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SR Performance Underdrive Pulleys - Black (Late 01-04 GT)

Market Price $169.99 You Save 18% ($30.00)
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  • Item 525575
  • MPN# 525575

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    Features, Video & Details

    • Free Up 10-15 Horsepower
    • Complete 3 Piece Kit
    • Durable, Lightweight Aluminum
    • Black Powder Coated Finish
    • Premium Quality Construction
    • Fits Late 2001-2004 GT Mustangs

    Review & Installation Video

    Review & Install Video

    Hey, guys. Stephanie with americanmuscle.com, here with a review of SR Performance underdrive pulleys for late 2001 to 2004 GT Mustangs. You're going to want to check out the SR Performance underdrive pulleys if you're looking to free up a touch of horsepower in a fast, easy, and very affordable way. The SR Performance costs the least out of any pulley option, and the theory behind underdrive pulleys is that the factory pulleys require a lot of energy. Instead of lightweight aluminum pulleys like these here, reduce the amount of parasitic drivetrain loss, by cutting down on the amount of power that it takes to run the accessories, like the water pump, alternator, and AC compressor. Some people mention noticing a difference after installing these underdrive pulleys. Underdrive pulleys are only a good idea if you plan on keeping your car NA. So just keep that in mind when you're figuring on your future plans. The install for these is going to be an easy one out of three wrenches on the difficulty meter, and you can plan on spending two hours to get the job done. So the engine uses its own power to rotate the serpentine belt, starting at the crankshaft. This pulley then uses the engine's power to rotate the rest of the pulley. So when you reduce the size of the crankshaft pulley, it'll require less energy to rotate the accessories. The pulleys on this side are lightweight aluminum, which means that they'll require even less energy to rotate. This set is powder-coated black, but SR Performance also sells a polished set too, if you prefer the look of those instead. The polished pulleys will cost about $20 more, though. So just keep that in mind. This kit is going to include the crank pulley, the water pump pulley, and the alternator pulley, as well as the hardware to get these installed. The nice thing about these, they're going to free up the power that the engine is currently using to rotate these pulleys, but you won't sacrifice the effectiveness of the accessories. So your water pump and your alternator will still function perfectly. They'll just require less power from the engine to operate. The only time you can see issues is if you have an aftermarket sound system and upgraded alternator. These items are more taxing on the car system, and require more work from the alternator. So if that's the case, I'd recommend steering away from underdrive pulleys. But for those of you that don't have that setup, these will reuse the stock belt. So you won't have to get a different-sized belt, which will make it easier when you need to replace your belt down the road. When it comes to fitment, adjust to make sure you're shopping for the correct year range here. This kit is for the late '01 to '04 GTs with the short water pump. Halfway through '01, Ford changed some things in production. So if you have an early '01 model, you need to pick up the other pulley set. The older water pump style, up until mid-'01, had a longer shaft, and will need a different water pump pulley because of this. As far as price, you're looking at a touch over $100 for this kit. It's the most affordable pulley kit currently at this time. Don't forget, you do have the choice of the SR Performance polished pulley kit if you didn't want the black set, or you have the choice of another brand, like BBK or Steeda. The install here is easy, and I'm going to call it a one out of three wrenches on the difficulty meter. You can expect to spend about two hours getting the install done, and you just need some basic hand tools to get the job done. You need to release the tension on your serpentine belt and set it aside. From there, it's a matter of unbolting the factory pulleys and replacing them with the underdrive pulleys from SR Performance. Once they're bolted on, release the tension pulley again and put the serpentine belt back on. You need to make sure it's on properly, following the diagram usually located on the rad cover. Wrapping things up here with the SR Performance underdrive pulleys, these pulleys are for the late '01 to 2004 Mustang GT, and you can check them out more online right here at americanmuscle.com.

    Free Up Horsepower. A set of SR Performance Underdrive Pulleys reduce parasitic drivetrain loss by cutting down the amount of power your accessories take up, these underdrive pulleys will free up 10-15 horsepower, without sacrificing cooling and charging functionality of your Pony.

    Premium Quality Construction. CNC-machined from lightweight aircraft grade quality aluminum alloy for strength and durability, these SR Performance pulleys feature a gloss black powder coated finish for aggressive good looks and long lasting corrosion resistance.

    Easy Installation. These SR Performance Mustang Underdrive Pulleys installs quickly and easily in under 2 hours with no modifications required.

    Application. This SR Performance 3-Piece Aluminum Underdrive Pulley Kit is designed for use on Late 2001 to 2004 GT Mustangs equipped with the SOHC 4.6L V8 engine and the a short water pump (bowed in face). Reuses factory belt.
    Technical Note. Midway through the production run for the 2001 model year Ford changed the design of the water pump on the 4.6L engine. The older style pump produced from 1996 to mid 2001 had a longer shaft. In January of 2001 the design of the pump was changed to a shorter shaft. This necessitated a change in the design of the pump pulley.

    Click here to see pictures of the different pulley styles.

