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. |
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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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i do find it odd some 99-01 cobras have 100+k with pullies and no problems.
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<-fat guy |
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i guess im ***ed then. cuz my redline starts at 5,800 and i take it to 7,100.
going TO or NEAR redline wont do anything lol. its hitting the rev-limiter thats HORRIBLE on parts. |
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i made da jump to a T-56 :smokin: |
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Look, every one has their own opinion. I used to have the pulleys installed (on my Ex's car) and I paid to take them off......it just wasn't worth the risk IMO. We dont' ahve a 2V car, so you can't compare them. The Cobra's are a slightly different 4V as well. You can't compare our motor to other modular's all the time. Do as you wish.........some of us just think it is better to not install them. |
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U/D dampers have broken many 96-01 Cobra and 2V GT oil pump gears as well, don't think for one second they are immune. And there are Machs out there with alot of miles on the sorry u/d dampers, but that doesn't mean those Machs won't lose their engines tomorrow.
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I'm sorry but i work for a lab that specializes in failure and analysis. In order to state these claims you better have all these steps. (please keep yourself from acting childish. I'm only trying to help in what i believe is correct. you may have your own opinions and i apologize if you feel threatened or offended. That is not my intention)
1.Collection of background data and selection of samples 2.Preliminary Examinatio of a failed part 3.Non-destructive/destructive testing 4.Mechanical testing 5.Macroscopic,Microscopic examination and analysis 6.determination of failure mechanism 7.chemical analysis (if applicable) 8.Analysis of fracture mechanics 9.testing under simulated service conditions 10.analysis of all the evidence, formulate conclusion, and write the report This is what i do for a living 9hrs a day. May be of some importance may not. i dontk know if this would help too..i posted it on another thread but read this Okay, so how does all this scientific mumbo jumbo translate into the real world dynamics of a spinning crankshaft? A crankshaft, like a flywheel, is a heavy rotating object. Whats more, it also has a bunch of piston and rod assemblies reciprocating back and forth along its axis that greatly complicate the problem of keeping everything in balance. With inline four and six cylinder engines, and flat horizontally opposed fours and sixes (like Porsche and Subaru), all pistons move back and forth in the same plane and are typically phased 180 degrees apart so crankshaft counterweights are not needed to balance the reciprocating components. Balance can be achieved by carefully weighing all the pistons, rods, wrist pins, rings and bearings, then equalizing them to the lightest weight. On V6, V8, V10 and V12 engines, it is a different story because the pistons are moving in different planes. This requires crankshaft counterweights to offset the reciprocating weight of the pistons, rings, wrist pins and upper half of the connecting rods. With "internally balanced" engines, the counterweights themselves handle the job of offsetting the reciprocating mass of the pistons and rods. "Externally balanced" engines, on the other hand, have additional counterweights on the flywheel and/or harmonic damper to assist the crankshaft in maintaining balance. Some engines have to be externally balanced because there is not enough clearance inside the crankcase to handle counterweights of sufficient size to balance the engine. This is true of engines with longer strokes and/or large displacements. When rebuilding an engine that is internally balanced, the flywheel and damper have no effect on engine balance and can be balanced separately. But with externally balanced engines, the flywheel and damper must be mounted on the crank prior to balancing. Customers should be told what type of engine balance they have (internal or external), and warned about indexing the position of the flywheel if they have to remove it later for resurfacing. Owners of externally balanced engines should also be warned about installing different flywheels or harmonic dampers and how it can upset engine balance. In other words, If you dont have any balance to any of these (cranks, pistons etc etc) than you're more than likely to experience a failure due to small/large amounts of harmonics that can harm certain FRAGILE parts in the motor. Being that this is internally balanced, the pulley should not have a negative output. However, a matter of testing would have to be performed in order for either you or myself to claim our statements as valid. |
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Todd |
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Here is an Experts opinion: Sean Hyland Mustang High-Performance Builders Guide 1994-2004 Cobra/Mach1 Reference info: .....The factory crankshaft damper, water pump pulley, and alternator pulley can be exchanged for underdrive units that reduce parasitic losses and reduce the speed of the accessories. This is especially helpful for the water pump, which can cavitate at higher RPM, reducing cooling efficiency. .... Many of the aftermarket underdrive pulley kits on the market reduce the effectiveness of the damper, resulting in increased harmonics and contributing to oil-pump-gear failures. Our newest design retains 92 percent of the original mass, reducing drag, but still providing adequate damping characteristics. The factory had a couple of different crankshaft bolts on the 4-valve over the years, and more than one torque specification. Since inadequate clamping load creates oil pump and crank gear problems, it's important to only use the black crank gear bolt (not the inferior silver one), replace the crank-gear-bolt every time it is removed, and torque it to 125 ft-lbs......
Like I said earlier...,aftermarket underdrive pulley oil pump failures can be caused by poor design / manufacturing or improper installation.:3amin: |
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thats a good post there! is this sean hyland book available at any major retailer? |
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Every crank damper bolt I've bought through Ford has been silver. I've only seen the black bolts from the factory.
Does anyone have a part number for the black bolt? |
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cant you reuse the black ones? why buy a new one?
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The Ford crank to damper bolt is TTY and should not be reused.
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The one I got from the local Ford Dealer was the black oxide coated one.
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It seems Ford has only been selling black crank damper bolt for a while now.
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Black crank bolt F5RZ-6A340-B $4.06 from the SVT parts guy on SVT performance.
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Cool! Pretty cheap too...
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the in theory by what i have read in this thread.....i theory a black bolt with a Steeda UDP wont cause problems.....
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well it seems that none do...but i dont really get how the bolt matters....
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The stock dampers do a more than adequate job when the factory rev limiter (for that particular crank/damper combo) isn't exceeded. ATI dampers do a more than adequate job for higher rpms.
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