AMERICAN POWERTRAIN Warranty and Return 

Policy: Read before Installation.

American Powertrain makes every effort to provide high quality parts, systems and support for your products.  However, due to the custom nature of our products we maintain a very strict warranty and return policy.  Please review this policy before installing your parts

WARRANTY: The information below constitutes our entire warranty both stated and implied.  By accepting and installing these products you are legally agreeing to abide by the terms of this warranty.

Your new Tremec transmission is warranted against defects in manufacture or workmanship for one year from the invoice date By Tremec.  American Powertrain’s 2 year warranty begins one year after invoice, or on the install date, whichever is earlier. The determination of the presence of defects in manufacture or workmanship is at the sole discretion of American Powertrain or its assignees.  

Some of the parts sold by American Powertrain are manufactured by other companies and are covered independently by those companies. (i.e. Wilwood master cylinder, Blueprint engines, Centerforce clutches, etc.).  American Powertrain reserves the right to inspect any failed parts for defects before repairing or replacing parts.  Shipping of parts for evaluation will be at the expense of the customer. If the part is determined to be defective shipping will be credited.

If a part is determined to be covered by warranty it is our obligation to replace or repair the product at our discretion.  

Under no circumstances will we refund a customer for the purchase of replacement parts purchased from another company.

Under no circumstances will American Powertrain pay for installation, labor, or R&R.  When you hire a third party to install your products you are contracting with that third party for charges incurred for installation.  Third party contractors (repair and restoration facilities) are not under contract with American Powertrain and will not be paid for labor, injury, etc… incurred by the use of these products.   If you are a repair facility you or your customer is responsible for all costs associated with installation and R&R.

American Powertrain is not responsible for any tool expense, time, injury, or hardship incurred during the installation of our products.

American Powertrain reserves the right to have your transmission repairs done by an alternative TREMEC dealer or specialist.  American Powertrain will stand behind this work as if it was completed in our facility and will make arrangements with offsite facility. Written consent must be obtained from American Powertrain before any work is begun by a 3rd party. If written consent is not obtained such actions void the balance of the warranty.

Voiding your warranty:  The following actions will make void any and all American Powertrain warranties and will absolve American Powertrain of all legal responsibility for your products:

  • Modification of American Powertrain parts without written prior consent of American Powertrain.
  • Service of parts or transmissions by an unapproved facility without written prior consent of American Powertrain.
  • Partial or complete disassembly of any gearbox or hydraulic slave.
  • Use of improper fluids in any of our transmissions or hydraulic systems.
  • Breakage due to improper installation or failure to follow American Powertrain instructions.
  • Posting of inaccurate or defamatory information about American Powertrain on any public forum.
  • Abuse of products or operation of products under the influence of alcohol or any controlled substance resulting in product failure.
  • The application of more engine horsepower or torque than the equipment is rated for.
  • The use of drag slicks not approved for street use. Drag radials will not void your warranty.
  • Failure to perform a bell housing alignment. 
  • Excessive driveline angle.
  • Using mounting bolts to pull the transmission into the pilot.

NOTE: This is a list of examples and does not constitute a comprehensive list.  


  • You may return parts that are in new and unused condition for store credit equal to the purchase price.  Returns must be   processed within 90 days of shipment.
  • Cash refunds are processed with a 15% restock fee to cover the cost of re-packaging, restocking and processing.  
  • We reserve the right to refund your credit card or remit a check.  Shipping is not refundable.  
  • If the part is damaged during return shipment you will be assessed a damage fee.  We will make every effort to send images and descriptions of the damage so you can make a claim to your shipping company.
  • Under NO CIRCUMSTANCES will we process a refund for a used clutch, flywheel or any other part that cannot be re-sold.  
  • All returned parts must be accompanied by a Return Merchandise Authorization (RMA) number.  One of our representatives will be happy to provide this number by phone.**
  • Shipping on all returns is the responsibility of the customer.

