rear end wiggle

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Apr 17, 2001 | 08:58 AM

dzjammer

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Senior User

Joined: Dec 2000

Posts: 435

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From: Nebraska Farm

rear end wiggle

Here's a strange one for you guys. For the past 6-9 months, my truck feels like the rear end slides side-side when you let off the gas. When you give it gas again, you can feel it in your seat kind of shift over to the left, then let off and it settles back to the right. Could the springs be causing this if one is weaker and twisting up? The shocks are good. The only other thing is the 9" third member is shot, but there isn't any play in the axles side to side. Otherwise it drives straight down the road, any ideas?
p.s. When it's in 4 wheel drive, it doesn't do it.
Dave,
79 F-150 4x4, 390 w/C6, Edelbrock carb, 33X12.50 on Weld wheels never will be finished.

Apr 17, 2001 | 09:47 AM

rusty68

Senior User

Joined: Sep 2000

Posts: 161

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rear end wiggle

mine used to do that, especially on rough road- but it seemed to go away when i replaced the rear shocks, which you've already covered-

Apr 19, 2001 | 11:13 PM

sleddingbetty

Junior User

Joined: Mar 2001

Posts: 55

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rear end wiggle

broken center bolt? one side is driving forward and causing "dogwalk" . maybe try adding power without moving and see what moves. just a thought

Apr 20, 2001 | 10:27 AM

Chuck P.

Elder User

Joined: Jun 1999

Posts: 861

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From: SE PA

rear end wiggle

Check the spring bushings and the mounting points of the front and rear of the springs and check the u-bolts, might have a loose set. Does sound like a centering pin snapped though. As recommended, try getting the movement with the truck sitting still and applying power.

Apr 20, 2001 | 12:17 PM

gsg1981

Freshman User

Joined: Mar 2001

Posts: 49

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rear end wiggle

I suspect it's the bushings. I'd check 'em out, and torque everything down back there. It seemed to make a differance for my rig.

Apr 21, 2001 | 09:32 AM

Ford79

Lead Driver

Joined: Mar 2000

Posts: 9,359

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From: Hampstead, NC

rear end wiggle

Had the same problem with my 79. It had a broken main leaf on one side and the other side had started to crack. Replaced both main springs,center bolts,u-bolts and bushings and the problem went away.

Apr 21, 2001 | 12:02 PM

alpo23

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Joined: Dec 2000

Posts: 385

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rear end wiggle

DZ, one question. Do this 'wiggle' cause the truck to pull to one side and the back again as you give it gas and then let off? thus cause you to correct by adjusting the steering wheel? If so run, don't walk, and check your FRONT tie-rod ends! You said it doesn't do the wiggle in 4-wheel drive. I had a '65 F-250 4x4 that did the exact same thing. The toe-in adjusting sleeve was loose and had beaten the threads to nothing thus allowing about .060 of an inch of play in the front end toe-in setting. While coasting the Caster angle would allow the front of the tires to settle inward. When accelerating the tires would toe-out and change the front end aliagnment. With the rig in 4x4 mode the front tires are pulling against the axle maintaining the same aliagnment all the time. I swore up and down that I thought it was my rear end too. I even had the Bed off for a while to look back at the axle when driving to find the problem. I hope this helps, Good luck.
Eric

Proud owner of a '73 F-250 4x4 High Boy, 460 V8, NP435, NP205
And a '68 Bronco 289 v8 , NP435 , Dana 20