szrdave Posted May 10, 2013 Report Share Posted May 10, 2013 The problem: Accelerating over a bumpy surface or changing full throttle first to second while leant over a bit has the steering shaking from side to side. It's never developed into a proper tank slapper, but it's not nice. The bike: Aprilia Falco Forks: Standard forks on standard settings, which feel about right Shock: RSV Ohlins with appropriate linkage. Set to standard RSV settings. Ride height adjuster set to 3.5mm of thread showing, I need to pick up a 24mm spanner to adjust it. Unladen sag: 19mm front, 7mm rear. Tyres: New Dragon Supercorsa Pro, 180 rear. 190/50 rear and a few different 180/55s have had no effect. Steering bearings: Replaced less than 1k miles ago. Correctly adjusted. No change after replacement (other than steering feeling much better!) Wheel alignment: Correct on adjusters, looks about right by eye. The rider: I know I tend to grip the bars a bit too tightly when on the throttle, not helped by the Aprilia having a long seat so I've nothing to rest against.. I'll try and get a spanner to adjust the rear ride height tomorrow, and take a mm or two off. I'm at the PB Snetterton trackday both days so if there is a suspension guy there I'll see if I can get a better setup. Any other thoughts though? Link to comment Share on other sites More sharing options...
chancho196 Posted May 11, 2013 Report Share Posted May 11, 2013 Steering damper? Sounds exactly like my mate's new Superduke when you give it shit leant over. Link to comment Share on other sites More sharing options...
szrdave Posted May 11, 2013 Author Report Share Posted May 11, 2013 I have got a Sachs RSV non-adjustable damper I was going to fit, although I need the fitting kit (which comes to about £30 from Aprilia for a few washers/spacers). The Falco does have a reputation for stability though, so if there is a problem I'd rather try and solve it than mask it with a damper. Link to comment Share on other sites More sharing options...
jollygiant Posted May 11, 2013 Report Share Posted May 11, 2013 My Racing Tuono used to do that but I fiddled with the Ohlins and new tyres sorted it! The main thing that helped it adjust the rear ride height, dunno if you can do that on the Falco shock? Or you could drop the forks in the yokes. Whats your tyre pressures? Link to comment Share on other sites More sharing options...
hylar1000 Posted May 11, 2013 Report Share Posted May 11, 2013 Do you need to tweek the steering stem down after a few hundred miles after replacing the steering bearings on the falco like you do on a 7r, I has this after replacing the bearings then not tightning after they beaded in Link to comment Share on other sites More sharing options...
BudgetBoy Posted May 11, 2013 Report Share Posted May 11, 2013 Add rear preload or raise forks in yokes or raise rear ride height. The front of the bike is getting too light "hence the headshake/wobble" try these first as they dont cost as much as other stuff. Remember:- make 1 adjustment,go for a ride and then alter.. Write down your current settings so you can revert back to them. Link to comment Share on other sites More sharing options...
szrdave Posted May 11, 2013 Author Report Share Posted May 11, 2013 I now have a 24mm spanner, so will pull the shock out again today. Why did I bother putting it back in! The Falco isn't the fastest steering bike, even with the shock set as it is, so I'll try just shortening the shock by 1mm and see if it has any effect. Link to comment Share on other sites More sharing options...
lorenzo Posted May 11, 2013 Report Share Posted May 11, 2013 Shortening the shock may well accentuating it as it'll take more weight off the front. Link to comment Share on other sites More sharing options...
