Types of transmissions
The purpose of the transmission is to transfer the power generated by the engine to the drive axle and wheels by using different gears. A car’s engine rotates within a fixed range of speeds, generally from 600 to 7,000 revolutions per minute (rpm) for most passenger vehicles. The vehicle’s wheels typically spin from 0 to 1,800 rpm, so the transmission uses different gears with specific ratios to match the most efficient use of engine power for the vehicle’s speed.
For instance, when starting from a full stop, your car’s engine is spinning much faster than the wheels so a lower-ratio gear that supplies higher amounts of torque is needed. When traveling at highway speeds, the wheels may be turning much faster than the engine, meaning a higher-ratio, low-torque gear is needed.
There are a few varieties of transmission types found in most modern vehicles:
Automatic transmissions: The most common type of vehicle transmission for cars built and sold in the United States, automatic transmissions automatically select the correct gear for the driving conditions. Beyond special circumstances like towing a trailer or extremely steep inclines or declines, most drivers simply have to put the vehicle’s gear selector into “D” for drive and the automatic transmission does the rest. Up until recent times, automatic transmission vehicles were typically less fuel efficient than their manual transmission counterparts.
Manual transmissions: Also known as a standard transmission or manual gearbox or simply “stick,” manual transmission vehicles are a relative minority in modern American vehicles. Manual transmissions rely on the driver to select and switch gears constantly. Manual transmissions are typically equipped with a clutch pedal that’s required for the driver to be able to switch between gears. Although manual transmission vehicles provide greatly improved fuel economy (and typically cost less than automatic transmission vehicles), the downside is the constant need for attention on the part of the driver.
Continuously variable transmissions (CVT): Typically found on lighter passenger vehicles, CVT transmissions are relatively new features in terms of the American automobile market, but they offer a special set of advantages. Although they employ a different technology than traditional automatic transmissions, they perform in the same manner in terms of driver experience. Moreover, they deliver increased fuel efficiency when compared to traditional automatic transmissions.
Signs of transmission problems
For most drivers, knowing if and when their vehicle has transmission problems can prove difficult. Other times, it’s obvious the vehicle is experiencing transmission trouble. If you experience any of the conditions noted below, it’s a good idea to have your vehicle inspected by a qualified mechanic or transmission repair specialist. These are signs of auto transmission problems that you can't ignore. Delaying needed repairs or services will only make the problem worse.
1. Transmission no longer operates normally
Yes, this is an ambiguous description, but there are a wide range of indicators that you need an auto transmission repair. One of the most common yet subtle signs of needed transmission repair is when the transmission slips or hesitates; while driving, you press on the pedal and the engine revs up, but there’s no corresponding increase in speed or a hesitation between when you push the pedal and the vehicle speeds up. This can happen particularly when first starting the car on a colder morning for the first time.
If you drive a manual transmission vehicle, you may notice that moving the gear shift into or out of gears becomes extremely difficult. For automatic transmissions, the reverse gear may go out or the vehicle may slip out of gear while driving, causing the engine to roar.
2. Strange sensations
Along with improper operation, another indicator of a failing transmission can be strange vibrations or shimmying sensations when driving. If you notice a strange vibration, especially at one speed or speed range in particular, it can indicate the transmission or a transmission component needs to be repaired or replaced.
3. Warning lights
Transmissions in modern vehicles rely heavily on electronic controls and systems. If you notice a warning light flashing on your instrument cluster — especially a light that says “O/D,” which indicates the “overdrive” gear — the vehicle’s on-board diagnostic system has registered an error with the transmission. P0700 is a code that can indicate a general transmission problem.
4. Strange or new noises, especially grinding, clunking or thumping
If and when a noise accompanies your vehicles shifts, such as a clunk or thump, it’s a sure sign there’s a serious error with the transmission that requires immediate attention. If you drive a manual transmission vehicle and notice a grinding noise, it can indicate the clutch gear is no longer disengaging correctly.
5. Burning smells or strange smells
Like your car’s engine, the transmission operates at high temperatures and without the correct amount of transmission fluid to lubricate it; the transmission can overheat and fail. You may notice a strange chemical or burning smell when the car is operating.
6. Fluid leaks, puddles beneath the car
Transmission fluid is absolutely essential for proper transmission operation. If you notice brown, red or pink puddles or leaks under your vehicle, it could be a transmission leak from a faulty gasket or seal. Knowing when to change transmission fluid helps avoid costly repairs. Experts say to flush the fluid at 60,000 to 90,000 miles and again at 120,000 to 150,000 miles, or when the fluid changes from a pink to a dark red or brown. Auto transmission fluid exchange has been known to correct shifting problems and delayed engagements. If you didn't notice a leak, but a auto repair shop says you need a fluid change, ask them to show you and explain why.
Transmissions problems are costly repairs, so take preventative measures by knowing how to protect your car from transmission damage.
Because your car’s transmission is an essential component for your car, it’s absolutely essential that it undergoes maintenance as recommended by the vehicle manufacturer. You can find recommended transmission maintenance in your owner’s manual or the manufacturer’s website.
