The transmission involves many moving parts which must be replaced by the end of their life. However, it must be separated from the engine by removing the bolts holding it. However, I find these bolts easy to miss, especially if you don’t know how many they are.
In most cases, eight bolts hold the transmission to the engine. However, some vehicles have seven and some nine. Usually, there are two bolts on the top and bottom. The driver’s side of the transmission can have more than two bolts, especially if it has more than eight.
The article discusses transmission removal from the engine, including how many bolts to expect on various types of transmission. Read on to learn more.
How Many Bolts Hold the Transmission to The Engine?
With time the transmission develops problems and needs repairing or replacing. Whining noise when revving the engine in neutral is one of these transmission problems that may signify a developing problem requiring repair.
These repairs or replacements require the transmission to be separated from the engine first, in a time and energy-consuming task. However, knowing how many bolts hold it on the vehicle’s engine can help save you time.
Most Transmissions Have 8 Bolts
In most vehicles, I usually find 8 bolts, two on each side, but they can vary in their position. For instance, a Silverado has eight, two on top, two on the driver’s side and passenger side, and two at the bottom
Some Ford vehicles, like Ford Ranger, also use 8 bolts to secure the bell housing onto the engine. Each side has two bolts with the bottom two usually going into the oil pan.
Various GM automatic and manual transmissions held to LS or LT series engines, usually 3rd, 4th, or 5th generation, also use eight bolts. For most Audi vehicles, you will also find eight bolts when separating the transmission from the engine.
Some Transmissions Have 7 Bolts
The T-45 transmission used on Ford Mustang holds the engine on seven bolts. Their replacement, Tremec TR-3650 also holds to the engine with five bolts. There are usually three on the driver’s side, two on top, and two on the passenger side.
Some Transmissions Have 9 Bolts
Some transmissions, like the 4160E used by General Motor vehicles, use nine bolts to hold onto the engine. Some Ford Mustangs with rear-wheel drive also use nine bolts, with the most, three, being on the driver’s side of the transmission. The rest are usually evenly shared on other sides, top, bottom, and passenger sides.
Usually, this information is in the owner’s manual in some cars, under the tightening specifications. However, it is not in all manuals, especially if one is using an online manual.
Also, the bell housing on some vehicles may have more holes, usually where various parts, like the starter, connect. Don’t confuse the number of holes by only observing the bell housing. Consult the manual to know the number you’ll require to hold the transmission to the engine.
Why Is the Transmission May Be Stuck on the Engine?
The engine block and the transmission are usually tightly mated together during installation to reduce vibrations and avoid damage. However, after unfastening all the bolts, the two should separate without much effort.
If that’s not the case, various things may be responsible, forcing the two to be stuck together. They include the following.
1. Rusted Dowel Pin
The dowel pin keeps the engine and the transmission aligned, preventing damage while running. However, during a separation, the dowel pin may prevent that from happening, especially if rusted. Spray a penetrating lube and let it sit for some time before trying again.
2. Wires and Harness
There are several wires and harnesses from the vehicle to the transmission on the sides. These harnesses are sometimes clipped to the transmission and can prevent the two from separating if not disconnected.
The speed sensor harness, which is usually connected to the transmission, is among the harnesses to disconnect. Ensure you unclip and disconnect each harness.
3. Transmission Mount
Most transmissions, especially those on a rear drive, have a mount that holds them in place. While these mounts are not easily forgotten, I have witnessed some people forgetting them and then wondering why the transmission is not separating.
4. Support Bar
In some vehicles, there is a support bar under the transmission which sometimes can get in the way when separating the two. You should first remove the support bar, which also makes installation easier.
5. Clutch Fork Pin
Some vehicles may not come out if the clutch fork pin still connects to the car. If the two parts are still stuck together, you should remove the clutch fork pin and retry.
Tips for Separating Transmission and Engine
I usually find separating the engine and transmission to be easy. However, this is because I consider various tips that help me avoid complications, improve the process, and avoid damage to parts.
1. Equipment
One tip is using quality equipment, which separating the transmission from the engine requires. Removing the bolts needs a torque wrench and a good set of sockets, extensions, and a universal extension.
You will also need a pry bar to separate the transmission from the engine.
2. Marking Bolts After Removing
Most bolts vary in size in both length and circumference and can create confusion during installation. I usually mark each bolt according to its position on the transmission or place them in order on a flat surface.
3. Support the Transmission
One of the reasons your car can develop transmission problems after an engine swap is due to damage during the replacement. One thing that I find helpful is a reliable transmission jack that allows you to strap down the transmission during a separation, preventing damage.
4. Support the Engine
Just like the transmission, the engine needs to be supported, especially just before the separation begins. The sudden weight shift can damage the engine or some of its parts. I usually use a jack with a piece of wood to support the engine and ensure it remains level.
5. Ensure Vehicle Is Raised High
A common mistake most people make is raising the vehicle too low, just enough for them to slip through. A transmission is big and requires more space, especially if the repair is on a sedan or coupe.
Ensure there are at least 20 and 24 inches below the car. Also, support the vehicle with steady equipment, like jack stands. Raising the vehicle high allows more room to wiggle the transmission off, preventing chances of damage.
Conclusion
The number of bolts holding the transmission to the engine varies with the transmission type and engine used. However, most vehicles use eight bolts, two supporting each side. However, the number can be more or less, with most transmissions from the 90s having fewer.
I suggest you check the user manual to confirm the number of bolts. The user manual also has information on the bolt’s size and torque needed to tighten them. Ensure you observe the various parts mentioned earlier if the engine is not separating, and check the tips for faster and easier removal.
Resources:
1. https://streetsmarttransmission.com/diy-remove-automatic-transmission-and-install-rwd/
2. https://www.instructables.com/How-to-Remove-a-Car-Engine-and-Transmission/
3. https://www.uti.edu/blog/automotive/transmission
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