PDA

View Full Version : Mis-shift into second gear?



cookie
04-28-2009, 07:06 PM
Has anyone found that when up shifting into second gear you really have to give it a firm pull when compared to the other gears. 3rd and up are smooth as glass but second takes that little bit of extra effort, otherwise I will miss it.
Thank you!:whistle

Semper_Fi
04-28-2009, 08:53 PM
i sometimes grab neutral, most of the time i shift fine.

For me it's pilot error :lurk

deilenberger
04-28-2009, 08:54 PM
Guessing it's the RT in your avitar (knowing what bike is usually helpful..) It might be a case where you want to adjust the shift lever a bit. Perhaps down, so "up" isn't quite as far up.

While I can feel going through neutral a tiny bit - I wouldn't say the effort is more..

cookie
04-28-2009, 09:02 PM
Oops, sorry 08 R12RT w/7000 miles, just breaking her in.

BeemerMike
04-28-2009, 10:19 PM
1-2 Shift:

1. Right before you shift, preload the shift lever with upward pressure
- do NOT roll off throttle . . . yet
- transmission will not shift as long it is under load from engine power
2. Continuing with firm upward pressure on shift lever (firm, but don't try to bend the shift lever!), shift as normal
- roll off throttle as you pull in clutch lever
- transmission shifts to 2nd (continue upward pressure on shift lever all the way through the lever travel)
- roll throttle back on as you let out clutch lever
3. After shift is complete and throttle back on, then release upward pressure on shift lever

Takes 1 second. You will probably never miss another 1-2 shift.

Semper_Fi
04-29-2009, 01:07 AM
1-2 Shift:

1. Right before you shift, preload the shift lever with upward pressure
- do NOT roll off throttle . . . yet
- transmission will not shift as long it is under load from engine power
2. Continuing with firm upward pressure on shift lever (firm, but don't try to bend the shift lever!), shift as normal
- roll off throttle as you pull in clutch lever
- transmission shifts to 2nd (continue upward pressure on shift lever all the way through the lever travel)
- roll throttle back on as you let out clutch lever
3. After shift is complete and throttle back on, then release upward pressure on shift lever

Takes 1 second. You will probably never miss another 1-2 shift.


Nice explanation - i can see where i sometimes grab neutral, not finishing the upshift - will be more mindful - thanks

planepaul1949
04-29-2009, 05:50 AM
1-2 Shift:

1. Right before you shift, preload the shift lever with upward pressure
- do NOT roll off throttle . . . yet
- transmission will not shift as long it is under load from engine power
2. Continuing with firm upward pressure on shift lever (firm, but don't try to bend the shift lever!), shift as normal
- roll off throttle as you pull in clutch lever
- transmission shifts to 2nd (continue upward pressure on shift lever all the way through the lever travel)
- roll throttle back on as you let out clutch lever
3. After shift is complete and throttle back on, then release upward pressure on shift lever

Takes 1 second. You will probably never miss another 1-2 shift.

Make no mistake that when you "preload the shift lever", you are creating major friction between the shift fork and the gear slot, and depriving that interface of lubrication at the same time. Do you really want to do that? It is your transmission, so do whatever you want. In the same way that a big mac a day will eventually give you a heart attack, you will destroy your transmission in time.

I've been a mechanic for 40 years, and I have seen my share of smoked and bent shift forks caused by goons who can't keep their toes off the shift lever.

The hexheads are not sport bikes, so my guess is that you want smooth above all else, right? First off, the shift motion should be proportional to engine speed, i.e., at higher engine speed the difference in rotational velocities of adjacent gears is relatively high, and the gear dogs will align with the corresponding slots fairly quickly. Go ahead and shift faster (not preloading). Conversely, if you are taking it easy, say, in town, the shift needs to be slower, in order to allow the aforementioned gear dogs and slots sufficient time to align. If your timing is good, it will shift like butter. All I can say is try it.

As for the 1st to 2nd shift, which was your main question, I have adopted a technique that works for me reliably. It involves an educated left foot, for sure, but it can become second nature in short order. Two things are working to make the 1st to 2nd shift more problematic. The first two gears have the greatest difference in ratio, which means that the mainshaft has to slow down more for the 1st to 2nd shift than any other. You also have the neutral detent to deal with. The neutral detent is actually the perfect tool to use.