**If you return a part or system without an RMA you will be charged for the return shipping and it will be returned to you.   If you fail to pay for the shipping the parts will be considered abandoned and will be stored for 90-days then disposed of if you have not paid for the return shipping.  No return or warranty item will be processed without prior authorization.

INCORRECT PARTS SWAPS: On rare occasions we will mistakenly ship you an incorrect part.  This may be our mistake or may be lack of correct information provided about the vehicle.  If you need to swap parts you must call and receive an RMA from one of our staff.  Parts sent without an RMA will not be processed.

When swapping parts you may choose to:  

  1. Pay for the new parts, have them shipped immediately and receive a 100% refund when the incorrect parts are received in new condition for restocking.  Parts returned in used or damaged condition will not be refunded and will be returned to the customer at the customer’s expense.


  1. Return the incorrect parts using an RMA and have your new parts shipped when the incorrect parts are received for restocking in new condition.

Shipping on Warranty/Returns: 

Shipping expenses are always the responsibility of the customer.  We can arrange shipping at our cost through UPS or FedEx to reduce your shipping charges, but these charges must be paid before you receive your shipping label.  If a returned item is deemed to be covered by warranty then return shipping of the replacement or repaired part will be paid for by American Powertrain.

ENJOY YOUR PRODUCTS:  American Powertrain offers more transmission related solutions than any other company and we strive to maintain our reputation of excellence and customer satisfaction every day.  Please call us if you have any issues with our products so we can give you the help you need.

    The VSS is located on the passenger side of the transmission at the rear, inline with the output shaft. They  are oriented upward toward the floorboard.  The photos below  are looking down at the sensor from above There are Ford and GM versions of the VSS.  We supply a two-wire connector for these.

     The VSS will generate a pulse signal based on driveshaft revolution and can be used with some electronic speedometers and/or engine control systems. Ford transmissions will generate 12 pulses per driveshaft revolution.  GM transmissions generate 17 pulses per shaft revolution.  The pin/wire on the left (toward front of car) is the Reference terminal (Blue wire on most wiring diagrams) and the one on the right (toward the rear of car) is the Signal terminal (Yellow on most wiring diagrams). Follow your speedometer manufacturers recommendation for wiring connections.  A pulse compensator/converter unit may be required to use the VSS with certain speedometers.

Ford Style  VSS (Ford TKO and ALL Magnums)

B [Blue] (Reference)   /   Y [Yellow] (Signal)

GM style VSS (GM TKO)

B [Blue] (Reference)   /   Y [Yellow} (Signal)

The Driven Man/American Powertrain Bellhousing Alignment Measurement and Correction

Background: Modern transmissions use tightly tolerated taper roller bearings to support the input shaft. These bearings are far superior to the ball bearing assemblies of older transmissions; however their exacting specifications require that the input shaft has almost perfect linear engagement to the pilot bearing in the crank shaft. Improper centering of the transmission to the crank can cause premature wear on the input shaft bearings, creating noise, vibration and the eventual failure of internal parts of the transmission.

Due to manufacturing abnormalities in traditional and modern bell housings and scatter-shields it is necessary to measure the accuracy of your bell housing as it relates to the crank shaft. This will insure that the input shaft, located by the bore hole in the back of the bell, lines up directly with the crank.


A video of this procedure can be viewed here:

You will need:
  • A magnetic base dial indicator with a .001” resolution (.0005” preferred)
  • Large ratchet handle, breaker bar or flywheel tool to turn crank
  • Appropriate tools for tightening bell housing bolts
  • Permanent black marker (Sharpie)
You may need:
  • Appropriate tools for removing dowel pins
  • Offset dowel pins to correct out of spec condition
  1. With the flywheel installed if possible, place the bell housing on the back of the engine and fasten with at least four bolts, insuring that the bell is seated against the block.
  2. Place magnetic indicator on the flywheel (or crank hub if flywheel is not installed). IT DOES NOT NEED TO BE CENTERED IN THE CRANK. Set the measuring finger on the inside of the bore of the bell housing (see photo) at the 12-o’clock position.
  3. Zero the indicator dial at 12 o’clock. With a permanent black marker, mark a zero on the back of the bell at 12 o’clock.
  4. Turn the crank until the measuring finger is at the 3 o’clock position. Record the measurement with the marker. Make sure you record if the result is positive (to the right of zero) or negative (to the left of zero).
  5. Repeat step four at the 6 o’clock and 9 o’clock positions, recording your results. Then return the indicator to 12 o’clock and make sure it measure zero. If the indicator does not measure zero at 12 o’clock then the base has moved during the procedure and you will have to repeat steps 3 through 5.
How to interpret the numbers:

