1973-1977 Buick Regal Transmission Kickdown Solenoid Guide
If your Regal has lost its passing gear, the transmission kickdown solenoid could be the problem.
- This part is properly called a 'kickdown solenoid' and its only job is to control the passing gear.
- The main symptom of failure is the loss of the kickdown function; normal driving is unaffected.
- Replacement requires draining the transmission fluid and removing the oil pan to access the solenoid.
- For this vehicle, a new aftermarket part is a practical and cost-effective solution.
Understanding the Kickdown Solenoid in Your Regal
The automatic transmissions in the 1973-1977 Buick Regal, typically the Turbo-Hydramatic 350 or 400, are known for their durability. Unlike modern cars, they don't rely on a complex computer and numerous sensors for every shift. Instead, they use a system of hydraulic pressures. The kickdown solenoid is one of the few electrical components involved in shifting. Its only function is to provide the 'passing gear' feature. When you floor the accelerator, it activates, forcing a downshift for better acceleration. If it fails, your normal driving and automatic upshifting will not be affected.
Symptoms of a Failing Kickdown Solenoid
The signs of a bad kickdown solenoid are very specific. Because this part only does one thing, its failure symptoms are straightforward. You will likely notice:
- No Downshift When Flooring It: This is the most common and definitive symptom. The engine will rev, but the transmission will not shift down into a lower gear to provide strong acceleration for passing.
- Car Feels Sluggish When Trying to Pass: Without the kickdown function, the car will try to accelerate from a higher gear, making it feel slow and unresponsive when you demand full power.
Is It the Solenoid or the Cable?
These transmissions also use a mechanical kickdown cable that connects to the carburetor. A misadjusted or broken cable can cause issues like late, early, or hard shifting during normal driving. A failed solenoid, however, typically only affects the passing gear function when the pedal is fully depressed.
🎬 See how to check and adjust your transmission kickdown cable.Choosing the Right Aftermarket Solenoid
For a classic vehicle like the '73-'77 Regal, finding original New Old Stock (NOS) GM or AC Delco parts can be difficult and expensive. Aftermarket brands like ATP and Pioneer Cable offer readily available and affordable replacements.
Brand Quality Assessment:
- ATP: ATP is a common aftermarket brand for various transmission components. For a simple part like a kickdown solenoid, their products are generally considered a functional and budget-friendly choice for a daily driver or restoration.
- Pioneer Cable: While known more for cables, Pioneer also offers electrical transmission components. Quality can be inconsistent according to some forum discussions on their other parts, but they remain a viable option given the limited choices for this specific part.
OEM vs. Aftermarket: For a simple, single-function part like this, a new aftermarket solenoid is often a more practical choice than hunting down an expensive and potentially decades-old NOS part. The technology is not complex, and a new part from a reputable aftermarket supplier is likely to perform reliably.
🎬 Watch this side-by-side comparison of old and new TH400 kickdown solenoids.Estimated Part & Labor Costs
| Part Type | Estimated Cost |
|---|---|
| New Aftermarket (ATP, Pioneer) | $62 - $121 |
| New OEM (NOS, if found) | $150 - $300+ |
| Used OEM | $25 - $75 |
| Shop Labor | $150 - $250 |
Frequently Asked Questions
Can I replace the kickdown solenoid myself?
Yes, this is a manageable DIY job if you are comfortable working under your car. The process involves safely jacking up the vehicle, draining the transmission fluid, removing the transmission pan, unbolting the old solenoid, and then installing the new one. The messiest part is dealing with the transmission fluid.
Is a kickdown solenoid the same as a shift solenoid?
No. On your Regal, the kickdown solenoid has one job: downshifting for passing. Modern vehicles have multiple shift solenoids inside the transmission that control all upshifts and downshifts. Your car does not have these other shift solenoids.
Were there any recalls for this part on my Buick Regal?
No, there have been no specific recalls or Technical Service Bulletins (TSBs) issued by the NHTSA for the transmission kickdown solenoid on the 1973-1977 Buick Regal.
How do I know for sure the solenoid is bad?
A mechanic can test the solenoid. This usually involves checking for a 'click' when 12 volts are applied to it or testing its electrical resistance. Since it's located inside the transmission pan, diagnosis is often done as part of the replacement process.
🎬 Watch a demonstration of a failed TH400 kickdown solenoid.Helpful Videos
Technical Specifications
1-terminal electrical solenoid for TH350/TH400 transmission kickdown function.
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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.