high load causing shift troubles

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Nov 4, 2011 | 09:22 PM

#16

copracr

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Mountain Pass

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Hey Mark, I had a 4r100 question for you. I have a 4wd 2000 6.8L excursion with a 4r100. If I got a hold of a 2wd diesel 4r100 would I be able to swap the output shaft and tailhousing from my gas trans over to the diesel trans?
Hope you're still watching this thread and thanks for your help thus far. I found out the PCM was programmed and I dropped a tank of 87 octane in it and the PCM responded by pulling loads of timing. I filled up with 93 and the issue is mostly gone. Weird huh.

Nov 5, 2011 | 03:02 AM

#17

Mark Kovalsky

Frmr Ford Trans Engr

Joined: Aug 1999

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From: SE Florida

Yes, you can convert a 2wd 4R100 to 4wd by changing the extension housing and the output shaft. You have to take everything out of the transmission to change the output shafts. When it's done you will have a 4wd diesel transmission that will not bolt to a 6.8L engine.

Nov 5, 2011 | 10:10 AM

#18

copracr

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Mountain Pass

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Quote:

Originally Posted by Mark Kovalsky

Awesome, thats what I'm aiming for. I'm preparing to swap the diesel out of my other truck into this one.
My other truck is a 2wd with the ZF 6 speed. That trans cant be turned into a 4wd trans is what I hear. So I'm gonna trade it for a 4r100 (most likely a 2wd unit).

Dec 4, 2011 | 05:57 PM

#19

copracr

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Mountain Pass

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Hey Mark, if you're still watching, I have more questions for you.

The diesel torque converter is supposed to be a 110K unit and low stall ones are 95 K. What is a K?

I also read that the 6.0l style converter that is made to mate to the 7.3l has a lower stall triple disk design and so its great for street trucks. AND that ford went to this design in 03 so the unit I would buy from ford for $300 is a 6.0L style(the one for the 7.3L of course).

Thanks for your help, its great having you on this forum.

Last edited by copracr; Dec 4, 2011 at 05:58 PM. Reason: grammer

Dec 4, 2011 | 07:03 PM

#20

Mark Kovalsky

Frmr Ford Trans Engr

Joined: Aug 1999

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From: SE Florida

K is a calculation that relates to the stall speed. K = RPM/[(square root) *torque]. It is a way to compare torque converters.

If with a particular engine a torque converter stalls at 1800 RPM and the engine is making 550 lb-ft at that RPM the K factor for that converter will be 1800/[(sqr_rt)550] = 76.

You can use this formula to predict stall speed if the engine torque is increased. Say that the engine is now making 700 lb-ft. Rearrange the equation to be RPM = k[(sqr_rt)torque] = 76 [sqr_rt700] = 2010 RPM. This formula is not exact, but an estimator.

Dec 4, 2011 | 07:22 PM

#21

copracr

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Mountain Pass

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Quote:

Originally Posted by Mark Kovalsky

Cool. so I could I use he advertised K value to predict the stall speed?
110[sqr_rt505]=2472rpm ? factory converter is 110, factory torque is 505, then factory stall is 2472???
Then the 95K converter would look like this--> 95(sqr_rt505)=2134rpm?

If I'm right so far how come I keep seeing the factory converter listed at 1800 stall and the "performance 6.0 style" is supposed to be 1600?

Dec 4, 2011 | 09:21 PM

#22

Mark Kovalsky

Frmr Ford Trans Engr

Joined: Aug 1999

Posts: 24,696

Likes: 2,617

From: SE Florida

Because the torque curve isn't flat. At lower RPM it makes less torque so the engine isn't able to get up to the higher RPM.

Dec 4, 2011 | 09:27 PM

#23

copracr

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Mountain Pass

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Quote:

Originally Posted by Mark Kovalsky

Because the torque curve isn't flat. At lower RPM it makes less torque so the engine isn't able to get up to the higher RPM.

OH yea, I should have thought of that. Do you recommend a particular converter for street truck use? Its going in a 4x4 Excursion, intake/exhaust and a chip upgrades, not sure on the trans upgrades yet (still learning). I want it to feel tight like a manual trans (within reason of course)