    Fitment: 2001 2002 2003 2004 Details

    What's in the Box
    • (1) Crank Pully
    • (1) Water Pump Pully
    • (1) Alternator Pully
    • (4) Bolts
    • (3) Washers
    • (2) Spacers
    • (1) Instruction Sheet
    Installation Info
    Tech Specs
    Underdrive Pulley Specifications
    Year/Model: Late 2001 to 2004 GT Manufacturer: SR Performance
    Material: Aluminum Finish: Black Powder Coat
    Crank Pulley: Piggyback SFI Certified: No
    Will it fit my Mustang?

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    5 Questions / 6 Answers

    Ask a Question

    So the harmonic balancer just bolts to the pulley correct? Because i heard it was bad for the crank is this true?

    Ray

    • The SR Performance Underdrive Pulleys will use a piggyback style crank pulley, retaining the OEM balancer. This allows the factory balancer to work as intended when using underdrive pulleys and will have no ill effect on the crank.

      AMRobD

    Helpful (0)

    Are these California legal?

    mob79

    • These SR Performance under-drive pulleys are California legal.

      KevinD92

    Helpful (0)

    would this fit 3.8l mustang 99

    Joosebox

    • These SR Performance Underdrive Pulleys would not fit your 3.8L, 1999 Mustang, I apoligize. We unfortunately do not currently carry a pulley kit for your year-model Mustang.

      AMJEFF

    Show 1 more answer Helpful (0)

    What size belt is needed?

    Scrotus

    • These underdrive pulleys are able to reuse the stock belt. You do not need to buy a different size.

      AshleyK

    Helpful (0)

    Does Item# 525575 fit an 04 4.6L Crown Vic Police Inter. motor?

    2002slow2V

    • While there are many similarities, we unfortunately are not able to confirm fitment on your vehicle, I apologize.

      AMJEFF

    Helpful (0)

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    Customer Reviews (30) Write a Review

    Overall Rating 4.4

    out of 5 stars

    Installation Time:Afternoon

    Installation Cost:$100-$250

    • Performance Gain 4.137931 4.1
    • Fit 4.241379 4.2



    • 5/5

      July 03, 2018

      Not yet installed...

      But that’s due to my own lapse in time management. The pulleys are insanely lightweight and are machined perfectly!!! As soon as I get my bigger throttle body, plenum, intake manifold and exhaust I’m going to do it all in one shot and go from blah to beast! Turnaround time was not at all like some of the comments but maybe it’s product availability. Three days and an awesome AM decal!

      RonnieS

      Year: 2003 Submodel: GT

      Helpful (0)

    • 1/5

      Installation Time: Full Day

      June 28, 2018

      They suck

      I don't recommend that anyone who owns a mustang gt 4.6l to buy SR Under Drive PULLEYS THE CRANK PULLEY DON'T FIT AT ALL THAT'S A FACT NOT MY PERSONAL OPINION BUY THE STEEDA PULLEYS BUT YOU ARE NOT GOING TO GET ENOUGH power from PULLEYS

      GordonB

      Year: 1998 Submodel: GT

      Helpful (0)

    • 5/5

      Installation Time: Afternoon

      April 09, 2018

      Good for the price

      Got them for my 01 GT automatic they were good so I decided to get them for my 02 Manuel only problem is I had to buy a shorter water pump other than that they're good

      Sickgt01

      Year: 2002 Submodel: GT

      Helpful (1)

    • 3/5

      Installation Time: Afternoon

      February 14, 2018

      Failed me on the hardware

      The pulleys are good quality and do the job regarding performance. That said, the hardware supplied should have matched the OEM standard for hardness. The crank pulley bolt OEM was a 10.9 which is equivalent to a grade 8 standard bolt, case hardened. The supplied bolt was an 8.8 or grade 5 standard. I ended up breaking the bolt in the crankshaft. Probably one of the top three worst nightmares when doing engine work. Thank God I was able to extract the bolt w/o damaging the crank but wasn't until I took the whole nose of the car off to gain straight access to it. Much too soft a bolt for a crank bolt. They need to at least supply the OEM bolt with the kit. Be careful!

      TonyG

      Year: 2001 Submodel: GT

      Helpful (4)

    • 5/5

      Installation Time: Shop Install

      Installation Cost: 0-$100

      December 28, 2017

      Pulled!

      Took 1 1/2 hours of install at the mechanics ,car pulled and I felt the power of it real quick ,paid 50$

      RUDY

      Year: 2004 Submodel: GT

      Helpful (1)

    • 1/5

      Installation Time: Afternoon

      October 03, 2017

      spend the money and buy the one piece!!

      SPEND THE $ AND BUY THE ONE PIECE LIKE THE STEEDA. I bought this as a quick add on. I could not get the lower pulley mated together at all. I had it apart three different times to get it right. It broke the bolt when tightened at 12 pounds (Im sure it was weakened by removing it three times)..also the top pulley would not fit dispite what the instructions said about the two spacers. American muscle was great and sent me another one. got it on the car and it wobbled like crazy...and yes it was put together properly....I sent it back and bought the steeda...MUCH better product with the single pulley and not the piggy back style. spend the extra $ if you want to do this upgrade.

      DavidN

      Year: 2003 Submodel: GT

      Helpful (2)

    • 1/5

      Installation Time: Afternoon

      September 26, 2017

      Spend the extra money and buy the one piece!!

