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Index > Engine/Drivetrain > Thread: Flywheel question.
Thread: Flywheel question.
sparky


Redlining
Posts: 299
posted February 14, 2006 08:15 PM

Flywheel question.

OK, I scored on a 83 rx-7 tranny, Thanks to Repumax. I modified the shift linkage so it will work fine. I ordered a 83 rx-7 clutch disc and found out it was too big for my flywheel and pressureplate. Here is my question. My flywheel has "KD24" stamped on the engine side. Can I install a 85 rx-7 gsl-se flywheel and pressure plate without changing the front counter weight. Also, If I need to replace the front counter weight, what engine/car has the same counter weight. Thanks, Sparky.
____________
'77 REPU
Stock 6-port
T-2 tranny
Weber IDA 48
Alum Flywheel
3rd gen Torsen in rear end.
DLDFIS ignition

       
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mazdarx605


Redlining
Posts: 314
posted February 15, 2006 04:03 AM

We need to know what year engine is in the truck.I think the front counter weight is the same for all 13B engines from 74-85,but the rear counter weight is different on the 74-75 13B's.Heck you may be using a 12A in the truck for all I know.I could be wrong on this,but others can help I am sure.I would think Mazdatrix could help you out as far as this is concerned.The thing is though if you just want to use a rear counter weight from mazdatrix you will need to use their light weight flywheel.If you want just a regular heavy flywheel you will have to get the right one for the engine I think.I am sure this post has not helped that much.

Chris
74 RE/PU
79 RX-7 GS
83 RX-7 LE parts car
92 Cummins diesel

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sparky


Redlining
Posts: 299
posted February 15, 2006 06:53 AM

Thanks Chris. The engine in the truck is a rebuilt 4-port 13B. It was in the truck when I bought it 2 years ago. I was hoping I could figure out what model flywheel I have and determine if I can use the 85 gsl-se flywheel and pressure plate with the existing front counter weight.
____________
'77 REPU
Stock 6-port
T-2 tranny
Weber IDA 48
Alum Flywheel
3rd gen Torsen in rear end.
DLDFIS ignition

       
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klaus42


Rotorhead
Posts: 1877
posted February 15, 2006 09:14 AM

Flywheel ID's:

...Dunno about the 'KD', but, the flywheels came in different weights... and the following is all the info. I have, (courtesy of Charles; thank you!!!):

'79-'80 12A 30 lbs.; no #

'74-'78 13B 31?lbs.; no #

'81-'82 12A 23 lbs.; 21 stamped on engine side

'83-'85 12A 26 lbs.; 31 " " " "

'84-'85 13B GSL-SE 26 lbs.; 304 stamped...

'86-'88 non-turbo 24 lbs.; 326 stamped...

'86-'88 turbo 27 lbs.; 318 stamped

'89-'92 non-turbo 21 lbs.; 350 stamped

'89-'92 turbo 23 lbs.; 370 stamped

'93-'95 TT 20 lbs.; N3A1 stamped

...hope that helps! :)

       
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RotaryRob


Revvin Up
Posts: 53
posted February 15, 2006 09:39 AM

Sparky,

I think you'll be OK using your GSL-SE setup on the old 4-port without changing anything else. The rotors are virtually identical in weight and configuration. The counterbalance needed is determined by the rotor weight. The total weight of the flywheel, of course, isn't the critical factor in the balance of the engine, but the counterbalance characteristic of the flywheel. I encourage you to review the use of the truck... If you are going to use it as a hot rod the lighter flywheel from the SE will help it rev more quickly; but if you are using it for heavy hauling or towing, sticking with the original heavier unit will definitely work better.

Happy Rotoring

Rob
____________
'77 RPU
'75 RPU (V-6)
'76 Courier
Rotary Sprite (3 - 2 project)
'85 IT 7
EP '85 Rx7 (in progress)
'85 GSLSE (4)
C6 Corvette Roadster

       
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sparky


Redlining
Posts: 299
posted February 15, 2006 10:14 AM

Thanks Klaus and Rob. I definitly am looking forward to a lighter flywheel for hot rod puposes. Also, the flywheel on the truck now uses a 8-1/2" clutch disc verses a 8-7/8" disc on the gsl-se flywheel. I looked on the mazdatrix website and was not able to reference the numbers stamped on the flywheel, It's the same info Klaus mentioned. I think I'll try installing the gsl-se flywheel. If the balance weight in the front is not compatable with the flywheel, will it be obvious? If so how? Vibration? ect. Thanks for all the response.
____________
'77 REPU
Stock 6-port
T-2 tranny
Weber IDA 48
Alum Flywheel
3rd gen Torsen in rear end.
DLDFIS ignition

       
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klaus42


Rotorhead
Posts: 1877
posted February 15, 2006 10:48 AM

You may want to...

...start by confirming the weight of your flywheel(s) in question... and, perhaps, seek expert confirmation of your counterweight ID situation, to save yourself the hassle of possibly installing the wrong one...

Vibration/out-of-balance is indeed a potential issue! Not something you want. I noticed Atkins has a brand-new balancing setup now... (Though the counterweight ID ought to be doable via a conversation...?)

Best, K.

       
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RotaryRob


Revvin Up
Posts: 53
posted February 15, 2006 12:24 PM

Sparky,

Reading this again it's appearant that what you have now is a 13B from an Rx4 or Cosmo. The original RPU flywheel would accept the diameter of the later disk. If your flywheel / clutch cover has 6 bolts instead of 9 this is definitely the case. RPU flywheels are even heavier and have bigger clutches and the 9-bolt configuration. It is not at all unusual to find Rx4 engines in these old trucks as the original, non-nitrided 13B's typically only lasted about 60 to 70 thousand miles. If you go with an after market flywheel you will need to buy a rear counterbalance that the flywheel bolts to. Be sure you get one for an "early" 13B.

Happy Rotoring,

Rob
____________
'77 RPU
'75 RPU (V-6)
'76 Courier
Rotary Sprite (3 - 2 project)
'85 IT 7
EP '85 Rx7 (in progress)
'85 GSLSE (4)
C6 Corvette Roadster

       
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sparky


Redlining
Posts: 299
posted February 18, 2006 09:04 AM

What a pain in the posterior. I gave up on the light flywheel thing. The flywheel I have has a 6 bolt pressure plate and most likely pre 78, which means it has the heavier rotors so I can't use a newer and lighter stock flywheel. Anyway, someday I'll upgrade to the turbo 2 tranny. I got the 83 tranny in the truck last night. It's alot different with the short throw shifter. Can't wait to modify the rear end with LSD. Thanks again for all the help. Sparky.
____________
'77 REPU
Stock 6-port
T-2 tranny
Weber IDA 48
Alum Flywheel
3rd gen Torsen in rear end.
DLDFIS ignition

       
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