If you’re dealing with a 1987 Fourtrax TRX350 shifting issue, you’re not alone. This classic Honda ATV is known for its durability, but its manual gearbox can develop problems over decades of use. Let’s get straight to the point and figure out why your TRX isn’t shifting smoothly and what you can do about it.
We’ll cover the common causes, from simple adjustments to more involved repairs. You’ll get clear, step-by-step guidance to diagnose the problem yourself. By the end, you’ll have a solid plan to get your Fourtrax back to clicking through gears reliably.
1987 Fourtrax TRX350 Shifting Issue Explained for Manual Shifting Gears
The 1987 TRX350 uses a manual foot-shift transmission with a semi-automatic clutch. This means you shift gears with your foot, but a centrifugal clutch handles engagement automatically. A shifting issue here typically points to a few specific areas: the external shift mechanism, the internal shift drum and forks, or clutch problems that affect gear engagement.
Common Symptoms of a TRX350 Shifting Problem
Before we dig into causes, let’s identify your exact symptom. This helps narrow down the problem fast.
- Stuck in one gear and won’t move up or down.
- Shifts roughly or makes a loud “clunk” or grinding noise.
- Feels like it’s between gears (false neutral).
- Lever feels loose or has excessive play.
- It shifts but then pops out of gear under load.
- The shifter moves but doesn’t change the actual gear.
External Causes: The Simple Fixes First
Always start here. These are the easiest and most common fixes for a 1987 Fourtrax TRX350 shifting issue.
1. Shifter Lever and Spline
The shifter lever is clamped onto a splined shaft. Over time, this clamp can loosen, or the splines can strip. This makes the lever feel sloppy or spin without turning the shaft.
- Check the clamping bolt on the shifter lever. Tighten it securely.
- If it’s loose, remove the lever and inspect the splines on both the lever and the shaft. If they’re worn, you’ll need to replace the lever.
2. Shift Linkage and Return Spring
Underneath the lever, a linkage rod connects to the shift shaft that enters the engine. A return spring brings the shifter back to center after each shift.
- Check the linkage rod ends for wear or looseness. Replace if needed.
- The return spring can break or lose tension. If broken, the shifter won’t snap back, making it hard to find the next gear. This is a very common failure.
3. Bent Shift Shaft
The shift shaft itself can get bent from impact or rough use. A bent shaft binds and won’t rotate properly.
You can often see this by watching the shaft as you move the lever. It should rotate smoothly. If it looks crooked or binds, it needs to be replaced. This requires draining the oil and removing the right-side engine cover, but it’s still an external component.
Internal Causes: When the Problem is Inside the Engine
If the external parts look good, the issue is likely inside the transmission. This is more serious but still fixable with patience.
1. Worn Shift Drum and Forks
This is the heart of the shifting mechanism. The shift drum is a star-shaped cylinder with grooves. Shift forks ride in these grooves and slide the gears into position.
- Over time, the grooves on the drum can wear or develop burrs, causing the forks to hang up.
- The shift forks themselves can wear down or bend, preventing them from fully engaging a gear.
- This often causes popping out of gear or difficulty finding specific gears.
2. Worn Transmission Gear Dogs
The gears have raised sections called “dogs” that lock them together. With rough shifting or age, these dogs and their matching slots can round off.
When they’re rounded, they can’t lock together solidly. This leads to popping out of gear, often with a nasty grinding sound. Fixing this requires spliting the engine cases and replacing the worn gears, a major job.
3. Centrifugal Clutch Issues
Remember, this ATV has a semi-auto clutch. If the clutch is worn or not engaging/disengaging correctly, it can mimic a shifting problem.
- A worn clutch can cause drag, making shifts clunky or hard to get into gear at a stop.
- Check the clutch shoes and springs inside the clutch assembly. Worn shoes or weak springs need replacement.
Step-by-Step Diagnosis Guide
Follow these steps in order to find your problem without wasting time.
- Park on a level surface and set the parking brake. Start the engine and let it idle.
- Observe the shifter lever. Does it have lots of side-to-side play? Is the clamping bolt tight? Wiggle it to check for looseness.
