1st Generation Specific (1979-1985) 1979-1985 Discussion including performance modifications and technical support sections

79-82 flywheel counter weight

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Old 09-10-08 | 03:00 PM
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79-82 flywheel counter weight

theres only one counter weight for the 79-82 12a?
but the flywheel chart says 70-80 is a type of flywheel and 81-82 is another type than 83-85 is another one

but theres only one counter weight for light weight flyhweel for 79-82? does this mean u can interchange the 79-80 flyhweel with the 81-82?
Old 09-10-08 | 04:10 PM
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what do you mean by "light weight" flywheel.

If its aftermarket you need the automatic flexplate/counterweight. The 83-85's have their own counterweight, 79-80 have their own and 81-82 have their own counterwight. so you need a matching assembly.

good info on the mazdatrix website under FAQ's.
Old 09-10-08 | 06:33 PM
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yeah and mazda trix only shows 2 counter weights

79-82 12A
11-751A-1883


83-85 12A
11-751A-N226
Old 09-10-08 | 06:39 PM
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even the combo kits with aftermarket flywheel with counter weights only have two options for the 12a.
12A
74 - 82 11440
83 - 85 11441
Old 09-10-08 | 08:47 PM
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I think the reason for 2 cw's is for only 2 different rotor weights. IIRC if you also use the front cw for a 79-80 then you can use the 79-80 rear cw and flywheel.
Old 09-10-08 | 09:39 PM
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so the two rotor weights are from 79-82 and than differ from 83 to 85?
Old 09-10-08 | 11:13 PM
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Originally Posted by RX7 allnight
so the two rotor weights are from 79-82 and than differ from 83 to 85?
Correct.

http://mazdatrix.com/faq/Rcounterweights.htm

12A Engines:
-79-82
-83-85

13B Engines:
-76-85
-86-88
-89-95
Old 09-10-08 | 11:24 PM
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save urself some cash and get teh 81-82 stock flywheel. they only weight 21 lbs appx. if you need them, come to 7stock and I will hand it to you.
Old 09-11-08 | 12:20 AM
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Originally Posted by wackyracer
save urself some cash and get teh 81-82 stock flywheel. they only weight 21 lbs appx. if you need them, come to 7stock and I will hand it to you.

I seem to remember reading somewhere that while the actual difference in weight was not much, the positioning of the weight changed the feel of the flywheel.

ah yeah, it was from RacingBeat:
Originally Posted by RacingBeat"
The weight of the stock flywheel is 30 lb (74-80) and 23 lbs (81-85), compared with 16 lbs for the Racing Beat Flywheel. The actual reduction in inertia from stock is much greater than the weights suggest, since the stock flywheel is 1 to 2 inches thick at its outside edge.
Has anyone actually tried both and noticed a difference?
Old 09-11-08 | 08:07 AM
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Originally Posted by Sgt Fox
I seem to remember reading somewhere that while the actual difference in weight was not much, the positioning of the weight changed the feel of the flywheel.

ah yeah, it was from RacingBeat:


Has anyone actually tried both and noticed a difference?

yes I have tried them all. do a search. there was a thread about it sometime last year or earlier in 2008.
Old 09-11-08 | 01:58 PM
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From: https://www2.mazda.com/en/100th/
Originally Posted by Sgt Fox
I seem to remember reading somewhere that while the actual difference in weight was not much, the positioning of the weight changed the feel of the flywheel.

Has anyone actually tried both and noticed a difference?
tried em all too, the 17 vs 21, isnt a huge difference, but either one is better than 30! thats just something to keep the boat from floating away.
Old 09-11-08 | 02:10 PM
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Ok, you know how there is a difference in front couterweights between '80 and '81? This change corresponds with the change in flywheel weights. Do the front counterweights weigh differently? or are they interchangeable? I ask because the rear counterweights are the same from '79-'82 but the rotors are the same from '76-'82 and the front counterweight is the same from '76-'80.

Can any '76-'82 rotating assembly parts be freely interchanged?
Old 09-11-08 | 02:12 PM
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I will let ya know tonight after a 12pack of course
Old 09-11-08 | 10:01 PM
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this is from 81-82? it says number 21 on it
Old 09-11-08 | 10:02 PM
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and this is from 79-80?
Old 09-11-08 | 10:04 PM
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lemme see the faces.
Old 09-11-08 | 10:05 PM
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side by side

Old 09-11-08 | 10:05 PM
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both are the same as pictured in the mazdatrix FAQ from 79-82
Old 09-11-08 | 10:06 PM
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the 83's are different there not smooth on the face.. they have highs and lows these are both smooth
Old 09-11-08 | 10:07 PM
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79-80???
Old 09-11-08 | 10:07 PM
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81-82???
Old 09-11-08 | 10:08 PM
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the bolt mounts on the 81-82 are much lower than the pre-81 and post 82. If I remember tomorrow, I can give you a better pix.
Old 09-11-08 | 10:10 PM
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can i interchange these flywheels without changing the front counter weight? since 79 through 82 share the same rear counter weight??
Old 09-12-08 | 12:33 AM
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I've never seen a stock flywheel. It looks like the counterweight is part of the flywheel?
Old 09-12-08 | 11:32 AM
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From: https://www2.mazda.com/en/100th/
Originally Posted by Jeff20B
Ok, you know how there is a difference in front couterweights between '80 and '81? This change corresponds with the change in flywheel weights. Do the front counterweights weigh differently? or are they interchangeable? I ask because the rear counterweights are the same from '79-'82 but the rotors are the same from '76-'82 and the front counterweight is the same from '76-'80.

Can any '76-'82 rotating assembly parts be freely interchanged?
rotor weight stays the same, so yes.

the 81-82 front counterweight is also different. instead of being 180 is like 90, so its smaller

old pro7/ita trick is to use the 81-82 flywheel/cw and the 83-85 rotors, you need to balance the assembly, but it ends up lighter than stock 83-85


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