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[mgmetalworks]

I know a lot of folks point the finger at caster and think it is the end-all, be-all metric but my experience shows that there isn't one number that works for every single straight axle vehicle. In general, I think you can say that some positive caster is good and negative caster is undesirable. I designed the brackets for this kit using CAD models (directly from Ford) of the E-series frame and the complete front suspension (at static ride height) of the F-series trucks. I tried, as much as the difference in the frames would allow, to mimic the F-series plus a couple extra degrees of caster. Now that's the virtual world...in reality, most of the vans we've done have measured out (real world, on modern alignment racks) at ~3.8-4.2 deg. Some maybe slightly less, some maybe slightly more. Remember that the weight of the van and the settling of the springs can affect this...that's the nature of radius arm suspensions. I think these numbers are appropriate for this application. My van, originally a Quadvan, was at 1.5 deg when I got it and it didn't drive all that great but when I converted over to my brackets and lift, caster went up to 3.8 deg and drivability (at least how it felt to me) greatly improved.

Ford's TSB (there have been many, but the most recent one I've seen) suggests setting caster at no more than 2.8 deg for the F-series. Ford claims that lower caster reduces the forces at play and makes the oscillation diminish faster. Now, the aftermarket and most all of the information you find online says go higher, more like 5-6 deg for a Super Duty truck. Funny how the OEM and then everyone else, amateur to professional have opposite philosophies. My wife's daily driver is a radius arm/coil spring, straight axle rig, big-ish heavy tires (Mercedes G500) with *GASP* 0.5 deg of caster and guess what??? Drives like a dream. Never had a single problem with that rig since we lifted it.

So some folks are at 7 deg and doing fine. I've been as low as 0.5 deg for years now and been fine. Is there one magic number that works for every rig in every instance and every combination of lift/tires/wheels? In my opinion, no. Caster is important, without a doubt. Is it the only variable of importance? Convince me cuz I'm not there yet.

 

[lilscorpion]

Edited: has a dampener. My mistake.

 

[another_mike]

Gregor,

I’ve looked back and can’t find a reference to a steering dampener being installed or a picture showing one. Is one installed on the Dana 60?

He has a steering damper and can see it in his video. Our coil conversion kit comes with a frame bracket and the factory super duty drag link has a mounting location.

 

[lilscorpion]

He has a steering damper and can see it in his video.

Admittedly I didn’t watch the video. Removed my post.

 

[lilscorpion]

[QUOTE="another_mike, post: 2470856, member: 162366”]
Our coil conversion kit comes with a frame bracket and the factory super duty drag link has a mounting location.[/QUOTE]

It mounts from the frame to the drag link?


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[another_mike]

It mounts from the frame to the drag link?


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yes, looks almost exactly like this

 

[lilscorpion]

It mounts from the frame to the drag link?


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yes, looks almost exactly like this

I’d be interested to understand the theory behind having one there. The traditional location for a steering stabilizer is between the tie-rod and the differential.

 

[cjken]

It mounts from the frame to the drag link?


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yes, looks almost exactly like this

I’d be interested to understand the theory behind having one there. The traditional location for a steering stabilizer is between the tie-rod and the differential.

Are those the Dynatrac ball joints?
I put the Dynatrac 60’s on mine.

I keep watching that video.
Many interesting ideas and observations from people with a better eye than me. I can’t tell what sets it off.

If you are going to keep it. Maybe try a new steering box, front brakes. To avoid setting off the oscillation.
Maybe the dual dampener could change the resonance frequency of the system somehow so that the oscillation does not amplify the way it seems to.

Definitely please share your progress.

 

[lilscorpion]

Are those the Dynatrac ball joints?
I put the Dynatrac 60’s on mine.

I keep watching that video.
Many interesting ideas and observations from people with a better eye than me. I can’t tell what sets it off.

If you are going to keep it. Maybe try a new steering box, front brakes. To avoid setting off the oscillation.
Maybe the dual dampener could change the resonance frequency of the system somehow so that the oscillation does not amplify the way it seems to.

Definitely please share your progress.

