Need help with rear "bounce" problem please

smokinstroker · Feb 21, 2015

Sterling6.7 said:
Stupid question and maybe asked before - are the FX4 trucks experiencing this less, same or more than the others? Mine does not have the FX4 package, but I looked under a '14 today that is and it has the additional skid plate under the transfer case. It is still a little thin, but it may serve the purpose. Also, I am thinking about spending the $30 or $40 on just that plate and stiffening it up so that it will serve the purpose. Thoughts?

The frame flex is coming from behind the cab. The skid plate by the transfer case will have little to no affect.

Sterling6.7 · Feb 21, 2015

Why not install one further back? Or multiples and tie them together? The best part is, it is the correct size to fit the frame spread.

Yellow1000 · Feb 21, 2015

I don't think tying the rails together will change it much. I think bracing with flat plates along the rails will do more.

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bigrpowr · Feb 21, 2015

I tried loosening my rear shackles so they weren't in a constant bind. it helped a decent amount but didn't totally solve the problem . definitely smoother though, and the bounce is a lot smoother as well as pulling into driveways .

hucorey · Feb 22, 2015

This will fix the issue 100%.

Either box the frame or double wall the vertical section of the frame from the trans crossmember back to the fuel tank if you dont want to drop the tank. Otherwise, go just past the front leaf spring mount.

You can also scissor truss the inside of the frame rail too, but jack the truck up a bit first before welding in the flatstock.

Also, add another cross member to tie the bottom legs of the C-channel of the frame to prevent outward flexing.

smokinstroker · Feb 22, 2015

bigrpowr said:
I tried loosening my rear shackles so they weren't in a constant bind. it helped a decent amount but didn't totally solve the problem . definitely smoother though, and the bounce is a lot smoother as well as pulling into driveways .

I noticed this too. Thought it may have been the deaver leafs I put in. but after watching it drive, you can definitely see the shackle allow some movement.

sootie · Feb 23, 2015

did you guys just back the big bolt off slightly? or how did you loosen...

smokinstroker · Feb 23, 2015

sootie said:
did you guys just back the big bolt off slightly? or how did you loosen...

Just loosened the shackle a hair. Still needs to be tight, and I put red lock tight on it. But just backed it off enough to where I could move it back and forth with some force

Mhatlen · Feb 15, 2016

Frame Stiffener

I know this is a older thread but I have no doubts that the issue still exists. In fact it's very common with these trucks. I have had two 2006 F250 trucks and my first one had it bad. My current truck does not hop at 45-50 mph. But I reproduced this for my current truck because it drives so much better with it.

Firms up the front end and truck tracks better and tightens up the steering as well as less body lean in turns. There are several threads in other forums that I have been involved with. Mainly on PowerStroke.org in the suspension forum.
Called: My Theory on the SuperDuty Hop and possible cure. Or something like that......lol

None the less this will cure that bounce and it actually starts where the frame goes to single C channel. Which is at the radius arm hangers and the leverage pulls up and down on the frame rails causing a bounce or resonounce in the frame.
Like others have stated if the chassis were to get boxed in it would most like also cure this problem. But that is a ton of work and not very practicle.
So if your handy with metal this is the answer.....guaranteed.

Mhatlen · Feb 15, 2016

Better picture.

This may be better pic.

WHY NOT · Feb 15, 2016

I need to do something to fix mine yet. I have watched another trucks frame flexing going down the highway as well and done about everything to the suspension I could think of. I guess I may need to build something to tie stuff together. My dad suggested just bolting something sturdy underneath the frame rails to stiffen them up.

Mhatlen · Feb 15, 2016

I would start on the radius arms and brace the frame up there back FIRST before anywhere else on the truck. It may seem like it's coming from the rear but it's not. It starts there and reverberates back down the frame rails. I spent a lot of time under my trucks and put crossmembers in several locations with no help.
Locking it all down right there is the answer.

WHY NOT · Feb 15, 2016

Looks like yours bolts to the radius arm mounts on inside then mounts to the trans crossmember?

SpartanDieselTech · Feb 15, 2016

How many of you experiencing this have the factory gooseneck/5th when hitch installed?

Out of all of our shop trucks, only one doesn't have the factory hitch. And it's the one that bounces. None of the rest do.

lincolnlocker · Feb 15, 2016

WHY NOT said:
I need to do something to fix mine yet. I have watched another trucks frame flexing going down the highway as well and done about everything to the suspension I could think of. I guess I may need to build something to tie stuff together. My dad suggested just bolting something sturdy underneath the frame rails to stiffen them up.

same here

live life full throttle

god bless america and the farmer who feeds your fat ass

lincolnlocker · Feb 15, 2016

Mhatlen said:
This may be better pic.

that looks nicely done.. i have read your posts from searching the interwebs.

live life full throttle

god bless america and the farmer who feeds your fat ass

Mhatlen · Feb 15, 2016

lincolnlocker said:
that looks nicely done.. i have read your posts from searching the interwebs.

live life full throttle

god bless america and the farmer who feeds your fat ass

I made a setup for a guy on Saturday with a 4 link front suspension but did it differently then I wanted to. He was hell bent on it only needing the radius arm hangers tied into transmission crossmember. It was his truck so we fabricated his idea of the solution and it did not stop the bounce completely. It did however firm up his front end and steering, he says it feels like it's riding on rails now.
But it will start the bounce and cycle 2-3 times before it stops. It's actually a 2003 with a coil spring conversion CCLB truck. Here is a picture of what he came up with for the truck.

Mhatlen · Feb 15, 2016

A different shot at a stiffener.

Here is a picture of a different setup. This one tied into the rear of the radius arm hanger with 3/8" angle 2-1/2" X 4" then 1-1/4" square tube and a 1/4" plate tied into the 3" channel inside transmission crossmember.

Profuzz · Feb 15, 2016

My 15 dually w/ factory installed 5h wheel plate does this !Mostly on cement freeways at speed . Blacktop freeways smooth as silk !

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WHY NOT · Feb 15, 2016

Mhatlen said:
I made a setup for a guy on Saturday with a 4 link front suspension but did it differently then I wanted to. He was hell bent on it only needing the radius arm hangers tied into transmission crossmember. It was his truck so we fabricated his idea of the solution and it did not stop the bounce completely. It did however firm up his front end and steering, he says it feels like it's riding on rails now.
But it will start the bounce and cycle 2-3 times before it stops. It's actually a 2003 with a coil spring conversion CCLB truck. Here is a picture of what he came up with for the truck.

Do you have any pics of yours off the truck? Looks like you used C channel to go between the radius arm mounts?