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

[BaZa]

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

With reference to the tragic loss of one of our club members here in the UK and very close friend to me, Chris Jonas on May 27th this year, here is a message from his brother Gary asking for any information if you have experienced any of the symptoms of a 'Tank Slap' etc.

Please email Gary if you have had this experience.

Thank-you in anticipation.

Hi BaZa,

Good to talk with you today.

I wonder if you can help me with this one?

As you know it’s now 3 months since my brother died after losing control of his 94 Roadking on the M74 in Scotland.

During this time I have been looking into possible causes for the accident.

I have spoken with many people including the police who were on the scene, Police vehicle inspectors, VOSA, Various Road king owners and lots more. I have been on many HD forums around the world as well as the HDRCGB site.

I have recovered Chris’s bike from Scotland and meticulously checked over myself.
I have a full report into the accident from the Scottish authorities.

I have the eye witness reports. They describe seeing the bike develop a high speed wobble/weave prior to crashing.

I have now reached the conclusion that Chris was another victim of the infamous Harley Speed Wobble also known as the Death Wobble.

As you know this is a well document problem with the Roadking and other Harley models. That’s why there are dozens of companies out there manufacturing after market stabilizer kits that may or may not help reduce the problem.

Create the correct scenario, speed, riders weight, luggage, cornering, road surface, etc and that’s it, you in it. If you’re lucky you may control it. If you’re not it will kill you. If you’re really lucky you may never create the correct scenario and therefore you will never experience it and you won’t know what I’m talking about.

Many people have a opinion on what the problem is. Most agree that the problem is caused when the front and rear wheels go out of alignment when cornering hard and fast. Properly due to a design fault in the relationship between the swing arm, frame and the power plant. Again this information is readily available on several forums. Just Google Harley Speed Wobble and you’ll find them.

The reason I’m asking for you help BaZa with this, is I would like to get to the bottom of this matter, so another family doesn’t have to go through all this pain.

I would like anyone who has experienced this problem to contact me so I can put together a full and comprehensive report on this subject. In the hope it may save some lives.

I do not want to knock HD, have anyone prosecuted or blame anybody. I just want to get a full understanding and the extent of the Speed Wobble problem. I owe it to Chris to find out as much as I can.

If you would be kind enough to post this email on the HDRCGB site and any other sites you have access to I would appreciate it.

My email address garyjonas@arrow-display.co.uk

Please put Reference: Harley Speed Wobble


Thanks

Speak soon,

Cheers

Gary.

This is the scene............

 

[Tom-T-Bone]

Heard about a similar accident last year....witnesses said his bike went into a "wobble" and that was that......unfortunate loss of life...he was riding an Ultra Classic...not sure what year....I hope you get the answers you're looking for........PS...sorry for your loss.
Tom

 

[Fossil]

Sorry for your loss. I have owned a few Harleys and have never experienced or see a Harley speed wobble. The few bikes that I have seen the aftermath of had a lack of adjustment or simply no maintenence by the rider or the dealer. Some of your checkups are supposed to have the bearings relubed and adjusted. Some maintenance is for adjustment. It takes time on a dresser to pull all that stuff off and not scratch any of it just to adjust the bearings in the neck of the frame. It is a simple process but I have known bikes that have never ever had it done. This isn't to say your brother was this way. If you have his bike and the forks are still whole read your manual and see if the bearings are loose. Pull the bearings out to see if there is any thing unusual. Check the race too. Good luck.

 

[FLHTK2010]

Very sorry to hear of the accident.
I personally experienced high-speed-wobble on my 1973 Triumph Bonneville many years ago in 1975. Obviously I survived, but I did go down on the highway at about 65 MPH. Luckily I just skidded along and did not hit anything, and nothing hit me. Tore off a lot of my skin though.
My repair shop told me that the front wheel was "out of round". This was in the old days of spoke wheels. I would not own a bike with spoke wheels because of that accident. God that hurt.
The bike had wobbled on me before, but had straightened out on its own. This day it didn't straighten out. I'd been told that when this happens, to give it more throttle to take the weight off the front wheel. I tried this, and it didn't get worse, but it didn't improve either. As soon as I let off the gas, it went wild. The front wheel went left and right so violently that there was no way to hang onto it. The bike went down and I stayed on it for quite a skid. Looking down I could see sparks flying and remember thinking , oh man, this is really going to hurt. I came off the bike and that is when I got a strong dose of road rash.
I quit riding for many many years.
Moral of the story is that this is not a Harley Problem.
Best wishes to you.

I should have included:
"I had just entered the highway via a long entry ramp, running through the gears to the top gear. Travelling on a brand new highway, no crosswind, going in a straight line. I had installed a windshield just prior to that ride, but don't know if it had any affect."

Thanks.

 

[NEWHD74FAN]

Actually in this case the windshield probably made the problem much worse if it was a handlebar mount one. Large windsail, out of round front wheel, questionable tire condition and steering head bearing/preload...certainly a lot of factors. Adding accessories on the front end should not be taken lightly and road worthiness tested prior to for static baseline, and after installation...long and hard at different speeds and such.

 

[catfishon]

not had this happen on my harley but i did have a 79 goldwing with full fairing that would start to wobble anytime i went fast and let off the throttle to fast. im pretty sure this was all due to the fairing and as long as i gave it more throttle it would stop . i would then back it off slow and it was ok .
but it would always scare the (EDIT) out of me.
sorry to hear of your loss.

Please read this...

A Friendly Reminder - Harley Davidson Community

 

[sprinklerfitter669]

Sorry for your loss.
Have not had this happen to me, but i will be doing more research.

 

[Patriot]

I had the "Death rattle or Harley high speed wobble" happened to me for the 1st time just the other day! Hope it never happens again!!! Heres the bike & scenero:
94 Road King newer tires, Windshild, hardbags.
Riding about 70 mph on a highway turn not sure it had embankment. Halfway through turn, the front end started shaking & shimmying and was difficult to keep in the turn. Lucky the highway had middle lane and no oncomming traffic. I regained control in the middle of the oncomming traffic lane by applying gradually both brakes, keeping it straight and leaning hard to the right without turning the handlebars because turning seemed to make the wobble much worse. I finally regained control about at the 45 mph I think. Carefull drove home through many more turns very slowly with no further incidents...thank GOD!

I'm here because I was researching what happened...and looking for advise & to share;' thios is my first time on this site. So far going to check out the neack bearing & repack it & closely check out the fork oil, measure & change it. Any other advise?

 

[sprinklerfitter669]

Welcome to the Forum, and glad you made it through, to share your story. :s

 

[Hoople]

Riding about 70 mph on a highway turn not sure it had embankment. Halfway through turn, the front end started shaking & shimmying and was difficult to keep in the turn.

Sounds like rear wheel steering caused by rear wheel alignment or engine/transmission rubber mounts being worn & too soft. Perfect rear wheel alignment along with correct axle shims so NO wheel offset exists between front and rear. That is a Must. Perfect rear wheel alignment in relationship to the front wheel is a Must (florescent light tube trick). Add a True-Trac 3 point stabilizer and I would bet you can say good-by to that wobble happening again.

These are the "big hitters" I would absolutely check. There are also a bunch of other secondary reasons how/why that can happen.