A Guide to Universal Joints for the 1975-1979 Chevrolet P20
Don't let a bad U-joint leave your workhorse stranded; here's what you need to know.
- For a heavy-duty P20, use a premium, non-greasable U-joint brand like Dana Spicer for maximum durability.
- Symptoms like clunking when shifting, squeaking at low speeds, or vibrations at highway speeds are urgent warnings to inspect your U-joints.
- A complete U-joint failure can cause the driveshaft to detach, leading to a loss of control and a serious accident.
- It is highly recommended to replace all U-joints at the same time, as they wear at a similar rate.
Symptoms of a Failing Universal Joint
A worn-out U-joint will give you clear warning signs. Ignoring them can be dangerous, as a complete failure can cause the driveshaft to separate from the vehicle. Listen and feel for these common symptoms:
- Clunking Noise: A loud "clunk" or ringing sound when you shift from park into drive or reverse is a classic sign of a bad U-joint. This is caused by excessive play in the worn-out joint.
- Squeaking Noise: A rhythmic squeaking or clicking that starts when you begin to move and changes with speed often points to a U-joint that has lost its grease. This sound can be drowned out by other road noise at speeds above 10 mph.
- Vibrations: A vibration that you can feel through the floor of the truck, especially at highway speeds, is a common symptom. This can be mistaken for an unbalanced tire, but if a tire balance doesn't fix it, the U-joints are a likely suspect.
- Visible Rust or Leaks: If you look under the truck, you might see rust-colored dust around the U-joint caps, which indicates the needle bearings inside are failing. You may also see a stripe of grease on the underbody above the U-joint, which has been flung out from the spinning driveshaft.
A Note on Driveline Clunk
General Motors has issued service bulletins explaining that a minor "clunk" can be normal in many of its trucks. This is due to the combined clearances (called lash) in all the gears of the transmission, driveshaft, and rear axle. However, a new, loud, or worsening clunk specifically when shifting into gear is a strong indicator of a U-joint problem and should be inspected immediately.
Choosing the Right Aftermarket U-Joint
For a heavy-duty vehicle like a P20, the quality of your replacement U-joint matters. While original OEM parts from the 1970s are no longer available, several aftermarket brands offer parts that meet or exceed original quality. They generally fall into tiers based on quality and reputation.
Tier 1: Premium Heavy-Duty (Dana Spicer)
Dana Spicer is widely considered the original equipment manufacturer for many American trucks and is the top recommendation for a demanding application like the P20. They are known for strength and durability. Many experienced mechanics and owners prefer their solid, non-greasable joints, which are forged for maximum strength and often last longer than greasable alternatives.
Tier 2: Quality Aftermarket (Moog, SKF)
Moog is a well-known aftermarket brand that offers good quality parts, including U-joints designed for heavy-duty use. They are a reliable choice and are often available with grease fittings (zerks) for maintenance. SKF is another respected brand, known for its expertise in bearings. Their U-joints are considered a solid choice if premium brands are not available.
Tier 3: Economy (GMB)
GMB is often positioned as a budget-friendly option. While GMB is a large manufacturer that produces parts for some automakers, their aftermarket U-joints have mixed reviews. Some users in forums have reported them feeling rough out of the box or not lasting as long as premium brands, making them less ideal for a heavy P20 chassis.
Greasable vs. Non-Greasable U-Joints
You'll have a choice between U-joints that are sealed (non-greasable) and those with a zerk fitting that allows you to add grease (greasable). While greasable joints sound better, they require regular maintenance every few thousand miles. The seals on greasable joints are designed to let old grease out, which also means they can let contaminants in if not maintained. High-quality, solid, non-greasable joints like those from Spicer are often stronger (the cross isn't drilled for a grease channel) and can last longer with zero maintenance. For a work truck, a sealed, premium U-joint is often the most reliable, "fit-it-and-forget-it" option.
Estimated Costs for Universal Joint Replacement
| Part Type | Estimated Cost |
|---|---|
| New Aftermarket Universal Joint (Single) | $18.53 - $237.75 |
| Shop Labor | $200 - $450 |
Cost estimates are for a single U-joint and can vary based on your location and the specific parts chosen. Your P20 likely has two or three U-joints.
Frequently Asked Questions (FAQ)
How many U-joints does my 1975-1979 P20 have?
Most standard wheelbase P20 vans have a two-piece driveshaft, which typically uses three universal joints and a center support bearing. Longer wheelbase models may have even more. It is best to inspect your vehicle to confirm the exact number before ordering parts.
Can I replace a U-joint myself?
This job is possible for an experienced DIY mechanic, but it can be difficult. It requires removing the driveshaft and using a hydraulic press, a large bench vise with sockets, or a hammer and sockets to press the old joint out and the new one in. Original U-joints from this era may be held in with injected plastic, which must be melted or broken out, adding a step. If you are not comfortable with this, it is best to have a professional shop perform the replacement.
Should I replace all the U-joints at once?
Yes. If one U-joint has failed due to age and mileage, the others are likely near the end of their service life as well. Replacing all of them at the same time is the recommended practice and will save you from having to do the same job again in the near future.
What happens if a U-joint fails completely?
Complete failure is extremely dangerous. The U-joint will break apart, and the driveshaft can detach from the vehicle while you are driving. This will cause an immediate loss of power and can cause the driveshaft to dig into the pavement, potentially flipping the vehicle or causing a major accident.
Technical Specifications
Universal joints are sized by their series number (e.g., 1310, 1350, 1410), which relates to their physical size and torque capacity. It is critical to measure your existing U-joint's cap diameter and width or use a part-specific catalog to ensure you purchase the correct size for your P20's specific driveshaft configuration.
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.
- 🛍️ Shop This Part
- Symptoms of a Failing Universal Joint
- A Note on Driveline Clunk
- Choosing the Right Aftermarket U-Joint
- Tier 1: Premium Heavy-Duty (Dana Spicer)
- Tier 2: Quality Aftermarket (Moog, SKF)
- Tier 3: Economy (GMB)
- Greasable vs. Non-Greasable U-Joints
- Estimated Costs for Universal Joint Replacement
- Frequently Asked Questions (FAQ)
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