A Guide to Transmission Filter Kits for the 1981-1983 Autocar S
Keep your heavy-duty Allison automatic transmission protected by choosing the right filter kit.
- Verify your specific Allison transmission model before ordering a kit.
- Symptoms like harsh shifting, slipping, or whining mean it's time to inspect the filter and fluid.
- Wix is a trusted brand for heavy-duty applications, while ATP is a viable budget option.
- There are no transmission-related recalls or TSBs for this vehicle; problems are due to age and wear.
Symptoms of a Clogged Transmission Filter in Your Autocar S
When the transmission filter becomes clogged, it restricts the flow of fluid. This can lead to a variety of shifting problems and potentially serious transmission damage. Because these trucks work hard, paying attention to early warning signs is key.
- Delayed or Rough Shifting: You might notice a long pause or a hard jolt when shifting from park into drive or reverse. Shifting between gears while driving may also feel harsh or erratic.
- Gear Slippage: The transmission may unexpectedly slip out of gear while you're driving, or the engine RPMs might flare up between shifts without an increase in speed. This is a serious safety concern, especially when hauling a load.
- Whining or Grinding Noises: Unusual noises from the transmission area, such as whining, humming, or grinding, can indicate the transmission pump is struggling to pull fluid through a clogged filter.
- Leaking Fluid: While not a direct symptom of a clogged filter, it's a common transmission issue. If you're already servicing a leak, it's the perfect time to change the filter and fluid.
- Overheating Transmission: Restricted fluid flow can cause the transmission to run hotter than normal, which can quickly lead to internal damage.
Choosing the Right Aftermarket Transmission Filter Kit
For a vehicle from the early 1980s, finding original equipment (OEM) parts is nearly impossible. The aftermarket is your primary source for a new transmission filter kit. The most important factor is ensuring the kit is correct for the specific Allison automatic transmission model in your truck (e.g., MT-640, MT-650). Always verify the transmission model before purchasing.
Aftermarket Brand Tiers
| Tier | Brands | Quality & Notes |
|---|---|---|
| Premium Aftermarket | Wix | Wix is a well-regarded brand for heavy-duty filters. Their transmission filters are designed to meet OE specifications for filtration and fluid flow, protecting sensitive shift-control valves. Many professional mechanics and truck owners trust this brand for its reliability. |
| Standard Aftermarket | ATP | ATP offers a more budget-friendly option. Their kits are designed to be direct replacements and include the necessary filter and gaskets. Some kits feature a "3rd Hand" gasket designed to hold pan bolts for easier installation. However, be sure to inspect the gasket upon arrival, as one user reported receiving a torn gasket due to poor packaging. |
No Known Recalls or TSBs
Searches of the National Highway Traffic Safety Administration (NHTSA) database and other records show no specific recalls or technical service bulletins (TSBs) related to the transmission filter kit for the 1981-1983 Autocar S. Any issues you experience are likely due to normal wear and tear on this 40+ year-old vehicle.
Frequently Asked Questions (FAQ)
How often should I change the transmission filter?
For a heavy-duty truck like the Autocar S, you should follow the service interval recommended by the transmission manufacturer (Allison). If that information isn't available, a good rule of thumb is to change the filter and fluid every 30,000 to 50,000 miles, or more frequently if the truck is used in severe conditions like constant stop-and-go driving or heavy towing.
What is included in a transmission filter kit?
A typical kit includes the transmission filter and a new pan gasket. Some kits from brands like ATP may also include other seals or o-rings required for the specific application.
Can I replace the transmission filter myself?
If you have experience working on heavy-duty vehicles and the right tools, this is a DIY-feasible job. However, it's messier and more involved than an oil change. You'll be working with a large transmission pan and a significant amount of fluid. The difficulty is moderate due to the size and weight of the components.
Will a new filter fix my transmission problems?
If your problems are caused by a clogged filter and low or dirty fluid, a filter and fluid change can make a significant difference. However, if the transmission has already suffered internal damage from running with a clogged filter, a simple service will not fix it.
Technical Specifications
Fits various Allison automatic transmissions used in Autocar trucks of this era, such as the MT-640 or MT-650 series.
We Have This Part in Stock
The information in this article is provided for general reference and educational purposes only. Vehicle specifications, procedures, and part compatibility can vary by production date, trim level, and region. Always consult your vehicle's factory service manual and verify part numbers before purchasing or performing repairs. Safety-critical components such as airbags, seat belts, and braking systems should be installed by a qualified professional.
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