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    Tranny problem

    Sup R3v,

    My sister and I recently bought a 91is. We're loving it so far but it does have it's small issues.

    The problem I am are having currently is that the car tries to fight back when i put it into first gear. It goes into first smoothly, not rough at all, but once I start letting go of the clutch and press down on the gas, the shifter tries to go back into neutral, seems to get stuck halfway, and makes a horrible grinding noise. Sometimes it shoots back into neutral with a loud popping noise.

    This use to happen randomly, mostly when the car first started cold, but it is now happening more often. I don't want to start it from second and only make the problem worse but I can't stand the grinding noise that happens randomly. If I stepp down on the clutch fast enough I can catch it and it won't happen.

    Was planning on changing the transmission oil soon, hopefully that helps somewhat but I'm starting to worry that I might be a bigger problem.

    Another thing I have been noticing is that it feels like I can shift the car without even using the clutch. However I haven't tried to do that yet. But It seems to shift way to easily like if the clutch isn't doing anything. Could it possibly be that?

    We have been tackling the small issues but I do not feel very comfortable dealing with the major things because I don't know much yet So I might take the car to a mechanic. Just wanted to hear what some of you had to say or give me some advice on how I can inspect this myself.

    Like always, thank you guys.

    #2
    Confirm the clutch is disengaging properly. To test it, park the car in 1st gear on a slight incline(one that would only get you moving slowly in neutral). With the motor off, press the clutch all the way in and see if you are moving at the same speed down the incline as if you were in neutral. The reason I suggest doing it with the car off is that you can also listen for any sounds of clutch engagement.


    If the clutch is disengaging properly, I would say the synchros are old and worn. Popping out of gear, needing to rev match, grinding... All classic synchro issues. The solution is rebuilding the transmission or, of course cheaper, getting a used one.

    Techniques to minimize synchro wear (and often these symptoms) are:
    -doing well RPM-matched shifts (both up and down)
    -never shift into a gear at idle and rolling unless you have "spun-up" the clutch to match RPM.
    -only shift into 1st when fully stopped and only after the clutch disc has stopped spinning. Some people when coming to a stop at a stop light or stop sign will preemptively shift into 1st gear when doing 15+mph. This forces the synchros to match 1st gear to whatever speed you are going when you shift into it. For example, At 30mph the input shaft (and clutch mind you) could have to spin at 6000+rpm(an extreme, but possible example) to match the theoretical speed of 30mph in 1st gear. This causes a lot of wear on synchros because they are working overload compared to the generally rev-matched up shifts of normal driving.


    My advice is to review your driving style and keep your eyes open for a new/used transmission while you make do with your current one. It sounds like it could be on it's last legs.
    '84 318i M10B18 147- Safari Beige
    NA: 93whp/90ftlbs, MS2E w/ LC, 2-Step
    Turbo: 221whp/214ftlbs, MS3x flex @ 17psi

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      #3
      Sounds like synchros to me. Most likely the previous owner as well as yourself have been downshifting into 1st with the car moving. Big no-no.

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