CSPBK5-WCt5_mainshaftSynergyn Syngear II Additive for A-5 Transmission (Only) 1A-5 Gear Kit 1994-95 Mustang 5

575 Torque A-5 Gear Kit Package (1985-93 Mustang)


1st-4th Kit, Mainshaft, Cluster Support, Solid Struts, Overhaul Kit, and Yoke

Out of stock

Product Description


This is a Gear Kit Upgrade Package for 1985-93 Ford Mustang 5.0L T-5 World Class 5 Speed Transmission to support up to 575 Torque Capability in a Stock Design Case, Tailshaft Housing, and Top-Cover.  Gear Kit Upgrade not only raises Torque Rating of T-5, but, also improves the 1st Gear Ratio to a Close Ratio 2.95.  Reusing the Stock V8 Overdrive (as long as it is reusable) yields a .59 Fuel Efficient Overdrive with Upgrade Package Installed.

Gear Package Includes the Following Components:

-New 9310 Alloy A-5 1st thru 4th Synchronized Gear Kit
-New 26 Spline Input Shaft
-New A-5 Cluster Support/Reinforcement Plate
-New A-5 Upgraded 9310 Alloy Output Shaft (aka Mainshaft)
-New T-5 "Master" Rebuild Kit w/Synchronizer Rings and Seals
-1 Qt. of Special Fluid Additive required when Upgrading 1st thru 4th Gears


A-5 Gear Kit Upgrade converts 3.35 1st Ratio T-5 to a Close Ratio 2.95 1st.  The Gears used in the Upgrade feature Reduced Helix Angles on Premium 9310 Alloy Steel Gears that remain Synchronized to give the end user the same exact shift effort/feel from a Brand New T-5!  The manufacturing process of our A-5 Gear Kit and Internals are made here in the U.S.  This gearbox upgrade has been considered by many the Last Upgrade you can perform to the World Class T-5 before considering a 6 Speed or Automatic Upgrade.  The T-5's lightweight design and small Girth make it the perfect original Gearbox to perform an A-5 Upgrade Gear Kit Package to.  In addition the Upgraded Gear Kit Upgrade only requires end user to Upgrade to a 26 Spline Clutch and Possible 28 Spline Slip Yoke Upgrade. If the original 28 Spline Yoke doesn't fit onto splines of our Upgraded Output Shaft of transmission build, this means the internal minor diameter of customers slip yoke is -0.001" under-size of 2010 and later design 28 spline slip yokes.  But, the Bellhousing, Clutch Linkage (Cable), Clutch Fork, Shifter, Cross-Member/Transmission Mount, and driveshaft Length all remain the same as original gearbox required.

Highlights of Upgraded A-5 Gear Kit  and "Why" it can support the Power Listed:

-Reducing the Helix Angles of Gear Teeth on 1st thru 4th gears so that "less side thrust" is exerted on rear main case. Reducing the helix angles on the A-5 gear Kit allow us to make the Gears thicker/larger/wider than any other Synchronized World Class T-5 Gear Kit on the Market.
-Premium Alloy Steel used is 9310 Alloy.  It is the same type of steel used by the U.S. Military as well as Many Performance Manual Transmission Manufacturers.
-The Upgraded Cluster Support/Reinforcement Plate used on our Builds acts as a "Girdle" for Rear Main Case.  It will not distort or bend under the amount of Loads that this Gearbox Upgrade suports
-Gear Kit upgrade includes O.E. Bearings, Synchronizer Rings, Seals, and Small Parts in a Master Rebuild Kit Form, included with Gear Kit Package Upgrade.
-Due to the type of Alloy of Steel used when Manufacturing the Gear Kit, this Gear Kit requires a special "Cocktail" when it comes to Gearbox Oil.  Astro Performance supplies 1 Qt. of additive with Gear Kit Upgrade.  End user must install the Astro Performance supplied Additive before topping off with Customer Supplied Dexron V (Synthetic ATF).  Gearbox will take approximately 2.75 Qts Total...including the 1 Qt. of Additive we supply.