The acceptable tolerances for Tremec transmissions is .005” of total runout. The following formula will tell you how much runout you have.

Reading at 12 o’clock – Reading at 6 o’clock = Vertical Axis Run Out

Reading at 3 o’clock – Reading at 9 o’clock = Horizontal Axis Run Out


1. 12 o’clock = 0


6 o’clock = -.004

Then your Vertical Runout is 0  –  -.004 = .004” (within tolerance)

2. 3 o’clock = .009”


9 o’clock = .006”

  Then your Horizontal Runout is .009 – .006 = .003” (within tolerance)

3. 3 o’clock = -.008


9 o’clock = .013

Then your Horizontal Runout is -.008 – .013 = .021” (.016” out of tolerance)


Interpreting The Numbers:
  • If you are out of tolerance (> .005” +/-) on only one axis, then you will correct directly along that axis. The vertical axis will be corrected by a direct north or south movement of the bell housing, the horizontal by a direct east or west movement.
  • If you are out of tolerance on both axes, then you will be correcting along a diagonal. For example, if you’re bell housing is sitting .008” to the south (down) and .009” to the east (right) of center then you will correct toward the northwest to move the bellhousing up and to the left.

If your two axis measurements are less than .005”, as shown in example one and two, then your bell housing is within tolerance and you can proceed to install your transmission.

If the number is greater than .005” (+/-) then you must use the following procedure to correct the runout.

  1. Remove indicator and bell housing and set aside for later use.
  2. Remove dowel pins using one of the following methods:
    • Some engines have punch holes behind the pins. If you have this style of engine you can simply use a pin punch and a hammer to remove the old pins.
    • Grasp with vise style pliers and slowly turn pin while pulling away from the block.
    • Our favorite method for removing ornery pins involves the use of an aerosol spray freezing agent available at most parts stores. Simply place vice style pliers on the pin, heat the block around the pin area, spray the pin with the freezing agent and pull. The pin will shrink away from the heated block and usually come away very easily.
  3. Once the dowel pins are removed you will need to install “offset” dowel pins in the block. Offset dowel pins come in .007”, .014” and .021” sizes and correct for twice their value. Therefore, a .007” dowel pin will correct for as much as .014” of total runout. These pins are available from us, or from your local speed shop or racing supply retailer.
  4. Remove the dowel pins from their package and using the permanent marker or bright nail polish, mark the high side of each pin. This will help you align the pins when you press them into the block.



  5. Once you have marked the high side, tap the pins into the block using a brass hammer, dredge or hardwood block to avoid mushrooming the pin. A light petroleum based lubricant should be used. Approximate the direction of correction as described above. In the example above we would put a .007” dowel pin in, with the high side pointing northwest.
  6. Once installed, place the bell housing back on the block and repeat the runout procedure. If you are still out of tolerance you can turn the new pins to fine tune their position. Most dowel pins have a slot or Allen head hole to make it easy to make fine adjustments after installation.
  7. Once you have reached a runout condition of less than .005” total runout, record your four measurements on this document and keep for warranty purposes.
Final Measurements:

12 o’clock ______________
3 o’clock_______________
6 o’clock_______________
9 o’clock_______________
Vertical Runout __________
Horizontal Runout ___________

Thank you for taking this important step in the installation process. If you have any questions or need help interpreting your results you can call us anytime at 931.646.4836.

Use only DOT3 or DOT4 high temperature non-silicone brake fluid. Use of other petroleum based fluids will result in O-ring seal failure. A high temp race grade DOT4 fluid is recommended to reduce heat absorption. We recommend EBC, Wilwood, or Pentosin brands of high temp fluid for their high boiling point and excellent stability.

