My 09 is the exact same way. Very unnerving. I keep waiting for the *** end to lose it

 

Personally I think that whole swing arm pivot running through the back of a cast aluminum trans is the most ridiculous thing I have ever seen. I buy wrecked bikes from the insurance auctions and have seen it all. I only buy the touring models and cant count how many trans i had to replace because the back wheel took a slight hit from behind and breaks the ear off the trans. Its no wonder there is bagger wobble. I can bet my left ******** that the swing arm mounting procedure is the culprit. Not sure about the new ones though. Havent heard much about them having issues since the new frames came out. Not crazy about the bolt together design on them as I am certain there is flexing going on there as well. Harley really need to step up to the plate and start addressing serious issues instead of adding more lipstick to the bikes. I laugh about the motors today as they are still the dinosaur "88's" with more lipstick added to them and a different number on the airbox. Doesnt matter if you put bigger jugs, pistons, heads on it, at the end of the day its still the outdated 88 motor

 

I first became aware of how severe the wobble can be when I thought I'd give the "Darkside" a try on my 2013 FLHTK Limited. Bought
a Michelin Premier A/S 205/55R16, it balanced up great and put it on the rear with new wheel bearings. Riding around town didn't
seem much different so I took it for a highway run down to Palm Springs. While transitioning from the interstate on a right turn sweeper
onto Hwy 111 at about 75 mph the wobble kicked in and it was far more noticeable than with the stock tire - actually so much so that I
tapped the rear brake which helped lessen the severity. I replaced the car tire with a new Michelin Commander and decided to give the
Alloy Art stabilizer a try - an easy bolt on. Just be sure to have the engine up to operating temperature / full expansion before your final
link adjustment with the bike level and straight up and down. At the same time I installed DK's 1 inch rear shock lowering block and
between both mods I only get wobble when I overly push it on sweepers. My experience fwiw & Michelin car tire for sale cheap.

 

The impact issue is interesting. The fix would be a conventional solid swingarm pivot with no transmission swingarm pivot ear and mouts/links to restrict rubber mounted engine/trans movement so as not to throw belts. The swingarm pivot ear exists to link the transmission to the swingarm and doesn't support the swingarm in any way. Instead of a pivot ear, a steel cross plate bolted to the back of a flat-backed trans case could use two rubber mounts and support the engine in space. The engine would have no inputs to the swingarm except reaction to drive belt forces. Controlling engine movement to prevent sideways rocking would ensure no thrown belts. The ideal swingarm bearing is the tapered roller design used on Shovelheads and previous. All subsequent bearings are much weaker (and the cheap bushing used on one side of Sporties and Dynas is just insultingly bad).

 

I've been studying bikes and their design since the 1960s, including many patents, hence why I wrote the original post. It's interesting to see your observations from a different perspective, however I would point out that over the decades many 'modern' design short-comings have come to light. An example is the introduction of cast alloy wheels, which may well be at the root of the damage you describe to trans casings from rear-end impact. It first came to light during the 1970s, when cast wheels were becoming more popular, but when bike brakes were pretty awful, especially the new supposedly better disc brakes (which initially were worst than decent drum brakes!).

The following was discussed in the bike press at the time. Whereas a wire-spoked front wheel would collapse at the point of impact, bend the forks back and then collapse at the rear on impact with the frame or engine, a cast wheel had a very different result. Being far stronger, the rim may be damaged on impact, but the wheel remain round and on impact with the frame or engine may suffer further rim damage, however still remain round. The 'crumple zone' was greatly reduced, with the consequence that the greater strength of the cast wheel transferred the energy of the impact into the frame via the steering head, extending damage far further than an identical impact with a wire wheel. Steering heads and frame tubes were routinely bent and the rider also suffered, with a far more sudden deceleration and hence was more likely to be thrown forwards off the bike, possibly suffering greater injury.

In any device there are going to be weaknesses. In a crane there is a deliberate weak-point, to ensure that any failure occurs in a predictable place and manner. I'm not sure that bike manufacturers employ the same strategy! I do wonder what problems you may identify if your preferred bike was say a Honda Gold Wing?! A frontal impact on any modern bike is almost bound IMHO to result in greater rider/passenger injury, simply due to stronger frames and cast wheels transferring greater energy than a bike of several decades ago. The same comment is probably valid for a rear impact.

So turning to your observations about the design of the s/a pivot, that has it's origins in the late 1970s, when Harley first conceived its rubber-mount design (introduced into production in 1980). That was in direct response to Norton's less refined 1960s design of its rubber-mounted Commando. As a design concept I maintain that Harley's system is a good one and it continues into the latest M8 models. Could that pivot be made more sturdy, to survive without breaking? Possibly, but that is likely to have the consequence of dispersing the energy of the damaging impact elsewhere around the bike until it finds another weak point.

That's an interesting topic to consider!

 

Phew, long read all 66 pages.

I picked up a 30k mile 08 ultra glide a couple weeks ago, rode it 200 miles home after signing the papers. Noticed the steering was a little sloppy, chalked it up to weight and worn dunlops. Got on the highway heading home and the first merge ramp at 70mph was a bit awkward, the bike kept changing lines on me while walking to the outside of the curve.

Stopped for gas and checked tire pressures, book spec for dunlops, ok. Checked air shocks, they read 12lbs, ok, and spec for my weight range. Finished the ride home. Carefully-ish.

Next day I played with the air shocks some more, opened up the system, cleaned out the lines and Schrader valve, reseated all the fittings and put about 8 lbs back in and went for a test ride. Found the bike to be much more tractable. No more wandering on curves, which is good because I tend to be a bit on the ride hard side solo, and a bit more conservatively with my rib along.

Hustled the bike commuting the next week and gained much confidence in its manners. Still ordered and installed a true track, made a additional improvement immediately noticeable in slow speed manners when I went out to the gas station. I'll have her out in a couple days to further access the change. And a two up ride on Sunday .

My take away is that if the suspension is too taught it will wobble, same for tire pressure, however the True track is a worthwhile upgrade even with the suspension sorted.

So after reading this whole thread I do have a couple of questions.
1 Are there further chassis improvement to be had combining products like the true track with the sta-Bo 2s and perhaps alloy art front isolator?
2 Do the spherical bushes wear out on the true track? And what are replacement options for them.

 

Have a few drinks, it will loosen up the death grip.

 

Phew indeed! Well done.

1. I don't recommend mixing brands of these things! Adding layers of different brands isn't going to gain any extra benefit IMHO, in fact they may fight each other! They don't all work well anyway! The other improvements you can make include using good quality suspension, front and rear, plus good aftermarket tyres. Between them you will get a more stable and comfortable ride. I use Ohlins and Avon respectively.
2. Eventually, I suppose, but don't hold your breath! They should last a very long time.

 

Different frame.

 

Similar problem, please read my first post. The later bikes are indeed different, however they still use a similar rubber mount system.