Muncie 20, 21, 22; Saginaw, Toploader, Borgwarner (T10), TH350, TH400, 727 Torqueflite, Toyoglide, Powerglide, etc.
Does your classic American or Japanese muscle car leave behind embarrassing stains on the pavement due to a leaky transmission? Has it been awhile since the transmission was serviced? Is the clutch making weird noises? Are you looking for an alternative to the high revving, howling, gas sucking effects of yester-year's transmissions?
It's not often a day doesn't goes by where a consumer calls or stops by looking to resolve an issue stemming from a neglected transmission. As time passes and cars move from one generation to the next, in many cases historical maintenance records are missed placed, not originally available, or outright ignored. Sadly, by the time a problem is discovered it's often too late to remedy with a simple fluid change.
So what's the first thing you should do if you have no recollection of the last time it was looked after? Well, if your car has an automatic transmission, pull the dip stick, usually found back near the firewall on either the driver or passenger side. Check the fluid's color, smell, as well as the texture. The engine should be running and vehicle's transmission in park with the emergency brake engaged. Let the it run for a few minutes before you pull the dip stick. Once pulled, note the marks at the end of the stick. It should read "Full and Add" or "Hot and Cold". If the fluid level is below ADD or COLD then there's probably a leak and it should be looked into by a transmission specialist. Good trans fluid should appear red, pink or light brown, and without bubbles and/or odor. If the fluid is a burnt brown or deep red and smells like burnt toast, then it's time to flush/change the fluid since it no longer contains the appropriate properties to dissipate heat and therefore unable to protect the transmission from catastrophic failure. If the fluid appears bubbly or foamy, it's likely there's too much fluid in the cylinder, an incorrect fluid used or the engine has a plugged transmission vent. In any event, the problem should be brought to the attention of a transmission specialist for further diagnosis.
Now let's explore manual transmissions in the same manner. Many of the newer vehicles will allow you to check the fluid using a dip stick. It can sometime be a challenge finding the little bugger but if you have access to the owner's manual or the internet, you can use either resource to look up the dip stick's location. If you discover your transmission does not have one then checking the fluid takes a bit more effort. You'll also need some shop equipment like a wrench, creeper, floor jack and jack stands. The emergency brake should always be set before attempting to jack up the vehicle. As a secondary precaution, place a block of wood behind the rear tires to insure the vehicle doesn't roll back while raising it with the floor jack. Place the jack stands in the appropriate points under the frame and once the vehicle is secure and all four tires are off the ground, you are now ready to slide under the vehicle using the creeper to locate the transmission plug. Again, you can use the owner's manual or internet to find the precise location of the plug. You'll need the wrench to remove the plug but be sure to have a rag handy since fluid may seep out during the plug removal. If no fluid oozed out then stick your smallest finger in the plug hole to gauge how much fluid is needed. Examine the color of the fluid as well, if it's more than a few shade darker than cooking oil, it's probably time to replace. One final point worth noting, some but not all transmissions contain a magnet inside the case. It collects any lose metal from gear wear and can be read like tea leaves, pointing to potential transmission trouble lurking in the near future.