I have a 2016 FXDL. Twice now while entering a sweeping right hand, down hill turn on the freeway(80ish mph), I have experienced wobble/tank slapping type of movement in the bars. Thankfully, nothing has happened but this is of great concern. I feel it important to list the modifications to see from any of you to try and help narrow down the cause and seek a cure. I have 13" forbidden risers with Protapers, conleys t-sport fairing, super brace and finally progressive 13" shocks. Tire pressure is good. There is also slight wobble while approaching speeds of 90mph. Any insight is appreciated.

 

Check fall away exactly as per service manual. I give the sem nut an extra 1/16 turn over spec

 

I don't understand. Fall away? Sem Nut?

 

Service manual

 

Try without the fork brace and double check air pressure..There is aprox 1 trillion threads written about this.Let the dealer check over the bike assuming its under warranty. But yea,some people like the brace and some say it's a "no go"

 

A couple of things to check, if everything else (including tires) checks out:

Vertical wheel alignment. The dealer may or may not know how to do this (mine didn't). It can be off from the factory, and is adjusted with the heim-jointed upper motor mount at the top of the heads.

See if it still does it with the fairing removed. Some fairings can produce airflow patterns which will alternate from side to side under certain conditions (think of a stop sign twisting in an oscillating motion in a high wind).

 

I am an insomniac(thanx PTSD). The shocks are 444s. I stiffened them up a bit. I will ride tomorrow without the brace and see what that does.

 

I had a wobble a70+mph on freeway sweepers & tried several things & finally cured it. not sure which was the answer or if there were several reasons but I replaced the lowered shocks with originals, check tire pressure often, adjusted belt tension & rear tire alignment @ service manual specs (bought the tools) also read an article suggesting a lighter grip on the handlebars in those turns.

 

Buy a service manual.

 

I had an 01 FXDXT a few years ago that was quite fast. I know it had a 39mm front end vs current 49mm front ends; but, it would shake near 100mph or when going down a steep hill. Tech told me to tighten fall away as per service manual and give it 1/16 extra turn. This tightens neck bearings a touch extra. Problem solved. I had a fork brace and didn't want to go to a steering damper; don't like the looks and didn't want to mask a symptom.
And yes; this is presuming all the other factors such as alignment, tires, motor mounts, etc etc, are correct...