Manual Transmission T56 | T5 | MN12 | Clutches | Hydraulics | Shifters

Clash in 2nd and 4th

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Old Sep 12, 2012 | 04:46 PM
  #1  
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Default Clash in 2nd and 4th

2004 6.0l coupled to a 2004 gto mn12 with a ls7 clutch in between. Everything had been working great for about 2 years with this setup. A few months ago clutch pedal made a popping sound and went all the way to the floor. After checking everything out I determined it was the tob. I installed a genuine gm tob and re-bled using every technique invented. Drained and filled case with royal purple synchromax.

Car shifted great for about 3 weeks. Now i get a slight gear clash when going into 2nd and a little heavier clash going into 4th. It only happens when the trans is warm. It doesn't seem to happen at low rpms. All the gear clashing happens while my foot is still depressing the clutch.

Any ideas? Clutch, hydraulics, trans?
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Old Sep 14, 2012 | 08:18 AM
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Im thinking because its only happening in 2nd and 4th that its an issue with the shift rail. The rail isnt sliding forward enough to engage the synchros fully. Not sure if this might be a lead. I'm goin to loosen the shifter plate bolts and try to shift it as far forward as I can, then re-tighten. Its worth a try right?
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Old Sep 15, 2012 | 10:09 PM
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Likely syncros are wearing or the fluid is causing an issue
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Old Sep 16, 2012 | 03:37 AM
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Thanks for the reply. It seems that I'm headed in that direction. Trying to rule out everything else out before I go for the rebuild. I removed the shifter today and found that the shifter cup was loose. I jb welded the shifter cup and put the shifter back in favoring it towards the front of the trans. Not much play actually for the shifter base. Took the car for a test drive and as soon as it warmed up it started grinding again. Thought i was on to something.
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