- Watch the shift shaft. Have a friend slowly move the shifter up and down while you watch where it enters the engine. Does the shaft rotate cleanly, or does it seem stuck or bent?
- Check for the return spring. Does the lever return to the center position after you release it? If not, the spring is likely broken.
- Try shifting with the engine off. Rock the ATV back and forth slightly while gently applying pressure to the shifter. Sometimes this helps gears align if it’s just stuck.
- Listen for internal sounds. If you hear loud grinding or clunking when trying to shift with the engine running, internal damage is likely.
How to Adjust and Replace the Shift Return Spring
Since the return spring is a super common fix, here’s how to do it. You’ll need basic tools.
- Drain the engine oil and remove the right-side engine cover (clutch cover).
- You’ll see the clutch assembly. The shift shaft and its mechanism are located near the top of this area.
- Locate the return spring. It’s a small coil spring attached to the shift shaft mechanism. It often breaks at the hooked end.
- Carefully remove the broken spring. Take note of how it was installed.
- Install the new spring, hooking it into the same holes or posts. You may need pliers to stretch it gently into place.
- Before reassembling, manually rotate the shift shaft with your hand to ensure it moves smoothly and the spring provides a solid return.
- Replace the cover gasket, reinstall the cover, refill with oil, and test.
When to Seek Professional Help
Some repairs are best left to a mechanic with experience on these older machines.
- If you’ve checked all external parts and the problem persists, the issue is internal.
- Splitting the engine cases to inspect gears, forks, and the drum is a complex task that requires special tools and a very clean work environment.
- If you’re not comfortable with major engine dissasembly, finding a trusted shop is the smart move. It can save you time and prevent costly mistakes.
Preventive Maintenance Tips
Keep your TRX shifting smoothly for years to come with these habits.
- Use the Right Oil: Always use a high-quality 4-stroke ATV or motorcycle oil. The wrong oil can make shifting notchy.
- Change Oil Regularly: Old, dirty oil accelerates wear on internal parts. Stick to the recommended change intervals.
- Shift Deliberately: Don’t kick the shifter. Use firm, positive motions. Don’t force it if it resists.
- Check Lever Tightness: Periodically check the clamp bolt on the shifter lever to prevent spline wear.
- Keep it Clean: Mud and debris around the shift shaft can work its way in and cause premature wear.
FAQ: 1987 Honda Fourtrax TRX350 Shifting Problems
Why is my TRX350 hard to shift, especially when cold?
Thick oil when cold is a common culprit. Ensure you’re using the correct viscosity oil. Also, a worn clutch can drag more when cold, making shifts rough. Let the machine warm up for a few minutes before riding.
Can I still get parts for a 1987 TRX350?
Yes! Many common wear items like return springs, shift levers, gaskets, and even internal gears are still available from Honda, online retailers, and aftermarket suppliers. The community support for these models is strong.
My Fourtrax shifts but won’t move. What’s wrong?
This is likely a different problem than a shifting issue. First, check that the rear differential is engaged (2WD/4WD lever). If that’s fine, the issue could be a broken axle, stripped splines on the rear hubs, or a completely failed differential.
Is it safe to ride with a notchy shifter?
For a short distance, maybe, but it’s not recommended. Forcing a shift can cause further internal damage. A notchy feel often indicates early wear on the shift forks or drum. It’s best to diagnose and fix it before a small problem becomes a big one.
How much does it cost to fix internal transmission damage?
Costs vary widely. If you do it yourself, parts for a full rebuild (gears, forks, drum, gaskets) can range from $300 to $600+. At a shop, with several hours of labor, the total bill can easily exceed $1,000. This is why checking the simple external causes first is so important.
Dealing with a 1987 Fourtrax TRX350 shifting issue can be frustrating, but it’s usually solvable. Start with the simple, external checks—the shift lever, linkage, and that pesky return spring. These fix a majority of the problems. If the issue lies deeper inside the transmission, you now have a clear understanding of what’s involved.
With its simple design and good parts availability, there’s no reason your classic TRX350 can’t be shifting smoothly for many more trail rides to come. Take your time, be methodical in your diagnosis, and don’t hesitate to ask for help from the knowledgeable online forums dedicated to these timeless Honda ATVs.