Trying to diagnose sudden balky shifting
10-06-2012, 10:00 AM
#11
Originally Posted by 4forall' timestamp='1348670440' post='22039119
What did you replace your trans fluid with? I read you used GMSMFM but i have never heard of that. If it is not the correct fluid then you may have damaged the syncros in the trans.
Hopefully its just the slave, keep us updated.
Hopefully its just the slave, keep us updated.
10-16-2012, 07:32 AM
#12
Thread Starter
Update:
In addition to my earlier work to relube the shifter, I've replaced the clutch master cylinder and clutch slave cylinder and adjusted the free play down to zero per billman.
There have been no changes to the shifting-- it still won't go into gear when I shift over 6000 rpm.
I'm going to replace the transmission fluid since this is easy, but am very skeptical that it will have any effect.
Then, I'll have the clutch replaced and make sure that extra attention is paid to cleaning/relubing the splines.
Any other thoughts?
In addition to my earlier work to relube the shifter, I've replaced the clutch master cylinder and clutch slave cylinder and adjusted the free play down to zero per billman.
There have been no changes to the shifting-- it still won't go into gear when I shift over 6000 rpm.
I'm going to replace the transmission fluid since this is easy, but am very skeptical that it will have any effect.
Then, I'll have the clutch replaced and make sure that extra attention is paid to cleaning/relubing the splines.
Any other thoughts?
10-16-2012, 09:26 AM
#13
Registered User
If it is RPM related then its almost always going to be syncros. Their job is to speed up the next gear so that they can slide together. Syncros stop doing their job and you will either not get into gear or grind at higher rpms. 
10-16-2012, 06:11 PM
#14
Thread Starter
Further update:
I drained the GMSMFM, it was indistinguishable from new. Added some Honda MTF, took it for a spin, and the car still won't shift above 6000 rpm.
I'm going to take it to a mechanic to get the clutch done.
10-17-2012, 06:56 AM
#15
Thread Starter
Just spoke to my mechanic and he is skeptical about the splines getting gunked up and causing the symptom. I'm going to bring it in tomorrow. Anyone have any good advice or theories on what's happening???
Thanks!
Thanks!
10-17-2012, 07:49 AM
#16
Registered User
The transmission is a mechanical system. Only so many things that can go wrong with it.
I would think that even if your syncros are going out or gone that after the rpms drop enough it would slip into gear.
I would think that even if your syncros are going out or gone that after the rpms drop enough it would slip into gear.
10-17-2012, 07:56 AM
#17
A few things you need to tell us. It was the lack of this information that I was reluctant to get involved in the first place.
1. Are you the original owner?
2. Do you know the history on the car?
3. Mileage on car?
4. With engine OFF, clutch to floor, can you detect any oddity when rowing through all the gears?
5. With engine ON, same as #4?
6. When you have trouble with the shifting, have you tried a double clutch? What happens?
7. Do you understand how the shift gates work? IE, gears 1&2 finds the shifter along the left side rail. Gears 5&6 finds the shifter along the right side rail. Gears 3&4 is aligned by the centering spring. 3/4 are the hardest for some people to find because they don't let the spring center the stick. They try to guess where that gate is and end up ramming it somewhere else or they shift on the diagonal (it's an "H" pattern, NOT a "Z" or "N" pattern). That's when things get bent. Not saying it's you but perhaps a previous owner?
8. (an after-thought).. If the clutch disc is old or heat checked, it can create a "dragging" situation. This can make for difficult shifting at high rpm when it's more important for the engine to be completely disengaged from the tranny.
GMSM-FM offers different outcomes to different people. Most will notice an immediate improvement, but this is because you just dumped the old fluid. Of course it will "feel" better. You'd probably feel an improvement if you just put in SAE 30 motor oil - for about an hour. Some will swear by it because they've jumped on the GMSM-FM bandwagon based on what others have said and they'll be damned if they're going to admit they got sucked in by the hype. Some will notice within hours or days that it was the wrong choice and know something is not the same and correct it immediately. In your case, I doubt a change in fluid will resolve your problem. Fluids, so long as they are not totally wrong for this car, will merely alter the feel of transmission operation and rarely, will it create a problem. In even more rare cases, a change in fluid will actually solve a problem or make the problem less.
