Muncie problem shifting into first after rebuild.
09-07-2014, 12:55 PM
#1
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Muncie problem shifting into first after rebuild.
Just had my M21 rebuilt by a well-known rebuilder while sorting through my clutch issues. Have it all back together and about 250 miles on the car, and thankfully all the clutch problems and vibrations are resolved. Unfortunately, I have now introduced a problem that wasn't present before. Sometimes the Muncie just will not go into first gear at a standstill. It is an intermittent problem. Lever slides about 3/4 of the way into gear and hits a stop. When this happens, you can grab any other gear and engage fully. Move back to first and it still hits a stop. Only way to get into gear is to move it to neutral, release the clutch, and try once more. Then it usually goes in. Also, there is an occasional clash on downshift from 4-3 that was never there.
Some other information:
-Problem can occur with engine running or off
-When I recreated the problem with the engine off and me under the car, I removed the 1-2 linkage and found the trans lever still would not go into gear. So the problem is trans internal, not the shifter.
-Clutch is adjusted perfectly. Friction point is ~ 2" off the floor and there is 1" of free play at the top.
-Shifter is adjusted perfectly. All the correct spring clips on the linkage rods and cotter pin on the 1-2 clevis. No binding in shifter.
-Oil is 85/90 GL4, non-synthetic
-Only parts (aside from all the wear parts) changed during rebuild were hubs and sliders and speedo gear. All else was in good condition.
-Trans is ultra quiet and I never feel any vibrations or unpleasantness through the shifter.
The rebuilder is going to stand behind it and warranty the problem, but I still have to R&R the box. If there is anything to try before pulling the trans, I am ready and willing to give it a shot. Bring all suggestions.
Some other information:
-Problem can occur with engine running or off
-When I recreated the problem with the engine off and me under the car, I removed the 1-2 linkage and found the trans lever still would not go into gear. So the problem is trans internal, not the shifter.
-Clutch is adjusted perfectly. Friction point is ~ 2" off the floor and there is 1" of free play at the top.
-Shifter is adjusted perfectly. All the correct spring clips on the linkage rods and cotter pin on the 1-2 clevis. No binding in shifter.
-Oil is 85/90 GL4, non-synthetic
-Only parts (aside from all the wear parts) changed during rebuild were hubs and sliders and speedo gear. All else was in good condition.
-Trans is ultra quiet and I never feel any vibrations or unpleasantness through the shifter.
The rebuilder is going to stand behind it and warranty the problem, but I still have to R&R the box. If there is anything to try before pulling the trans, I am ready and willing to give it a shot. Bring all suggestions.
09-07-2014, 02:24 PM
#2
Just had my M21 rebuilt by a well-known rebuilder while sorting through my clutch issues. Have it all back together and about 250 miles on the car, and thankfully all the clutch problems and vibrations are resolved. Unfortunately, I have now introduced a problem that wasn't present before. Sometimes the Muncie just will not go into first gear at a standstill. It is an intermittent problem. Lever slides about 3/4 of the way into gear and hits a stop. When this happens, you can grab any other gear and engage fully. Move back to first and it still hits a stop. Only way to get into gear is to move it to neutral, release the clutch, and try once more. Then it usually goes in. Also, there is an occasional clash on downshift from 4-3 that was never there.
Some other information:
-Problem can occur with engine running or off
-When I recreated the problem with the engine off and me under the car, I removed the 1-2 linkage and found the trans lever still would not go into gear. So the problem is trans internal, not the shifter.
-Clutch is adjusted perfectly. Friction point is ~ 2" off the floor and there is 1" of free play at the top.
-Shifter is adjusted perfectly. All the correct spring clips on the linkage rods and cotter pin on the 1-2 clevis. No binding in shifter.
-Oil is 85/90 GL4, non-synthetic
-Only parts (aside from all the wear parts) changed during rebuild were hubs and sliders and speedo gear. All else was in good condition.
-Trans is ultra quiet and I never feel any vibrations or unpleasantness through the shifter.