Requirements/Modifications Required when Upgrading to this Gear Kit Package:

In order to install the 1st thru 4th Upgraded A-5 Synchronized Gear Kit & Components, End User must:

-Install Upgraded Components into a World Class T-5 Core from a 1985-95 Ford Mustang 5.0L, 1987-93 Ford Mustang 2.3L, or 1994-04 Ford Mustang 3.8L.
-Clearance the 1st/2nd shift Fork so it doesn't touch/rub the fork when engaged into 1st.  If end user would like to purchase a hand-modified 1st/2nd Fork, please send an email to sales@astroperformance.com and reference part number 1352-096-002A5
-Apply Pre-Load to both the Input Shaft (Maindrive Gear) and Cluster Gear Tapered Bearings.  Since the Cluster Bearings are considered "slip fit" design, it is important to not only take the end play of both the cluster and input shaft to 0.000" end play, but, it is also important to pre-load the bearings to have at least -0.003" worth of pre-load.  Another words if the Cluster Gear took a .115" thick shim(s) to get to 0.000" end play, install about +0.003" more of shim to get desired pre-load.  The same holds true for the Input Shaft/Maindrive Gear.
-Install the Astro Performance supplied Bronze Reverse Idler Bushing in place of the Rubber O-ring found from the O.E. This spacer/bushing "spaces" out the reverse idler gear more than the o-ring so the reverse idler doesn't touch the 2nd gear on the cluster.
-Use Astro Performance supplied Synergyn Syngear II Additive into Assembled Gearbox and then top off gearbox with approximately 1.75 Qts of Mobil 1 Synthetic ATF(Customer Supplied).

There may be other components that the Core that is being considered for Upgrade may need.  But, it is important for the end user to tear down, clean, and inspect the internals of Core before ordering upgraded components to avoid additional freight charges and/or time needed to acquire additional components.  Our Upgraded Gear Kit package supplies the "Always Needed" components to Upgrade to the Torque Rating listed of Gear Kit Package.

Shipping ETA of Gear Kit Package once Ordered:

A-5 Gear Kits and Components are usually only available from Manufacturer to us for Transmission Builds and Upgrades from February thru July every year.  Before or Thereafter we only sell replacement components for A-5 Gearboxes already out in the field for Repair/Refresh.  So, with this being said it is Never a good idea to Assume Astro Performance has the A-5 Gear Kit and Upgrades on the shelf throughout the Year.  The A-5 Upgrade and Sales are usually most prominent during both the U.S. and Australia's Income Tax Return Season.  Of course this window of 6 months proves to be very busy for the A-5 Upgrade.  Please send all inquiries to sales@astroperformance.com . Most all Sales/Orders for A-5 Gear Kits and Packages are shipped Late Winter/Early Spring thru Mid-Summer.

We will ship all A-5 Gear Kits and Gear Kit Packages via UPS or Fedex Ground. Of course ETA will be determined once it is determined all components for Upgrade area available for shipment.

Benefits of Ordering A-5 Gear Kit and Package online vs over the Telephone:

Over the years we have found that the way we are able to stay more productive is by different means of electronic communication vs verbal communication via telephone.  With this being said, we have listed longer descriptions than most do to try and share as much information on the Upgraded A-5 Gearbox or Gear Kit Package being considered for Upgrade.  Most of this stuff can't be processed and remembered by the End User considering the upgrade, especially if the Upgrade is down the Road a bit.  So, our Online Pricing is Cheaper than what the Pricing of the Gearboxes are over the Telephone.  We will still honor telephone orders Monday thru Friday 10:30am-2:30pm CST.  But, you will see and/or hear pricing quoted verbally different from what is listed here on our website.

Any questions/concerns you have on the Gear Kit Package Upgrade being considered can be forwarded to us via Email to: sales@astroperformance.com We will return/reply to these questions/concerns in a timely manner. Sometimes even quicker than what a return phone call is made in!  In closing thank you for considering Astro Performance Warehouse an option for your Driveline Upgrade!

Additional Information

Weight 52 lbs
Dimensions 25 x 12 x 13 in
Car Year

1965, 1966, 1967, 1968, 1969, 1970, 1971, 1972, 1973, 1979, 1980, 1981, 1982, 1983, 1984, 1985, 1986, 1987, 1988, 1989, 1990, 1991, 1992, 1993






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