trans upgrade
it looks like we are going to have to wait to upgrade to a newer MH so I would like to upgrade the Turbo Hydramatic 400 to the 700R trans. Has anyone done this here? Seems at 65 mph its topped out, so...
Forum Discussion
Of course the 7427 ECM can also be retrofitted for fuel injection down the road as well. It is a very well documented ECM, and a big favorite amongst ThirdGen owners. (ThirdGen is one of 2 primary sources on the net for ECM customizing. The guy who wrote TunerPro is a Third Gen Camaro owner, and initially wrote the software for himself. It has since evolved into the best tuning software out there.)
One big thing that the 7427 ECM does is monitor slip between the input and output shafts. As the slip increases as a result of wear, the ECM automatically increase the pump pressure to compensate. This means that for the full life of the trans, it will always shift like it did when new. This also reduces the wear, as the trans gets closer to the end of its life. One other feature is the variable TC lockup. GM designed a special clutch inside the TC, which is porous. This allows fluid to work its way through the clutch to cool it. Based on conditions, the clutch pressure is varied to intentionally allowing slip. This keeps the engine RPM up when needed for power. They also begin to engage the TC in as low as second gear to improve mileage throughout the upshifts. TC engagement is soft, so you hardly feel it. I would be very surprised if any after market controller uses this scheme. OF course the other side of this is, that one must use a GM TC. Any after market rebuilders must buy the TC clutch from GM. Otherwise it will not hold up. GM has a patent on the clutch design, so it is exclusive to them.
One big thing that the 7427 ECM does is monitor slip between the input and output shafts. As the slip increases as a result of wear, the ECM automatically increase the pump pressure to compensate. This means that for the full life of the trans, it will always shift like it did when new. This also reduces the wear, as the trans gets closer to the end of its life. One other feature is the variable TC lockup. GM designed a special clutch inside the TC, which is porous. This allows fluid to work its way through the clutch to cool it. Based on conditions, the clutch pressure is varied to intentionally allowing slip. This keeps the engine RPM up when needed for power. They also begin to engage the TC in as low as second gear to improve mileage throughout the upshifts. TC engagement is soft, so you hardly feel it. I would be very surprised if any after market controller uses this scheme. OF course the other side of this is, that one must use a GM TC. Any after market rebuilders must buy the TC clutch from GM. Otherwise it will not hold up. GM has a patent on the clutch design, so it is exclusive to them.
