2017 Speed Wobble, constructive help appreciated. - Ducati.ms - The Ultimate Ducati Forum
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post #1 of 58 (permalink) Old Aug 3rd, 2018, 7:58 pm Thread Starter
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2017 Speed Wobble, constructive help appreciated.

Experienced it last weekend on a 4 day trip. Coincidentally, just had new Pilot Road 5's put on, and had a few hundred miles on them at the time. Conditions were: 2017 Multi S touring, about 3000 miles on it, with factory panniers, trunk, and Ducati touring screen. Bike is stock, air was clean. My height/weight, 6' 1" 260lbs. Bike was in sport mode, factory settings(going to double check that), preload 2 up (24) with bags, because I'm heavy and had luggage for trip. Nothing strapped externally. Riding with two other new GS1200's, friends of mine. One buddy decided to run me from a roll and was coming up, we stayed in it and somewhere just over 100mph my bike went into a wobble that was BAD. It kept oscillating worse and worse, I thought I was dead. I did not chop throttle, gently rolled it back and did not touch brakes. Seriously BAD, almost a tank slapper. Shook me up big time. Tires are balanced(new), pressures were F36 R42psi. I am so disappointed, I sold an S1000XR that also had a speed wobble, it began exactly at 120mph. I am not sure what speed the Multi was at, I am scared to duplicate it, and was not looking at speedo. Friend thought just over 100mph. I wasn't even out of 4th IIRC, stock gearing. it baffles me when the GS's have SQUARE panniers and trunk, with zero aerodynamics, and they are rock steady. I have ridden my bike with JUST the tail bag and stock tires before this, and I am sure I must have gone this fast. It had not wobbled before. It is either the new tires, or the fact it had panniers on and was loaded with gear. Definitely when accelerating hard, and front starts getting light, it triggers it. I love to wheelie too! Argh! Was in uphill passing lane pulling my friends just before that, road was irregular and front tire rose maybe 1" off pavement on a rise, did a minor wobble but not bad. Didn't thnk much of it, probably 80-90 mph I'd guess.

2017 Multi Skyhook, Touring and Enduro bits.
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post #2 of 58 (permalink) Old Aug 3rd, 2018, 9:24 pm
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What is your front preload set at? At your size with gear and luggage, you should be running near maximum preload (10 full turns) on the front, which is a manual adjustment, even on the Skyhook. If you're running factory preload, it's dialed all the way out, and your forks are going to have an alarming amount of slop in the top of the suspension travel, just exactly what you don't want at triple digit speeds. Bad preload setting in the front have been known to cause speed wobbles.
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post #3 of 58 (permalink) Old Aug 3rd, 2018, 10:15 pm Thread Starter
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Thank you! I did not know that at all! I will have to go investigate, it's the way it was set up from the dealer, as I have never changed it.

2017 Multi Skyhook, Touring and Enduro bits.
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post #4 of 58 (permalink) Old Aug 3rd, 2018, 10:32 pm
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You'll probably find you like riding the bike more with correctly adjusted preload, too. They tend to dive and wallow in corners when it's too soft.

There is information about this in the owners manual, btw.
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post #5 of 58 (permalink) Old Aug 3rd, 2018, 10:39 pm Thread Starter
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Thanks so much, I'll have to find manual. Read through it last year, guess my retention sucks at 58 yrs old. Is the spring in just one fork tube, or both?

2017 Multi Skyhook, Touring and Enduro bits.
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post #6 of 58 (permalink) Old Aug 3rd, 2018, 10:44 pm
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Electronic adjustments for compression and rebound are in the left fork, preload is on the right.
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post #7 of 58 (permalink) Old Aug 3rd, 2018, 10:58 pm Thread Starter
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Originally Posted by AXSPwr View Post
Electronic adjustments for compression and rebound are in the left fork, preload is on the right.
Yep, just went out and looked. I will check and see what position it is, its a little counterclockwise from the mark but will have to count turns. Realized my manual is 1200 miles away at other home, so downloaded pdf version. It only speaks to the non skyhook adjustments, no mention of preload on skyhook that I could find. Excited that it looks like the wobble will be easily corrected. I guess I better spend some tme on adjustments for sag and such. Thanks again!

2017 Multi Skyhook, Touring and Enduro bits.
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post #8 of 58 (permalink) Old Aug 3rd, 2018, 11:21 pm Thread Starter
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Was able to get 9.5 gentle turns clockwise. I guess I never noticed how much it sagged, because it doesn't move at all until key is on. I will try it at full preload, especially since sometimes she goes along too. It doesn't feel like it compresses spring much though when turning adjustment, maybe it is fine threaded...

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post #9 of 58 (permalink) Old Aug 4th, 2018, 12:16 am
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I'm about your size and noticed quite a difference, but I also only rode maybe twice before I made the adjustment. I have heard people say they don't believe the fork preload adjustment on these bikes really does anything. That wasn't my experience, but maybe they changed something on the 2018s. Mine also wasn't noticeably easy to turn, I doubt I could move it with a socket driver, the leverage of a ratchet/wrench is necessary.

If it were me, I wouldn't consider the problem solved at this point, just a likely contributor eliminated, possibly. It's certainly true that over-soft preload, combined with high speed and high drag on the rear of the bike, could lead to a floaty front-end. But so could your new tires, if one of them has some defect that only shows up at speed.

The one thing I doubt is causing the problem is your luggage. Most of the people on this forum have probably had a MTS w/ 3-piece luggage attached over 100 MPH a time or two. I don't think you're even exceeding Ducati specifications until you hit 110. As long as you had the weight distributed well, weren't overloaded, and the bags were attached right and in good condition, IMO the luggage is solid.
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post #10 of 58 (permalink) Old Aug 4th, 2018, 2:03 am
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Check your rear preload also, if the bike is squatting on hard acceleration, the front will feel light and dance on the road surface, i presume these Sach Multis have a progressive spring, which means the first part of the travel the spring is soft then gradually gets firmer through the suspension's stroke, definitely put some more preload up front, as while the rear is squatting under hard acceleration, the front is rising in the stroke to where the progressive spring is at its softest part of its stroke. It wouldn't hurt to do a rider sag measurement to see how much travel rider and bike are using. ideally rider on bike should travel about 1/3 (total travel=180mm, solo rider sag up front should be around 60mm)....i have my multi set at 60mm up front and 50mm rear solo rider.
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