4 WD Bounce
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Senior User
Joined: Sep 2004
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From: Columbia MO
4 WD Bounce
Today while I was shoveling out my driveway I watched a new F-250 turn the corner. As he made the turn he started to get stuck in the deep snow and his front end started to bounce as the truck was digging away in 4wd. Well after I got out on the road and came back into the subdivision I turned a different corner and got stuck also. As the truck was digging to get traction and go forward my front end started to bounce also. I didn't pay attention to this until my neihbor was saying that he was watching the Ford trucks go by and they seemed to bounce as they dug in, but the chevys seemed to be smoother and not bounce (yeh he is a chevy man).
Is the bouncing because I wasn't in 4wd Low? Or is this just a quirk of the Ford front ends?
Is the bouncing because I wasn't in 4wd Low? Or is this just a quirk of the Ford front ends?
Lead Driver
Joined: Sep 2002
Posts: 9,182
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From: Gateway to the West
Its u-joint bind. Ford uses universal joints at the steering knuckles which when put into hard-over steering maneuvers tend to bind and "bounce" in and out of the bound condition. If you could watch the u-joints as you drive, you would see this happening.
(GM went to CV joints years ago to alleviate this issue. The major drawback is the relatively SHORT lifespan and considerably weaker construction of a CV joint compared to a U-joint. Personally, I'll deal with a little bind and not have to replace CV joints.
Now, for those of you who just cannot be comfortable with this situation, you can always crawl under the truck (at least the Bronco and F-series of similar vintage) and back off the "stop" bolts that determined the range of motion for the steering knuckles. You will lose some turning radius but your "bounce" will be lessened or gone.
On a side note, trucks equipped with an LS differential will experience a similar situation if one front wheel slips and as power transfers the steering will get pulled left-to-right as the power shifts from one wheel to the other.
(GM went to CV joints years ago to alleviate this issue. The major drawback is the relatively SHORT lifespan and considerably weaker construction of a CV joint compared to a U-joint. Personally, I'll deal with a little bind and not have to replace CV joints.
Now, for those of you who just cannot be comfortable with this situation, you can always crawl under the truck (at least the Bronco and F-series of similar vintage) and back off the "stop" bolts that determined the range of motion for the steering knuckles. You will lose some turning radius but your "bounce" will be lessened or gone.
On a side note, trucks equipped with an LS differential will experience a similar situation if one front wheel slips and as power transfers the steering will get pulled left-to-right as the power shifts from one wheel to the other.
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Senior User
Joined: Sep 2004
Posts: 240
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From: Columbia MO
Greystreak I understand what you were saying about the u joint bind but both my truck and that 250 I saw the wheels were almost straight. I was already pointed in the right direction I just needed to go foward. U joint bind shouldn't happen until a fair amount of wheel turn is introduced.
Lead Driver
Joined: Sep 2002
Posts: 9,182
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From: Gateway to the West
Remember too that the front axle is geared ever so slightly shorter than the rear. (about 0.01:1 difference) The bounce could well be due to this discrepancy and to be honest, that bit of bounce should actually help with the digging. Without it, all four wheels could easily spin their way down into four ruts and do nothing. That slight gearing discrepancy makes the front pull a bit and the rear lag a bit giving a natural forward-back rock to the motion of the truck as it begins to dig in.
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