Deleted account 191119001
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Just takes a little bit of getting used to, but mine is nice and smooth, 20017 may build GS
GSAP Question
- Thread starter Engineer
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Just takes a little bit of getting used to, but mine is nice and smooth, 20017 may build GS
fred_jb
Registered user
Unlike DCT type systems, I am pretty sure that GSAP has no connection to the clutch. However, it detects the gear lever movement and takes action to unload the transmission by reducing the torque output of the engine momentarily while the shift takes place, I assume through changes to ignition and/or fueling. In the case of a downshift, it times a throttle blip to increase engine speed between disengaging the current gear and engaging the lower one, so that the engine speed matches to the road speed in the lower gear.
I tend to agree that clutchless changes are a bit offensive to one's mechanical sympathies, but they do seem to work OK, at least in the higher gears, though the greater clunkiness in the lower gears does show up the extra mechanical stresses involved. Overall I feel these type of systems are a bit of a cludge, and having owned a DCT equipped bike, I think that is a far superior system.
Fred
I tend to agree that clutchless changes are a bit offensive to one's mechanical sympathies, but they do seem to work OK, at least in the higher gears, though the greater clunkiness in the lower gears does show up the extra mechanical stresses involved. Overall I feel these type of systems are a bit of a cludge, and having owned a DCT equipped bike, I think that is a far superior system.
Fred
Deleted account 191119001
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I found that the more you use it the better it gets (GSAP). It works better when used as designed i.e. riding hard rather than pottering after all why would you need to quick shift when cruising along.
I have also found, on my bike, that it responds better when I make firm solid changes rather thank a 'light click' on the gear shift.
I use through all the gears when 'on a mission' and I think mine works all the better for it.
I have also found, on my bike, that it responds better when I make firm solid changes rather thank a 'light click' on the gear shift.
I use through all the gears when 'on a mission' and I think mine works all the better for it.
Victor c
Registered user
For down shifts, it will be a very harsh change if you are in too a high gear for your road speed. I find anything above 3000 rpm works best for down shifts. And don’t fanny about, be positive with the change in both directions.
I had it retro fitted on my 2015 GS, and it has never blipped when changing down, with the throttle closed I change down, and at the same time as I change, I slightly open the throttle again, and it changers ok, but only ok. Going up the box when I'm giving it a bit, it is a dream over 4500 rpm, but I only use it 3rd to 4th and up. I think the latest models have a better gear box, and are a lot smoother.
The idea is to match input and output shaft speeds when in the neutral bit to give the synchromesh less effort to engage the next gear. The load in effect is reduced to facilitate a smoother gear change.
Shifting up cut the ignition. Shifting down speed up the input shaft. LaFerari uses the electric motor to keep momentum going for the split second it takes to change gear. Clever thingy.
The future is whatever colour you want.
Shifting up cut the ignition. Shifting down speed up the input shaft. LaFerari uses the electric motor to keep momentum going for the split second it takes to change gear. Clever thingy.
The future is whatever colour you want.
Remember also mechanical sympathy on GSAP downshifts is also cushioned by the back torque limiter.
fred_jb
Registered user
You are only supposed to use it on downshifts with the throttle fully closed, so if you don't it is quite likely to be clunky. I've noticed this myself in the lower gears when you can sometimes get too much engine braking if you close the throttle completely, so I often don't, but GSAP doesn't like that so I tend to only use it down to third.
I probably did not make it clear, I have tried the throttle fully closed, and there is no blip, just a clump. The dealer said it’s had all the upgrades done. When I say that I open the throttle a little, whilst changing down, that is my way of getting it to work as it should. After about a year of having it fitted, it wouldn’t change up using the quick shift, so had to have a new part fitted that was 550 Euros. Do I trust the dealer NO.
Wise man as they should definitely 'blip' as you push the lever down.
There is no synchromesh in a dog driven gearbox.
Nutty he has not used his yet
Irrelevant. He should have known exactly how it works before BMW even invented it.
Godzilla
Registered user
I found this quote in an article about synchromesh v dog gear boxes. It seems to be that using the clutch is less mechanically sympathetic to adog box:
"The most destructive method of shifting dog gears is attempting to change gears in a “passenger car” or “synchromesh” manner. This involves slow shifting and use of the clutch—i.e. lifting off the throttle, depressing the clutch, moving the gear lever slowly, releasing the clutch, and applying the throttle—a scenario typically found in stop-and-go traffic."
http://www.superstreetonline.com/how-to/transmission-drivetrain/impp-1109-synchromesh-vs-dog-box/
"The most destructive method of shifting dog gears is attempting to change gears in a “passenger car” or “synchromesh” manner. This involves slow shifting and use of the clutch—i.e. lifting off the throttle, depressing the clutch, moving the gear lever slowly, releasing the clutch, and applying the throttle—a scenario typically found in stop-and-go traffic."
http://www.superstreetonline.com/how-to/transmission-drivetrain/impp-1109-synchromesh-vs-dog-box/
Turn up your speakers.
This is how GSAP works and sounds on a 2017 BMW R1200GS Adventure
Does it's job great and loads of fun, no manual clutch changes at all
<iframe width="560" height="315" src="https://www.youtube.com/embed/skNyQ91Va1A" frameborder="0" allow="autoplay; encrypted-media" allowfullscreen></iframe>
This is how GSAP works and sounds on a 2017 BMW R1200GS Adventure
Does it's job great and loads of fun, no manual clutch changes at all
<iframe width="560" height="315" src="https://www.youtube.com/embed/skNyQ91Va1A" frameborder="0" allow="autoplay; encrypted-media" allowfullscreen></iframe>
Victor c
Registered user
My 2016 came with it fitted by the factory. It is intelegent enough to only blip the throttle if needed. If the engine speed and road speed are closely matched already at the point of shift, there is no need for the blip on down shifts.
Yes, this is what happens in a synchromesh. Even though there is no synhromesh in the dog box you still have to match shaft speeds so you either cut ignition or dip the clutch to move up a gear and speed up the input shaft when when going down a gear. By loading the ring gear to the next gear you are trying to match the gears and a momentarily pause in power transmission aids the selection to move the gear over to a new ratio.
The function of a gearbox is to convert the input rpm to either lower or higher output rpm. In the case of motorised vehicles it usually is a lower rpm which has the effect of increasing torque and thus affecting the power output for a given rpm. As confusing as it may sound to some but the gearbox input and output shaft speeds are indeed a product of the engine rpm and reduction ratio of the gear set and has nothing to do with road speed. For shifting gears in a gearbox the shaft speeds are the concern, not road speed.
Technical gobblygook.
fred_jb
Registered user
Not sure how you come to that conclusion. By definition engine speed is matched to road speed in the gear you are in just before you initiate a shift. Changing gear changes the gear ratio, and all things being equal, automatically and inevitably introduces a mismatch between engine revs and road speed in the new gear unless you or the bike take action to change the engine speed to suit the new gear.
For example, in the case of non-GSAP upshifts you can drop the revs as you make the change, or in the case of downshifts raise the revs through a blip. You can also momentarily slip the clutch to allow the mismatch to equalise, and as a lifelong blipper I was surprised to find that this is apparently an accepted technique for downshifts, though it seems a bit hard on the clutch to me, and unlikely to be as smooth as an accurate blip.
Victor c
Registered user
It is what it is. Mine does not always blip the throttle and if positive with the gear lever, down shifts from 6 down to 2 are smooth, auto blip or not.
