Muncie 3rd Gear Rattle

Discussion in 'U-shift em' started by crewser, Nov 15, 2015.

  1. crewser

    crewser Platinum Level Contributor

    Well finally got the Muncie in to the 65 Special. Only took 10 Months. Transmission works great, Shifter smooth as silk. But has a rattle noise in 3rd gear under throttle. Have checked all the linkage and Stops. Only thing that seems to lighten the rattle is to put light pressure on the clutch pedal. I know that makes it sound like maybe the throw out bearing rattling. But if it is why does it not do it in other gears?

    Any help appreciated.

    JIm C
  2. gstewart

    gstewart Well-Known Member

    Perhaps because, u put the tranny and associated hardware under more stress in high gear under throttle than u do in a lower gear.
  3. crewser

    crewser Platinum Level Contributor

    Hi Gerry,

    Does it all the way thru the gear from start until it shifts. Can load 4th even harder and is quite. Does go away under decal.

    Jim C
  4. philbquick

    philbquick Founders Club Member

    3rd gear is the gear that is furthest front on the main shaft. Could be worn needle bearings on the front of the main shaft or a bad input bearing. Were all the bearings replaced? Was it sitting for a long time? Could any of the gear teeth have rust pits on them? 4th gear will always be silent since it's is straight through and doesn't go through any gears.
  5. crewser

    crewser Platinum Level Contributor

    Hi Phil
    Coming to the Chili Bowl this year.
    All bearings are new on counter shaft and input plus new needle bearings on front of main shaft.. No noise in 1st or 2nd. Been back in twice to check everything. Replaced all syncros and 1st 2nd and 3rd gear because they had pitting on the syncro surface. Countershaft looked great.

    Guess I will pull it one more time.

    Jim C
  6. philbquick

    philbquick Founders Club Member

    Jim, I'll be at the Chilli Bowl, my team broke-up after winning the ARDC championship, so, no car.
    Pitting on the syncro surface shouldn't make any noise. Compare the back lash of 3rd gear to 1st and 2nd, Any unusual wear patterns on the teeth? If a gear was used for a long time with a worn bearing it could be multi-facited.
  7. crewser

    crewser Platinum Level Contributor

    Thanks for the info Phil I will have it out this weekend and look one more time.
    Let me know when you are going to be in Tulsa and maybe we can get together.

    Jim C
  8. philbquick

    philbquick Founders Club Member

    Another idea. I once had a Borg Warner in a 64 Special and the drive shaft was too long. It eventually damaged the roller bearing surface on the front of the main shaft. To check this measure the inside diameter of the input gear and the diameter of the rollers. ID - 2(roller diameter) = outside diameter of the roller surface of the main shaft. You can also check this by removing everything from the main shaft, put the rollers inside the input gear and insert the main shaft into the rollers. Radial play should be .005" or less.
  9. crewser

    crewser Platinum Level Contributor

    You May be on to something there Phil. My son had this in his Chevelle and lost 2 seconds on his 1/4 mile time because he couldn't figure out how to speed shift. I built him a 700 with all the good parts in it. In trade for the Muncie. He picked his time back up. Before he took the Muncie out he had broken the drive shaft on a shift from second to 3rd. Maybe I had better look at the front of that main shaft and the input gear a little closer. I did just put new bearings in the whole trans but never checked run out on the input to main shaft bearing. Sounds like weekend fun. I think I have zippers on this thing now.

    Jim C

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