timbrell Posted May 11, 2013 Report Share Posted May 11, 2013 Shortening the shock may well accentuating it as it'll take more weight off the front. Yep. Increase the length of the shock first, like lorenzo said it will put more weight on the front, and if you're happy with the rear it won't alter how the rear reacts and feels as much as changing the preload does. Like it was said earlier increasing the amount of fork leg showing above the yokes would also help. It would put more weight on the front, but it will also have an effect on your steering because you change the steering geometry with each adjustment. This would help your Falco steer quicker too. If you do change the front don't be tempted to make a big change in one go (this is from experience!), it'll make the steering much quicker and you'll brick it the first time you tip in to a fast corner, and end up heading towards the grass on the inside. 'changing full throttle first to second while leant over a bit' - Try changing gear at a different rpm, I'm on a twin and found changing slightly before the redline smoothed things out a lot and you can make the most of the drive from the midrange more in the next gear which made for a faster lap overall. Also (unless you use a quickshifter) letting the clutch out more gently will smooth out the gear change, minimising pitching and helping the bike to stay settled and planted up front. Link to comment Share on other sites More sharing options...
szrdave Posted May 11, 2013 Author Report Share Posted May 11, 2013 For track riding I think making an effort to be smoother on the way out of a corner will help, I'm also still riding the twin a bit like a four and could probably be a gear higher most of the time. A bit more weight on the front sounds like a good thing, but I was under the impression that raising the rear would steepen the steering angle and reduce the trail, hence making the bike less stable. I've wound the bottom shock eye in by 1.5 turns so I'll see how it rides tomorrow. I've also just found the front wheel bearings are past their best, no play but you can just feel them starting to grumble. I don't think they're the cause, but they'll be getting changed one evening next week. Link to comment Share on other sites More sharing options...
Mr.Incredible Posted May 12, 2013 Report Share Posted May 12, 2013 I've just taken my Faco forks from 5 rings showing above the yoke to 3. It's as stable as a very stable stable. I have an Ohlins on the back (off the shelf as opposed to RSV; dunno how different they are) but haven't touched it yet. Wouldn't mind looking at it directly next to yours when we're at Snett to see how they compare height-wise. Mine's on a 180-section rear tyre. What made you go for a wider one? I did notice that it doesn't take much to get to the edge of the tyre ans the rear's scrubbed to the edge in normal road riding. Link to comment Share on other sites More sharing options...
timbrell Posted May 12, 2013 Report Share Posted May 12, 2013 A bit more weight on the front sounds like a good thing, but I was under the impression that raising the rear would steepen the steering angle and reduce the trail, hence making the bike less stable. That is what it does but if your problem is on the exit under power or powering over bumps then the front forks will be extending mostly (effectively increasing the rake) and are light anyway as the power lifts the front. So if that's when it happens then raising the rear to put more weight on the front will help keep the front tyre planted in those situations. If your problem was that it was getting sketchy on the way in to a corner when there is already weight on the front then you would do the opposite and shorten the rear or raise the front which would put more weight on the back and make more relaxed steering geometry. In my experience changing the front fork height has a more dramatic effect on the steering and stability than changing the rear. It's all a balancing act and it's your decision as to what feels right for you. If you increase the rear height and find it's getting slappy or the steering is too fast then raise the front a small amount at a time until you're happy with it, if you do it that way round then you're increasing your ground clearance as you get it set up too, which is never a bad thing for cornering. Hope that makes sense, I'm not the best at explaining these things. You'll enjoy experimenting at Snett anyway, see you on the tuesday! Link to comment Share on other sites More sharing options...
szrdave Posted May 13, 2013 Author Report Share Posted May 13, 2013 There is a road on the way to work (Lower Hampton Rd, runs parallel to Staines Rd) which is a bit twisty and bumpy as fuck. It's a 40 limit but runs between two reservoirs so no side roads, and is perfect for checking stability. Lowering the rear slightly has...made no difference whatsoever. Tomorrow night I'll re-extend the shock and wind the rear preload off a bit, and test it again on Wednesday. PS Looking forward to Snett, even if the weather forecast is shite! Link to comment Share on other sites More sharing options...
