1987-1988 Chevrolet R20 Speedometer Cable Guide
Is the speedometer in your Chevy R20 bouncing, noisy, or dead? Here’s how to choose the right replacement cable.
- A bouncing needle and noise from the dash are the most common symptoms of a failing speedometer cable.
- Always lubricate the new inner cable with grease before installation to ensure longevity.
- Verify if your truck needs a one-piece or two-piece cable (common with cruise control) before buying.
- Properly routing the cable away from sharp bends and heat sources is crucial to prevent quick failure.
Is Your Speedometer Acting Up?
A faulty speedometer cable is the most common reason for speedometer problems in these classic Chevy trucks. Because it's a moving part, the inner cable can wear, kink, or break after decades of use. The outer housing can also get damaged, allowing dirt and moisture in, which causes the inner cable to bind.
Common Symptoms of a Failing Cable
- Bouncing Needle: The speedometer needle jumps around, especially at certain speeds. This is often the first sign the cable is binding or unlubricated.
- Loud Noise: A squealing, grinding, or clicking sound from behind the dashboard that changes with vehicle speed points to a dry or frayed cable.
- No Speed Reading: If the needle doesn't move at all, the inner cable has likely snapped completely.
Choosing the Right Aftermarket Speedometer Cable
Since original GM parts for these trucks are often discontinued, the aftermarket is your go-to source. The good news is that for a part like this, aftermarket quality is generally very good. The main differences come down to standard replacement versus premium/custom options.
Aftermarket Brand Tiers
| Tier | Brands | Price Range | Best For |
|---|---|---|---|
| Standard Replacement | Pioneer Cable, ATP | $17 - $40 | Daily drivers and stock restorations. These brands offer direct-fit cables that function like the original. They are affordable and widely available. |
| Premium / Performance | Lokar, B&M | $70 - $150+ | Custom builds, heavy-duty use, or owners wanting a higher-quality component. Lokar cables often feature stainless steel housings and are 'cut-to-fit' for custom routing. B&M focuses on performance applications and may offer components for specific transmission setups. |
Pro Tip: Lubricate Before You Install! Many new cables come with little to no lubrication. Before installing, pull the inner cable out of the housing and apply a thin coat of white lithium grease or a specific speedometer cable lubricant along its entire length. This will ensure smooth operation and a longer life.
Common Ordering Mistakes
For the 1987-1988 R20, speedometer cables can vary. Some trucks used a single, one-piece cable, while others (especially those with cruise control) may have a two-piece setup with an upper and lower cable. Always verify your truck's specific configuration before ordering. Measuring your old cable is the best way to ensure you buy the correct length.
Warning: Routing the new cable is critical. Make sure it follows the original path and is secured with all factory clips. Avoid sharp bends or routing it too close to hot exhaust components, as this can cause premature failure.
Frequently Asked Questions (FAQ)
How do I know if it's the cable or the speedometer gauge that's broken?
A simple test is to disconnect the cable from the transmission. Attach the end of the inner cable to a power drill. Run the drill in reverse at a low speed. If a helper sees the speedometer needle move, the gauge is working, and the problem is likely the cable or the drive gear in the transmission. If the needle doesn't move, the gauge itself may be the issue.
My truck has cruise control. Does that change the cable I need?
Yes, it can. Trucks with cruise control often have a two-piece cable system that runs through a cruise control transducer. You may need to replace either the upper or lower section, or both. It's essential to identify which piece has failed before ordering a replacement.
Is it difficult to replace the speedometer cable myself?
For a DIYer with basic tools, this is a very manageable job. Accessing the back of the speedometer can be tight, but often doesn't require removing the whole dashboard. The transmission end is usually easy to reach. The most common difficulty is routing the new cable correctly through the firewall and along the frame.
Are there any recalls or technical service bulletins (TSBs) for the speedometer cable on my truck?
Searches of the National Highway Traffic Safety Administration (NHTSA) database and other sources show no specific recalls or TSBs related to the speedometer cable for the 1987-1988 Chevrolet R20. Problems with this part are typically due to age and normal wear and tear.
Technical Specifications
Cable length and end fitting types are critical. The speedometer head connection is typically a clip-on style, while the transmission end is a threaded nut (commonly 7/8-18 or 5/8-18 thread). Lengths can vary, so measuring the original cable is recommended.
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.
- Chevrolet R20: