1998 scary tank slapper - almost lost it

Hello Viffers

Bought a 1998 with 42,000 kilometres last month (sold my 1986 vfr 14 years ago). I decided to test the suspension on a bumpy railway track near my home that I have been driving over for 15 years on several previous bikes (ST2, VTR1000, Goldwing) with no problems. As ussual I sped up to about 100kph (64mph), accelerating just at the track to fully extend the front forks and upon hitting the tracks went intpo the nastiest tank slapper in my 37 years of riding. Had to grab the bars with all my strength and back off the throttle, just saving it. Wow, my life flashed before me as it was veering into the opposite lane with oncoming traffic. Fork preloads set to about half the tuns... no idea about fork oil, but no leaking at the stanchions.

Any ideas what is going on? Anyone had a similar incident?

best regards, Chuck

 

Check for worn steering head bearings.

 

steering stabilizer. Ohlins. Expensive, worth it, never rode without one.

 

+1 to RCMD's post. You shouldn't need a steering damper unless you're riding on bumpy racetracks at speed. I've never found a need for one in nearly 50 years of street riding. You should check everything on the chassis. Make sure swingarm bearings are good and tightened to spec. Make sure the forks and shock are working properly and setup for your characteristics. Putting a steering damper on the bike would just mask the real source of the problem.

 

Aren't you supposed to apply throttle when you get a tank slapper going? In order to unload the front tire to get it straightened out?

 

braking makes it worse, accelerating doesn't help. Just let off the throttle and slowly let out of it. And hope it doesn't turn into this: [Motorcycle Accident]TT-Tankslapper-19sec - YouTube

 

Never had one on any VFR, but the best (but scariest) way out is to relax your tight grip on the bars.....

 

Was this a 90° crossing, or angled a bit? You may have caught the front tire in a groove. Sounds scary.

 

I had something similar. My all stock '04 VFR handled it just fine. I just backed off the throttle, and applied a pinch of brake. I got spooked, but I was more impresses how the VFR handled it. Like FoothillRyder, I've never had found a need for a dampener.

 

If we don't need dampers maybe we're just not riding fast enough......

I think it's been established years ago that most gen 4 bikes have a slow-speed front wheel wobble (which most bikes don't have) if the riders hands are removed from the bars, never recommended riding practice. Lots of discussion back then, new tires usually helped but not eliminated the hands-off wobble........but why would anyone ??

 

The squirrel has it right. The natural human tendency - to try and 'force' the oscillation to stop - will never work. It always adds input as a response, which is of course out of phase and tends to increase the amplitude of the oscillation.

As far as accel/decel, it really depends on the root cause of the problem. Unloading the front (by applying power) is usually a good thing; but not always. Relaxing the death grip - on the other hand - will always help.

 

or perhaps we're just more relaxed when riding fast ...

Almost any bike can demonstrate this characteristic - with the hands OFF of the bars - at some speeds/conditions. I don't know that I've ever ridden a bike that couldn't be coerced into a wobble. I don't think this is related to chostovs problem, as he most likely had his hands on the bars.

 

Just Googled " Scary tank slapper " and come up with this pic, anyone know what it means ?

 

Some of the load on the front end can be lightened by shifting the rider weight to the rear of the bike. IMO this bike needs a new steering head bearing for starters.

 

The bike was just safetied at the Honda dealer so I didnt even think to check! But yes, the bearings are shot, and I am even more surprized to see Honda was using cheap ball bearings in the 5th gen VFR! I installed tappered rollers in my GS1000 in 1979! LOL

Now I just have to decide whether to install the rollers bearing myself or go to the shop?

 

I saw that film, think it was the Isle of Man TT. I backed off the throttle, no brakes, grabbed the handbars real hard and let it slow down and straightne up... kinda all institintive.

 

No, hit the bumpy tracks at 90 degrees

 

Not sure on your bike but if memory serves a bearing from one of the STs. fits. Again it's been awhile but on my 91 I think the races were plastic.

Run that service manager and the wrench to a Honda dedicated forum to see what is going on out in the big wide world. This forum might be a good place to start for them. Some forums similar to this one are hosted by "big brother" types..