The rebuilder is going to stand behind it and warranty the problem, but I still have to R&R the box. If there is anything to try before pulling the trans, I am ready and willing to give it a shot. Bring all suggestions.
Some other information:
-Problem can occur with engine running or off
-When I recreated the problem with the engine off and me under the car, I removed the 1-2 linkage and found the trans lever still would not go into gear. So the problem is trans internal, not the shifter.
-Clutch is adjusted perfectly. Friction point is ~ 2" off the floor and there is 1" of free play at the top.
-Shifter is adjusted perfectly. All the correct spring clips on the linkage rods and cotter pin on the 1-2 clevis. No binding in shifter.
-Oil is 85/90 GL4, non-synthetic
-Only parts (aside from all the wear parts) changed during rebuild were hubs and sliders and speedo gear. All else was in good condition.
-Trans is ultra quiet and I never feel any vibrations or unpleasantness through the shifter.
The rebuilder is going to stand behind it and warranty the problem, but I still have to R&R the box. If there is anything to try before pulling the trans, I am ready and willing to give it a shot. Bring all suggestions.
09-07-2014, 03:59 PM
#3
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Moving from Cars For Sale to General discussion area.
09-07-2014, 04:20 PM
#4
Team Owner
I'd carefully check the clutch adjustment before anything else.
However, what you are doing to get into first sounds like "double clutching" to me -- which is what you did (back in the old days) to synchronize gears in non-synchro trannys.
Meaning - perhaps its a synchro problem...but Lord knows I'm no transmission guru.
I think your rebuilder owes you an explanation.
However, what you are doing to get into first sounds like "double clutching" to me -- which is what you did (back in the old days) to synchronize gears in non-synchro trannys.
Meaning - perhaps its a synchro problem...but Lord knows I'm no transmission guru.
I think your rebuilder owes you an explanation.
09-07-2014, 06:19 PM
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09-07-2014, 06:24 PM
#8
Melting Slicks
The sliders should have a sharp edge on the ends of each of the internal splines. These sharp edges must engage with sharp edges on each of the small synchro teeth on every gear (except reverse). If these teeth on first gear are rounded, there will be times when that gear can not be engaged until they are aligned.
It might be time to inspect these small synchro teeth on each of the shifting gears. This inspection can be done by removing the side cover and using a mirror and flashlight, but it isn't fun.
It might be time to inspect these small synchro teeth on each of the shifting gears. This inspection can be done by removing the side cover and using a mirror and flashlight, but it isn't fun.
09-08-2014, 08:19 AM
#10
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Unfortunately, taking the car to the rebuilder is not a possibility due to distance. I'll make a video to capture the issues as best I can before I pull the trans.
Gearset is all OEM and he found all to be in excellent shape on teardown. The trans is smoother on upshifts than it ever was. The hubs and sliders are new replacements, not torque lock type. The blockers are forged, not the cast versions.
Feels to me like the first gear issue is a blocking ring too tight on the cone, and not sure about the 4-3 roughness on downshift.
I am going to request the old hubs and sliders go back in. I looked at them this morning and I think they are good enough to reuse.
Sucks to have to pull the trans again, but I am so pleased the clutch and vibration issues are gone that it isn't all bad. A trans is easy to fix. I drove the car at very high speeds this weekend and the driveline feels as smooth as my 2013, so overall I am happy. I was starting to worry the vibration was in the engine itself, so it's glad to find out that isn't the case.
Gearset is all OEM and he found all to be in excellent shape on teardown. The trans is smoother on upshifts than it ever was. The hubs and sliders are new replacements, not torque lock type. The blockers are forged, not the cast versions.
Feels to me like the first gear issue is a blocking ring too tight on the cone, and not sure about the 4-3 roughness on downshift.
I am going to request the old hubs and sliders go back in. I looked at them this morning and I think they are good enough to reuse.
