2011 3500HD Dually shudders at takeoff under load

[heypilch]

It's brand new & I bought it to tow a 2011 Fuzion 360, which is almost (but not quite) 40'.

I noticed that when taking off from a stoplight for instance, I feel a slight shudder which seems to be coming from the rear end. It's not a really bad shudder, but I wasn't expecting to feel one at all. My truck is rated to pull 21,700 in 5'er config, which is why I bought it - I wanted it to be enough truck to pull this trailer. The shudder goes away once the truck gets going & only appears when taking off at an intersection from a dead stop.

Anyone else experiencing this, or know what's causing it?

[TXiceman]

Rated to pull a 21700# trailer and actually pulling one are two different animals. to any tow rating, there are tow parts of the towing equation. What you can pull and what you can haul.

Is your truck a SRW or a DRW? What does your truck weigh when loaded fro travel with the hitch mounted? What is the actual weight of the trailer and the actual pin weight.

Look in the owners manual for the GCWR for you actual engine, axle ration and cab. Look on the drivers door jamb and find the GVWR.

GCWR - loaded truck = Max loaded trailer weight.

GVWR - loaded truck = max loaded trailer pin weight.

A 5er will typically have a pin weight close to 20% of the trailer GVWR. If you are "rated" to pull a 21,700# 5er, your truck will have to handle a pin weight of about 4300#.

Now the manufacturer's tow ratings are based on a stripped base model truck, no cargo, no hitch, and only a 150# driver. This is usually buried in the fine print on the rating page.

Now the problem you are experiencing can be a number of things....
Over loaded suspension and wrong drive line angle.
transmission/torque converter.

Let us know a bit about your tow vehicel and what is going on.

[heypilch]

thanks for the reply so quick!

Mine is a DRW & the hitch is a Reese 20k. According to Keystone's website, the shipping weight is 13160 and the hitch is 2900 lbs. It wasn't loaded with toys and none of the tanks were full.

As I mentioned, the shudder isn't that pronounced as I don't mash the pedal at the green light & I kind of let it ease itself into cruising speed.

Other than the slight shudder, there isn't any noise associated with it and it goes away between 5-10 mph.

[mhs4771]

I have the long bed dually and tow a 34' Montana @ approx 12.5K (10.2K shipping weight) without any problem. Is the your hitch securely mounted? Is it possible the trailer brakes are hanging up a little? Just some thoughts
See you already replied while I was posting. Sounds like you have the same hitch as I do. Did you go with the univeral mounts or the Reese custom frame mounts? Either way, I would check and make sure everything was tight. When I removed my hitch from my 2005 to xfer to the 2011, I found all the bolts for the rails to the univeral brackets were just over finger tight, kind of scarey

[bullheaded]

I pull a 36' Eliminator offshore boat around #10k with a mildly modified 08 Duramax. I feel a shutter under a heavy foot, change the fuel filter and it goes away. Something to think about.

[VanDiemen23]

I have a 2001 8.1L/allison with 95K miles and I get a slight shudder pulling away loaded or not. I don't have the LSD, so I always figured it was either a tiny bit of wheelspin or something transmission related.

No codes set, no nasty fluid, hard to diagnose, so I've left it alone figuring it will either go away after some kind of service (it hasn't) or will get worse and thus easier to diagnose (it hasn't).

[frankdamp]

Everyone's assuming it's auto, but if it's a stick, it may be a clutch isue.

[heypilch]

Originally Posted by frankdamp

Everyone's assuming it's auto, but if it's a stick, it may be a clutch isue.

No, it's an Allison auto trans.

[rops]

Hello,

Does your 2011 truck have a limited slip differential? If it does check to see if it has the proper fluid and amount of fluid in the differential. Just a suggestion.

If there is a shudder and then stops, something somewhere is slipping. If it was drive shaft angle it would get worse with speed not stop shuddering.

rops

[TXiceman]

Is it just a vibration/shake or is there any noise associated with it?

Ken

[Eric_H_E]

Does it do it when not towing?

[Workshop]

Originally Posted by heypilch

I noticed that when taking off from a stoplight for instance, I feel a slight shudder which seems to be coming from the rear end.....
Anyone else experiencing this, or know what's causing it?

I have a 2011 F350 DRW and tow a 33' Excel that weighs 'bout 14,800 with #3060 on the pin. I have the slight shudder that you discribe. Only from a stop will this occur and only when connected to the trailer. Sometimes so slight you might not notice and only from a full stop.

This information on the DieselStop forum might be helpful to you. I have less than a 2 inch drop when connected and have ordered a set of airbags to bring it back to the unloaded height. Sounds like this might help as it could be a drive line angle issue.

workhorse

[powerboatr]

my F350 did it loaded as well....
it was a long bed crew cab with a million foot long drive shaft and center carrier then down to the punkin.
all that TQ under load twists alot of things underneath...
i would guess your carrier bearing is torquing some and causing a slight out of alignment at the u-joints upon takeoff, combined with the engine mounts, frame and leaf springs...if your really pulling 21k, and a sizeable pin weight.

just my .02

[heypilch]

It doesn't do it when it's not loaded. I have a theory though. What if taking off from a dead stop under load causes a bit of axle wrap, which then causes the driveline to go out of alignment until inertia takes over after 5 mph (under a light foot) and the initial stress is taken off the rear end and/or driveline.

Anything there?