Harley Speed Wobble, Tank Slap, also known as the Death Wobble

[The Tourist]

I never had a tank-slapper, but I did have 'pogo' and it scared the crackers out of me.

I was headed into Middleton by "the back way" and I saw the stoplight on a lightly traveled cross-street start to flip. I could have accelerated through it, but there was a enough room, so I touched the back brake and started to downshift the gears.

Since I was on a slight, and I emphasize the word 'slight,' downhill grade, I came to a very slow rolling stop, put two fingers on the front brake and began to lower my feet.

The original Sportster front end on my 2004 Dyna completely collapsed, but then rapidly extended and brought the front end up! I had never felt that before! I was going at a walking pace!

I only give people and things one free shot to kill me. I had that front end yanked off, and a 2006 CVO inverted fork put on.

The mechanics told me there was nothing wrong with that original fork. They were, of course, welcomed to put it on their bike...

 

[R_W_B]

I never had a tank-slapper, but I did have 'pogo' and it scared the crackers out of me.

I was headed into Middleton by "the back way" and I saw the stoplight on a lightly traveled cross-street start to flip. I could have accelerated through it, but there was a enough room, so I touched the back brake and started to downshift the gears.

Since I was on a slight, and I emphasize the word 'slight,' downhill grade, I came to a very slow rolling stop, put two fingers on the front brake and began to lower my feet.

The original Sportster front end on my 2004 Dyna completely collapsed, but then rapidly extended and brought the front end up! I had never felt that before! I was going at a walking pace!

I only give people and things one free shot to kill me. I had that front end yanked off, and a 2006 CVO inverted fork put on.

The mechanics told me there was nothing wrong with that original fork. They were, of course, welcomed to put it on their bike...

Wow I've never heard of that. Sounded like the fork springs stuck on the bottom end and the let loose after you stopped. Did they give you new forks ?

 

[The Tourist]

Did they give you new forks ?

Nope, not even a chance for a re-build.

But I have to be honest with you, the whole idea (from 1971 until now) of trying to back-engineer Sportster forks to a big twin has been a bad idea.

They have increased the tube diameter year after year. I've owned several down the line, including a "bowling ball bike." None of them met my idea of a decent front end.

Now, I personally think the inverted fork is the best idea here. It's good looking, properly designed and can be paired to the rider by using differing viscosity oils. It should be a permanent fixture in the Super Glide line.

I am hopeful for the latest Fat-Bob, however, and it would be the only current Dyna I would purchase.

Back to the OP. Despite my lack of faith in the back-engineered Sportster front end, I have never heard of a Dyna doing a tank slapper.

 

[massmikey]

Younds!!! So very sorry and disheartened for all the tragic losses that have followed this thread for over 2 years and give condolance to all who have felt the sting of a loss. This especially seeing as how the problem shadows a wide range of yrs and ages of scooters and even might be a stacked problem.It's kept me up two nights straight trying to sponge up all information that I could find in order to increase my and my riding buds chances if and when it ever occurs. It is surprising to me that it seems to me that only the riders that have had the condition grip their throats. That only means that HD has really done a great job covering up this, what could be, MASSIVE FINANCIAL BOONDOGGLE that they manufactured. What to do???Well I guess if I want to keep ridin' in a style that I enjoy...everything has to be done from the cast wheels to the stabilizer to the shocks to the Nth. All that said I once again have to thank the site creaters, mods and all the solid folks that contribute to the flow of info that comes from every inch of this site. You have no doubt saved people countless $$$ and without question MANY LIVES. Cheers to you all.

 

[R_W_B]

Nope, not even a chance for a re-build.

But I have to be honest with you, the whole idea (from 1971 until now) of trying to back-engineer Sportster forks to a big twin has been a bad idea.
... .. . .. . ..
I am hopeful for the latest Fat-Bob, however, and it would be the only current Dyna I would purchase.

I love the FBs, just couldn't find one used at the right price when I got my 07 SB. Same frame, mounts as FB & SG But whole different front end and rear wheel, brakes are different. My SB rides pretty good. Never had it over 85, but rides great since I put a new mount and shimmed the stretch out.

Back to the OP. Despite my lack of faith in the back-engineered Sportster front end, I have never heard of a Dyna doing a tank slapper.

Oh I have, I belong to a total now of 10 different bike forums, and I have heard of tank slap on just about everything from RK's to Dynas, Japan to English and in between. Some with Windshield, some without, going straight, some on curves. BUT HOWEVER, that has been MORE occurances recorded on the HD touring bikes than any other brand (or HD model). And yes there have been a few instances reported on newer bikes (a 2011) that supposedly addressed stiffer mounts and other issues on these models.

