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WARNING - High speed instability

I got a chance to really wring out the new bike today, and I just want to offer this up as a word of warning.

At near top speed, the steering on the 2012 starts to get a little vague and it feels like weight is lifting off the front and transfering to the back. You'll probably first start to notice just a little bit of a weave as you approach top end speed. If you continue to push, it gets worse and you may induce a tankslapper, which would not be fun at that speed.

My suspicion is that the new front fairing and larger rear saddlebags have changed the aero on the bike enough that it is causing this. I've felt this on other bikes with top boxes mounted at high speeds when the front end lightens and the top box at the rear start to move around from the buffeting. Though I've never seen this occur on a GL1800 before.

I'd advise anyone with a new 2012 not to go in search of the top end on this bike. It can get a little hairy, and I don't think I'll try it again without first packing some spare underwear in the trunk and making sure my will is up to date. Fortunately I was able to recover the bike in time, but the last time I felt a bike do what this one did today, I ended up sliding down the road.
 

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Hi Fred,

Are you still running stock suspension on the bike?

Trev.
 

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Discussion Starter #3
Hi Fred,

Are you still running stock suspension on the bike?

Trev.
Yes. Stock suspensions and stock Bridgestones set at 40/42, rear shock at 15, windsheild in lowest position, saddlebags pretty much empty with the exception of a tool kit, and riding one up.
 

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Thanks Fred,

It will be interesting to see if anyone does a "full monty" set up on the 2012 for comparison. Think I will sit back and watch this thread with interest.

Trev.
 

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Thanks Fred,

It will be interesting to see if anyone does a "full monty" set up on the 2012 for comparison. Think I will sit back and watch this thread with interest.

Trev.
I plan to convert mine to full Traxxion front and rear.

I know that suspension can influence this type of wobble, but the impression I got was that it was caused by the front end loosing weight, and I'm not sure you can do anything to suspension to fix that. The only thing I can think that might help would be lowering the front end in the triple trees. Or maybe some more preload on the rear shock to change the bikes attitude. But it really felt to me like it was airflow induced. I could feel the front tire gradually becoming more and more unresponsive to steering inputs. Once it started wobbling, I had a tough time getting it stopped. I don't think I'll be wearing these underwear anymore.
 

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high speed

Fred, I got near 120 and the bike felt pretty stable. It was not at top speed, it had plenty more to go..... I remember what my 03 felt like at around that speed and I can't tell any difference. The 03 had progressive front and rear. I will have to take another look at the top end.....I'm curious!
 

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Fred, I got near 120 and the bike felt pretty stable. It was not at top speed, it had plenty more to go..... I remember what my 03 felt like at around that speed and I can't tell any difference. The 03 had progressive front and rear. I will have to take another look at the top end.....I'm curious!

Be very careful. You have been warned.
 

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In thinking back Fred on thing I noticed was how granular that fresh road surface was too and maybe that contributed a little to wandering in the front tracking... it was a fairly large aggregate surface. I just felt the overall bike floating around more than I was comfortable with and I was not at top speed.
 

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I plan to convert mine to full Traxxion front and rear.

I know that suspension can influence this type of wobble, but the impression I got was that it was caused by the front end loosing weight, and I'm not sure you can do anything to suspension to fix that. The only thing I can think that might help would be lowering the front end in the triple trees. Or maybe some more preload on the rear shock to change the bikes attitude. But it really felt to me like it was airflow induced. I could feel the front tire gradually becoming more and more unresponsive to steering inputs. Once it started wobbling, I had a tough time getting it stopped. I don't think I'll be wearing these underwear anymore.
I had those similar thoughts of dropping the front end etc. Maybe just uprate the rear spring with a progressive or similar for a start. Interesting.

Trev.
 

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Discussion Starter #11
In thinking back Fred on thing I noticed was how granular that fresh road surface was too and maybe that contributed a little to wandering in the front tracking... it was a fairly large aggregate surface. I just felt the overall bike floating around more than I was comfortable with and I was not at top speed.
That's a good point, and there are so many dynamics involved that it's hard to put a finger on one thing and say that caused it. Wind speed and direction, how well the front tire is balanced, road surface, and a 100 other factors all play into the equation. I also forgot to mention it was in a downhill grade that slowly transitioned to uphill. I can't say it will do this every time or on every bike, and I don't care to try to find out again either. But I would like to caution anyone that at the first sign of even a slight weave, they need to back off, because when I attempted to push through it, it got much worse.
 

