The Myths And Misconceptions Surrounding Transmissions
Your car's transmission is often one of the most misunderstood components of the car. Very often, owners don't quite understand how the transmission works, and often end up abusing it without even knowing it! This week I will provide you with some hints and tips to keep your transmission shifting smoothly for many years to come.
Let's start by talking about automatic transmissions.
The automatic transmission is one of the most complicated automotive components ever created. I can't go into the specifics of how they work here, but in short, they work hydraulically, which means that they use hydraulic fluid as both a lubricant and a coolant. That said, you can imagine that a loss of this fluid would be detrimental to your transmission's health. Even so, most people don't bother to check their transmission fluid, or don't even think about it when they take their car in to be serviced. Compounding this problem is the fact that many car manufacturers now proclaim to have 'service-free' transmissions. I personally think this is a huge disservice to car owners, because let's face it - there's really no such thing as a service-free transmission.
In the past, I've owned two cars that came with an automatic 'service-free' transmission. While the transmission (sometimes referred to as a 'tranny') itself may be service-free, this is highly dependent upon there being enough fluid in the transmission.
Most transmissions utilize a cooler in the front of the car, which is typically attached to the car's radiator.
To get the fluid there...
It has to run through hoses underneath the car. On one of these cars, the previous owner's wife had dragged the car over something concrete, damaging one of these lines. The result was a slow leak of precious transmission fluid. The owner never noticed, because there is no easy way to check the transmission fluid on these cars. However, when driving the car, if you slammed on the brakes, and then stepped on the gas, the car would pause and then 'slam' into gear, moving forward. This was caused by the low amount of transmission fluid slopping towards the front of the lower transmission pan when you slammed on the brakes. If all the fluid is at the front, then it can sometimes become dry and empty underneath the all-important pickup tube that is located in the center of the sump.
The bottom line: Don't trust the manufacturers! Have your automatic transmission fluid checked about once a year, and also change the fluid and filter at least every 30,000 miles.
Moving on, I wanted to talk about...Using Your Transmission to Help with Braking Down Long Hills.
When you're traveling down a long, steep hill, you should shift your automatic transmission into a lower gear using the gearshift. Typically, you will have the choice of 'D','3','2' and '1' or something similar to that.
By shifting into one of the numbered gears, the car will stay in a higher gear without downshifting. This will rev the engine higher, and it will slow the car down as you descend the hill.
It's perfectly okay for you to do this to your engine and transmission, although if you are unfamiliar with the technique, you'd swear it couldn't be good for the car. The flip side of the coin is that if you 'ride' your brakes down the mountain, you will most likely overheat them, which will make them lose their effective braking power. Under extreme conditions, they might even fail! I am surprised at how many people don't know this - you can always tell the people who are 'in the know' and who aren't by looking at the brake lights of people in front of you as you descend the hill. The people using engine braking will almost never hit their brakes, while the people who don't know any better will have their brake lights on all the way down the hill. Be smart - use engine braking. Owners of cars with manual transmissions almost always know this tip, but most people with automatics don't.
Now let's talk about...Manual Transmissions.
These are much better understood by most people than automatics, but there are still many things people do that aren't good for them. The first thing that comes to mind is having a poorly adjusted clutch cable. The clutch is responsible for disengaging the transmission from the engine when shifting. This reduces any mismatch in speed between the engine and the transmission and avoids the grinding of gears (more on that next week).
If your clutch cable is out of adjustment, then you may have a situation where your clutch is never fully engaging. What are the symptoms of this? Grinding into first and reverse are sure-fire signs of misalignment. You can also do a simple test to check. With the car at rest and the transmission in neutral, push the clutch pedal in. Now, count to ten slowly. Then try to shift it into reverse. If it grinds, then your clutch cable is almost surely out of adjustment (or one or more of your clutch components are not working properly).
What does this test do? Basically, when the transmission is in neutral, it is not engaged in any gear, but it is still connected to the engine and spinning internally. When you press the clutch pedal in, the transmission is disconnected from the engine, and should start spinning down to a stop internally (that is what you are waiting for when you count to ten). If you go and shift into reverse, the engine should be completely disconnected, and it should not grind. However, if the clutch cable is out of adjustment, then the transmission will never spin down. When you shift into reverse, the transmission will still be spinning, and you will grind some gears.
A poorly adjusted clutch cable will destroy your transmission in very short time, because it's similar to shifting without using the clutch.
You will grind gears and destroy synchros (more on these next week). If the above test reveals problems with your cable or clutch - get it looked at immediately. It's a lot cheaper to fix or adjust your clutch than it is to rebuild your entire transmission.
Next week, I'll touch on the following issues:
· Which transmission gear oil to use?
· Bad shifting habits that will hurt your transmission
· Improving a poorly shifting transmission
· Myths and truths about short shift kits
See you next week!
Wayne R. Dempsey
Principle Owner of DriveWerks
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