And ALL of them were caused by DIFFERENT (or COMBINATION OF) different things. It is not all design, (couldn't be with all types and brands reporting it) but maintenance, parts wearing out etc. BUT there is some design that contributes to it. One bikes have gotten bigger and heavier over the past 20 yrs. This magnitude of motorcycle cannot always handle braking, torquing and rider + it's own weight in every single scenario that the road brings on. They could "un-rubber" the engine (which is tied to the rear end and swing arm) but then rider comfort (and sales) would suffer IF they didn't redesign the engine balance.

I definitely feel the "stretch" design is a total failure. It sounds good on paper, stretch mount the engine between two rubber mounts to asborb vibration. But fact is my foot pegs vibrated so bad my feet felt like they were gonna slide off them. I put new a mount in (since the old one was stretched to deformity) and shimmed ALL the stretch out, and now above 50 my bikes rides smoother than ever. I'll bet my mounts last longer too.

Cost factors, economy, sales, competitors bikes, everything plays into the scenario. I kinda think all big bikes should have a bit more rake. Maybe like a degree less than the Wide Glide across the board. Anyhow life goes on, we shall see.

 

[The Tourist]

RWB, clearly something is going on--I just haven't seen it first-hand. However, that's the beauty of www style forums and chat areas. You get reports and opinions from a very wide variety of people with anecdotal evidence.

I am left wondering if MoCo's stripping parts off bikes and then creating visually appealing bikes is in our overall best interest. There is a large lot next to our dealership for the "Riders Edge" program, and many of the instructors are motor officers on police bikes. For decades these bikes are pushed to the point where they scrape the undercarriage. Can we do that with all of the middle weight big twins?

Since we best notice wobble on the front end it might seem a rush to judgement to look there for answers. But my last two Harleys badly needed proper shock absorbers. The ones on my 48 were downright cheap. For all I know this wobble issue could be a suspension problem.

Coupled with my personal experience and reading about the problems in our general public, I'd like to see some real answers.

 

[DailyRider]

I have a 2012 Heritage and I see there are over 29,000 posts on this subject. It seems that from what I have read that almost 60 to 75 % of the people posting here have experienced the wooble. If so many people are having this problem why isn't Harley Davidson doing something about it? I have this problem and thought I had fixed it when I found almost every spoke on my rear wheel loose. After having to replace my rear tire after a flat tire it has slowly returned. I have checked the spokes and they are fine, so now I am assuming they didn't balance the tire after mounting or may have messed up the alignment. I've been riding my whole life and have never had to experience this problem until I broke down and traded my Indian on this NEW 2012 Harley.

 

[Axlegreaze]

Hey BaZa, sorry to hear about the loss. I have experienced the wobble myself. In my case it was caused by breaking on a slightly damp paved surface, with a rear tire that should have been changed. The main thing for me was I came through it alive because I didn't panic one bit. Honestly, as I ride a 2003 FLHRCI ANNIVERSARY. I was more concerned about the embarrassment of dropping it. Don't panic, ride it out, no braking and corrective steering if [possible. Ride safe.

 

[gframe]

Really sorry to hear about your loss. Thank you all for such great information contained in this thread. I have experienced the beginnings of the wobble and as far as I can tell there is no pattern. I absolutely agree with some of the posters who say to lighten your grip and have constant throttle control to maintain traction. I almost take my hands off the bars, slowly accelerate and the wobble works itself out. I learned this from a video my friend told me about, its called Twist of the Wrist II, search Amazon. At first glance you will think its a video about sport bikes, but all of the lessons taught in the video are 100% applicable for our touring bikes. I was cornering totally wrong until I watched this video now I can navigate almost any turn with only the right hand barely on my cramp buster. I encourage anyone who wants to be a better rider to watch it a few times. I know its already saved me at least once, maybe my life, but certainly my bike.

--Greg
2005 FLHPI

 

[jhbd2075]

hello everyone. as I am sure youre all aware I am new here. this will be my first post. I have a 1998 dyna fxdwg and have been expirencing this wobble in my bike since I bought it 3 years ago. I hav replaced the front spoke wheel with a mag, had it checked for true and balanced as well as replaced the tire. it still did it. so now I am replacing the rear wheel with a mag and the rear shocks as well as the springs up front. I haven't had it back together yet with all these other improvements so I don't know if its going to help or not. any other suggestions? I have had my neck bearings checked and my swingarm bearings checked as well and all is good. this wobble is scary as (EDIT) and has got me spooked when I ride!

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