Shifting at high rpm presents conditions inside the tranny that are not encountered at lower rpm. Although the % difference is the same, the actual rpm difference gets much bigger between the input side and output side of the gear box. Alignment of things need to be more precise. In the same token as when you try to downshift into first gear when your rpm is too high (where the "blocker ring" comes into play), something like this is occurring at higher rpm in other gears as well, particularly when you are trying to downshift - upshifts at high rpm, less so but still a similar principle applies. That's where double clutching may reveal a useful finding. If it can be done with d. clutch, that may indicate that your syncros may be severely worn but still functional (barely) or point you in the direction of a dragging clutch. If d. clutching doesn't produce any better results, that may be an indication that something much more severe has happened.
Our trannies utilize a direct linkage (as opposed to cable linkage or linkage by external rods and levers) and as such, "stuff" can more easily get bent out of shape, particularly when the operator gets frustrated with how things are going. When that happens, one tends to use more force or sacrifices a bit of the clutch/throttle/shifter synchronization. In this case, what could result is the bending of shift forks, shift pieces, etc. These things must be in perfect alignment because as we all know, the S2000 transmission is a very close gated, short throw device. Any part of the shifting mechanism that may get bent can negatively affect how everything else aligns. In some areas, a shift piece may just miss another shift piece by a fraction of a mm. There is a very fine line between say ............ shifting into 3rd gear and shifting into 1st gear or shifting into 2nd gear and shifting into 4th. Imagine (as one example) if you were trying to upshift to 3rd at high rpm and something is bent (shift piece or shift fork). You may actually be trying to shift into 1st - not gonna happen. That blocker ring won't let you.
Anyway, try those things I listed and go ahead and change the fluid. You never know, the solution may be that simple.
1. Are you the original owner?
2. Do you know the history on the car?
3. Mileage on car?
4. With engine OFF, clutch to floor, can you detect any oddity when rowing through all the gears?
5. With engine ON, same as #4?
6. When you have trouble with the shifting, have you tried a double clutch? What happens?
7. Do you understand how the shift gates work? IE, gears 1&2 finds the shifter along the left side rail. Gears 5&6 finds the shifter along the right side rail. Gears 3&4 is aligned by the centering spring. 3/4 are the hardest for some people to find because they don't let the spring center the stick. They try to guess where that gate is and end up ramming it somewhere else or they shift on the diagonal (it's an "H" pattern, NOT a "Z" or "N" pattern). That's when things get bent. Not saying it's you but perhaps a previous owner?
8. (an after-thought).. If the clutch disc is old or heat checked, it can create a "dragging" situation. This can make for difficult shifting at high rpm when it's more important for the engine to be completely disengaged from the tranny.
GMSM-FM offers different outcomes to different people. Most will notice an immediate improvement, but this is because you just dumped the old fluid. Of course it will "feel" better. You'd probably feel an improvement if you just put in SAE 30 motor oil - for about an hour. Some will swear by it because they've jumped on the GMSM-FM bandwagon based on what others have said and they'll be damned if they're going to admit they got sucked in by the hype. Some will notice within hours or days that it was the wrong choice and know something is not the same and correct it immediately. In your case, I doubt a change in fluid will resolve your problem. Fluids, so long as they are not totally wrong for this car, will merely alter the feel of transmission operation and rarely, will it create a problem. In even more rare cases, a change in fluid will actually solve a problem or make the problem less.
Shifting at high rpm presents conditions inside the tranny that are not encountered at lower rpm. Although the % difference is the same, the actual rpm difference gets much bigger between the input side and output side of the gear box. Alignment of things need to be more precise. In the same token as when you try to downshift into first gear when your rpm is too high (where the "blocker ring" comes into play), something like this is occurring at higher rpm in other gears as well, particularly when you are trying to downshift - upshifts at high rpm, less so but still a similar principle applies. That's where double clutching may reveal a useful finding. If it can be done with d. clutch, that may indicate that your syncros may be severely worn but still functional (barely) or point you in the direction of a dragging clutch. If d. clutching doesn't produce any better results, that may be an indication that something much more severe has happened.
Our trannies utilize a direct linkage (as opposed to cable linkage or linkage by external rods and levers) and as such, "stuff" can more easily get bent out of shape, particularly when the operator gets frustrated with how things are going. When that happens, one tends to use more force or sacrifices a bit of the clutch/throttle/shifter synchronization. In this case, what could result is the bending of shift forks, shift pieces, etc. These things must be in perfect alignment because as we all know, the S2000 transmission is a very close gated, short throw device. Any part of the shifting mechanism that may get bent can negatively affect how everything else aligns. In some areas, a shift piece may just miss another shift piece by a fraction of a mm. There is a very fine line between say ............ shifting into 3rd gear and shifting into 1st gear or shifting into 2nd gear and shifting into 4th. Imagine (as one example) if you were trying to upshift to 3rd at high rpm and something is bent (shift piece or shift fork). You may actually be trying to shift into 1st - not gonna happen. That blocker ring won't let you.
