TH475 vs TH400: Difference Between a Turbo 400 and a 475
The more things change. The more they stay the same. That is the way it seems as transmission and engine and other manufacturers keep trying to put out new and improved products. They may seem different in name but under close examination, there is very little difference between the old and the new versions.
About the only major difference between these two transmission models is the gear teeth. The 475 has straight-cut teeth while the 400 has the helical-cut teeth. Both are said to be quite strong and the 475 is said to be the dump truck transmission.
To learn more about this topic, just continue to read our article. It has the information you need to know about so you can decide if you want the TH475 or the TH400 transmission to help your vehicle move. They are basically the same transmission model.
Turbo TH475 Transmission
This transmission model has a 3” deep pan and requires about an inch longer pick up tube to make sure the fluid gets to where it needs to be. Plus, this model has been placed in more RVs and bigger trucks due to the strength of the gears.
The straight cut is said to be stronger than the helical cut. Also, you will find that this version may have an emergency drum back attached to it. That was because this transmission was placed in motorhomes.
That drum brake may cause some owners' drive shaft problems. If you can get used to the whine as you drive, then the extra noise may not bother you. It is a noisier transmission than the TH400.
In essence, the TH475 is the TH400 except for these minor differences. The more things change, the more they remain the same. You may be paying more just to have different cut gears that may or may not last as long as the TH400 gears.
What's The Difference Between a Turbo 400 And a Turbo 475?
Externally, the two transmissions are exactly the same. They look alike and should install about the same. It is where you can’t see that has the differences between these two transmission models.
The biggest difference, as we have already said, is the cut of the gears. The TH400 has the helical cut which makes it a quieter transmission. But that cut of the gears does not make it a stronger transmission to have in your RV or car.
The straight cut is the stronger of the two and should last longer under the right conditions. The other major difference would be the depth of the pan. The TH475 has a deeper pan which requires a little bit more transmission fluid.
The minor differences are the longer pick up tube and the 1-inch thick bushing spacer that helps push the filter a bit lower. The TH475 also has the HD cast into the bell housing and a six-bolt torque converter.
TH475 vs TH400
The best that can be said in this type of comparison is that the TH475 is more of a heavy-duty transmission than the TH400. After that, there is no real comparison as the TH475 is a version of the TH400 but made for bigger vehicles.
The TH400 was found more in light trucks and cars and some of those vehicles that have or had a TH400 in them are as follows:
1965-1967, 327 V8 (Rambler/AMC)
1968-1971, 350 V8 (Buick)
1969-1972, 225 V6 (Buick)
1972-1975, 232 I6 (AMC)
1975-1979, 258 I6 (AMC)
1972-1979, 304 V8 (AMC)
1972-1979, 360 V8 (AMC)
1974-1975, 401 V8 (AMC)
GM
Jaguar
Ferrari
Another version of the TH400 was the TH375, also for light-duty applications. However, it is very hard to tell them apart if their tags are missing. You would have to strip them down to see the gears to know which transmission was which.
The TH475 would last longer because of the stronger gears inside and the deeper pan for more fluid to keep the transmission cooler, etc.
Problems With The TH400
Every part will have its weaknesses. The TH400 has a share of its own although they may not be major faults. One problem is the early shift and lower efficiency when the motor revs high.
This problem was traced to the failure of the kick down switch or the vacuum hard line location. It is too near the engine and transmission and can melt due to the high heat both parts put out. This hard line tube is made of rubber and is attached to the intake manifold.
Then, if the tube was not sealed correctly, transmission fluid would leak into it. This would cause other problems for the owner.
Finding a TH475 Transmission For Sale
The first and probably the best place to look would be at different transmission shops. They would have these older transmission models lying about and they should be in fairly good shape.
One such shop is called BullRipper Transmission Technology and you can find them online. The drawback is that this transmission may cost you over $2500 to get.
Another place to look would be the different RV brands’ discussion forums. They have classified sections and list just about anything related to RVs in those threads.
If you can’t find anything at those two places, try eBay. They have one or more for sale from time to time and you might be able to pick one up at a reasonable price. If you can’t find the transmission, you can certainly find parts for it at that marketplace.
The Transmission Exchange Company rebuilds or refurbishes old transmissions. They may be an excellent place to find TH475 transmissions.
Some Final Words
When you need a transmission for heavy-duty applications, the TH475 is the one you want. The TH400 is for other applications and both are strong, good, and long-lasting transmissions.
You should not go wrong in selecting either one as long as it is in good shape. Parts should still be available as well.
