Axle wrap - 2020 7.3 with 4.30 gears

Bottom Line

Bottom Line

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Florida
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2020 Tremor 7.3
Any body else seeing bad axle wrap with the 7.3, 4.30 gears and stock suspension. Seems like if I'm barely on the throttle in loose, thick sand the rear end will start hopping bad (forward or reverse) with traction control on or off. If I stomp it it powers past it but with low to medium throttle it can be bad. My old '05 with the 5.4 and 3.73 gears did it with stock tires but when I changed to 35's it stopped.
 
I think that's unavoidable with a heavy duty truck. Suspension is stiff. I have the 6.7 and when i was on the beach trying to tow a boat out of the water my suspension was hopping so bad I thought I was going to snap something. it was either keep going or get stuck and buried in the sand. Truck made it but it wasn't a pleasant experience. Basically said screw it, it's still under warranty and sent it. I'm getting some traction bars as I can only imagine it will get worse with 37's and a 2" lift I'm planning on. I don't want to get a sway bar as others on this forum have because that kinda defeats the purpose of an off road truck and limits articulation. Although not sure that a sway bar would even help that. Not sure what i'm going to do with the front axle as that was hopping just as bad. Do they make them for the front???

Rears i'm thinking something like this:

17-22 F250 & F350 BDS Recoil Traction Bars & Mount Kit for 0-6" Lifts 123416+123409

www.stage3motorsports.com www.stage3motorsports.com
 
I haven't noticed this year, in 6300 miles or so.
 
This is very common with Super Duty because of the long rear leaf springs. I had a tuned deleted 6.4l that did it badly when towing my 15k lb 5th wheel. Put on a set of PMF traction bars and solved the issue, also makes it shift very smoothly also with no spring wrap up. Was a great investment.
 
Had it happen a bit in the sand dunes recently. I am going to need to find a solution, probably some taller springs to get rid of the lift block.
 
Bottom Line said:
Any body else seeing bad axle wrap with the 7.3, 4.30 gears and stock suspension. Seems like if I'm barely on the throttle in loose, thick sand the rear end will start hopping bad (forward or reverse) with traction control on or off. If I stomp it it powers past it but with low to medium throttle it can be bad. My old '05 with the 5.4 and 3.73 gears did it with stock tires but when I changed to 35's it stopped.
Click to expand...
Yes , first snowstorm of the season I noticed the same thing with mine in snow
 
I noticed it on wet pavement just after it started to rain, with the stock duratracs.
Have the 6.7 but still same condition. I would not consider it bad as I got off the pedal.
 
Traction bars will solve the axle wrap problem. At the expense of articulation and ride. (read: stiffer) also you will lose some ground clearance.

I wonder if Caltracs will work on these?

Also, getting rid of the lift block and putting in the Carli mini packs will help. (won't completely eliminate, but will help)
 
Bottom Line said:
Any body else seeing bad axle wrap with the 7.3, 4.30 gears and stock suspension. Seems like if I'm barely on the throttle in loose, thick sand the rear end will start hopping bad (forward or reverse) with traction control on or off. If I stomp it it powers past it but with low to medium throttle it can be bad. My old '05 with the 5.4 and 3.73 gears did it with stock tires but when I changed to 35's it stopped.
Click to expand...
Rub it in... we don't have sand here, just lots of snow! :cry:
 
I did take my Tremor for a 8 mile test ride today and pulled into some unplowed roads with the 4H engaged. I stopped a few times going uphill and hit the gas to test out the 4WD. Didn't notice anything but a nice straight pull through the snow uphill. Maybe if it were in 2WD I would have experienced some axle wrap. Picking it up at the dealer tomorrow after they are done with the checklist and detailing.
 
Terrible wheel hop at low throttle/slow speeds.. Soft or wet snow and in 2wd, it is very annoying.
 
Do yourself a favor and put on some good quality floating traction bats from PMF, It will fix your issue and there will be very little loss of articulation with these bars. I have used them on an 6.4 liter with a 300HP HS Performance Tune and they fixed the axle wrap. Contact Trevor Hall at PMF and he will set you up with the correct application. Check out their web site .
 
There are plenty of inexpensive solutions like these out on the market. These are an old school mod that people have been doing on 4x4's for years. I've done them on plenty of 4x4 trucks I've owned in the past, especially the diesels that I've owned, and it works pretty well. They were even included in several Superlift lift kits that I have used in the past to reduce, solve the spring wrap problem.

 
What exactly is happening mechanically during axle wrap and causing the hopping?
 
funnyman3000 said:
What exactly is happening mechanically during axle wrap and causing the hopping?
Click to expand...
It is a phenomenon created by loading and unloading the springs as the axle wants to twist in relationship to torque. The axle will want to keep up with tire rotation as the tire has traction, the axle pivots down at the Ujoint until it meets resistance from the spring. The spring then uncoils and snaps the axle back into place. Rinse and repeat, very quickly. This generally occurs with leaf springs. Combatting this is why you see on rear shocks, the right shock is mounted on the front of the axle and pointed forward and the left rear shock is mounted at the rear of the axle and pointed rearward. To defeat axle wrap, different methods are used from CalTracs, Drag Bars or so called "traction bars".
 
The springs want to lift in a certain direction and will actually start to separate. Those clamps keep the springs from being able to do that and keep them together as a unit. This is also a common problem on drag cars with rear leaf springs.
 
funnyman3000 said:
What exactly is happening mechanically during axle wrap and causing the hopping?
Click to expand...
I'll try to describe so you can visualize...

Standing facing the right rear tire, as the tire starts to turn and has traction on the ground, the axle also wants to turn in a clockwise fashion with the tire. As the axle turns, where the axle mounts to the spring, it causes the spring to start forming an "S" shape in relation to the axle mount which is only a very small contact patch and acts somewhat of a lever. The spring will only "S" out so far and it violently snaps back, either as the wheel lifts off the ground losing traction or by sheer force of the spring. A drag bar eliminates this effect simply by providing a point where the only direction an axle can move is up and down and does not allow it to pivot circumferentially at all.
 
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