4L transmission issues

Issue, in 4L on a decent drive down a mountain, switchbacks etc. Off road mode, 4L lockers on.

1st gear runs 3k or so with me riding the brakes, if I let off the brakes the rpms build and build on their own, no gas, truck gets louder and louder till finally hitting red line and slamming into 2, throwing the truck forward. This can't be normal, NY suggestions? Its down right dangerous. I have video.

If I don't use 4L the truck is like a brick bouncing down the mountain, I have to stay on the brakes, I also notice this is when the tires get chunked the most.

Brett

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This sounds like a warranty issue.

What happens when you go into hill decent mode?

Hill decent works fine. What I'm talking about is a long drive from let's say 13k feet to 5k

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The gearing in this truck in 4l is only 2:64 to 1, and this is a 6000 lb plus truck, I really don't see this as a warranty problem. I know if I go wot sometimes the truck will bang off the rev limiter, and slam into 2nd, thinks that's pretty common. I think Ford realised all this and developed the hill descent for these situations.

Well 4h and the truck runs down the mountain like a brick, I don't think you run hill decent for 10 miles? On pavement twisty roads what to you guys do? Lock out 5 and 6 gear? On million dollar hyw I pulled over and smoke was coming from our brakes.

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How fast are you going in 4L? Hill decent is good till 20mph if I'm not mistaken.....did you set your hill decent speed? You have to push the gas while holding the brake, then you would release the two pedals together at the same time to set your down hill decent speed. I think I remembered it this way. I rarely use my 4L unless crawling I guess you could say.

SwampKing said:

How fast are you going in 4L? Hill decent is good till 20mph if I'm not mistaken.....did you set your hill decent speed? You have to push the gas while holding the brake, then you would release the two pedals together at the same time to set your down hill decent speed. I think I remembered it this way. I rarely use my 4L unless crawling I guess you could say.

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Didn't know that about hill decent. It's always too slow for me! Thanks

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Was not using hill decent, was traveling down hill, few mph , 4L it held 1st gear and just does not want to shift, finally at red line it slams forward into second. Its not smooth its hurky jerky.

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Both my trucks did the same thing. I usually start in 2nd or 3rd in 4 LO because the gearing is so low and shift manually.

Sounds like your on a pretty gnarly hill dude. I don't see why you couldn't use hill descent that long, but I'm not sure. That jerkiness sounds pretty normal for 4l, and you could always shit manually. This all sounds pretty normal.