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Is there any thing special about shifting between 5th and 6th?


Penrod

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On a 2004 R1150RT, I've mastered the shifting except for between 5th and 6th. Bike is under warranty and has been back twice for this, being re-shimmed once and changed to synthetic fluid. Performance improved, but still experiencing a distinct (and disturbing) clunck when shifting up and down. Pre-loading and throttle control do not significantly reduce it either.

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ShovelStrokeEd

Strange, being that the ratio spread is smallest between 5th and 6th, it should be the smoothest of the shifts. What happens if you don't let off the gas at all? Can you do the shift clutchless? (Just preload and very quickly flick the throttle off and then on) Are you accelerating to the desired speed in 5th and then just seeking to maintain speed in 6th?

 

Answers to those questions might provide a hint as to what is wrong, if anything.

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Paul Mihalka
Strange, being that the ratio spread is smallest between 5th and 6th, it should be the smoothest of the shifts.
I don't have the numbers in front of me and I'm too lazy to find the book and calculate the gear steps in %, but by gut feeling the step between 5th and overdrive 6th is huge, about 25%. When I shift from 5th to 6th rpm drops from about 4000 to about 3000. That shift needs different throttle/clutch action the the other gears. Shifting up it takes more backing off the throttle and shifting down more blip of throttle than other gears to do it smoothly.
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I found that I get the best shifts from 5th to 6th by rolling the throttle all the way off, touching the stop position while shifting. That added portion of a second delay seems to help syncronize engine to transmission speed.

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I have found no way to comfortably shift from 5th to 6th up or down, dino nor synthetic...jerk her into gear and go.

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ShovelStrokeEd

Hmmmm,

Paul, you may be right. I'm used to my 1100S which has way different gearing than an RT. Basic principles of RPM to wheel speed matching still apply as does clutch action. My Honda is pretty much the same as the S so no help there. Only thing I might add here is to wind 5th further before dropping into 6th. Might not be practical as speeds can get higher than local limits. If the ratio spread is, indeed larger between 5-6 than it is between 4-5, a more deliberate approach might actually work better.

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The best way to shift into an overdrive gear is to get your desired speed up to your desired ground speed in fifth, then shift into 6th (overdrive) matching your rpm to ground speed accordingly. The "clunk" may be caused by an over worked synchro.

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The best way to shift into an overdrive gear is to get your desired speed up to your desired ground speed in fifth, then shift into 6th (overdrive) matching your rpm to ground speed accordingly. The "clunk" may be caused by an over worked synchro.

 

Bike gearboxes do not have synchros. The clunk is the dog gear sliding into place.

 

I find the smoothest up-changes occur when I don't use the clutch, just upward pressure on the changer and 'dip' the throttle. On the R1150RT that needs a deeper dip into sixth.

 

The ratios on the R1150RT are a little odd, they follow the usual pattern of reducing difference from 1 to 5, then there's a big jump to 6th 'overdrive'.

The clunk will not break the box and with time you will notice it will no longer happen, as you will have been trained to the bike.

 

Cya, Andy

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Strange, being that the ratio spread is smallest between 5th and 6th, it should be the smoothest of the shifts.
I don't have the numbers in front of me and I'm too lazy to find the book and calculate the gear steps in %, but by gut feeling the step between 5th and overdrive 6th is huge, about 25%. When I shift from 5th to 6th rpm drops from about 4000 to about 3000. That shift needs different throttle/clutch action the the other gears. Shifting up it takes more backing off the throttle and shifting down more blip of throttle than other gears to do it smoothly.

 

in order to maintain approx 4k rpm when i do shift to 6th my rpm's in 5th need to be in excess of 5500 and even then i come in around 3800. let me clarify one thing...i don't get a big, bad-ass clunk, but it's not as smooth as shifting up thru the gears to 5th. as paul indicated i just assumed the "spread" was greater between 5th/6th.

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Penrod, I noticed the same thing when I went from a BMW 5 speed to the later 6 speed RT.. It won't take you long to figure it out & get a smooth 5-6 shift..

What works for me is to let up on the throttle just a wee little just before the shift,, then start the 5-6 shift using your foot on the shift lever & just as the foot lever starts to move QUICKLY de-clutch & drop the throttle about 1/2 way between where your were & closed throttle.. The secret for me here is to quickly de-clutch & re-clutch while the preloaded shift lever quickly goes into the higher gear.. I have it down now so it is smooth as silk on the up shift & livable on the down shift..

Twisty

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6th gear? Who uses 6th gear? grin.gifgrin.gifgrin.gif

 

Mine doesn't like 6th unless I'm going about 80 indicated on a flat stretch of slab.

 

But, the others are correct, the hop between 5th and 6th is HUGE and I've found that a long deliberate throttle slightly out, clutch in, slow shift, and smooth re-engagement of clutch and throttle works best. Almost like slow motion compared to the other shifts.

 

And, dropping to 5th "at speed" in order to accelerate requires a pretty good steady increase of the throttle (rather than the proverbial 'blip') to do smoothly.

 

Weird dang gear ratios on the 1150 RT, I've never understood them from a "why'd they make them this way" point of view, but have learned to just accept them as part of the boxer character.

 

Now, take 1st gear for example.... you've got a tall bike that is a tad top heavy to begin with, so you slap in a 1st gear so tall that if you have a bottle cap under your front tire it will bog and kill the motor unless you rev the hell out of it and slip the clutch a bit -- never mind taking off seriously up-hill and two up loaded. Makes perfect sense to me. confused.gifconfused.gifconfused.gif

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Paul Mihalka

Now I had it handy to check gear ratios.

Percentage drop of rpm with each upshift, with the overdirve gearbox: 1-2 28%, 2-3 26%, 3-4 22%, 4-5 15%, 5-6 28%!

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