Yes, it has the Dynatrac ball joints (the front 60 is actually a complete Dynatrac Dana 60 unit brand new less than a couple thousand miles). Out of the box it had death wobble which helped me narrow down quickly to the list of things that were most likely (less complicated than what Gregor is attempting to do). My hypothesis is that when I removed the factory drag link from the factory diff, the splitting fork damaged the ball within the drag-link end just enough that it created a loose spot. That loose spot is/was the initiation point of the DW but it was nearly impossible to find because the DL end doesn't seem damaged until it was removed again and played with outside the vehicle. While searching I also found that the track bar bushings on my new Teraflex Monster trac bars had bolt sleeves that were slightly oversized which allowed the diff to move ever so slightly within the bracket. So, my speculation is that when I hit a bump, the drag link end and the trac bar allowed the diff to shift sideways and initiate the harmonic that resulted in the death wobble. What's more interesting is that the solution to the DW wasn't in fact fixing the aforementioned issues, it was to add a steering stabilizer to the front differential (like in the above pictures). As soon as I did, the DW went away.

The key to solving DW is understanding it. The reason why DW is so frustrating is it's a systemic issue not a component issue. Like my example above, it may be caused by the parts (new and old) working in concert to create a specific situation where a vibration, which may not actually be avoidable, turns into a harmonic. Most of us don't realize the efforts automobile manufacturers put into reducing vibrations in the vehicles we purchase and the sheer number of hours they spend testing in the process. If you put a 1-ton pickup up on a rack and know what you're looking for, you'll find dozens of tweaks all with the intent of reducing vibrations and all of them are designed to work in concert with the components that were installed at the factory. Take one of them away you may get DW directly off the assembly line. Now imagine you switch out the factory components for some aftermarket ones on a vehicle which was tuned for the vibrations it had previously but has no accommodations for new vibrations. I am not saying that the conversion kit used was in any way at fault, I'm saying that the system may need additional tweaks after it's installed for drivability purposes.

In my personal example, the solution of the problem may have been to replace all of the components that contributed to what enabled the DW. Oddly enough though, I didn't need to replace or fix the issues to stop the DW itself. So, for Gregor, I recommend shifting the way you're looking at the issue. Think about how the front wheels are moving during the harmonic then consider where such a stabilizer sits within the equation. The damper will be right in the mix. For about $75 and a couple of hours in the shop you could add a steering damper/stabilizer between the long side Dana 60 tube and the tie-rod like I did and see if it dampens the front end just enough to prevent the harmonic. Is the stabilizer you have now (frame mounted) charged? (if you compress it does it attempt to grow back to full length).

 

[bknudtsen]

^^^You meant to say between the long side of the D60 tube and tierod, not tracbar.

 

[VisionxOrb]

Has anyone looked into building a sector shaft support like the attached picture I know it helps quite a bit on the rams

 

[lilscorpion]

^^^You meant to say between the long side of the D60 tube and tierod, not tracbar.

Yes, that’s what I meant. Between the long tube and track bar wouldn’t do squat if even move at all.


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[Justgosurfin]

This thread went quiet exactly when I started considering the coil setup for larger breaks.... any updates?

 

[Fork-N-Road]

This thread went quiet exactly when I started considering the coil setup for larger breaks.... any updates?

I don't know where you are located, but if you are planning on being at the "Cars and Coffee" meetup this Sunday, I'm planning on being there with my MG 4X4 Coil Conversion. I haven't had the issues that Gregor is dealing with and have been pretty happy with the conversion so far. Hopefully Gregor's conversion gets straightened out soon!

 

[Justgosurfin]

I don't know where you are located, but if you are planning on being at the "Cars and Coffee" meetup this Sunday, I'm planning on being there with my MG 4X4 Coil Conversion. I haven't had the issues that Gregor is dealing with and have been pretty happy with the conversion so far. Hopefully Gregor's conversion gets straightened out soon!

Dunno where Cars and Coffee is but I’m in South Florida ...for the next couple years at least.

Thanks for the offer. I rode in another a couple weeks ago that seemed perfectly fine too