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

flywheel swap?

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Old Nov 7, 2005 | 09:06 AM
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flywheel swap?

How bad would it be to put an 82 flywheel onto an 84 engine?
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Old Nov 7, 2005 | 11:11 AM
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i think you would have to change the front counterweight to make it work.
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Old Nov 7, 2005 | 12:14 PM
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also take into consideration that when you do it you will have to use the 82 starter (been though that problem way to many damn times). the 82 and 84 starter are different.
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Old Nov 7, 2005 | 12:40 PM
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dare I ask about the magic year of 83?
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Old Nov 7, 2005 | 02:11 PM
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I am not 100% which year they switched the starters. but when i got my 84 it had an 82 motor. so i bought an 84 starter and it didn't work. then i got an 82 starter and the motor blew up and i put an 84 motor back in. So now i have a brand new 82 starter that will not work. It will fit but the gear is different
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Old Nov 7, 2005 | 04:05 PM
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Originally Posted by Midwest 7's
i think you would have to change the front counterweight to make it work.
It still won't match the weight of the rotors.
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Old Nov 7, 2005 | 05:07 PM
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oh well, baring nothing else...atleast I know that I need a new starter...teh 82 is what WAS in there, but I have an 84 cause it was cheaper than rebuilding the 82
Well, then my question is, once I swap out the rotors, will the e-shaft be unbalanced?
Also, would it run super rough and wear out faster if it wasnt properly balanced, like say I did go through w/ jsut swapping the counterweight and flywheel, or am I in a bad boat since the clutch and pressure plate were removed before i got ahold of it and cant put it back just the way they came off?
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Old Nov 7, 2005 | 10:06 PM
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This should answer some of your questions http://www.mazdatrix.com/faq/flywheel.htm
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Old Nov 7, 2005 | 10:52 PM
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just get an 84 clutch and starter and you should be all good.
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Old Nov 7, 2005 | 11:03 PM
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Rotors and counterweights/flywheels are balanced ASSEMBELIES.That means you cant mix and match parts from one to the other.The E-shaft itself makes no difference,but the rotors,front counterweight and flywheel are all balanced to each other.Running out of balance will destroy the engine after a while,a total waste of a good engine,esencially.Stick to the swap guide as indicated by this Mazdatrix page.....
http://www.mazdatrix.com/faq/rotorwgt.htm

Last edited by steve84GS TII; Nov 7, 2005 at 11:05 PM.
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Old Nov 7, 2005 | 11:05 PM
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Well now my 76 RX4 has a 86 fly wheel still useing the 76 trans and starter
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Old Nov 7, 2005 | 11:07 PM
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If its a 76 13B with an 86 flywheel,then your off by a pound and a half on your rotor balance.
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Old Nov 8, 2005 | 01:09 AM
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ive got a complete 79 engine (w/fly and pressure plate) bolted to an 83 5spd using the 83 clutch disc and starter.. no problems here

the 83 fly and pp were much beefier, and the clutch disc is a smidgen big for the 79 assy, but it fit.
thats the magic year of 83
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Old Nov 8, 2005 | 01:58 AM
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The 83-92 non turbo engines used a 225MM clutch as opposed to the 215MM clutch of the earlier years.The 225MM is a little bigger which provides more hold,the 215MM clutch being smaller will give you quicker shifts due to its lower mass on the trans input shaft.

Either gain is mimimal...
Its likely the 225MM clutch came about with the introduction of the Jspec turbo 12A in 1983.They just made it standard equipement on all engines till the TII upped the ante...
The 215MM clutch held up fine for a decade on earlier engines.The turbo 12A had more torque which dictated a bigger clutch.This plays well for later engines like the SE and 2nd gen n/a 13Bs,both of which have substantially more torque than the n/a 12A.
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Old Nov 9, 2005 | 06:58 PM
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Well, it seems to me that if the assembly is balanced the way it is...moving to a lightened flywheel such as Mazdatrix's or using a lighter flywheel and counter balance much like going to the 82's 23# verses the 84's 26# would mess up the engine, yet people buy the lightened flywheels. Are the 84's rotors' weights unbalanced compared to the 82's? Or were they uniformly lightened?
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Old Nov 10, 2005 | 12:40 AM
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Aftermarket light flywheels always use a factory A/T rear counterwieght to keep proper internal balance.The aftermarket flywheel itself is a perfect circle with neutral balance.You could run the engine with just the rear counterweight and no flywheel,and itd be balanced.
If anyone tries to sell you a "lightened" stock flywheel,pass on it.In order to make any substantial difference in rotating mass,the weight removed from a flywheel needs to be towards the outer edge.On stock rotary flywheels,the counterweight "lump" is on the outer edge.Removing material from that area will disturb the balance of the engine since the rear counterweight will now be lighter than the front weight.

Any time the weights of the rotors are changed,the counterweights on both ends have to be adjusted accordingly.This includes swapping in rotors from different series engines AND race lightening stock rotors.The E-shaft is neutral and aftermarket flywheels are neutral.Just remeber to use the proper A/T rear counterweight for your series ROTORS,when installing an aftermarket flywheel.
Stock M/T flywheels,A/T rear counterweights,front counterweights and rotors MUST ALL be from the same series engine to get proper balance.Compression is of no concern,but rotor weight MUST be matched to the right counterwieght/flywheel.

Series are as follows.....
76-82 12A ------10.15lbs
83-85 12A-------9.60lbs

74-78 and 84-85 13B------11.58lbs
86-88 N/A and TII 13B-----10.04lbs
89-92 and 93-95 13B------9.54lbs

Last edited by steve84GS TII; Nov 10, 2005 at 12:45 AM.
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Old Nov 10, 2005 | 08:18 AM
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ok cool, thanks
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Old Nov 10, 2005 | 03:28 PM
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Starters are interchangeable for the most part. I've tried all sorts of combos, but the largest spread has been S4 NA starter on a '74 REPU. All I had to do was to grind out some of the casting flash inside the bellhousing. It's easier if the engine is not in the way.
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Old Nov 10, 2005 | 04:12 PM
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i currently have an 82 starter in my 84 with no problems.
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