Lets discuss how a General Motors T-400 transmissions and how they operate on a simplified basis. Although it uses different components to produce some of the gear ranges in terms of transmission theory than the 3 speed TF727 transmission, the end result is an automatic transmission with 3 forward speeds.
1. When you put the vehicle in Drive you are applying the forward clutches and the low/reverse sprag. This combination produces first gear in the drive range.
2. Here is where the major functional difference in theory between a transmission that uses a band for second gear, and a transmission that uses a set of clutches for second gear. As mentioned in the Transmission Theory-1 article using a TF727 transmission as an example, which uses a band for second gear, the T-400 uses a set of clutch plates to produce second gear. This is an extremely efficient way to produce a third gear shift. Essentially the shift to second is not much different except for the difference in components at work.
The beauty of using clutch plates for second gear over a band is that when you use clutch plates for second gear instead of a band, when the transmission shifts into third gear, there is no band that has to release in order for a smooth shift to third. As opposed to a 727, which has to fully release the second gear band in order to make a clean third gear shift. For the majority of people this is not an issue. For drag racers it is a big issue, meaning that the third shift occurs faster in a T400 since a band does not have to release before the third clutches apply.
I’m not saying that a 727 can’t shift as fast a a 400. With the correct racing shift kit, one can exact the same quick shift to third in a band unit as in a clutch unit. It is more complicated and involved, but it can be done reliably.
Without getting into the details of reverse or downshifting, this is the way a unit with clutches operates as opposed to a unit that uses bands and clutches. Not that this is very important when it comes to purchasing a replacement Chevy T-400 transmission for your car.
What is important when it is time to find a transmission for sale? Knowing the transmission supplier you deal with gives you a product you can count on to exceed expectations. Knowing that you will deal with transmission experts and specialists in terms of helping you choose the transmission that is in your best interest.
For more transmission information, you can read our array of transmission articles on our blog, right here. If you want to speak with a professional, call GotTransmissions.com @ 866-320-1182.
