tank slap v11 sport

[guido]

I have had a fall on my 2000 V11 sport, thread posted here:

http://www.morini.com.au/index2.html

 

anyone with similar experiences?

 

Regards

 

Ps I find the registration required on this forum a bit of an overkill, yet more passwords to remember, and for what.? Have a look at the above forum, seems to work fine without. Much easier to give your five cents worth!

[Guest Fox]

I have had a fall on my 2000 V11 sport, thread posted here:   

http://www.morini.com.au/index2.html

 

anyone with similar experiences?

 

Regards

 

 

39768[/snapback]

 

Guido that link wont work - this is the link to your post: http://morini.com.au/phpBB2/viewtopic.php?t=1327

 

Please allow me to reprint your post for everyone anyway as it's an interesting topic:

 

" Having done 1100km on my new (early 2000) v11, I was yesterday thrown off my bike at approx 100km/h, on a straight piece of road with a lot of smallish bumps. No warning. I had started to move slowly over in the other lane, as there was a car parked at the side of the road, in case somone would open a door.

Next thing I'm skidding down the road on the left side of my bike, looking at the smoke from my clothes, wondering what is going on.

The injuries to me are my fault, no gloves and no leathers! My helmet didn't get a scratch. No broken bones but some rash. Lucky!

Bike has moved the steering both sides, so the stop tabs are broken. Steering damper not (switched)on, never had any warning that it was needed, tyres and pressure ok, skid marks 4 to 6 meters in between. crescent shaped along soft curve into the grass. Distance about 80 meters from first mark, of this 60m on tar, ouch!!.

What really makes me worried is, that this came totally unexpected, the speed was not high, I was fully awake, both hands on the steering, fingers on brake and clutch, ready, in case the car was going to move etc.

Within a fraction of second, I was off. I have never ever experienced anything like this on my other bikes, yes, an occasional flutter of the

steering, but omething that disappears by itself.

I am just worried that this scenario could repeat itself, even in retrospect, I can't see I did anything wrong, and the looks of the road was not so that it warned me, There is clearly a relationship between the speed. the distance between and the sixe of the bumps, and it came on a piece of road that had been retarred and repaired for a short section, but it does no looke dangerous, this worries me."

[Admin Jaap]

Guido, sorry this has happened to you, Glad you're ok! There are some stories of early V11's doing a tank slap, but as I recall ith much higher soeeds.

 

As for the registering on this forum: It's quite normal that you have to register to be allowed to write on a forum.

 

Good luck!

[Steve G.]

I've always thought the steering geometry a tad "sensitive" on my '01. Only once I've had a scare and I think most bikes would do the same. Last year whilst riding the locally famous Duffy Lake, I crested a hill at 75mph while banked over in a right hand turn. As the front end came back down, I had a "moment", as the handlbars started a tank slap. I was ready for it and held on hard with my big mitts, and it feathered off. Got my attention, and reached down to tighten up the damper 4 notches.

Ciao, Steve G.

[Guest motomaniac]

I may be a big dummy, but I don't think I've ever heard of this. It makes me want to turn the steering damper up on my bike just in case.

 

This scares the bejesus outta me.

[guido]

I may be a big dummy, but I don't think I've ever heard of this.  It makes me want to turn the steering damper up on my bike just in case.

 

This scares the bejesus outta me.

39783[/snapback]

 

 

One of my mates came by this afternoon, and pointed out, that my steering damper is actually broken. The eye is on the cylinder, but the rod has snapped off, so in effect, no damper.

I would ,ost likely put this down to result of, rather than cause of problem.

I have asked the Moto Guzzi/Aprillia imprter to come by for a coke tomorrow, where I will discuss further. I have run out of battery in my camera, but will post one pic here when i can. The bike is still standing on my truck as we picked it up.

[GuzzTim]

Guido.. sorry to hear about the fall, glad to see you can still type.

 

I've got a 2001 V11 and never had this problem. I spent a day at a local race track (Laguna Seca) earlier this year and never experienced any sort of wobble or slap.

 

Was the rod broken after or before the fall ?

 

Cheers, Tim

[staedtler]

I know

 

it's

[RacerX]

anyone with similar experiences?

 

I wrote my $.02 about this back in 2001; http://www.guzzitech.com/V11SportWobble-Todd_E.html

 

ToddGuzziTech.com

p.s. Note my comment on the steering damper.

[Guest ratchethack]

Guido, I've been haunted by your posts since I read them yesterday on the Aussie forum. I'm pleased that you came out of this walking and without serious injury!

 

My 2000 Sport also has the steeper rake and shorter wheelbase common to Sports of this year. This gives the Sports an inherently greater tendency toward tank slap when not making use of the steering damper over that of the great majority of Guzzi chassis (including the later LeMans and other Sport variants), as was pointed out yesterday (not without some controversy) on the Aussie forum.

 

I think the key to this undoubtedly lies in your chassis set-up. Of course there's a list of the usual set-up items, all of which could contribute to tank slap, but here's my greatest curiosity: Did you have the fork tubes raised in the triple clamps, and if so, by how much?

 

I'm not sure if anyone has pointed it out, but depending on how you set up your fork, this can greatly add to the inherent danger of tank slap on a steeper angle fork when not using the damper. I run my fork tubes raised between 2 and 8 mm, depending on my current tires, loads, and what I want to experiment with for the day. With "long wheelbase" bikes, this would not likely be the case, but over 8-10 mm I generally find the Sport begins to get a little nervous, and I start to get concerned about tank slap. But that's what steering dampers are for.

