Help me diagnose odd vibration

[Manhattan]

This one's new to me...
2006 with 101,000 miles
2" IronMan springs, TBs, FoamCell Shocks; SPC UCAs; no diff drop - installed around 7,000 miles ago
Original CVs, boots, etc.
275/70/18 BFGs

I'm getting an odd vibration - more of a "thump thump thump" - that feels like it's coming from the front end. The best way to describe the feel is (work with me here)... you know those cables DOT lays on the road to count traffic... well, it feels like I'm running over those... but they're not there... I've looked.

Adding to the mystery - it's not constant, e.g. it'll come and go.

Guesses? Those CVs?

Thanks!

 

[Manhattan]

I guessed. ACC diagnosed. Then fixed:

Actually, they're even better than that. Towers test drove the truck, came back and said "It does feel a bit like the tires are out of balance AND it feels like the axles... because, it's both." That was yesterday. We set up the repair for today. After I left yesterday, I went to Discount Tire. They did a road force balance, and yep - the tires were out by as much as an oz.

That seemed to knock out about 10-15% of the vibration. Towers said the out of balance tires were exacerbating the issue with the axles. A couple hours later, the 100 is back to normal.

And yes - I really am aware how fortunate I am to have ACC this close!

 

[pmccraney]

I'm running almost the exact same setup as you - Ironman lift and coils with no diff drop, same tire size, etc.. I just got it installed on Saturday. Did ACC recommend that you install a diff drop? I've heard the CVs are happier with one and would gladly the spend the 285 bucks if it will keep my CVs from failing.

 

[dnp]

I'm running almost the exact same setup as you - Ironman lift and coils with no diff drop, same tire size, etc.. I just got it installed on Saturday. Did ACC recommend that you install a diff drop? I've heard the CVs are happier with one and would gladly the spend the 285 bucks if it will keep my CVs from failing.

Just do it. Any reduction in CV angles (to an extent) will pay benefits

 

[Manhattan]

Brian (ACC owner) said, from his experience the CVs will fail anyway, just like the U-joints, when you take them out of there happy spot - the one they've been running in for miles /years and put them in a new position. However, once new ones are in place they will wear in at the new angle and be fine. No diff drop required.