil pump at higher RPMs if you don't. The one-piece damper/pulley designs like Steeda, March, ATI, Innovators West are much better than the piggy-back jobs at controlling the crank vibrations.

the_camo_snake

So I should just buy a new one? Do they make them in different sizes so I can keep the under drive?

OzzDOA

You didn't keep the stock damper?

According to the MAC install instructions you should have bolted it to the new pulley.

http://www.macperformance.com/store/...structions.pdf

livefast1

+1 i would be very worried about slinging that oil pump apart with out a dampener considering the way it is driven.

the_camo_snake

I didnt read the instructions thouroughly. Im kicking myself in the *** now because they are alreeady ont he car. I still have the stock dampner but I have a feeling its gonna be a pain to attach it without taking the crank pulley off. Thanks for the info.

pcs

from experience, always read the instructions thoroughly and understand them before you start.