Speed shifting the LT?

3682 Views 11 Replies 9 Participants Last post by NCCCC1, Apr 26, 2012

NCCCC1

Discussion Starter · Apr 25, 2012

Can anybody out there tell me about their expirience with shifting gears on the LT at "proper", if possible, RPM's without using the clutch. I assume that these bikes innards might be extra sensitive to this in a bad way??? Now that I'm a half century old, I'm just starting to read a few, isolated articles about motorcycle safety. This may be 40 years delinquent. But one article I just read said that you should avoid pulling the clutch on any bike during cornering unless you have to. They didn't say "except when shifting". I haven't put that much conscious thought into the dynamics of motorcycle cornering before. "Just do it". When my wife took a motorcycle safety course a year ago, I just flat out never even condered taking it for myself . On other bikes I've done a bit of "speed shifting" without much transmission or final drive problems, and yet I am cautious with my "new" ( just bought it on Oct. 30, 2011 from a University of Iowa professor having 20k miles on it for $4,800) 12 year old "baby".

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Axle

· #2 · Apr 25, 2012

I would have to say why would you not want to use the clutch

that's what it is there for, you should always shift up or down before entering a corner so the bike and you are setup and ready for the maneuver correct rpms etc. do I ever shift without the clutch NO my LT is worth far more to me than being lazy, not saying you are.. but it is not a racing machine it is for enjoyment,,

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JoeTerry

· #3 · Apr 25, 2012

The tranny is synchronized, but the ratios between gears seems too wide to reasonably speed shift without being too rough on the equipment. Other bikes I've ridden generally have close ratios between gears and a higher ratio in high gear making speed shifting easy albeit with much higher rpm in top gear. I'm eager to hear other opinions.

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gary45

· #4 · Apr 25, 2012

I would not do it in corners but as easy to shift without the clutch as the K11 or K100 - preload and quick throttle movement - I normally use clutch on the LT because of the little shift linkages versus direct connection on the other K's

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mreuter

· #5 · Apr 25, 2012

I know some guy's over here do this. We have there some discussions on the German BMW LT Forum about this point. But in my opinion it wouldn't give you anything. Due to the high pressure on the shifter you could easily break your ball connectors in the shifter link. It will not do any damage in the Gear Box that should work if you do it on the right rpm.

Manfred

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1dbweldor

· #6 · Apr 25, 2012

These gearboxes are NOT synchronized. You have a more considerable amount of control in a corner under power versus not under power. Shifting with the clutch will prolong the power phase in a corner resulting in less control. This small control loss may be just enough to get out of shape (so to speak) resulting in going down.
Speed shifting will not hurt the drive train if done properly, however if not done properly it could result in damage. Just before shifting put a small amount of pressure on the shift lever in the direction of the next higher gear and blip the throttle off and then back on while holding the pressure on the shift lever. You will feel it slip into the next gear. When you roll the throttle back on release the pressure on the shift lever. Myself when I do this I won't back the throttle completely off, just enough to put a little slack in the tranny so the gears can slide into the next range. Once you get the feel for this it will be positive shifts and no false neutral. I don't float the tranny all the time just when my left hand is busy doinh something else when time to shift.
When I was racing I would NEVER use the clutch except for taking off or stopping. On my racing bikes I would undercut the dogs and mating holes on all my meshing gears so as to to guarantee no miss shifts. In a nutshel, You can float the tranny without damage on any motorcycle or manual shift vehicle if done properly. Just get the feel and be gentle.

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JoeTerry

· #7 · Apr 25, 2012

If the BMW gearbox is not synchronized, I don't think it would be possible to increase or drop multiple gears without either being stationary or clutching between gears (and it would not be a sequential gearbox). I have driven a few of old trucks and lots of tractors with asynchronous gear boxes that required double clutching and gear grinding was difficult NOT to do when shifting - especially down. With those asynchronous gear boxes engine RPM and transmission speed had to match perfectly or I was "grinding another pound" as the saying goes around here. I find it hard to believe any sequential gearbox is not synchronized, so if I'm wrong, please educate me.

