odd buzzing/grinding sound when shifting from 1st to 2nd

  • #1

    odd buzzing/grinding sound when shifting from 1st to 2nd

    hi i just bought a 1985 z31 n/a. whenever i shift from 1st to second i hear this buzzing/vibrating sound. the shift knob also kinda vibrates for like 1/2 a second. i can sometimes solve this by double clutching, but this doesn't always work. Is this the syncros or what? not to familiar with manual transmissions yet. If you think it is something else please let me now. should i get this looked at now or should i just try and continue to double clutch into 2nd? please let me know what you think. i also was thinking if a changed out the clutch fluid or gear oil. sorry if this is an obvious question.
    thanks
  • #2
    Change your gear oil with the factory specified transmission fluid. Check to ensure the master cylinder has the proper amount of DOT 3 brake fluid and check your clutch system (master cylinder, slave cylinder) for leaks. Changing the fluid will solve a transmission problem before worrying about having to replace the clutch or transmission. The problem may only be minor now. Continuing to double clutch will most likely cause more damage and lead to a major repair or a new transmission.
  • #3
    Try slowing down your 1-2 shift by holding the clutch to the floor for 1/2 a second before you move the shifter.

    I've also found that the fluid type / manufacture makes a big difference. The non world class T5 takes both ATF and gear oil.

    I've found that Redline D4 ATF works extremely well even compared to normal ATF.

    When I run gear oil it does not shift well until the transmission is warmed up.
    Life's short
    Go fast
    Have a blast
    Leave a good looking corpse
  • #4
    Maybe worth checking the clutch fork too?
  • #5
    I've also found that the fluid type / manufacture makes a big difference. The non world class T5 takes both ATF and gear oil.
    Interesting. The FSM states using API GL-4. The fact sheet for the DT ATF says it can be used in manual transmissions. Though I only drive the Z's in the summer, I'll still have to check that out.

    Comment

    • shromy
      #5.1
      shromy commented
      09-29-2016, 11:47 AM
      only use atf in the t5
  • #6
    Thanks for the response. i replaced the gear oil and the problem is better. i believe is just one of the syncros slowly going bad. Now it only buzzes when i shift 1 to 2 very quickly. slowly shifting solves the problem completely too.
    thanks
  • #7
    The 71C is a very robust transmission. It's the same transmission used in the 720 pickup. They're hard to break unless you are an ogre and have superhuman strength. Change the gear oil every 45,000 to 60,000 miles and they should be fine. When your shifting, make sure you put the clutch pedal all the way to the floor. If I don't do it on the Turbo Z, I'll get a hard shift. Also, when stopped or at a red light, make sure your foot is completely off the clutch. Keeping the foot on the pedal can wear it down fast.

    I would suspect the clutch before the transmission. It may just need an adjustment, or it may need to be replaced. How many miles are on the car? When was the clutch last replaced? My clutch was replaced in 2012 and has only been driven around 5000 miles since then. The shifts link together smoothly with no issues.

    Some Z31 guys say the 71C is also supposed to be stronger than the Borg Warner T-5 which is what's used in the turbo model. However, I think the debate is still out on that because there are Z31 builds with over 450 horsepower using the factory T-5.
    Last edited by daniel_pearce; 09-28-2016, 12:46 PM.
  • #8
    I need to replace the clutch sometime soon. i just haven't had the time or money yet. I bought it on CL and i have no idea how old the clutch is. There is 165,000 miles on the car.
  • #9
    Ask the previous owner when the clutch was done, that way you're not wasting extra money if it simply needs an adjustment.
  • #10
    if you do the clutch do a search on using a 250mm clutch off a naturally aspirated 350Z or G35.

    Even though your clutch disk is only 240mm the flywheel has room for a 250mm disk and pressure plate if you have the whole flywheel surfaced flat.

    This opens up a whole world of additional parts that available.


    I'm running a stage 2 clutch/pp off a 370Z right now on my daily driver.
    Life's short
    Go fast
    Have a blast
    Leave a good looking corpse
  • #11
    You're running a stage 2 clutch for DD? Aren't you finding the shifts a bit harsh?
  • #12
    Good sign that you may need to bleed the master/slave cylinders as well.