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I was on a four lane parkway yesterday that has very little traffic on it. And as this black Corvette came around me I felt the need for speed! He punched it about the same time as I did, I was up to 130 and still pulling, the corvette was about half a car length behind me! My Red 2012 was pretty stable considering I was at 130! I do have the Centramatics installed and my preload was set at 15.
 

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Discussion Starter #13
I was on a four lane parkway yesterday that has very little traffic on it. And as this black Corvette came around me I felt the need for speed! He punched it about the same time as I did, I was up to 130 and still pulling, the corvette was about half a car length behind me! My Red 2012 was pretty stable considering I was at 130! I do have the Centramatics installed and my preload was set at 15.
While I'd still recommend extreme caution, its good to know this doesn't affect all bikes. I may simple have a tire that isn't balanced real good on my bike. I'll be going over the bike head to toe, and if I find anything out of the ordinary, I'll come back and post it here.
 

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I had a Vetter Windjammer fairing and Bates bags on a GL1000.

While sort of racing a big Norton I was up to 105.

The front end was so light that I was afraid hitting a pebble would flip the whole bike over backward.

The downward angle of the fairing bottom, in the wind made it lift.

I no longer have any ugre to do much over 100.
 

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Some very good post on this topic. As others have suggested, I have had front-end lift near top speed on a 1975 GL1000 with Vetter faring, 1985 GL1200A with Honda fairing. On my 1972 R75/5 BMW with an Avon fairing, I had no lift all the way to the very top.

When I first read Fred's post, the first thing that came to mind were aerodynamics. Subsequent to that, sjones post about the Centramatics really has me wondering. No, not wondering from a balance perspective but more from the mass and energy difference perspective between one of the wings with additional unsprung weight (i.e., Centramatics).

sjones, are you running the centramatics on both wheels?

Also, if anyone knows...I have asked several times...what do the individual centramatics disks weigh? Does a rear centramatic disk weigh the same as a rear centramatic disk? :shrug:

Edit: forgot to add. Regardless of speed I have never had my 2004 GL1800 get light in the front, with or with out Traxxion, at the top end. This would also be with or without a CT on the rear.
 

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Richard, I don't know if you could tell the difference when we swapped bikes. The two front discs weigh more than the single rear disc. Not to sure about the actual weight of the discs, but they weren't more than a pound or so.
 

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Discussion Starter #18
If you look at the redesign of the front fairing and the wider saddlebags, it's pretty obvious that the 2012 is punching a larger hole in the air than the previous GL1800's. The angle on the larger side panels that face forward is such that it will create lift against the wind stream. And the larger air pocket behind the fairing is going to increase back pressure which will also act to increase lift of the front end. And at the same time, the larger saddlebags are going to create drag at the rear of the bike, which will further act to cause weight to transfer to the rear. So it all makes sense that the 2012 may get lighter in the front end at higher speeds, and this is exactly what it felt like to me was happening. If it gets light enough, it can indeed start a wobble.

And while this is not a huge deal, since I don't often get the bike up to the speeds needed to make this happen, I think it is something every 2012 owner needs to be aware of before they go trying to find the top end.

The other thing I've noticed, is that it feels to me like the 2012 has a little more grunt on the top end than my 2009 or my 2002 did, and it seems to get up to these speeds with a little less effort, and it also seems to have ever-so-slightly more torque all across the powerband. I won't say it's a huge difference, but it's enough that I can feel it. Maybe it's just cause the engine is so new and crisp, but it does feel quicker.
 

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Some very good post on this topic. As others have suggested, I have had front-end lift near top speed on a 1975 GL1000 with Vetter faring, 1985 GL1200A with Honda fairing. On my 1972 R75/5 BMW with an Avon fairing, I had no lift all the way to the very top.

When I first read Fred's post, the first thing that came to mind were aerodynamics. Subsequent to that, sjones post about the Centramatics really has me wondering. No, not wondering from a balance perspective but more from the mass and energy difference perspective between one of the wings with additional unsprung weight (i.e., Centramatics).

sjones, are you running the centramatics on both wheels?

Also, if anyone knows...I have asked several times...what do the individual centramatics disks weigh? Does a rear centramatic disk weigh the same as a rear centramatic disk? :shrug:

Edit: forgot to add. Regardless of speed I have never had my 2004 GL1800 get light in the front, with or with out Traxxion, at the top end. This would also be with or without a CT on the rear.
Yes, I have the Centramatics on both wheels. I also had a very calm air day, hardly any wind and a good straight road! And I agree wit Fred on the extra grunt!!! My 2012 has more get up and go that my '08 did!!! And a lot more top end pull. When I was at 130 it was still pulling, but my pucker string broke and I let off of the throttle.:shock:
 
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