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jzeiler

· #8 · Apr 25, 2012

NCCCC1 said:
But one article I just read said that you should avoid pulling the clutch on any bike during cornering unless you have to. They didn't say "except when shifting". I haven't put that much conscious thought into the dynamics of motorcycle cornering before. "Just do it".

Bottom line is be in the right gear BEFORE you enter the turn. If you are in the right gear for the corner (regardless of speed) you should not have to ever change gears nor hit the brakes.

The gear will normally match the warning sign speed recommendations first digit. 25 MPH be in 2nd. 35 MPH be in 3rd. All the while rolling along 45 to 55 MPH. The LT sings @ 6-7,500 rpm in the twisties and you will not need the brakes just roll off and on the throttle.

Now on the subject of shifting with out the clutch. The LT transmission is a constant mesh unit. All the gears are meshed all the time (therefore no syncros are needed). Shifting merely bangs four-cogg shaft locks that change which of the fully meshed gears are in contact with the shafts. It is a little different than shifting a conventional auto transmission where you are meshing and unmeshing individual gears, but most bikes use this type transmission anyway. And yes it will shift up and down with pressure on the shift lever without using the clutch. If you don't get the timing right then you eventually round the corner of the coggs and they will start popping out of gear on you. Your choice.

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New2rt

· #9 · Apr 25, 2012

jzeiler said:
Bottom line is be in the right gear BEFORE you enter the turn. If you are in the right gear for the corner (regardless of speed) you should not have to ever change gears nor hit the brakes.

The gear will normally match the warning sign speed recommendations first digit. 25 MPH be in 2nd. 35 MPH be in 3rd. All the while rolling along 45 to 55 MPH. The LT sings @ 6-7,500 rpm in the twisties and you will not need the brakes just roll off and on the throttle.

Now on the subject of shifting with out the clutch. The LT transmission is a constant mesh unit. All the gears are meshed all the time (therefore no syncros are needed). Shifting merely bangs four-cogg shaft locks that change which of the fully meshed gears are in contact with the shafts. It is a little different than shifting a conventional auto transmission where you are meshing and unmeshing individual gears, but most bikes use this type transmission anyway. And yes it will shift up and down with pressure on the shift lever without using the clutch. If you don't get the timing right then you eventually round the corner of the coggs and they will start popping out of gear on you. Your choice.

Most automotive manual transmissions also have the gears constantly meshed. the gear set is a fixed assembly on the countershaft. The gears spin at different speeds on the main shaft so they use a synchro as both a brake (speed match) and for alignment to allow the synchro hub to engage the gear.
Reverse is a gear to gear mesh using an idler gear.
You can directly select a gear without sequencing, as in a motorcycle trans (within reason) but they are heavier, bulky, and more complex.

As noted, shifting without using a clutch can round the dogs and cause it to jump out of gear under load.

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tips727

· #10 · Apr 25, 2012

I never tried to shift my '00 LT without using the clutch. The transmission was clunky enough while using the clutch that I never considered shifting without it. But on my '05 model, the transmission is much smoother and quieter. I understand that this is the first year of a change in the type of transmission gears used. Clutching is such a habit with me that I do it automatically but I have tried shifting without the clutch a few times just to see if I could and it worked pretty well - most times I could shift smoothly but a few times not so. I don't expect to practice enough to get good at it - was just wondering since I used to shift my Japanese bikes without clutching all the time with no apparent harm.

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jzeiler

· #11 · Apr 26, 2012

New2rt said:
Most automotive manual transmissions also have the gears constantly meshed. the gear set is a fixed assembly on the countershaft. The gears spin at different speeds on the main shaft so they use a synchro as both a brake (speed match) and for alignment to allow the synchro hub to engage the gear.
.

Yeah thats right.

The dog clutches have many more teeth on them compared to the four on the LT tranny. That is why they "grind" when the synchros wear out and ours just go "clunk" all the time.

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NCCCC1

Discussion Starter · #12 · Apr 26, 2012

Really good input men. It is much appreciated!!!!

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