Anyway, try those things I listed and go ahead and change the fluid. You never know, the solution may be that simple.
10-17-2012, 08:11 AM
#18
Thread Starter
A few things you need to tell us. It was the lack of this information that I was reluctant to get involved in the first place.
1. Are you the original owner?
2. Do you know the history on the car?
3. Mileage on car?
4. With engine OFF, clutch to floor, can you detect any oddity when rowing through all the gears?
5. With engine ON, same as #4?
6. When you have trouble with the shifting, have you tried a double clutch? What happens?
7. Do you understand how the shift gates work? IE, gears 1&2 finds the shifter along the left side rail. Gears 5&6 finds the shifter along the right side rail. Gears 3&4 is aligned by the centering spring. 3/4 are the hardest for some people to find because they don't let the spring center the stick. They try to guess where that gate is and end up ramming it somewhere else or they shift on the diagonal (it's an "H" pattern, NOT a "Z" or "N" pattern). That's when things get bent. Not saying it's you but perhaps a previous owner?
8. (an after-thought).. If the clutch disc is old or heat checked, it can create a "dragging" situation. This can make for difficult shifting at high rpm when it's more important for the engine to be completely disengaged from the tranny.
GMSM-FM offers different outcomes to different people. Most will notice an immediate improvement, but this is because you just dumped the old fluid. Of course it will "feel" better. You'd probably feel an improvement if you just put in SAE 30 motor oil - for about an hour. Some will swear by it because they've jumped on the GMSM-FM bandwagon based on what others have said and they'll be damned if they're going to admit they got sucked in by the hype. Some will notice within hours or days that it was the wrong choice and know something is not the same and correct it immediately. In your case, I doubt a change in fluid will resolve your problem. Fluids, so long as they are not totally wrong for this car, will merely alter the feel of transmission operation and rarely, will it create a problem. In even more rare cases, a change in fluid will actually solve a problem or make the problem less.
Shifting at high rpm presents conditions inside the tranny that are not encountered at lower rpm. Although the % difference is the same, the actual rpm difference gets much bigger between the input side and output side of the gear box. Alignment of things need to be more precise. In the same token as when you try to downshift into first gear when your rpm is too high (where the "blocker ring" comes into play), something like this is occurring at higher rpm in other gears as well, particularly when you are trying to downshift - upshifts at high rpm, less so but still a similar principle applies. That's where double clutching may reveal a useful finding. If it can be done with d. clutch, that may indicate that your syncros may be severely worn but still functional (barely) or point you in the direction of a dragging clutch. If d. clutching doesn't produce any better results, that may be an indication that something much more severe has happened.
Our trannies utilize a direct linkage (as opposed to cable linkage or linkage by external rods and levers) and as such, "stuff" can more easily get bent out of shape, particularly when the operator gets frustrated with how things are going. When that happens, one tends to use more force or sacrifices a bit of the clutch/throttle/shifter synchronization. In this case, what could result is the bending of shift forks, shift pieces, etc. These things must be in perfect alignment because as we all know, the S2000 transmission is a very close gated, short throw device. Any part of the shifting mechanism that may get bent can negatively affect how everything else aligns. In some areas, a shift piece may just miss another shift piece by a fraction of a mm. There is a very fine line between say ............ shifting into 3rd gear and shifting into 1st gear or shifting into 2nd gear and shifting into 4th. Imagine (as one example) if you were trying to upshift to 3rd at high rpm and something is bent (shift piece or shift fork). You may actually be trying to shift into 1st - not gonna happen. That blocker ring won't let you.
Anyway, try those things I listed and go ahead and change the fluid. You never know, the solution may be that simple.
1. Are you the original owner?
2. Do you know the history on the car?
3. Mileage on car?
4. With engine OFF, clutch to floor, can you detect any oddity when rowing through all the gears?
5. With engine ON, same as #4?
6. When you have trouble with the shifting, have you tried a double clutch? What happens?
7. Do you understand how the shift gates work? IE, gears 1&2 finds the shifter along the left side rail. Gears 5&6 finds the shifter along the right side rail. Gears 3&4 is aligned by the centering spring. 3/4 are the hardest for some people to find because they don't let the spring center the stick. They try to guess where that gate is and end up ramming it somewhere else or they shift on the diagonal (it's an "H" pattern, NOT a "Z" or "N" pattern). That's when things get bent. Not saying it's you but perhaps a previous owner?
