C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

M21????

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Old May 6, 2002 | 10:09 AM
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Default M21????

Anyone know of a way to swap in a Muncie M21 tranny into a C4 (85)????? My Richmond is very nice but the gear hum is starting to get on my nerves. Any help appreciated. :chevy
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Old May 6, 2002 | 11:30 AM
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The 4+3 transmission available in 84-88 was based off of a Borg Warner Super T-10 four speed. Since BW took over Muncie, I would think it would be an easy thing todo.
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Old May 6, 2002 | 03:12 PM
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Default Re: (scorp508)

The 4+3 transmission available in 84-88 was based off of a Borg Warner Super T-10 four speed. Since BW took over Muncie, I would think it would be an easy thing todo.
I guess what I'm wondering about is the attachment to the C beam???
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Old May 6, 2002 | 03:34 PM
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Default Re: (GRX)

You don't like gear hum, then don't get a M21 or M22. Just swap in a richmond 6 speed.
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Old May 6, 2002 | 03:36 PM
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Default Re: (GRX)

Yeah, I think the C-beam issue will put a kink in that plan. Richmond made a special tailshaft housing for the 5spd & 6spd in order to accomdate the C-beam. I don't know if the Muncie's are at all related to these boxes, kinda doubt that. Anybody have first hand knowledge?

If you wanna switch back to the 4+3 I'm ready and willing to swap transmissions with you. I'll even do all the work! :)


[Modified by jmr302, 1:43 PM 5/6/2002]
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Old May 6, 2002 | 03:37 PM
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I'm just guessing that the 4+3 is quieter than the Richmond.
Mine is pretty silent.
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Old May 6, 2002 | 03:41 PM
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Default Re: (scorp508)

OOPS! I misread that! You have a richmond and it whines?!? :eek: Wow, that's strange.
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Old May 6, 2002 | 03:59 PM
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Default Re: (TIMSPEED)

Yeah, the gears are 'straighter' cut than stock street applications. I was considering welding up a bracket that could bolt up a muncie with the C beam. Maybe attach it at the typical crossmember mount area and maybe pick up 2 bolts mouting at the bellhousing. ....or even custom weldup a steel C beam that could mate between the Muncie and the rear end?
Any ideas?
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Old May 6, 2002 | 07:07 PM
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Default Re: (GRX)

I think you've got the right idea here. Maybe a couple pieces of ~8" long 1/2" Black Standard pipe for the c-beam bolts, welded to a 1/2" thick solid (no rubber mount) steel strap to fit the Muncie rear trans mounting bosses. Cut a triangle-shaped piece or two to weld into the 90* angle these other pieces make, and you've got that nailed.

Adapt the C4 shift rods to fit the Muncie shift arms. Should be easy. I even have a complete C3 shifter I'll sell you (Muncie 4 speed).

Driveshaft...hmmm, you may have to have a C3 yoke mated to a C4 driveshaft; it may even have to be shortened or lenghtened...Still not too hard; a specialty shop near me does it (they made a custon shaft for my last kitcar), there's surely one near you - look in The Yellow Pages under U-Joints and/or Driveshafts.

Use a 10 1/2" C3 friction plate (if the spline is different from C4; I don't know), and that should take care of that...
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