Sucks to have to pull the trans again, but I am so pleased the clutch and vibration issues are gone that it isn't all bad. A trans is easy to fix. I drove the car at very high speeds this weekend and the driveline feels as smooth as my 2013, so overall I am happy. I was starting to worry the vibration was in the engine itself, so it's glad to find out that isn't the case.
09-08-2014, 08:56 PM
#11
Safety Car
Larrywalk explains it well. If you had no internal problems, why were the sliders changed? Worn sliders usually show up as "jumping" out of gear or difficult or impossible high rpm shift. Worn blocking rings can cause gear clash.
09-08-2014, 11:33 PM
#12
Burning Brakes
Unfortunately, taking the car to the rebuilder is not a possibility due to distance. I'll make a video to capture the issues as best I can before I pull the trans.
Gearset is all OEM and he found all to be in excellent shape on teardown. The trans is smoother on upshifts than it ever was. The hubs and sliders are new replacements, not torque lock type. The blockers are forged, not the cast versions.
Feels to me like the first gear issue is a blocking ring too tight on the cone, and not sure about the 4-3 roughness on downshift.
I am going to request the old hubs and sliders go back in. I looked at them this morning and I think they are good enough to reuse.
Sucks to have to pull the trans again, but I am so pleased the clutch and vibration issues are gone that it isn't all bad. A trans is easy to fix. I drove the car at very high speeds this weekend and the driveline feels as smooth as my 2013, so overall I am happy. I was starting to worry the vibration was in the engine itself, so it's glad to find out that isn't the case.
Gearset is all OEM and he found all to be in excellent shape on teardown. The trans is smoother on upshifts than it ever was. The hubs and sliders are new replacements, not torque lock type. The blockers are forged, not the cast versions.
Feels to me like the first gear issue is a blocking ring too tight on the cone, and not sure about the 4-3 roughness on downshift.
I am going to request the old hubs and sliders go back in. I looked at them this morning and I think they are good enough to reuse.
Sucks to have to pull the trans again, but I am so pleased the clutch and vibration issues are gone that it isn't all bad. A trans is easy to fix. I drove the car at very high speeds this weekend and the driveline feels as smooth as my 2013, so overall I am happy. I was starting to worry the vibration was in the engine itself, so it's glad to find out that isn't the case.
My tranny out three times to get things right. Very frustrating for sure.
Best of luck to you.
09-09-2014, 08:27 AM
#13
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The forks were also changed (the old ones were heavily worn). When I recreate the Neutral to First hangup, the shift mechanism is bound up inside the trans somehow, pushing the lever and fork out against the cover. It cannot walk in/out if you push on it. Even when I pull back and engage second fully, then slide it back to first, the end play never opens up. It feels like the fork is not pushing on the slider at diametrically opposed points, instead that its pushing on one side of the slider and causing it to get cocked on the hub and bind up the whole mechanism. This is supported by the fact that releasing the clutch and re-engaging corrects the problem and allows it to shift into First (fork acting on another location of the slider to un-jam it). I will take the cover off and look.
09-09-2014, 08:37 AM
#14
Melting Slicks
09-09-2014, 09:47 AM
#15
Burning Brakes
I posted an update here
https://www.corvetteforum.com/forums...hp-help-5.html
09-09-2014, 12:48 PM
#16
Safety Car
The forks were also changed (the old ones were heavily worn). When I recreate the Neutral to First hangup, the shift mechanism is bound up inside the trans somehow, pushing the lever and fork out against the cover. It cannot walk in/out if you push on it. Even when I pull back and engage second fully, then slide it back to first, the end play never opens up. It feels like the fork is not pushing on the slider at diametrically opposed points, instead that its pushing on one side of the slider and causing it to get cocked on the hub and bind up the whole mechanism. This is supported by the fact that releasing the clutch and re-engaging corrects the problem and allows it to shift into First (fork acting on another location of the slider to un-jam it). I will take the cover off and look.
09-13-2014, 01:23 PM
#17
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It is definitely something in the 1-2 hub and slider assy causing it to hang. I was able to watch the slider move through the fill hole while my wife shifted it between 1-2. Trans has to come out, no way around it.