Manual valve body automatic transmission

[almightybmw]

How is this different from a newer manual shifting auto? Example Audi Tiptronic. Select a gear, mash the throttle, it doesn't change gears till redline, or till you drop rpm below idle to downshift. Basically does what you're doing right? Full control to use each gear as you see fit, without needing a manual clutch.

[Shawn D.]

Originally Posted by frugal builder

A manual valve body will eliminate a portion of Automatic trans power waste. It will shift like nothing else, though. There is no RPM reduction during the gear change so the torque converter will be the only place to absorb the shock. The joints in the driveline will need to be of excellent quality. Wet weather drivability will be something that will need to be delt with. It will be so much fun, you may never see a mileage improvement.

It's not the "manual" part of the valve body that causes the hard shifts, it's that because manual valve bodies have always been for racing purposes and thus inherently include a reduction in clutch application times due to the elimination or modification of fluid-damping devices such as check balls and accumulators.

I do agree that harders shifts are extremely fun! The shattered differential and split driveshaft from my '57 Chevy would disagree, though!

[wagonman76]

I wonder what the danger might be of adding a lockup switch to my car? I would probably only use it in third gear, and sometimes fourth to keep it from unlocking itself. But why isn't it enabled for third gear from the factory? Am I risking damage by forcing lockup in third?

Not sure why it was not done from the factory, except like Christ was saying, maybe it is designed to not spend a lot of time in 3rd. All my vehicles lock the TCC in both 3rd and 4th.

The only drawback I can think of is if the ECM considers it an error, and dumps you back to warmup mode. My van does that if it senses anything out of factory spec, and you have to pull over and restart (since it won't restart in N). Then it would certainly not be worth it with the fuel wasted in warmup mode.