ok so......i bought a FFP underdrive pulley......and im like "hey dad check out my new pulley" and he tells me "dont' put that thing on ur car ull set up vibrations and shit in ur crank and rip up ur bottom end" he says because it no longer has a rubber ring it won't do its job....it sounds valid and there have been some reports of this.....but it still seems like theres no way this could slip through the cracks so easily when all i hear is good stuff about this mod.......so anyone credit or discredit this complaint....basically my dad likes to piss on all my parades (asshole)....so i just wanted to see if the FFP ud could be a hazard!???!?!?
heres the aurgument!!
http://www.3000gtvr4.com/pages/underdrivepully.html
verry good argument.
Thous..I am not going to get one. I don't need to anyway. Want free hp..remvoe your PS pump and AC compressor... :lol:
The FFP pully was made for cost. They'd rape you if they went with a 3 piece unit.
I was the first person to put a FFP pully on a TGP. And I've never had any problems running it. 8)
Quote from: 90TGPI was the first person to put a FFP pully on a TGP. And I've never had any problems running it. 8)
The reason you've never had any problem is because the 3.1 is internally balanced (no external balancer i.e. harmonic balancer)(or like the 3.8 with the balance shaft above the camshaft). So therefore the underdrive pully would not make any difference in the vibration of the engine and would not cause any problems. :wink:
Key word "harmonic".
QuoteTorsional vibration: Every time a cylinder fires, the connecting rod hammers the crankshaft, making it twist as well as spin. After every twist, there's a rebound as the crank unwinds. This twist/rebound cycle is known as torsional vibration and if not controlled, it will result in rapid bearing and crank journal wear and can lead to a broken crankshaft. ( Source: Fluidampr's tech pages. )
Harmonic balancer: The harmonic balancer, or vibration damper, is a device connected to the crankshaft to lessen the torsional vibration. When the cylinders fire, power gets transmitted through the crankshaft. The front of the crankshaft takes the brunt of this power, so it often moves before the rear of the crankshaft. This causes a twisting motion. Then, when the power is removed from the front, the halfway twisted shaft unwinds and snaps back in the opposite direction. Although this unwinding process is quite small, it causes "torsional vibration." To prevent this vibration, a harmonic balancer is attached to the front part of the crankshaft that's causing all the trouble. The balancer is made of two pieces connected by rubber plugs, spring loaded friction discs, or both.
When the power from the cylinder hits the front of the crankshaft, it tries to twist the heavy part of the damper, but ends up twisting the rubber or discs connecting the two parts of the damper. The front of the crank can't speed up as much with the damper attached; the force is used to twist the rubber and speed up the damper wheel. This keeps the crankshaft operation calm.
( Source: AutoInsight training program )
QuoteWhat the other side argues:
The 3000GT/Stealth engine is so well balanced that it does not need a harmonic balancer. My reply: The balance of the engine has nothing to do with torsional vibration. In a perfectly balanced engine ( which is impossible to achieve) there would still be torsional vibration and a need for a harmonic balancer.
Its your bearing that will suffer,,and your crank. Since we have a harder finish on our cranks..the bearings would give out down the streatch.
They were arguing on w-body and saying that the tranny absorbs the torsional vibration. I still shy away.