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Discussion Starter #1 (Edited)
Hey everybody, I'm starting this thread to show my theory of the SuperDuty Hop that's common on our trucks. This problem has spanned many years from what I've read and people I've talked to, but this has been most prevalent in the CCLB Super Duty platform. From 2000's with 7.3s to 2014s with 6.7s and all years in between there's a bunch of folks who seem to have this problem.

This isn't death wobble. That's the intense shaking of the front axle back and forth, due to front end parts being loose like ball joints, track bars, etc.

This is the weird vibration that feels like the rear end is hopping. It happens when driving down a straight road at a speed of usually 40-45mph, and when it's bad enough, you can see it. People with it can drive under that and its ok, then it comes on around that speed, then goes away once you get above it. That's ok for most folks, but for some of us with 45mph speed limits in areas, it really sucks. Check out these threads for more info.

http://www.powerstroke.org/forum/6-0-drivetrain-problems/508202-rear-end-hop.html

Rear end bounces @ 40-45 MPH - Ford Truck Enthusiasts Forums

Wheel hop/ back seat shake - Ford Truck Enthusiasts Forums

There's a bunch more, just check out google.

Most of the time, this gets (IMO) misdiagnosed as an unbalanced driveshaft, bad shocks, warped rotors, bad springs, etc. People spend a lot of time and money replacing these things and yet still have the same problem. Ford even came out with a TSB for us 05-07 guys that involves a $450 damper kit that attaches to the rear driveshaft and is supposed to fix it. Well guess what, it doesn't. Mine has this damper and it still has the hop.

My primary mechanics specialty is suspension/brakes/steering, with engines as a secondary. I've done a lot of work on a lot of different vehicles and have come up with a running theory that until now, I wasn't so sure was even in the ball park, until I talked with a member on here, Mhatlen. He thought along the same lines as me and had done some work on his truck and it got rid of the hop.

My theory is that it's not the drivetrain or axles that are vibrating/hopping, but the frame itself flexing........think like a large I-beam only supported by the ends and you jump up and down in the middle. Especially under a CCLB, there's a ton of open frame area that has no crossmembers, and I don't think the stamped crossmembers running across the top of the frame in front of the fuel tank/front axle are working well enough. They're holding the frame well side to side and back and forth to a degree, but they don't hold it that well from flexing up and down.

I started thinking this because I can't believe there are that many faulty springs/driveshafts/axles causing this issue and it seemed to be the only thing that would explain the wide range in years that this happens to.
 

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Discussion Starter #2 (Edited)
So, after talking with Mhatlen and seeing that he too thought this and had actually made a fix on his truck, I got motivated and started outside. I wanted a few things out of my fix.

1) A bolt-in application with minimal modification to the frame

2) Semi-easy to duplicate/modify to work for many years

3) Of course, I want it to get rid of the problem

So first off, here's a pic of underneath my truck. 2005 F350 4x4 6.0L Auto CCLB





Don't mind the oil spots....at this time I had already been spraying some penetrating oil. As you can see, it's a big blank space without any support. I was first going to build a support right in the middle here, but there are a lot of products that people use that fit in this big blank spot so nicely. Air compressors, aftermarket fuel/water separators, extra battery trays for trailer haulers.....some people actually already have this space full so that was out. So I decided that I'd try to just reinforce the crossmember that's in front of the fuel tank. This probably won't work for anybody that has a bigger aftermarket fuel tank, but I figure there's less people that do a bigger underbody and they just do a transfer tank in the bed.

I'm making this out of 2" OD 0.25 wall DOM tubing and some 1/4" steel plate. Not the best saw to cut DOM with, but it works



Two 6" long pieces with a 45 degree cut on each end.



After cutting, they get beveled with a grinder for better penetration and more strength when they're welded together.



The steel plate, drilled to the pattern on the frame....ish (found that out later :doh).



Ok, here's where I got really into doing this and forgot to take some pictures. I'll go out and take some more when my camera charges up, but for now here's some with some steps skipped. There's a bunch of small holes in the framerails right in front of the fuel tank. I took 4 of those holes and drilled them out to 1/2". On the drivers side, there's some fuel/electrical lines so you gotta be careful, on the passenger side, just the exhaust hanger. I unbolted the exhaust hanger and trimmed the steel plate to fit the bend in the frame, then transferred the pattern to the other plate. The nice thing is you only have to do one side, then just make a mirrored version for the other side of the frame.

Here's a pic of the holes in the framerail. These holes are already there, I used a reamer bit to open them up to 1/2" and used grade 8 hardware to hold it together

Drivers side:


Passenger side:


With the plate in, I want the tube to be angled up and towards the rear. This should let the crossmember work on both the horizontal axis and the vertical axis. Towards the front would work just fine too, but going towards the rear was easier because the carrier bearing was in the way.

