3rd Gen Engine and Drivetrain -> 2003-2007 5.9 liter Engine and drivetrain discussion only. PLEASE, NO HIGH PERFORMANCE DISCUSSION!

48RE TC slip = torque multiplication effect

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Old Apr 23, 2007 | 02:15 PM
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From: Northern VA
48RE TC slip = torque multiplication effect

Question: I don't understand why it's considered bad for the stock TC to slip. Isn't that what a torque converter is supposed to do, and does that not generate more torque via the torque multiplication effect? Isn't that why these transmissions only have a 2.XX ratio for first gear?

In 3rd and OD, the TC locks so there's no issue of slippage there.

Why does TC slippage get such a bad rap? Seems like it's necessary and even beneficial.
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Old Apr 23, 2007 | 02:25 PM
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They are talking about slipping in the transmission or slipping the lockup clutch inside the torque converter.
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Old Apr 23, 2007 | 02:58 PM
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DC engineers want slippage to help cushion the drivetrain from the CTD's power... helps with the warranty.

You don't want to put rated power through the stock TC or OD clutches too much - they won't like it. Upgrade those clutch packs and enjoy!

Similiarly, the stock converter stalls too high (for my preference) for a powerplant that produces most of it's torque right off of idle... but again, it helps the parts last through the warranty.

The CTD makes so much power, it doesn't need a whole lot of torque multiplication through the converter.
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Old Apr 23, 2007 | 08:11 PM
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The TC slipping problem is not that it slips when it's not locked up. It's suppose to, as you stated. The problem is when it slips when it is in the lock up position. Too much power will cause this to happen.
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Old Apr 23, 2007 | 09:29 PM
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Originally Posted by HOV
Question: I don't understand why it's considered bad for the stock TC to slip. Isn't that what a torque converter is supposed to do, and does that not generate more torque via the torque multiplication effect? Isn't that why these transmissions only have a 2.XX ratio for first gear?

In 3rd and OD, the TC locks so there's no issue of slippage there.

Why does TC slippage get such a bad rap? Seems like it's necessary and even beneficial.
The problem is that it isn't matched well to the Cummins. The power band of the diesel at a much lower rpm than a gasser. The torque converter should have a stall speed to match it. Instead we get a 2000rpm stall converter that will stall 2200rpm+ with the Cummins instead of a 1600-1700rpm converter that would make it more drivable. Don't get me wrong, torque and torque multplication are good but torque doesn't get the truck down the road.
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Old Apr 23, 2007 | 10:24 PM
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Yes, as I posted earlier - the stock converter stalls too high for the Cummins for my druthers.
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Old Apr 24, 2007 | 06:45 AM
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Thanks for the answers. High stall speed seems like a pretty good answer.



Originally Posted by omaharam
The TC slipping problem is not that it slips when it's not locked up. It's suppose to, as you stated. The problem is when it slips when it is in the lock up position. Too much power will cause this to happen.
The TC slips when locked up? I haven't noticed it happening yet while towing, but I haven't towed a bunch yet.
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