For Mark Kovlasky
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Sit. Stay.
Joined: Oct 2001
Posts: 18,308
Likes: 20
From: Washington State
For Mark Kovlasky
Mark,
You reffered me to a site that helped explain the workings of the automatic transmission. I wanted to thank you but also still have questions about what exactly happens when the torque converter lock & unlocks. Even though I understand better, they still are PFM to me.
Up in the diesel forum a guy is asking a question. Which, in turn, made me wonder the same thing.
We both have the 4R100. If you turn off the OD and run through the gears, you can make out what appears to be 4 seperate shifts. yet, it's a 4 speed, (with OD being the 4th gear). After the shift into third, a subsequent shift will happen but doesn't feel the same. The RPM will drop about 300RPM and is not very firm.
If OD is on, the same sensation is there with the exception that after this "little" shift you'll definantly feel it drop into OD. Is this related to TC lockup/unlock at all?
Could you give me, and others, a brief explaination to what is happening when the TC is locked?
Thanks!
You reffered me to a site that helped explain the workings of the automatic transmission. I wanted to thank you but also still have questions about what exactly happens when the torque converter lock & unlocks. Even though I understand better, they still are PFM to me.
Up in the diesel forum a guy is asking a question. Which, in turn, made me wonder the same thing.
We both have the 4R100. If you turn off the OD and run through the gears, you can make out what appears to be 4 seperate shifts. yet, it's a 4 speed, (with OD being the 4th gear). After the shift into third, a subsequent shift will happen but doesn't feel the same. The RPM will drop about 300RPM and is not very firm.
If OD is on, the same sensation is there with the exception that after this "little" shift you'll definantly feel it drop into OD. Is this related to TC lockup/unlock at all?
Could you give me, and others, a brief explaination to what is happening when the TC is locked?
Thanks!
Frmr Ford Trans Engr
Joined: Aug 1999
Posts: 24,734
Likes: 2,663
From: SE Florida
For Mark Kovlasky
A torque converter uses ATF to transfer torque. Because it uses fluid there is slip. The input speed will always be higher than the output speed because there is no mechanical lock.
When the torque converter clutch locks there is a mechanical lock. This clutch connects the input and output of the torque converter so that they spin at exactly the same speed. This clutch works exactly like the clutch in a manual transmission, except that this clutch runs in ATF and the manual transmission clutch is dry.
The extra shift you feel is the torque converter locking. When OD is off the truck will usually shift 1-2, 2-3, and then the converter lcoks. If OD is on, it will shift 1-2, 2-3, and then lock during the 3-4 shift, so you might not notice the converter locking.
At different throttles the lock happens at different points, so you can see operation that is different from what I just wrote.
Mark
When the torque converter clutch locks there is a mechanical lock. This clutch connects the input and output of the torque converter so that they spin at exactly the same speed. This clutch works exactly like the clutch in a manual transmission, except that this clutch runs in ATF and the manual transmission clutch is dry.
The extra shift you feel is the torque converter locking. When OD is off the truck will usually shift 1-2, 2-3, and then the converter lcoks. If OD is on, it will shift 1-2, 2-3, and then lock during the 3-4 shift, so you might not notice the converter locking.
At different throttles the lock happens at different points, so you can see operation that is different from what I just wrote.
Mark
