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Transplant ‘79 12A into ‘84 series 3

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Old Jan 4, 2021 | 11:36 PM
  #1  
Aaron Thomson's Avatar
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From: orlando
Transplant ‘79 12A into ‘84 series 3

Hi there friends.
helped my 16 year old son buy a ‘84 GLS FB with 12a motor in parts. Then we purchased an entire crashed ‘79 to use the 12A motor.
being ‘79 has points dizzy. Has air pump intact. 81k miles (it was crashed in 1989 -
sat for 31 years )
The ‘79 SA flywheel is obviously 215mm heavier one. Which matches the rotor weights and engine balance.
but clutch won’t match the 1984 gearbox (or will it ?)
I’d have the early SA 5 speed that’s on the motor. But the gearstick pops up in wrong position. Also drive shaft is different.
so - what do I do?
A) bolt up the 84 gearbox into your existing SA clutch and flywheel. It will work.
B) Change the flywheel and use your 84 flywheel (can’t do this I’ve read Because it’s diff weight to match lighter rotors used in 84 -85 )
C) buy billet flywheel get the correct counter weight from the SA auto (this sounds like winning a lottery )
D) some other approach. (Buy a Prius?)

I’m all ears- so much for Gen 1 being the same.
appreciate all your insight in advance.
Aaron
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Old Jan 5, 2021 | 09:05 AM
  #2  
diabolical1's Avatar
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welcome to the board Aaron.

the distributors physically mount the same. just find TDC on the engine and find the mark on the dizzy shaft.

the '79 engine will bolt to your '84 transmission with the older clutch. no problem there. i swapped my 1981 engine to my '83 car when i bought it. as far as i know all Type M (the N/A trannies) trannies have the same input shaft.
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Old Jan 6, 2021 | 12:08 PM
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If you can find an 81/82 manual flywheel, they are compatable with the 79 engine rotating assembly and save about 7lbs of weight from the 79 flywheel. Simple bolt on.

Last edited by diabolical1; Jan 6, 2021 at 05:33 PM. Reason: removed solicitation.
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Old Jan 7, 2021 | 01:16 PM
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Aaron Thomson's Avatar
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From: orlando
Thanks, Diabolical1,
I successfully mated the SA 79 gearbox to the FB '84 gearbox. The input shaft was the same as you said.
Then I checked the 84 driveshaft I got with the 84 car, that's Staked. It has a bad UJ (Universal joint). I called a shop in Orlando. They said they don't repair them!
New one is like 350$ the guys said.
Now I discovered that the tranny gear stick doesn't return to centre position when you rock the stick left to right. (Im not talking about the reverse lock out).
I checked a spare that came with the car in parts. Both of these Type M, boxes - the shifter return spring is broken. It's a single spring with 90 degree bends, in shifter housing under the three bolts - when you pluck out the shifter - there is also rectangular plate side access with 10mm bolts- that's where that spring lives - in that cavity - I wonder if it can be purchased?
In regards to the dizzy - I will set the engine at TDC and swap that - the one I have has two large igniter modules on sides.

Thanks for your help.
Aaron
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Old Jan 7, 2021 | 01:46 PM
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I had my staked driveshaft repaired in my 1985 RX-7. Cost me $110 and now I can replace them myself. Search the first gen technical section for staked and you'll find what I've posted including the u-joint number to use.
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Old Jan 7, 2021 | 05:51 PM
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for the shifter return spring, i don't know if they are still available, but if they are you can check with Mazdatrix, Atkins or Ray Crowe .... in no particular order. for Ray Crowe, you'll have to fish around for his contact information because i heard he's by himself now, and no longer with Malloy.

Driveshaft Thread
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