      Spend the $$ and buy the set with the one piece crank pulley! I put this on per the instruction. The crank pulley wobbled like crazy. I was afraid it would damage something so I bought the stedda....do alittle home work on these!

      DavidN

      Year: 2003 Submodel: GT

      Helpful (1)

    • 4/5

      Installation Time: Shop Install

      Installation Cost: $100-$250

      September 18, 2017

      2004 GT

      These helped with the RPM and a good investment to lighten the load on engine.

      sidwell

      Year: 2004 Submodel: GT

      Helpful (1)

    • 5/5

      Installation Time: Less than 1 Hour

      August 29, 2017

      Amazing!

      Amazing product by SR performance! It's not a big difference but I can feel a small one there and it just puts a smile on my face:)

      NghtMre

      Year: 2002 Submodel: GT

      Helpful (1)

    • 5/5

      August 07, 2017

      Underdrive pullies 03 mustang

      Nice black finish, fit perfectly. Easy to install.

      RogerH

      Year: 2003 Submodel: GT

      Helpful (1)

    • 5/5

      Installation Time: Less than 1 Hour

      Installation Cost: $100-$250

      July 14, 2017

      Sr performance underdrive

      Awesome kit , easy to install in glad I choose this kit !! No complaints

      CammiM

      Year: 2001 Submodel: GT

      Helpful (1)

    • 5/5

      Installation Time: Less than 1 Hour

      July 12, 2017

      Great buy!

      Easy to install. Marginal difference but important for the overall build.

      ChaseT

      Year: 2003 Submodel: GT

      Helpful (1)

    • 5/5

      Installation Time: Less than 1 Hour

      June 07, 2017

      GOOD BUY!

      I PUT THESE ON AND NOTICED A DIFFERENCE IN ACCELERATION.

      04gtHELLRAZOR

      Year: 2004 Submodel: GT

      Helpful (1)

    • 4/5

      Installation Time: Less than 1 Hour

      May 29, 2017

      Battery ran dry

      I love the boost in low end torque, but it seems that you need to upgrade to a higher output alternator. My car ran the battery dry and I had to get towed back home. The description says no change in cooling or charging but I found that to be untrue. Wish they would have said something, otherwise 5/5.

      JeffS

      Year: 2002 Submodel: GT

      Helpful (1)

    • 5/5

      Installation Time: Less than 1 Hour

      April 17, 2017

      Lighter than spected

      Fits perfect. Kit includes everything needed apart from the puller

      Kenner

      Year: 2003 Submodel: GT

      Helpful (1)

    • 5/5

      Installation Time: Less than 1 Hour

      March 17, 2017

      Underdrive Pulleys

      Great product. Easy quick install tool about 30minutes given that I had to let the car cool down. Hardware that comes in the box is handy and the black finish on the pulleys cleans up the look.

      JesseZ

      Year: 2002 Submodel: GT

      Helpful (1)

    • 5/5

      August 05, 2016

      Great Starter Mod

      Great product overall. Everything fit fairly well. The instructions are easy to follow and also gives tips to help with the install. The pulleys look great. No chips or scratches in the paint. Having all the tools in the tool list will make the install go faster. I used a strap wrench to help with the crank pulley. I can feel a difference when I drive. It was not a huge difference, but definitely enough to put a smile on my face.

      StreetMuscle

      Year: 2003 Submodel: GT

      Helpful (2)

    • 5/5

      Installation Time: Shop Install

      Installation Cost: $100-$250

      June 03, 2016

      Sr performance

      You can feel the difference my car has more ponies. Thank AM for another great product

      Truly03Gt

      Year: 2003 Submodel: GT

      Helpful (2)

    • 4/5

      Installation Time: Afternoon

      March 10, 2016

      More power, not bad.

      Great little mod, hate that I had to use the old harmonic balancer and piggy back it with this. But, for how big of a pain in the butt it was to do this, it was worth it. 1. Unscrew the 3 bolts for the coolant reservoir and move it for some room 2. Use impact fun on alternator and loosen the bolt and take it off with impact. Won't work any other way that I could find. 3. Loosen water pump pulley bolts. 4. Breaker bar, car in 5th gear. Crack loose the crank pulley bolt. Take belt off 5. Use pulley puller to get harmonic balancer off 6. use the 3 bolts with the 3 washers to squeeze the harmonic balancer and the new pulley for the crank together. @ 12 lb trq 7. Use the bigger ring supplied from package for alternator pulley and swap them out with the new ring behind the alternator pulley 8. Water pump pulley self explanatory 9. Put harmonic balancer with new pulley facing motor and fit into key way, get in far enough to start using the supplied bolt to install. When put in all the way crank to 60 lb trq. 10. Put belt on

      MooStang

      Year: 2004 Submodel: GT

      Helpful (2)

    • 5/5

      Installation Time: Afternoon

      February 18, 2016

      SR underdrive pulleys

      Good quality, easy to install, good Hp gains. Great starting mod!

      Cole

      Year: 2002 Submodel: GT Joliet, IL

      Helpful (2)

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