To underdrive or not to underdrive...

[Shift__BODOM]

hi all, i was recently looking into underdriving my car, but i have run into a few problems.

it has been brought to my attention that if i underdrive my car, the balancing wouldn't be sufficient enough, and i would ultimately burn out my engine. is this true? what are all the adverse effects of underdriving my car? i need to know this because i'll be buying or not buying a pulley very soon.

thanks for the help!

[Chingon]

define "underdriving"

[s13EastTN]

Dude, you drive under something, like a bridge or some ****.

Freakin newbies.

hehe all joking aside I think he means underdrive pulleys, if not well...i'm stuck.I've never heard bad things come of them, and I have heard they help a lot, but thats just my friends point of view, and they're stupid most of the time.

[[Zero-S]]

Most underdrive pullies remove the harmonic balancer that comes with the stock pulley. Doesn't matter if your crank is balanced (which ours is from the factory), but if not, you're going to spin a main bearing, and have much fun with that.

I've never heard any horror stories from the 240sx guys about underdrive pulleys though. It'll be something I'll do later on.

[BadMojo]

I think we just discussed this somewhere else. IMO, underdriving the accessories isn't the best thing in the world for them but a lighter pulley won't affect the engine.

Like Zero said, I've never personally heard of any engine damage related to a lightweight crank pulley. I'll personally be getting an ASP pulley sometime in the future (whenever I find a good deal on one) but it's not high on my list of mods to do. The only bad thing I've heard about the ASP is that the timing marks aren't errr...right.

[fregisr]

I had an ASP pulley on my old engine and it disentegrated my piston rod bearing, piston 1 and 2. I am still using the ASP pulley balanced with the crank and the fidanza flywheel.

[Chingon]

i've heard oil starvation can occur, from failing to replace the front underdrive oil seal.. Don't know why..

[BadMojo]

I believe someone (maybe Orion) mentioned there was a design flaw in one of the underdrive pulley sets that chewed up the front seals. I don't think it was particularly related to an underdrive or lighter pulley.

Fregisr, not to dispute what you're saying but how did you link the bearing failure to the pulley?

[Shift__BODOM]

yeah, i meant a lighter and slightly smaller crank pulley...more specfically, the unorthodox pulley. ive heard good things about unorthodox and ASP, and i dunno why i chose UR. anyway, i just dont want to mess up my engine doing it. accessories are no problem, i dont want to underdrive those, so dont worry about that, i just dont want to fry my engine, because having to get a new 240 doesnt sound like a good thing to do...all the 240's for sale around here are complete crap. damn houstonians driving like morons.

[[Zero-S]]

If you get an underdrive crank pulley, you will be underdriving your accessories as well. Remember that the crank pulley drives all the accessories attached to the engine (ac, alt, ps, etc)

[Drifterxl]

this may sound like a simple question to most here, but seeing as this thread is here i thought i'd ask. how exactly does an underdrive pully work? i've heard the term a lot, and never fully understood what it is and what it is doing. if someone wouldn't mind, could you explain it to me. thank you.

[Red coupe]

Im not sure if its underdrive of what that is but the unorthodox and asp pullys if im not mistaken are mainly just ligher. the ligher pully can change speeds easyer. Im not sure if the unorthodx and asp pullys are smaller though. if they are the same size I would say it wouldnt be any worse then the stock one wich doesn't have a harmonic balancer anyways.

[madbouncy]

The underdrive pulley mostly is just lighter, very little of the gain is from underdriving. The only time I've heard anything bad about it is if the person had a huge stereo in their car. Though I think unorthodox started making a line of pulleys that are the same size but lighter, for like people that can't underdrive but still want a light pulley. Would probably be good for like superchargers where you wouldn't want it to underdrive at all.

[chandler]

well, the underdrive pully, undredrives the accesories, by using a different diameter pully, usually the accessory pullys are larger diameterv, and the crank is larger, but since they are made of aluminum they can be lighter also, im saving my pennies for a set of ss pullys