Mr.Incredible Posted May 14, 2013 Report Share Posted May 14, 2013 I've just gone down a tooth on the front sprocket and got the open airbox mod (the one that seals against the base of the tank) so maybe I'll be able to keep up with you now. I need to set my front and rear sag and damping settings; tyre wear on track will be a good gauge of success. One final thing Dave, what was your noise test rating last year? Were you close to the 102db limit? And stop talking about the weather. Link to comment Share on other sites More sharing options...
szrdave Posted May 14, 2013 Author Report Share Posted May 14, 2013 I've just gone down a tooth on the front sprocket and got the open airbox mod (the one that seals against the base of the tank) so maybe I'll be able to keep up with you now. That sounds like a challenge I need to set my front and rear sag and damping settings; tyre wear on track will be a good gauge of success. One final thing Dave, what was your noise test rating last year? Were you close to the 102db limit? And stop talking about the weather. Mine was just under 102db last time, don't really see how though as it's bastard loud! I'll be taking the baffles this year in case they're needed but fingers crossed. Link to comment Share on other sites More sharing options...
fuelline Posted May 14, 2013 Report Share Posted May 14, 2013 I've just gone down a tooth on the front sprocket and got the open airbox mod (the one that seals against the base of the tank) so maybe I'll be able to keep up with you now. No you won't. Link to comment Share on other sites More sharing options...
fuelline Posted May 14, 2013 Report Share Posted May 14, 2013 Re. noise at Snett the Ape puts out 106 single Aprilia race can the tester just shrugged and let me get on with it. Link to comment Share on other sites More sharing options...
Mr.Incredible Posted May 14, 2013 Report Share Posted May 14, 2013 Yeah, well he failed the 900SS last year for 105.5. The baffles took it down to 102 point something. Not taking any chances with the Falco; I don't have any baffles for the race cans, so the standard ones will be there as a contingency and also an excuse for when Dave is faster. Link to comment Share on other sites More sharing options...
toosmooth Posted May 14, 2013 Report Share Posted May 14, 2013 Noise testing at Snett seems to have more teeth to it now. Not that it makes them test things any better - waving a tester around whilst the revs dont settle anywhere near the required rpm an then you get a fail and told to go away and make it quiter. Unimpressive levels of customer care. Go with baffles/packing whatever. Link to comment Share on other sites More sharing options...
chrisexup Posted May 15, 2013 Report Share Posted May 15, 2013 I have got a Sachs RSV non-adjustable damper I was going to fit, although I need the fitting kit (which comes to about £30 from Aprilia for a few washers/spacers). are any of these bits any use? Link to comment Share on other sites More sharing options...
szrdave Posted May 15, 2013 Author Report Share Posted May 15, 2013 Hi Chris, looks like the two top hat spacers and o-rings for the body mount and spacer for the rod mount are the bits I need. Do you have a set you'd be prepared to part with? Link to comment Share on other sites More sharing options...
suspensionsmith Posted May 15, 2013 Report Share Posted May 15, 2013 Check your front rebound adjustment.....when getting quickly on the gas if it is rebounding to slow then the front goes extra light because it can't extend quick enough to keep the tyre in firm contact with the road....and if it is real slow then the suspension will pack up in this case over successive bumps. Link to comment Share on other sites More sharing options...
chrisexup Posted May 15, 2013 Report Share Posted May 15, 2013 Hi Chris, looks like the two top hat spacers and o-rings for the body mount and spacer for the rod mount are the bits I need. Do you have a set you'd be prepared to part with? everything in that picture is spare, i'll pop it in the post. Link to comment Share on other sites More sharing options...
szrdave Posted May 15, 2013 Author Report Share Posted May 15, 2013 Check your front rebound adjustment.....when getting quickly on the gas if it is rebounding to slow then the front goes extra light because it can't extend quick enough to keep the tyre in firm contact with the road....and if it is real slow then the suspension will pack up in this case over successive bumps. Cheers for the advise SS, we've got two days on track so I should get a chance to play with the settings a bit. everything in that picture is spare, i'll pop it in the post. Thanks Chris Link to comment Share on other sites More sharing options...
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