The best 20 tooth speedometer gear options deliver accurate gearing for TH350 and other 3/4-speed transmissions, helping you maintain correct speedometer readings and smooth operation. This guide highlights five strong choices, explains who each is best for, and explains how to choose between them. Perfect for DIYers, professional mechanics, and classic car enthusiasts who want reliable, easy-to-find parts.
| Product | Best For | Why It Stands Out |
|---|---|---|
| GOLKNHA TH350 20-Tooth Speedometer Driven Gear with Speedo Housing Kit | GM TH350 enthusiasts | Includes both drive gear and housing kit for a complete replacement. |
| GOLKNHA TH350 20-Tooth Driven Gear with Housing Seals | GM TH350 users needing seals | Blue 20-tooth gear with seals for a secure seal and fit. |
| GOLKNHA 6 PCS Speedometer Driven Gear Kit (17–22 Teeth) | Gear variety for multiple transmissions | Comprehensive set covering several tooth counts, handy for mixed-use applications. |
| 20-Tooth Speedometer Driven Gear & Speedo Housing Kit for GM TH350 | Complete TH350 replacements | Kit includes O-ring, housing, bolts, and sleeve for a full install. |
| Ciuouient 18–22 Teeth Speedometer Driven Gear and Bullet Kit | GM Muncie to TH350 range | Multiple tooth options with bullet housing for robust performance. |
GOLKNHA TH350 20-Tooth Speedometer Driven Gear with Speedo Housing Kit Include Seals and Retainer Bracket
Model fitment: GM TH350 (Turbo 350). Color: Blue. Included in package: TH350 20 Tooth Speedo Driven Gear with Seals kit (1), Speedo Housing Kit with Seals and Retainer Bracket (1).
Best for: TH350 owners needing a complete replacement that includes both the gear and the housing seals. This kit minimizes extra purchases and simplifies installation.
Why chosen: The bundled housing seals and retainer bracket help ensure a proper seal and alignment, reducing the risk of leaks or speedometer inaccuracies. A limitation is that it targets TH350 transmissions specifically; unrelated transmissions won’t benefit from this exact kit.
GOLKNHA TH350 20-Tooth Speedometer Driven Gear with Housing Seals
Model fitment: GM TH350 (Turbo 350). Color: Blue. Included in package: TH350 20 Tooth Speedo Driven Gear with Seals kit (1).
Best for: Those who want a focused 20-tooth gear replacement with seals, without extra housing components. The blue gear helps distinguish it in a toolbox.
Why chosen: The gear-with-seals combination supports a reliable seal without needing a separate housing kit, which can streamline the replacement process. A potential limitation is that it may not include all housing components some builders prefer for a full rebuild.
GOLKNHA 6 PCS Speedometer Driven Gear Kit (17–22 Teeth) for GM Muncie & Saginaw
Included teeth: 17, 18, 19, 20, 21, 22 (one each). Color options: Purple, Brown, White, Blue, Red, Grey. Includes one 20-tooth gear among other sizes.
Best for: Shops or drivers who need a ready set of gears for multiple transmissions or future use. It’s especially useful when exact tooth counts vary by vehicle model.
Why chosen: This kit covers a broad spectrum of tooth counts, enabling quick replacements across several transmissions. Caution: O-rings are not included, so you’ll need to source those separately for a complete install.
20-Tooth Speedometer Driven Gear & Speedo Housing Kit Compatible with GM TH350
Compatibility: TH350 Turbo 350. Package contents: 1 x 20 Tooth Speedo Driven Gear with O-ring seal, 1 x Speedo Gear Sleeve Housing, 1 x Hold Down Retainer Bracket, 2 x Bolts, 1 x Washer. Material note: Viton O-Ring.
Best for: Builders who want a complete TH350-oriented kit with a solid housing assembly and seals. The Viton O-ring provides chemical resistance and longevity.
Why chosen: The included hardware and high-temperature O-ring improve ease of installation and durability. Limitation: This kit is TH350-specific and may not fit other transmission families without modification.
Genuine Ford Parts – Gear – Driven (C8SZ-17271-B)
Part number: C8SZ-17271-B. Description: Gear – Driven. Genuine Ford Parts.
Best for: Ford transmissions or legacy setups that require OEM Ford components. The part is labeled as a genuine Ford replacement, aligning with factory specifications.
Why chosen: For Ford installations, using an OEM part can be advantageous for fit and compatibility. A limitation is that this is Ford-specific and not ideal for GM TH350 applications.
Ciuouient 18–22 Teeth Speedometer Driven Gear and Bullet Kit
Contains geared options from 18 to 22 teeth, plus Bullet Housing O-ring & Inner Seal. Material: High-quality plastic with glass fiber reinforcement. Replacement part numbers included: 18–22 teeth per 3987918–3987922 series.
Best for: Vehicles requiring a precise tooth match within an 18–22 range, including Muncie, T10, Saginaw, T5, Powerglide, and TH350 transmissions.
Why chosen: The kit’s variety makes it a flexible option for mixed-power transmissions. A caveat is that plastic gear material, while reinforced, may wear differently than metal gears under high load.
Buying Guide: How To Choose The Right 20-Tooth Speedometer Gear
- Match the transmission type. The TH350-driven gear options are tailored for GM Turbo 350; Ford OEM gears suit Ford transmissions. Always confirm the model compatibility before purchasing.
- Consider the kit contents. Some sets include seals, housings, or O-rings. If you’re replacing the drive gear only, a simpler kit may be enough. For a full rebuild, choose a kit with housing and brackets.
- Assess material and durability. Gears available in metal or reinforced plastic differ in wear resistance and heat tolerance. For high-mileage or heavy use, metal gear sets may be preferable.
- Check installation hardware. Kits that include bolts, washers, and brackets reduce the number of additional purchases. Ensure the hardware size matches your vehicle’s requirements.
- Be mindful of tooth compatibility. If you’re replacing on a family of transmissions, a kit offering teeth from 17 to 22 ensures adaptability for future projects.
- OEM vs. aftermarket. OEM Ford parts are suited for Ford applications, while aftermarket TH350 gear kits prioritize availability and coverage for GM transmissions. Choose based on reliability needs and vehicle compatibility.
FAQ
- What does a 20-tooth speedometer gear do? It sets the calibration for the speedometer by matching the drive gear’s tooth count to the transmission output, ensuring accurate speed readings.
- Can I install a 20-tooth gear in any transmission? No. Tooth counts are designed for specific transmissions. Check your model (GM TH350, Muncie, Saginaw, etc.) before buying.
- Do these kits include seals and housings? Some kits include seals and housings, while others provide only the gear. Review the product details to confirm included components.
- Is a 17–22 tooth kit better than a 20-tooth-only kit? A broader tooth range provides flexibility across multiple vehicles, but a 20-tooth-specific kit may offer a tighter fit and simpler installation for a single application.
- Are OEM gear parts necessary for a classic Ford? OEM Ford parts ensure compatibility with factory specifications, which can be important for a period-correct restoration or precise fit.
- What maintenance helps speedometer accuracy? Regularly inspect the drive gear, housing seals, and cables for wear. Replacing worn O-rings and seals helps maintain accuracy and prevent leaks.