Typical regular transmission maintenance items may include inspecting and adjusting the clutch pedal on manual transmission vehicles, and inspecting, topping off or flushing the transmission fluid in the transmission case for automatic and manual transmission vehicles. Many transmission repair specialists recommend checking your transmission fluid level at least twice each year.
Check your vehicle manufacturer’s recommended maintenance schedule to determine if and when these services should be performed and remember to follow recommendations specific to more severe driving conditions such as dusty environments or regularly towing or carrying heavy loads. If your stuck in slick weather conditions, it's best to call a tow truck. Trying to get your vehicle unstuck may cause transmission damage.
Some transmission fixes can be quite inexpensive, while others may end up costing more than the value of the car itself. Transmission repair costs can easily range from a few hundred dollars to many thousands of dollars. That’s one good reason to have your transmission inspected by a qualified mechanic if you suspect something may be amiss.
If you know something is wrong with your transmission, the causes can be numerous. A simple lack of transmission fluid level can leave important parts unprotected by lubricant and allow internal components to warp and gaskets or seals to fail. Modern transmissions also contain a number of electronic modules and controls that could fail and cause transmission problems.
In manual transmission vehicles, one of the most common major repairs is replacing a clutch that’s become worn over time or damaged out by improper driver shifting. In all types of transmissions, sometimes an overhaul, rebuild or replacement may be necessary depending on the severity of the problem.
Questions to ask
When facing an expensive transmission repair such as a rebuild or replacement, vehicle owners should ask themselves a few questions. First, is the transmission under warranty? Many vehicle manufacturers now offer power train warranties that cover some, but not all, transmission components for as many as 100,000 miles or five years. Having a transmission repaired under warranty represents a much less expensive proposition.
If a repair shop or auto service provider has proposed an expensive repair based on their sole diagnosis, it may prove useful to get a second opinion. With some transmission problems such as a issues that prevent the car from even driving, this may represent an extra expense in towing the vehicle to another location, so consider exercising this option judiciously. Call around to other transmission repair providers to get an idea of the cost range based on the prescribed repairs.
Finally, if facing an expensive transmission repair, especially for an older, high-mileage vehicle, determine if you should repair the vehicle or replace it. The first step is determining how much repairs will cost. Next, find your car’s retail value by using car pricing tools available at websites such as edmunds.com, nadaguides.com or kbb.org.
If the cost of the repairs greatly exceeds the value of your car, you may want to avoid repairing your transmission. On the other hand, if your car is in otherwise fair condition and transmission repairs can help ensure many more years of trouble-free operation, it may be wise to consider investing in repairs, especially if you want to avoid the effort of purchasing a new vehicle and making monthly payments.
Before authorizing any transmission repair, ask if they plan on replacing parts and where those new parts will come from, Shilling says. (Photo courtesy of Angie's List member Jim F. of Palm Harbor, Fla.)
Finding a transmission repair shop
If you have the time to search out a transmission provider, making a few key determinations can mean the difference between an effective repair or a shoddy one and a high cost repair rather than an affordable one. Consider these choices when searching out a transmission repair shop:
Dealership service vs. independent garage
Having a good auto repair shop on your side is a time saver and stress reducer when your car needs work.
If you drive a late-model car and its power train warranty is still active, this decision is a no-brainer – use the dealership. You’ll see the benefits of mechanics trained by the factory, using factory-supplied parts and at little or no cost to you, depending on the problem. If you’re out of warranty for transmission repairs, however, the biggest disadvantage to using a dealership is the higher cost. An auto service shop or a transmission shop that’s independent of the vehicle manufacturer may be able to provide transmission repairs that are just as effective, but at a significantly lower rate.
Transmission repair shops vs. general auto mechanics
If you’ve decided to go outside of the dealership service bays for your transmission repairs, the next question will be whether you plan on using a transmission specialist or a general automotive services shop. If you’ve established a regular relationship with an auto service provider, it’s a good idea to get their opinion on your transmission problem first. They may be able to provide an effective repair, if they have the right amount of experience or expertise, or they may recommend a transmission specialist.
You may find several different transmission repair specialty shops in your area, from mom-and-pop shops to franchise operations. It’s important to note that because these businesses specialize in transmission repairs only, they typically charge a higher fee than a generalist auto repair provider.
New, rebuilt or remanufactured transmissions
Almost as important as the shop you select for the work is how the transmission may be repaired. If you’re faced with the prospect of replacing or repairing a faulty transmission, it’s important to know the differences between different types of repairs. The cost of a new transmission can often cost as a much as a car engine, so many vehicle owners opt to go for the less expensive routes: rebuilding their existing transmission, or installing a rebuilt or remanufactured transmission.
Rebuilding an existing transmission will involve removing the damaged or broken transmission completely from the vehicle and then repairing or replacing any damaged parts. Installing a rebuilt transmission means that the transmission in question has already been rebuilt to manufacturer specifications at a facility outside the shop. Remanufacturing a transmission is essentially the same as rebuilding, with the exception that it takes place in a factory setting.
Warranties and guarantees
No matter where you get your auto transmission repaired or how it’s repaired, getting a warranty or guarantee on the parts and labor is an essential step. If you’ve gone to the trouble of spending hundreds or thousands of dollars on expensive transmission repairs, a warranty or guarantee on the actual work performed, as well as the new parts installed, is always recommended.