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4bt to 6r80 trans

7841 Views 35 Replies 11 Participants Last post by  Redark1
I've decided to go another route on my 07 expedition. I've been rolling with a m5r2 trans for the last 5 years and 35k miles and something in the clutch system is not good. I also haven't been able to get 4x4, or cruise control working. So its time to change it up. I'm going with a 6r80 trans which is quite proven in the gasser world. So I have a few questions, I doubt the trans has been put behind a 4bt yet. Ill be machining the adapter plate myself. My current power is probably 225hp...assuming 450tq. The trans is easily rated for this from the 5.4.

Should I use a stock converter to get a baseline for how it will run? Will a stock HD flexplate be good for this application? Will a 5.4 starter start a 4bt?

Trans will be tuned with hp tuner.

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Converter needs to be taylored to torque curve of 4bt, not gasser. Needs to be able to provide adequate operating system pressure at that RPM, otherwise will not clamp bands properly and will fail.

Ed in Co.
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