Tacked up





I did the other side too, but that's one of the things I forgot to take a pic of.

This is where I ended up today.....



I'm waiting on some more DOM tubing and some gas for my MIG welder....in case you were wondering why the tack welds looked like crap :doh: Also, you can see where my holes "missed" and I had to drill new ones. This will be fixed as well.
 

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You need to get your tires balanced if your experiencing shacking at particular speeds. These trucks do not require extra frame cross bracing, you are wasting effort.
 
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Discussion Starter #5
You need to get your tires balanced if your experiencing shacking at particular speeds. These trucks do not require extra frame cross bracing, you are wasting effort.
My truck does the same thing but is intermittent. Tires were just road force balanced and they are perfect.
^^Same here. Tires are balanced, driveshaft is balanced, no u-joint problems. Obviously yours doesn't do it Rob or you wouldn't be so quick to say it's a waste. I'd bet that's because of your suspension work. From what I've found out, folks that have an upgraded suspension package seem to have this problem less, but I think there's more to it than that. Either way, its my effort to waste and if it works great, if not, too bad I'll post results either way.
 

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Not trying to be abrasive guys, just saying Donahoe racing and many others have run the Baja 1000 on Superduty frames both modified and stock. Amy good shop could find your problem in under 2 hours. Your local ford dealer is not the shop I'm reffering to. I'm in DC till July then Vegas after that, also in NM for aug and sept. if you anywhere close we can hook up and I can help you.
 

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Your definitely not doing any harm by reinforcing the frame. I have my front end reinforced pretty good tying bumper mounts to shock mounts. The Rize link cage I have also connects the frame crosswise in two locations under transfer case. I actually have rear bracing too, I have the fifth wheel attachment that uses 1/4 steel plate for 20 inches along frame rail in rear and is connected by the two rails horizontally. Worth the effort if you've already tried the other stuff and done the research
 

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Fuel it up again Dummy
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No wasted effort in beefing up the chassis. These frames do move all over the place depending what your doing with the truck. Surely everybody feels the frame bounce in these Superduty's when hitting a dip in the road etc. I myself call it frame bobble because it doesn't want to do it only once. Like a bobble head lol.
I am very interested in how you go about it with your truck. I have installed 3 additional crossmembers in my truck and reinforced my transmission crossmember. I tied it in with diagonal bracing to each frame rail. Also installed one of the crossmembers if you want to call it that between the radius arm hangers. From there back to the transmission crossmember.
The truck handles completely different now and without the bobble. It really tightened up the steering. These trucks flex around more than you know and it plays a part in how they handle. You tighten up the chassis and it will tighten up the handling.

I think the crossmember that you are doing your work near is a good one to experiment with a stiffener. Making the driveline carrier mount much more solid may have a positive difference.
Keep the pics coming your not wasting a minute of your time.
 

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Discussion Starter #9
Not trying to be abrasive guys, just saying Donahoe racing and many others have run the Baja 1000 on Superduty frames both modified and stock. Amy good shop could find your problem in under 2 hours. Your local ford dealer is not the shop I'm reffering to. I'm in DC till July then Vegas after that, also in NM for aug and sept. if you anywhere close we can hook up and I can help you.
No problem Rob, I see where you're going with that, and I've tried a few shops, but they've all told me the same thing. Tires/driveline out of balance, bad shocks, even done some experimenting with changing pinion angles and nothing's seemed to make it 100% better or go away. I'm not saying that the frame is weak, I just think that it starts to bounce as the suspension stresses on it, causing the "rear end hop" that a lot of people see/feel.


Your definitely not doing any harm by reinforcing the frame. I have my front end reinforced pretty good tying bumper mounts to shock mounts. The Rize link cage I have also connects the frame crosswise in two locations under transfer case. I actually have rear bracing too, I have the fifth wheel attachment that uses 1/4 steel plate for 20 inches along frame rail in rear and is connected by the two rails horizontally. Worth the effort if you've already tried the other stuff and done the research
Again another reason why I figured that your truck wouldn't have this problem :lol: I knew it was already beefed up pretty well.

No wasted effort in beefing up the chassis. These frames do move all over the place depending what your doing with the truck. Surely everybody feels the frame bounce in these Superduty's when hitting a dip in the road etc. I myself call it frame bobble because it doesn't want to do it only once. Like a bobble head lol.
I am very interested in how you go about it with your truck. I have installed 3 additional crossmembers in my truck and reinforced my transmission crossmember. I tied it in with diagonal bracing to each frame rail. Also installed one of the crossmembers if you want to call it that between the radius arm hangers. From there back to the transmission crossmember.
The truck handles completely different now and without the bobble. It really tightened up the steering. These trucks flex around more than you know and it plays a part in how they handle. You tighten up the chassis and it will tighten up the handling.

