Truck Shudder when towing

[Marcottemw]

2002 F-250 SuperDuty

Hoping someone out in the SuperDuty World can help. My 02 with auto tranny has a shudder when taking off from a stop and towing my equipment trailer. The shudder exists primarily when towing but can be felt slightly when not towing. Shudder happens from 0-20 mph. I've recently spent a lot of $$$ on front and rear axle/differential seals, bearings and clutches. Tranny was completely rebuild 2 years ago with ATS kit that's said to be rated for towing approx. 20,000 lbs. Critical for my business.

The shop that worked on the front (leaking seals) and rear axles said it was the rear axle clutches so they replaced those. NO CHANGE! They therefore replaced them again. STILL NO CHANGE! Man I'm tired of throwing my money away. Seams like either no one want to work on it or if they do they want to play hit-and-miss and charge for something that's not the problem.

Any ideas out there guys?

 

[DaveBen]

Do you have posi trac rear end? My guess is you do. They have caused shudder when startling out with a load. Nothing to worry about.

 

[01yellerCobra]

What about spring wrap? The axle would be rotating more when towing causing the spring to wrap up more.

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[79jasper]

Do you have posi trac rear end? My guess is you do. They have caused shudder when startling out with a load. Nothing to worry about.

Wouldn't that show in a corner? Or would it do that while straight line driving?
He did say they replaced the clutches in the rear.
I would look at the carrier bearing if it has one. (The mount on the driveshaft)

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[hoodshauler]

Stupid Question but. Did the shop put friction modifier in the rear ended ?


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[FiveOfastback]

Wouldn't that show in a corner? Or would it do that while straight line driving?
He did say they replaced the clutches in the rear.
I would look at the carrier bearing if it has one. (The mount on the driveshaft)

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I. Would look at drive shaft if they put back in out of phase u joints
I assuming you have a 2 piece driveshaft and or carrier bearing.

 

[powerstoked]

The rear end clutch should only slips when truck is in a turn or if one wheel has way more grip than the other in hard acceleration, so my thinking is that would not be the problem. I'm wondering if the trailer brakes are not fully releasing after the last time brake was applied. Maybe surge brake needs adjusting if that is what is on the trailer. Just my thoughts. Good luck.

 

[powerstoked]

Just re-read the original question and saw it also happens when not towing. So.......
as Gilda Radner use to say, never mind.

 

[Kleetus]

I would put my money on a junk driveshaft carrier bearing. I've gone through 2... it will wobble from a start, worse with more load on it, and then it will sometimes show up at 35 and 70 mph as well.

If it's making noise, replace it with a Ford one, they're not that expensive amazingly... It will sound like tire noise if you're not familiar with it. Easy way to tell is jack the rear end up and *gently* run it up to speed.. if you hear tire noise with no tires on the ground... mr bearing is dead.

Notes on the friction modifier... DO NOT ADD MORE. Your limited slip will become even more useless than it's horrible factory specs.