8. (an after-thought).. If the clutch disc is old or heat checked, it can create a "dragging" situation. This can make for difficult shifting at high rpm when it's more important for the engine to be completely disengaged from the tranny.
GMSM-FM offers different outcomes to different people. Most will notice an immediate improvement, but this is because you just dumped the old fluid. Of course it will "feel" better. You'd probably feel an improvement if you just put in SAE 30 motor oil - for about an hour. Some will swear by it because they've jumped on the GMSM-FM bandwagon based on what others have said and they'll be damned if they're going to admit they got sucked in by the hype. Some will notice within hours or days that it was the wrong choice and know something is not the same and correct it immediately. In your case, I doubt a change in fluid will resolve your problem. Fluids, so long as they are not totally wrong for this car, will merely alter the feel of transmission operation and rarely, will it create a problem. In even more rare cases, a change in fluid will actually solve a problem or make the problem less.
Shifting at high rpm presents conditions inside the tranny that are not encountered at lower rpm. Although the % difference is the same, the actual rpm difference gets much bigger between the input side and output side of the gear box. Alignment of things need to be more precise. In the same token as when you try to downshift into first gear when your rpm is too high (where the "blocker ring" comes into play), something like this is occurring at higher rpm in other gears as well, particularly when you are trying to downshift - upshifts at high rpm, less so but still a similar principle applies. That's where double clutching may reveal a useful finding. If it can be done with d. clutch, that may indicate that your syncros may be severely worn but still functional (barely) or point you in the direction of a dragging clutch. If d. clutching doesn't produce any better results, that may be an indication that something much more severe has happened.
Our trannies utilize a direct linkage (as opposed to cable linkage or linkage by external rods and levers) and as such, "stuff" can more easily get bent out of shape, particularly when the operator gets frustrated with how things are going. When that happens, one tends to use more force or sacrifices a bit of the clutch/throttle/shifter synchronization. In this case, what could result is the bending of shift forks, shift pieces, etc. These things must be in perfect alignment because as we all know, the S2000 transmission is a very close gated, short throw device. Any part of the shifting mechanism that may get bent can negatively affect how everything else aligns. In some areas, a shift piece may just miss another shift piece by a fraction of a mm. There is a very fine line between say ............ shifting into 3rd gear and shifting into 1st gear or shifting into 2nd gear and shifting into 4th. Imagine (as one example) if you were trying to upshift to 3rd at high rpm and something is bent (shift piece or shift fork). You may actually be trying to shift into 1st - not gonna happen. That blocker ring won't let you.
Anyway, try those things I listed and go ahead and change the fluid. You never know, the solution may be that simple.
1. I'm the second owner. I purchased it in 2004 with 28K.
2. Not from prior to my ownership, but I've taken the car to the track once and autocrossed it probably about 50 days for probably 200+ runs on r-compounds. I've only autocrossed it one time since 2007. I use VTEC on a normal basis while driving on the road. So, it's lead a hard life, but the only items I've had to replace on the car are the rear wheel bearings (other than consumables).
3. 88,912.
4. No oddities with engine off.
5. No oddities with engine on, rowing through gears with clutch pedal depressed.
6. I have not tried double-clutching while upshifting. I regularly do a heel-toe double clutch downshift, and found the shifting to be balky at high rpm downshifts, similar to the single clutch upshifts.
7. Yes.
8. Very possible that the clutch is near the end of its life.
Just to clarify: I replaced the 4000-mile-old GMSMFM last night and found it to be in as new condition. I replaced it with Honda MTF. There was no difference in the shifting afterward.
I guess my true question is: what should I do now?
Thanks so much for you input! I do appreciate it greatly!
10-17-2012, 08:54 AM
#19
As for what to do next, I'd go with the fluid change first. That's a couple bottles of juice and a bit of your time. If that doesn't do much, then it's time to take it to a trusted mechanic. Explain what you're experiencing and suggest he do some driving tests to home in on what might be the clutch's condition. If he can eliminate the clutch, then it's the tranny (or the linkage). Tearing it apart and putting it back together is a labor intensive job and that doesn't even include removal, installation and doing any repairs. It may not be worth it. Consider finding a second hand tranny from a wrecked S2000. There's got to be lots of those around these days. If you go this route, consider getting one from an AP2 ('05 or newer) so long as this doesn't affect your competition class. It shouldn't. The gearing in AP2's give more low end grunt. Some '04 trannies have the 2nd gear pop-out. You may find one for well under $1000.00. Rebuilding yours may be almost that much. A brand new tranny runs in the $3000.00+ range.
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