Rookie question... Barney style

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randyp83

Member
Joined
Aug 20, 2007
Messages
263
School me on stal converters please. I know they are for autos. What do they do? Some say they lock and some say they don't lock. I have read where they range from 2800-3200 rpms. Are they ok for daily driving? I have always had a manual mustang and i'm looking foward to picking up a GN when I get back from Iraq this simmer.
 
A stall converter, aka torque converter, is just a donut looking hydraulic fluid coupler that sits between the engine crankshaft and the transmission input shaft. Their job is to allow for slippage so that you can remain idling in gear when at a stop light, etc. and also depending on how the converter is set up, allows for slippage up until a certain rpm.

The stock converter on most overdrives are lock ups. Some aftermarket converters are not lock ups.

A stall converter can range in numerous rpms besides the 2800-3200 as you have heard. Depending on the pitch of the vanes to the output torque of the engine will depend on where and when a stall converter will stall. Some stall converters stall as low as 1600 rpm while others are 5000 rpm or more.

My big block Chevelle had a 3000 stall Hughes converter in it. It was required because I had a pretty big camshaft that required that size of a stall to make it work. (had I went with a smaller stall it would have been a real pooch off the line) I could cruise around town all day but as soon as I floored it, the stall allowed the engine to get into where it was really making power. The end result was a neck snapping tire roasting set up with **** loads of torque.

On a turbo Buick, a bigger stall is sometimes required with a turbo upgrade, depending on what size turbo you go with.

Hope this helps you.
 
Ok so you want a quick learning course on fluid dynamics.

Well I cant help you but I can try to give you a basic understanding of how it works.

So take 2 box fans and point them at each other. Turn one on low, it blows the fan on the other. If you turn the first fan on high it moves the fan faster on the other. This is basically what an automatic convertor does.

The engine turns the outer piece and as it spins faster and moves fluid over the veins of the stator it turns the stator causing the power to be applied to the input shaft of the transmission which in turn causes the wheels to turn.

The speed at which the outside of the convertor starts to move fluid to turn the stator at the same speed or close to the same speed as the convertor body is considered as the stall speed. This stall speed can be affected by many things, size of the convertor, the veins ( Think blades from the fan description above), weight of the car the operating speed of the engine all play a part in this number.

The lockup portion of a convertor is similar to a clutch in your mustang. It has a plate on the stator that engages a surface on the convertor to provide a more solid connection. This Torque Convertor Clutch as it is called is actuated by pressure and a solenoid in the trans controlled by the computer.

Hope this helps you understand what a Torque Convertor basically does.

Ask any more questions and we will try to help
 
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