Reverse-Shift Problem May Be Too Costly to Fix, but There Is Another Solution
Question: I find it increasingly difficult to shift into reverse on my 1991 Toyota Camry. The manual transmission just seems to get stuck and won’t go into the reverse position; it goes into first without any problem. The dealer said the transmission needs to be pulled out and rebuilt. But I’m wondering if there’s another option. The car is otherwise in good shape with 110,000 miles on it, but I don’t want to sink more than $1,000 into an 8-year-old car.
Answer: The problem you have is not unusual on older cars with manual transmissions, especially if they have been abused through the years either because of careless use or a bad clutch.
Quite possibly, the points on the teeth of the reverse gears have been worn off. To understand the problem and how you can avoid the repair, you’ll have to get a little lesson in transmissions.
Manual transmissions have two shafts, each with arrangements of gears that allow you to vary the drive ratio from the engine to the wheels. One critical feature is that all forward gears are so-called synchromesh gears that equalize the speed of the two shafts during shifting. They will ensure that the gears can be downshifted or upshifted even while the car is in motion.
But the two reverse gears on the shaft and countershaft of the transmission are different. Transmission designers correctly assume that people only shift into reverse (or should) from a stop and will not need synchromesh gears.
When you want to go backward from a stop, you depress the clutch and shift into reverse. By depressing the clutch, you disengage the transmission from the engine and allow both shafts of the transmission to stop. The two reverse gears can then mesh together. Unlike most gears with blunt ends on their teeth, the reverse gears have points that allow them to slip together.
After many years of use, however, the points can become worn off. If you ever shift into reverse and hear a grinding sound, that’s the reverse gears getting their teeth points ground down.
It often happens because the clutch is out of adjustment and doesn’t allow one of the two transmission shafts to stop fully. It can also occur if you try to shift too quickly into reverse, because the shafts can take about one second to stop. A warped clutch plate will also cause this problem.
After the points on the gear teeth get worn, shifting into reverse becomes more difficult. Sometimes the two gears will be positioned so that the teeth jam against one another and won’t mesh. That’s what is causing your problem.
An easy way to avoid this damage to the reverse gears is to always shift into first before shifting into reverse. This will force the shafts to come to a stop. It’s an old car trick, but it still works well.
I agree that you should not spend a bundle on rebuilding your transmission just for this reverse-gear problem. When it happens, do not try to force the transmission into reverse. Instead, put the car into first and inch the car forward. Then try again. The movement will reposition the gears, and you won’t be trying to mesh two blunt points together.
Q: My 1997 Buick Regal has a humming noise coming out of the front end. The garage I took it to wants to sell me new wheel bearings, CV joints and tires. Can all those things be causing the hum?
A: No. When the constant-velocity, or CV, joints go bad, they click. Tires almost never make unusual noises, unless they have belt separation, and then the sound is a thump. The most likely cause of the problem is the wheel bearings. I’d suggest finding a new garage that will fix only what’s broken.
Ralph Vartabedian cannot answer mail personally but responds in this column to automotive questions of general interest. Write to Your Wheels, Business Section, Los Angeles Times, Times Mirror Square, Los Angeles, CA 90053. Via e-mail: firstname.lastname@example.org.