Recognizing The Signs Of A Bad Synchronizer
Manual transmissions are relatively simple devices when compared to the complexity of an automatic transmission, but modern models still have a variety of parts that can potentially fail. While most manual transmissions are durable, a common issue on many older or higher-mileage transmissions is synchronizer (or "synchro") wear. Your gear synchronizers allow your transmission and your engine to match speeds, preventing harsh grinding or jerking and removing the need for perfect rev-matching and double-clutching.
Like many innovations found on modern manual transmissions, synchros make your life easier and provide a smoother and more enjoyable driving experience. Since many drivers choose stick shift vehicles for the driving experience, it can be especially frustrating when a bad synchronizer gets in the way of clean, smooth shifting.
Why Do Synchronizers Fail?
If you've been driving a stick shift car for a while, then you're probably used to the sensation of your gear lever being "pulled" into gear. As you move the selector from gear to gear, the synchros provide the speed matching that is necessary for the collar to engage smoothly. That pulling sensation occurs when the collar and gear speeds have been synchronized. If you have ever noticed resistance when pushing the gear lever, then what you are feeling is the synchronizer struggling to match speeds.
So, why do synchronizers fail in the first place? For transmissions with very high mileage, it can simply be the result of normal wear. Your synchronizers take a bit of abuse every time that you shift gear, and they will eventually wear out. More commonly, bad synchronizers are the result of user error. When you quickly shift into gear, you are putting extra wear on your synchros, potentially causing them to prematurely fail. Wear of this type often occurs as the clutch (or another component in the clutch system) fails, since this can often make shifting into gears difficult.
The Symptoms of Bad Synchronizers
Fortunately, bad synchronizers tend to produce fairly noticeable symptoms. The two most common symptoms are grinding and popping out of gear. Since each gear has its own synchronizer, symptoms will usually be limited to one or more individual gears. If you always grind when pushing the gear selector into 2nd gear, for example, then it's a good bet that your 2nd gear synchronizer is worn out. Likewise, your gear selector regularly popping out of one gear is a good sign of synchronizer failure.
While the initial symptoms of a bad synchro are usually not severe, the problem will only get worse as time goes on. You can also potentially damage the gears themselves by driving with bad synchronizers for too long.
Repairing Failed Synchros
Unfortunately, replacing a bad synchronizer always involves pulling and rebuilding the transmission. Luckily, rebuilding a manual transmission is usually less expensive and labor-intensive than repairing an automatic transmission. If symptoms point to synchronizer failure, then replacing just the failed synchro can save some money on the rebuild, although you can still expect to spend over a thousand dollars on the repair. Regardless of the cost, repairing a bad synchronizer is vital for both the performance and longevity of your transmission.
For more information, contact a local transmission shop.