If your clutch engages or disengages too quickly, you may have an incorrect pedal ratio. The pedal ratio is the distance that your foot moves versus the distance the rod going in and out of the master cylinder moves. Pedal ratio is an important component in creating a smooth pedal feel with excellent clutch modulation. One of the biggest mistakes made in hydraulic conversions is creating a low pedal ratio.

Ideally, you want between 5:1 and to 6:1 ratio. This means essentially that if your master cylinder rod moves 1”, your foot needs to moves 5-6”. The Wilwood master cylinder supplied with our Hydramax kits require 1.12″ of travel; this means that your pedal needs to move 6″ to achieve a 5:1 ratio. Most stock pedal pivot points give an excellent pedal ratio, however if you move the rod lower on the pedal, or you are building a custom car and you have a ratio lower than 4:1, you may consider artificially raising the point at which the pedal rod hits the pedal arm to increase this ratio. If this is not possible, you can also consider moving the master cylinder bracket assembly lower on the firewall to increase the rod angle and therefore the pedal ratio.

If your clutch pedal is hard to push, the first thing to check is for any binding in the linkage between your clutch pedal and the master cylinder. Secondly, check to make sure you have not created too steep of an angle in the actuation of the rod moving in and out of the master cylinder.

Next, verify your pedal ratio is within specification. The pedal ratio is the distance that your foot moves versus the distance the rod going in and out of the master cylinder moves. Pedal ratio is an important component in creating a smooth pedal feel with excellent clutch modulation. One of the biggest mistakes made in hydraulic conversions is creating a low pedal ratio.

Ideally, you want between 5:1 and to 6:1 ratio. This means essentially that if your master cylinder rod moves 1”, your foot needs to moves 5-6”. The Wilwood master cylinder supplied with our Hydramax kits require 1.12″ of travel; this means that your pedal needs to move 6″ to achieve a 5:1 ratio. Most stock pedal pivot points give an excellent pedal ratio, however if you move the rod lower on the pedal, or you are building a custom car and you have a ratio lower than 4:1, you may consider artificially raising the point at which the pedal rod hits the pedal arm to increase this ratio. If this is not possible, you can also consider moving the master cylinder bracket assembly lower on the firewall to increase the rod angle and therefore the pedal ratio.

To determine the ratio of the pedal, you need to do some measuring. There are two measurements you need to take: the length from the pivot (fulcrum) of the pedal to the pushrod hole (Y), and from the fulcrum to the center of the brake pedal (X). The formula is X/Y=Ratio. For example, your stock clutch pedal is 14 inches long (X), with a pickup point measuring 4 inches from the center of the fulcrum (Y). 14/4=3.5, which is 3.5:1. While this may have worked for the factory manual linkage, it is about half of what it needs to be for a hydraulic set up. In this situation, 100 pounds of foot pressure yields 350 pounds of pressure to the master cylinder. Move the pickup point up 1.75 inches, (Y measurement of 2.25”), and that same 100 pounds of foot pressure yields 600 pounds at the master cylinder.

Yes! Consider, however, that you are installing a modern performance transmission and then attempting to actuate it with a combination of parts designed over 50 years ago. American Powertrain’s patented HYDRAMAX hydraulic systems and components are the most advanced systems on the market today. For more on the Hydramax system, please review the following video.

According to Tremec:

“Maintenance Recommended oil change intervals should be based on specific usage. In most cases a “fill for life” is adequate, while in severe applications such as drag racing, or road racing a more frequent fluid change should be prescribed. Excessive heat will cause most fluids to breakdown and ultimately cause damage to the transmission.”

Internally balance engines have weights added to the crankshaft counterweights to achieve proper balance in the rotating assembly. The rotating assembly consists of the crankshaft, connecting rods, pistons, and wrist pins. To achieve proper balance in the rotating assembly, externally balanced engines require the use of added weight to the flywheel/flexplate, or weight removed from one side of the flywheel. Below is an excellent article from hotrod.com to further explain internal and external balancing and why it is important to select the correct flywheel/flexplate for your engine.

