Boy. Did we get up on the wrong side of the bed today. Chris, what is with the big chip on the shoulder? Is this where we pull out ****s to see who has the biggest?
Yes. I do remember that sales call. You were trying to sell me your forward drum. Strangely, you were much more pleasant then. Judging by your attitude so far, it appears I made the right decision not to buy. I stood there listening on the phone while you did what most of us transmission guys like to do. Try to impress each other with their building skills. Not criticizing you for that. It's one of those things that happens when two technically minded people get together. Your right about me being very surprised when you told me about air checking through the VB exhaust holes. I politely elected not to comment about it at the time, but since you seem to be using my surprise as some kind of sign that I don't know what I'm doing, I'll tell you why I was surprised.
Why the heck would you wait so long in the assembly process to check your drums?
That procedure is great on AODs to check for excessively leaking valve bore end plugs, but on the 200-4R it is an unnecssary step. If you check your gasket fit and alignment during assembly, torque the VB correctly with the correct pattern and air check your pressure switches when you O/H the VB and check carefully for nicks and burrs on the case and VB gasket surfaces, you won't have a crossleak there. I've never had one anyway. You should air check the drums on the support and again in the case after you've torqued the support bolts. If a problem shows up during either of those air check procedures, you don't have to take so much of the trans assembly back apart to find out where the problem is. It will save you time when a bad air check presents itself. I can't imagine waiting until after you've installed the VB before air checking. Your making a big assumption, that the air check will be fine and you won't have to take all that assembly back apart. On a 200-4R, it is not the thing I would want to see my tech do. If there is a specific reason for doing such a check, I haven't come across the need yet, and I've done a lot of 200-4Rs.
How does the Honda fit into the picture? Let me explain. One torque signal comes from the throttle position sensor. As throttle opens, TPS signal changes and the computer will modify output signals to the transaxle. This is similar to our throttle valve cable. As the throttle is opened, the TV cable is pulled and a lever in the trans acts on what is called the TV plunger. This action increase TV pressure. One of its purposes is to modify line pressure. As TV pressure rises, so does line pressure.
The other torque signal in the Honda transaxle comes from the stator support. As engine torque acts on the stator in the torque converter, it twists the stator support and through a lever, a valve is stroked in the valve body to increase line pressure.
Line pressure is the main working pressure of transmissions and is mainly used to apply bands and clutches, or just clutches in the case of the Honda. The more torque going through a clutch or band, the more line pressure needed to keep it from slipping. Line pressure in the trans rises with engine torque increase. With the Honda system, any increase in engine torque AT ANY POINT IN THE RPM BAND is immediately met with an increase in line pressure.
How does this relate to the 200-4R? Remember the 200-4R only has one torque signal. The TV cable. The rise in transmission line pressure is tightly connected to throttle blade position, PERIOD. The rate of cable pull is dictated by the geometry of the cable attachment point on the throttle lever in relation to the throttle shaft centerline, and the geometry of the lever at the other end of the cable in the pan.
This means that the line pressure ramp up is solely dictated by throttle position. 'NOT THE ENGINE TORQUE CURVE!' Ouch!!! Remember the Alpha-N discussion? The Alpha-N EMS system was unable to compensate for minor or major changes that might occur in the torque band of the engine because of its ASSUMPTION of the engines torque curve. If an engine modification were done on such an engine, the timing and fuel curves would have to be reprogrammed after the new torque curve of the engine was determined. Hopefully the torque curve would not stray from the predetermined estimate. If for whatever reason the torque increased 20 ft lbs at 2500 from the predetermined estimate, the engine would run lean and with possibly too much timing, depending on the tolerances established during the original programming of the ignition table. You can see how a system like this could be disasterous with a turbo engine.
Back to the transmission (200-4R). If an engine modification is done that increases torque output at mid-throttle, there will be NO MATCHING INCREASE in line pressure at that point to compensate for the additional torque that must go through the bands, clutches, and TORQUE CONVERTER CLUTCH. This makes slipping of the friction elements possible. This example would be of particular concern if the stock transmission and torque converter were still being used and a turbo setup were used that spooled much quicker than stock in the mid-throttle positions.
Ok. I hope I have stirred the thought processes in some of you. Lets discuss this.
Yes Buicksx3. Some of us do read books. If we didn't we would have to depend on the opinions of our friends and family. That's just plain lazy. You can close your book now. It doesn't seem to be helping.