Under Drive Pulleys..and the problems they cause.
I felt it was time to make a sticky about these things and end all threads about them.
Under Drive Pulleys (or commonly referred to as UDP's) are used to slow down the engines accessories. by doing so, you free up HP and TQ that would normally been lost. The problem in doing so is...when you decrease the size of the harmonic balancer, you decrease the amount of vibrations that can be absorbed and canceled out. This is a MAJOR problem when running the factory oil pump, the gears in these pumps are very weak. and any increases in vibrations reaching the teeth GREATLY increase the chance of failure. This failure will most likely occur at very high RPM's, when vibrations are at the highest frequency and intensity. if oil pump failure occurs at 7,000 RPM's...your engine is TOAST. My Recommendation: ALL people who own a Mach 1 is to STAY AWAY from them. 15hp is NOT worth the chance of jepordizing your engine. |
Re: Under Drive Pulleys..and the problems they cause.
Something I wrote in another thread:
The harmonic damper is there to absorb torsional vibrations of the crank, principally at harmonics of the rotational frequency. The crank is not rigid, it twists and rebounds like a very stiff spring in response to the power pulses coming from the individual cylinders and associated pistons. The crank in conjunction with the harmonic damper forms a classic "spring-mass-damper" system. The response of such a system is sensitive to the spring rate, the effective mass, and the characteristics of the damper. In the case of a rotational system, the absolute mass is not as important as the rotational effective mass which is a combination of the static mass and the mass moment of inertia (MMOI - essentially a measure of the geometry of the system and how the mass is distributed). Smaller pulleys, with a lower dynamic mass thanks to decreased MMOI, allow excessive torsional vibrations, and those are what damages the relatively brittle gerotors in the pump. Or at least that is my understanding... |
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Thanks yall I didnt know that and I was about to get some pulleys. I finnaly found a thread I needed.Thats awesome.
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Also, 15hp is very optimistic. For most DOHC's 5hp would be more accurate.
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WHy does this not break parts on the 99-01 Cobra? |
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15hp is what they advertise.
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Hummmmmm...... I have the pullies on an 04 Mach auto.I have not had any problems.But it was strange that the box from Steeda said Part# 701-0004/Mustang 01 Cobra.I called them to tell them they sent the wrong ones .They said those are the ones that work on a Mach without any issues!:weird: That was 2 years ago.
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what about light weight pullies? with no under driving.
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Hey, I really do not know ,mabey the 01 Cobras pullies are different and do not cause failures I know some brands have had problems ,but I have seen cheap ones at the shop not fit well or installed wrong and wobble.But the broken oil pumps from the pullies have also happened on the GT cars too.Pauls Hi Performace says the same thing.I know that Moto Blue and Steeda are known quality and both have ties to Ford.I am NOT saying there may be a not be problem though!!:3amin:
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Mabey the higher RPMs on a 5 speed when a gear is missed adds stress too ?
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it adds ALOT of stress.
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Im not trying to sway anyones opinion of UDP's.Below is what Steeda has to say about their pulleys. So anybody ever experience problems with these? Or are the problems occuring in other manufacturers?
http://www.steeda.com/products/steed...ve_pulleys.php Product Details Steeda's is the leader in underdrive pulley design for the 4.6L engines. Steeda was the first to achieve SFI approval on our underdrive pulleys for all 4.6L engines. Our underdrive pulleys are the only pulleys engineered through our unique partnership in Ford's technology transfer program to have the proper torsional vibration dampening characteristics for your 4.6L engine. No other manufacturer can make this claim. Dont be fooled by other manufacturer's and their "state of the art" process claims. Steeda uses the latest technology directly from O.E. sources. Steeda's crank pulley is a one piece nodular iron, injection molded rubber design. Not a cheap "piggyback" design like many of our competitors use. Special rubber materials were chosen for their ability to absorb the torsional vibrations and their ability to withstand underhood temperatures. Steeda's underdrive pulleys slow down accessory speed by about 25% reducing parasitic acccessory drag on the engine. This drag reduction results in an increase of up to 10 horsepower and increased gas mileage! Get back the horsepower and torque your belt driven accessories steal and start enjoying better performance and gas mileage today! *03 Mach 1 doesnt use alternator pulley. Crankshaft U/D pulleys in very limited surplus, order now while supplies last. |
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and heres a head up for you guys that didnt know.....mach 1's come STOCK with a UD pulley on the alternator.
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Steeda sends 3 pullies when you order but tells you the Alt .pullie is not to be used unless worn or damaged on a MACH. Motoblue has been making FFRP pullies forever! .:3amin:
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01 cobras may have a differnt oil pump. i havent looked into the specs on them.
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Redlining your car is going to cause problems with UD's or not. The increased vibrations will always be there, the UD's will just let more of the vibrations resonate throughout the crank. Here is how that is solved: DON'T BE STUPID AND REDLINE OR GET ANYWHERE NEAR THAT!
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ive told conflict before not the get UDP's....he doesnt listen to me...
If he doest go "any where near redline" I'd love to know what he shifts at at the track |
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