How to Balance An Engine – Engine-Balancing Basics

Finding your driveline angle is the easy part; deciding what angles work best for you, however, can be a challenge. Please review the following video for a demonstration of driveline angle affect.
Driveline Angle Affect.

Simply put, an incorrect driveline angle can create vibration, cause premature universal joint failure, and reduces power to the rear wheels. Consider the following article from hotrod.com.
How To Set Pinion Angle.

Tremec has created a free app for smart phones that measures the driveline angles and displays whether they are within specification. Below is a link to a PDF of the app’s instructions as well as a link where the app can downloaded.

TREMEC Driveline Angle Finder App Instructions

Get The Tremec Driveline Angle Finder App

The measurement is known as “seal to center” and is the distance between the case of the transmission next to the rear seal and the centerline of the pinion yoke. When ordering a driveshaft you must complete the following form. Email this completed form to support@americanpowertrain.com, or fax the form, front and back to 480.393.4180. How to measure the driveshaft and determine your rear universal joint size is demonstrated on the form. For late model Mustangs, a second page is provided to determine your rear flange size. Turnaround time, once your form is submitted, is 24 to 48 hours to build along with the amount of time require to reach your location via FedEx Ground (1 to 5 days).

American Powertrain Driveshaft Order Form

Your new transmission has a 500 mile break-in period, during which the transmission should be operated rather gently to allow the synchronized gears to self-tolerate. After this break-in period, drain your transmission into a clean pan, check for abnormal particulate in the fluid, and refill using TREMEC HP-MTF, GM Synchromesh, Pennzoil Synchromesh, or Mobil 1 ATF.

NOTE: Some sloughing off of material is expected when performing the break-in fluid change. A magnet in the bottom of the transmission will trap ferrous particles, but it is normal for some aluminum and brass to be suspended in the fluid.

  • Reverse Lockout
  • Fill Plug
  • Drain Plug
  • Mechanical Speedometer
  • Vent Tube
  • Electronic Speedometer Port
  • Reverse Light
TKO 500 & 600

TKO 5 Speed

  • Vent Tube
  • Spring Retention Bolt (Do Not Remove)
  • Mechanical Speedometer Port
  • Neutral Safety Switch
  • Electronic Speedometer Port
  • Fill Plug
  • Drain Plug

Transmission fluid is the life blood of your transmission. Proper wear and synchronization depends on using correct fluid. Use only GM Synchromesh (part# 12345349), Pennzoil Synchromesh or Mobil1 ATF. Or the new Tremec HP-MTF fluid here. Any other fluid used may cause premature wear and grinding synchronizers and will VOID YOUR WARRANTY.

NOTE: You can use standard Dexron III ATF for break-in, but it must be drained after the break-in period and replaced with Synchromesh or Mobil1 ATF as your permanent fluid.

Filling Transmission Case:
  1. If you removed the rubber bung from the tail housing during test fitting, replace before filling transmission or, if available, install your driveshaft.
  2. Remove the square headed filler bolt located on the side of the main case about half-way up. Passenger side of transmission. (lower hole is the drain plug)
  3. The TKO 500 & 600 Tremec transmissions require approximately 3 quarts.
    The 6 Speed Tremec Magnum transmissions require approximately 3.45 quarts.
  4. Using a hand operated fluid pump, slowly add fluid until it reaches 1/8” from the bottom of the fill hole when transmission is level. You can easily test this by placing your small finger in the hole to the first knuckle. You should be able to feel the fluid by bending your finger.
  5. Replace the filler bolt.
  6. Store extra Synchromesh or HP-MTF in an airtight container in a dry environment to prevent water absorption. Improperly stored fluid should be discarded.
  7. The recommended break in period is around 500-1000 miles. Once you drain your fluid you may notice some very tiny amounts of metal particles in the oil. This is common for syncros to break in. Drain the fluid and refill with Tremec HP-MTF or Syncromesh.   



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