4 wheel jumps

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Jul 9, 2004 | 09:29 PM

purpleford

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4 wheel jumps

I can't figure out what is going on with my 4 wheel drive. When I put it in 4x4 occasionally it will make a crack sound under the truck and the truck will literally jump. It sounds like something is going to come up through the floor.
I kind of seems like it is trying to slip out of 4H. It does it particularily when I pull something.
Other times it won't do it at all. I have looked under there several times and nothing looks wrong. I check the fluid in the T case and it is full.

I recently changed the front Ujoints, could this have any affect?

thanks!

Jul 10, 2004 | 09:02 AM

SoCalDesertRider

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From: USA

We need more info about your truck: What kind of truck is this? Does it have a full-time or part-time transfer case? Automatic hubs or manual lockouts? Is the transfercase electric shift or manual? Are you operating on hard ground or soft?

Jul 10, 2004 | 11:47 AM

purpleford

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it is a f-150 177,00miles
auto hubs but manually shift into 4x4 via stick on floor
i am generally on gravel roads,farm fields or boat ramps when this happens
thanks!

Jul 10, 2004 | 01:00 PM

ramboss429

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From: South Dakota

What year F150 is it?

Jul 10, 2004 | 01:14 PM

cleatus12r

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From: Reed Point, MT

Your chain is probably jumping teeth. I run into this a lot with people and their new vehicles that think they need to run them in 4wd......"it's safer". I guarantee that your chain is making the pop and jump action. You don't have a surface that's slick enough to allow slippage of tires, so therefore, something has to give.

Jul 10, 2004 | 02:21 PM

purpleford

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It is a 1994 f-150

what chain is slipping? in the transfer case? is this something i need to fix or just stop using the 4x4

thanks

Jul 10, 2004 | 02:25 PM

cleatus12r

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From: Reed Point, MT

Yeah, the chain in the transfer case, over time, will develop enough slack to actually jump teeth on it's drive gears. When the front and rear driveshafts turn at different speeds in 4 wheel drive (just about ALL the time unless your tires are all exactly the same circumference), and no wheel slippage is possible due to hard terrain, that chain's going to be the weak link.

It's not a major safety issue, but if you get into a jam when you really need 4x, you will not have it...just chain grindage inside the t-case.

Cody