When shifting from 1st to 2nd, just feel the lever go to the neutral detent, pause there for a split-second, and then complete the shift. This allows the mainshaft just a little time to acquire the rotational speed of 2nd gear. Again, try it. You just might be amazed. As I mentioned above, pace the shift according to engine speed. The higher up you are in 1st, the less time you pause through neutral, and vice-versa. My guess is that I pause about a quarter of a second in neutral, on average. It works for me, and my gearbox will last forever.

Good luck.

Paul in CA

indycar
04-29-2009, 12:17 PM
As for the 1st to 2nd shift, which was your main question, I have adopted a technique that works for me reliably. It involves an educated left foot, for sure, but it can become second nature in short order. Two things are working to make the 1st to 2nd shift more problematic. The first two gears have the greatest difference in ratio, which means that the mainshaft has to slow down more for the 1st to 2nd shift than any other. You also have the neutral detent to deal with. The neutral detent is actually the perfect tool to use.

When shifting from 1st to 2nd, just feel the lever go to the neutral detent, pause there for a split-second, and then complete the shift. This allows the mainshaft just a little time to acquire the rotational speed of 2nd gear. Again, try it. You just might be amazed. As I mentioned above, pace the shift according to engine speed. The higher up you are in 1st, the less time you pause through neutral, and vice-versa. My guess is that I pause about a quarter of a second in neutral, on average. It works for me, and my gearbox will last forever.

Good luck.

Paul in CA

will give that a try today. I'm wanting to avoid the 'clunk' i get on about half my first to second shifts, this sounds like the ticket.

thx

BeemerMike
04-29-2009, 01:22 PM
Make no mistake that when you "preload the shift lever", you are creating major friction between the shift fork and the gear slot, and depriving that interface of lubrication at the same time. Do you really want to do that? It is your transmission, so do whatever you want. In the same way that a big mac a day will eventually give you a heart attack, you will destroy your transmission in time.

I've been a mechanic for 40 years, and I have seen my share of smoked and bent shift forks caused by goons who can't keep their toes off the shift lever.

Almost anything can be done incorrectly bad enough to cause problems, when doing it correctly will not cause problems. Which is why I said:

1. "Right before you shift", preload the shift lever . . . as opposed to, say, 10 seconds before you shift when you first start thinking about shifting (or riding around with your left foot on the shift lever all the time!),

and

2. "firm [upward pressure], but don't try to bend the shift lever!"

and

3. "After the shift is complete . . . release the upward pressure" on the shift lever,

and

4. "Takes 1 second".

My suggestion is not "goons who can't keep their toes off the shift lever", and there is no way one could read my post to say that. I'm also not talking about speed-shifting without using the clutch, or using an air shifter. Jeez. :rolleyes

If done correctly, this technique probably does not put load on the shift fork any more than waiting until you release the clutch to pull up on the shift lever, or maybe only slightly more. It does however, also avoid having the transmission "jump out of second gear" back into neutral (gear dogs only partially engage), and therefore reduces this wear on the gear dogs, which is probably a good thing for transmission longevity. There are pluses and minuses to almost everything.

Your technique sounds like it would work also (it is similar to the technique for shifting a Porsche 915 transmission), although I suspect it is probably a little more difficult to master, because there are more steps and timing involved. Even in your technique, I think one needs to keep the shift lever loaded until the clutch is reengaged and the throttle back on to ensure the transmission is fully engaged in second gear, in order to avoid a false shift.

planepaul1949
04-30-2009, 06:06 AM
Please realize that the goons I was referring to were those whose transmissions I encountered in the fairly distant past.

Here's the thing........Any time you load the shifter, you are producing a force on the shift fork that it was not deisgned for. I'm not about to try to calculate the side forces on the fork against the gear/slider slot, but it is surely many times more than what is produced when there is no resistance (horsepower) being produced through it. And it is totally unnecessary.

Similarly, holding firm pressure on the shift lever while you disengage the clutch is not a good idea. Either the shift is complete or it isn't. Holding pressure against a complete shift does no harm. Holding it against an incomplete shift puts the same undesirable side thrust as preloading the shifter, only here you are, in effect, preventing the gear dogs from aligning until the clutch reenters the friction zone. You then get excessively forceful contact on the edges of the dogs that you are trying to avoid in the first place.