 

BTW - my steering damper has been continuously deployed since day 1, and I always crank in more damping at higher speeds. On top of this, I always dial in a few more clicks on the damper for uneven and rougher surfaces. I prefer the feel of the front end this way and I've not had as much as a hint of wobble or headshake in the 11K miles I've put on it.

 

I'm hoping others will chime in on this.

 

Again, I'm sincerely relieved to know that you're OK :!:

 

Ratchethack

[Lex]

While I don't disagree with what Todd said in his post, his ideas make the best of a poor situation, I would like to suggest there is a much better approach. Rather than putting band-aids on the problem fix the source. I have made multiple posts on this subject have "sworn off" making any more. But after reading about a forum member having a full-on speed wobble and a frightening crash I'm back whining again.

 

Your bike's fork springs were too soft the day the bike left the factory and seem to be of very poor quality as well. The same is true of the rear but I'm talking about the front today. You can reduce the effects with ride height adjustments, stiff damping and setting the steering damper but the source of the problem is the bike's chassis geometry being changed by soft springs.

 

I have been told the stock fork spring is rated at 0.60 Kg/Cm. The replacement used by average size folks is 0.90 spring. Heavier/ more aggressive riders are using 1.05s. The most often used spring is 50% stiffer than stock, can I make this any more clear? Guzzi screwed up, you need to fix the mistake. I can't be quite as sure about this but I think there is a strong empirical case the fork springs are "sacking". Sacking means the springs are becoming shorter, making the front end collapse even more.

 

Todd refers to the steep rake of newer bikes, the combination of too soft, sacked out springs lead to even steeper rake and less trail. Throw in the poor damping (another subject for another day), not overly stiff frame and rear end biased weight distribution and you have a recipe for disaster. All in all Guido was lucky, the next person may not get off so easily. And NO more pre-load will not make up for soft springs.

 

It would be great if we were all rich and could throw the stock forks and shock in the nearest trash can and replace them with better equipment. Back in the real world most of us need to balance cost with results. Better fork springs will result in in a bike that is safer, rides better, doesn't dive as much on braking and not dent your wallet too badly. Your forks probably need the oil changed anyway, changing the springs will not add much to work (if you are doing the work) or labor bill (if you are paying for the work).

 

Start with your local shop, they should be able to get you stiff, better quality springs. If they can't help find out where the local racer get their work done. Be careful you have a race oriented shop change the fork damping or set up a shock, race track set-ups will go too far in the other direction. Tracks are much faster than the street and generally smoother as well.

 

Failing that:

 

The best known shop in the US: Race Tech

 

The shop I used have the suspension on my V11 re-sprung and valved: LE

 

I hope Guido and his bike heal quickly,

 

Lex

[Guest Bruce]

Boy, good input guys. Sobering. Guido, glad to hear you're in one piece. I've been planning to work on the suspension next spring but now I am thinking maybe I don't want to be the test pilot.

 

From first hand experience a bump can get it started and if there is a hump between the normal wheel tracks for cars ( old, heavily travel pavement or dirt roads ) this can really get it going.

 

It was raining hard and I did exactly this on my trusty and very stable CZ. While 'walking it' off I took a good look at the road bed and was surprised to see not much other than that hump.

 

Since getting the V11 I've wondered if the steering damper was actually doing anything but I guess if you never wobble you can assume it is. Think I'll tighten mine down a notch.

[Guest Fox]

Fantastic info guys! Certainly opened my eyes. I'm guessing the V11s with Ohlins would not have this problem .....

[guido]

Just a short rejoinder.

My steering damper is actually broken on the short rod, attaching the body to the lower front fork! And yes, there is dampening on the unit when you move it. How much I don't know, as I have left all as is, for an anticipated visit today by the local importer.

What that means though, is most likely, that the dampener was working at the start of the incident, assuming it has been snapped by the violent movements.

I have read all your contributions with great interest, but I have not even finished breaking the unit in, with 1100km on the clock. So I have not been in any conditions which could be regarded as extreme (like speed or track), and there has been no issues with handling before, apart from low speed wobbles, and "fall ins" , initially, in curves, cured with slightly higher air pressure and slightly modified driving technique (which, come to think of it, most likey had something to do with a working steering on this unit) sompared to my other Guzzis. So the bike is as received from the importer, and, as said, all seemed fine like that. The only thing I would have said is that the suspension felt far better than on any of my other bikes.

And tanks Fox for pointing to the right link, can't post this reply on the aussie site though, citing "invalid session"

[Guest Fox]

Posted that link on the Aussie Guzzi site to here for you Guido. Hope you don't mind but here are the links to the pix you put on the Aussie site:

 

 

road towards scene, travelling rhs towards viewer

http://tinypic.com/view.html?pic=149n5l

 

type of broad sideways skidmarks made

http://tinypic.com/view.html?pic=149nhv

 

travelling uphill, car parked 3 to 5 car lenghts behind cars parked

http://tinypic.com/view.html?pic=149nrs

 

skidmarks and scrapes clearly visible

http://tinypic.com/view.html?pic=149pqs

 

sad remains of a brand new bike

http://tinypic.com/view.html?pic=149qhe

 

self expl. notice all damage on rhs. I skidded next to the bike, towards the centre of the road

http://tinypic.com/view.html?pic=149qo9

 

all damage front and other side of bike, how this is possible, I don't know

http://tinypic.com/view.html?pic=149x09

 

my leg, my fault, no leathers

http://tinypic.com/view.html?pic=149x7n

 

same here, backside and hand you can imagine

http://tinypic.com/view.html?pic=149xfa