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...

Re: Under Drive Pulleys..and the problems they cause.
 

Thanks yall I didnt know that and I was about to get some pulleys. I finnaly found a thread I needed.Thats awesome.

Re: Under Drive Pulleys..and the problems they cause.
 

Also, 15hp is very optimistic. For most DOHC's 5hp would be more accurate.

Re: Under Drive Pulleys..and the problems they cause.
 

My escort got 6 whp :)

WHy does this not break parts on the 99-01 Cobra?

Re: Under Drive Pulleys..and the problems they cause.
 

15hp is what they advertise.

Re: Under Drive Pulleys..and the problems they cause.
 

I agree.. Yep.

Re: Under Drive Pulleys..and the problems they cause.
 

It does.

Re: Under Drive Pulleys..and the problems they cause.
 

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.

Re: Under Drive Pulleys..and the problems they cause.
 

Then why do I not see all this "OH GOD NO DONT DO THAT" on the cobra sites?

Re: Under Drive Pulleys..and the problems they cause.
 

what about light weight pullies? with no under driving.

Re: Under Drive Pulleys..and the problems they cause.
 

As I have said many times, automatics are affected far less by the reduced dapening effect of smaller balancers/pullies due to the big liquid filled balancer on the rear of the crank (also known as a torque converter).

Re: Under Drive Pulleys..and the problems they cause.
 

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:

Re: Under Drive Pulleys..and the problems they cause.
 

Not to mention slowMatics have a lower redline. Most guys that have autos and get up there in the 'scary rpms' dont' have UDs...much less a stock motor (SHOOSH BILL).

Re: Under Drive Pulleys..and the problems they cause.
 

Mabey the higher RPMs on a 5 speed when a gear is missed adds stress too ?

Re: Under Drive Pulleys..and the problems they cause.
 

it adds ALOT of stress.

Re: Under Drive Pulleys..and the problems they cause.
 

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.

Re: Under Drive Pulleys..and the problems they cause.
 

What he said.................but that all depends on if the driver was smart enough to get out of it in time, or not.
Steeda's and motoblue alike have caused problems.

Re: Under Drive Pulleys..and the problems they cause.
 

and heres a head up for you guys that didnt know.....mach 1's come STOCK with a UD pulley on the alternator.

Re: Under Drive Pulleys..and the problems they cause.
 

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:

Re: Under Drive Pulleys..and the problems they cause.
 

01 cobras may have a differnt oil pump. i havent looked into the specs on them.

Re: Under Drive Pulleys..and the problems they cause.
 

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!

Re: Under Drive Pulleys..and the problems they cause.
 

so what would you say is a safe rpm? 6k?

Re: Under Drive Pulleys..and the problems they cause.
 

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

Re: Under Drive Pulleys..and the problems they cause.
 

i do find it odd some 99-01 cobras have 100+k with pullies and no problems.

Re: Under Drive Pulleys..and the problems they cause.
 

Not every fat person will have a heart attack either.

Re: Under Drive Pulleys..and the problems they cause.
 

that makes me feel better
<-fat guy

Re: Under Drive Pulleys..and the problems they cause.
 

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.

Re: Under Drive Pulleys..and the problems they cause.
 

im an ex-auto.

i made da jump to a T-56 :smokin:

Re: Under Drive Pulleys..and the problems they cause.
 

Yep...I used to have a set of Steeda's......the alt pulley is already a 'UD', that's why they say not to install it. Just because Motoblue has made some FRPP pulleys, doesn't mean they are safe.
Let us know your track times shiftin' at 5500...I'm curious to know how that works out.


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.

Re: Under Drive Pulleys..and the problems they cause.
 

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.

Re: Under Drive Pulleys..and the problems they cause.
 

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.

Re: Under Drive Pulleys..and the problems they cause.
 

This issue is more about controlling harmonics, not balance. Even though they are related they are different issues with different solutions.

Todd

Re: Under Drive Pulleys..and the problems they cause.
 

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:

Re: Under Drive Pulleys..and the problems they cause.
 

thats a good post there! is this sean hyland book available at any major retailer?

Re: Under Drive Pulleys..and the problems they cause.
 

I know he has a book for building 4.6L motors at book stores

Re: Under Drive Pulleys..and the problems they cause.
 

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?

Re: Under Drive Pulleys..and the problems they cause.
 

cant you reuse the black ones? why buy a new one?

Re: Under Drive Pulleys..and the problems they cause.
 

The Ford crank to damper bolt is TTY and should not be reused.

Re: Under Drive Pulleys..and the problems they cause.
 

The one I got from the local Ford Dealer was the black oxide coated one.

Re: Under Drive Pulleys..and the problems they cause.
 

It seems Ford has only been selling black crank damper bolt for a while now.

Re: Under Drive Pulleys..and the problems they cause.
 

Black crank bolt F5RZ-6A340-B $4.06 from the SVT parts guy on SVT performance.

Re: Under Drive Pulleys..and the problems they cause.
 

Cool! Pretty cheap too...

Re: Under Drive Pulleys..and the problems they cause.
 

the in theory by what i have read in this thread.....i theory a black bolt with a Steeda UDP wont cause problems.....

Re: Under Drive Pulleys..and the problems they cause.
 

I wouldn't listen to people that can't read and write english correctly, either.:)

Re: Under Drive Pulleys..and the problems they cause.
 

I think you've misunderstood the thread. The Steeda UDP does an inadequate job of damping harmonics regardless of what bolt is used to secure it.

Re: Under Drive Pulleys..and the problems they cause.
 

well it seems that none do...but i dont really get how the bolt matters....

Re: Under Drive Pulleys..and the problems they cause.
 

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.