Rebuild M21 or Borg Warner T5?

Discussion in 'Got gears?' started by josehf34, Feb 12, 2020.

  1. josehf34

    josehf34 Well-Known Member

    Hello guys!

    Finally the Muncie M21 in my 70GS seems to be asking for a rebuild. Since I own the car I have a noise in neutral and it goes away with the clutch pressed. Since a couple days the noise has become a lot louder and now I have a grinding noise ins 1st, 2nd and 3rd which confirms my suspect of an input shaft bearing failure.

    I have driven a couple friend's Camaros and Mustangs with Borg Warner T5 and 5th gear isn't much usable where I live but I really liked how stiff and precise the shifter feels in this transmission, in my M21 feels like gears takes much shifter movement to have them going into, almost feels like driving an old 18 wheeler :confused::D.

    I've read a T5 can live behind a big block in normal conditions (like no 1/4 mile, which I don't do) so I'm not sure if this is at least a viable option for my Buick

    I know the ideal scenario should be a TKO 500 or 600 but that's a $3k+ work and right now my budget is mor focused in the car restoration so isn't an option.

    So what you guys think? should I rebuild the M21 or give the T5 a try? Take in mind what I most like in the T5 is the shifter feeling, the 5th OD gear is a good to have but I don't really need it
  2. 436'd Skylark

    436'd Skylark Sweet Fancy Moses!!!!!

    T5s are not good. It'll last a while if you don't shift hard into third. I know the shifter location is different and will require a new hole in the floor. I'm not sure about the overall length. You'll definitely need a to change the yoke.

    I wouldn't invest much money in the swap if any at all. Whats the t5 out of? The v6 version had a 1" 14 spline shaft that is about useless..
  3. BrianTrick

    BrianTrick Brian Trick

    Rebuild your Muncie
    GranSportSedan likes this.
  4. josehf34

    josehf34 Well-Known Member

    The T5 I can buy for $700 has a 26 spline so it should have came out a v8 car
  5. hugger

    hugger Well-Known Member

    T5 is garbage,..noise in throw out bearing is bad is the noise you hearing

    Husrt comp plus with steel bushings will provide a MUCH better feel,..or you can go with a Hightower shifter setup
  6. josehf34

    josehf34 Well-Known Member

    Is that hurst shifter better than stock hurst shifter in the 70 GS?
  7. Andrew Sury

    Andrew Sury Well-Known Member

    I'd pull the throw out bearing and check it first. T5s are tight because they are internal rail. A decent tranny if you use the clutch to shift. I usually don't. When I drive my Chevelle I pretty much only use the clutch to back out and take off. It's an M22.

    I did this in my 89 S10 I bought new and put three T5s in it in 155K. Never a clutch though/
  8. josehf34

    josehf34 Well-Known Member

    You just woke up my curiosity, If you don’t use clutch to shift so, how you shift?

    what engine you have in the S10?
    Andrew Sury likes this.
  9. 436'd Skylark

    436'd Skylark Sweet Fancy Moses!!!!!

    I wouldn't spend 70 bucks on it. There is a reason why T5s have all but disappeared. Rebuild what you have including the shifter.
  10. Andrew Sury

    Andrew Sury Well-Known Member

    Shift timing and torque. Every engine has a sweet spot in every gear that will let you easily upshift or downshift without the clutch.

    S10 was an Iron Duke that I beat mercilessly delivering pizzas when I was 18. Local boneyard had a contract with the county. They were always wrecking them and I could get a 50k mile T5 back then for $75 if I pulled it.

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