I think the crossmember that you are doing your work near is a good one to experiment with a stiffener. Making the driveline carrier mount much more solid may have a positive difference.
Keep the pics coming your not wasting a minute of your time.
I know this is an apples to oranges kind of thing, but in my experience Fords have always had a twisty shifty frame when stock. I have an '87 bricknose that when articulated, the frame twists enough for the bed to touch the cab, and that's on Deavers front and rear. The OBS platform got a little better, and the Super Duty's are even better. I've had this one articulated pretty well and the bed only gets about 1/2" out of line with the cab. It's not much, but that 1/2" is proof to me that that loooong frame is still twisting when the suspension is putting some stress on it.

So, my thinkings that if it can twist, it can bounce (if you can dodge a wrench you can dodge a ball). I'd absolutely love to have a GoPro or something like that to mount underneath a couple of trucks with this problem and actually get a good look at what's happening in real time, but that'll have to be for the more privileged lol. Even if it is a waste, like I said its my time to waste.....gives me something to do in the afternoons lol.
 

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I'm interested in this myself and I only have a Single cab. I've loosely chased this problem for the last 2 years but haven't come up with a solution.

Right at 60km/h the truck bobs. I've had a new driveshaft made ( for the lift), 31's, 35's, and now 37's all dynamic balanced so dead perfect. Rear suspension completely rebuilt (lift blocks to spring and shackle lift)

Nothing ever seems to touch it, rotating the tires, paying to have them balanced the normal way ( which sucked on the 37's). I borrowed some stock tires to drive on for a day and it made no change.

Only thing that seems to make a difference is it got WAY worse when I had the gas tank skidplate out, which makes me think you ARE on the right track.

I would also really like some of the 08+ guys to chime in, I wonder if the goofy un centered leaf springs that our older trucks have make a difference. 08+ the front hangar is 8" IIRC farther forward because they lengthened the spring to where, I think, it should have always been
 

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Discussion Starter #11
I haven't talked to or heard of many '08-'10 SDs that do this (and that doesn't mean they're not there), but the 6.7 guys seem to have this problem too.

If you read through the "Rear end bounces" thread that I posted up above, those guys actually got the opportunity to have field engineers from Ford come out and look at their rigs with vibration/harmonics equipment. After trying different driveshafts/axles/tires/wheels they came up with that it's the "nature of the beast in a heavy duty truck" which I can't believe.

Some have said with weight in the bed it goes away, and some have had it happen even with weight in the bed. There doesn't seem to be any rhyme or reason as to why some trucks do it and some don't. Maybe they've been put through something in their lives....IDK.

Going to the steel yard today to check on my order.
 

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In it to win it! :thumb: :D
 

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Discussion Starter #16
Is it just me or does your carrier bearing look bent to the driver's side of the truck? :tard:
Haha, good catch. I had actually already unbolted it one the one side and was halfway through removal on the otherside and went DOH :doh: forgot to take pictures....
 

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You should get a one piece driveline made, only about $3-400 and will fix your issue.
 

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Fuel it up again Dummy
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How are you going to tie the two frame rails together ?

90 degrees straight across or at a angle? Have you pondered doing a X type of cross connection? I know it would be much easier if you could get rid of that driveshaft and exhaust pipe. :)

I'm watching with mucho enthusiasm. I'm still interested in strengthening of the crossmember that has the carrier bearing tied to.

Keep the pics coming
 

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Discussion Starter #20
You should get a one piece driveline made, only about $3-400 and will fix your issue.
If it was a driveline vibration I'd think about it.....really if you rode in it or any other truck that has this hop you'd know it wasn't a drivetrain vibration....although that's what it normally gets misdiagnosed as.

Ever had a tire about to separate and bounce? That's what it feels like. But it will do it with any tire/wheel combo.

How are you going to tie the two frame rails together ?

90 degrees straight across or at a angle? Have you pondered doing a X type of cross connection? I know it would be much easier if you could get rid of that driveshaft and exhaust pipe. :)

I'm watching with mucho enthusiasm. I'm still interested in strengthening of the crossmember that has the carrier bearing tied to.

Keep the pics coming
The two 45 degree pieces will get tied together with another piece of tubing once it gets here. I have pondered the "X" type and while I know this works (your truck as an example) I'm hoping I can get the same result from this. If this doesn't work, I'll do some more playing around with the design.

I think this would really work better right in front of the rear spring hangers, but I don't want to have to try to work around the fuel tank....yet :look:
 
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