Smooth and "measured" is the key to slick shifts. (I used to work at a Moto Guzzi shop, and Guzzis were notorious clunkers. I found that I could feel the neutral between any gear through my foot, and give just enough pause to achieve totally silent shifts, almost without fail.)

I'm sure you can visualize that when the shift fork pushes against the mating slot you are displacing oil. The more forceful the push, the more oil is displaced. The cushion of oil that is there to prevent galling is needlessly challenged. Once galling occurs, wear and heat are produce much more quickly. That is why shift forks from lunched transmissions are measureably galled and turned blue from the heat.

I've never missed a shift on my 1200RT. But here's one observation I'll add; I consider the RT to be one of the most challenging bikes to ride smoothly, and I've owned something around 40 bikes over 44 years of riding. It doesn't much like going slow.

Paul in CA

BeemerMike
04-30-2009, 02:16 PM
Please realize that the goons I was referring to were those whose transmissions I encountered in the fairly distant past.

OK, two POVs on the 1-2 shift technique. People can choose which (or another) they think will work best for them.

indycar
04-30-2009, 02:37 PM
OK, two POVs on the 1-2 shift technique. People can choose which (or another) they think will work best for them.


Wow . . . Imagine that! :hide

PGlaves
04-30-2009, 04:00 PM
First to second shifting is almost always a bit more troublesome than 2nd to 3rd or other shifts because the transmission tends to want to pause in neutral. I have never measured it but I think the throw of the lever is actually slightly longer than other upshifts. We certainly appreciate that tendency to find neutral when we are trying to shift into neutral, and cuss the thing when we go up-down-up-down-up down finding neutral.

Lightly preloading the shifter to smooth shifts has been done by thousands of BMW riders since before the days of the /5 and if done correctly I don't think it accelerates the need for repairs. To the contrary, the two things I see that physically damage transmissions are bent shift forks from "stomping" or "knee jerking", and rounded off shift dogs from applying power with the shift only partially completed.

Yes - in theory and in fact, riding around with pressure on a lever for prolonged periods of time will increase the wear rate on shift forks. But most BMW dry clutch equipped bikes require a rather methodical and deliberate shift action: even, steady pressure followed by a quick pull of the clutch lever, coordinated with matching the RPMs (engine and input shaft) for the new gear being selected.

If done properly the momentary pressure on the shifter makes the shift a single smooth action past neutral and fully engaging the 2nd gear dogs before power is reapplied. The avoidance of damaging clashes and wear on the shift dogs more than overcomes the wear from the momentary contact of the shift forks.

And as an added comment, certainly difficult downshifts, and to a real but lesser extent difficult upshifts, most often mean the clutch hub spline is suspect and needs cleaning and re-lubrication at a minimum.

Here is a recent photo of an R1100RT spline. You know, the type that some folks insist are hardened, plated, and so whizbang that they never need lubrication.

hlothery
04-30-2009, 05:51 PM
Agree that the RT is a little difficult to shift smoothly from 1st to 2nd. I use the preload method as well, but have found the most effective method is to shift above 4K RPM, and hold the throttle steady (or even back off a bit) to make sure the engine load is stabilized (lessened) just prior to attempting to shift.

Works for me.

planepaul1949
04-30-2009, 11:11 PM
I certainly defer to the BMW mechanic who has considerable gearbox experience. My question would be, how often do you see galled and/or bent shift forks?

My experience consists of most of the Japanese brands (Suzuki has the best gearboxes), Guzzi, Ducati, and other lesser brands. I have yet to see a shift mechanism that I cannot improve upon, usually with a rotary burr. Some notoriously hard shifting bike could fairly easily be made to shift flawlessly. The Honda CB-750/900/1000 series comes to mind. But I digress............

My easiest shift is 1st to 2nd, hands down, because I use the technique I described in my earlier post. Don't knock it if you haven't tried it. I will add that the most important timing aspect of the shift is the throttle roll-off to clutch engagement to shift lever pull interface. If all that happens concurrently, the shift will be good. End of story.

Paul in CA
'05 R1200RT

andrewsi
05-01-2009, 06:51 PM
I find all of this discussion very interesting, because I've never had the slightest issue, or need for special technique, going from 1st to 2nd. However, my bike's quite new: I have an '09 RT that came in November without about 1500 miles total. I do usually get a pretty major Klunk from 2nd going down to 1st, however.