Flywheel vs. plexplate? DIFFERENCE??? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

jess66chevy · 08-03-2009, 12:30 AM

Whats the difference between a flywheel and a flexplate?

PrerunnerRob · 08-03-2009, 01:00 AM

A flywheel is used in with a manual transmission, a flexplate is used in an automatic.

MacAttack · 08-03-2009, 10:44 AM

Flexplate:

Flywheel:

Mac.

ol Curt · 08-03-2009, 10:47 AM

Hmmmm....I guess that means I have to buy a flex plate in order to hook up the TH350 I am getting this Friday. Are they sized by engine, transmission or some other means?

Thanks!

TheDark1 · 08-03-2009, 05:35 PM

Should be sized by engine and starter location. Some engines are internally balanced and others externally balanced. Some starters bolt to the block and some bolt to the transmission, each requiring a different ring gear tooth count.

jess66chevy · 08-03-2009, 06:13 PM

How do I know if I need an "external" or "internally" balanced flexplate?

**bigsnookmaster** · 08-03-2009, 06:44 PM

If you have a small block 400,you need an external one. All other small blocks are internally balanced. I believe that 454's are also externally balanced as well.

TheDark1 · 08-03-2009, 08:21 PM

I think BigSnook is right. Stroker 383's are external also. I don't know about the inline sixes though.

Tx Firefighter · 08-03-2009, 08:30 PM

My first answer to the difference is about 45 pounds.

Seriously though, inline 6 engines in 230 and 250 size use the same unit as the normal internally balanced small block. 292 has larger bolts, so the holes are too large for small block use.

Easiest way is to go to any common parts store and tell them you want a Pioneer FRA100. That's the common flexplate that fits all small blocks but the 400.

Expect to pay about 35 dollars. Places like O Reilly keep them on the shelf in stock.

hungarian1964 · 06-15-2012, 12:15 PM

I installed a 168th tooth (14") on my 68C-10
250 Inline 6, backed with a TH350. That is the WRONG Flexplate, the starter shaft hits it, needs the 153th (12 3/4") Flex
Posted via Mobile Device

Tx Firefighter · 06-15-2012, 01:40 PM

Starters and flexplates have to match. You had a mismatch between your starter which was intended for a 153 tooth plate and the 168 tooth flexplate. It's not that the 14 inch one was wrong, it just didn't match your combo. You can use either as long as you keep the differences in starter in mind when you choose.

hungarian1964 · 06-15-2012, 02:21 PM

That's great info, but when I go to the autoparts store, they only come up with one starter for my application , what should Zi order??
Posted via Mobile Device

bama63 · 06-16-2012, 06:19 PM

if your starter bolts to the block the diagonal bolt pattern starter head fits the 168 tooth flex plate and the straight across pattern fits the 153 tooth hope this helps

08-03-2009, 12:30 AM	#1
jess66chevy Registered User Join Date: Jul 2009 Location: glendale, az Posts: 192	Flywheel vs. plexplate? DIFFERENCE??? Whats the difference between a flywheel and a flexplate?

08-03-2009, 01:00 AM	#2
PrerunnerRob Registered User Join Date: Jan 2007 Location: San Jose Posts: 847	Re: Flywheel vs. plexplate? DIFFERENCE??? A flywheel is used in with a manual transmission, a flexplate is used in an automatic. Last edited by PrerunnerRob; 08-03-2009 at 01:00 AM.

08-03-2009, 10:44 AM	#3
MacAttack 283 Drama Queen Join Date: Dec 2004 Location: Surf City, CA Posts: 2,435	Re: Flywheel vs. plexplate? DIFFERENCE??? Flexplate: Flywheel: Mac. __________________ For about 12 years of my adult life I had a severe speech impediment. My ex-wife never let me get a word in edgewise.

08-03-2009, 10:47 AM	#4
ol Curt Junior Member Join Date: Dec 2006 Location: Newburgh, IN Posts: 1,247	Re: Flywheel vs. plexplate? DIFFERENCE??? Hmmmm....I guess that means I have to buy a flex plate in order to hook up the TH350 I am getting this Friday. Are they sized by engine, transmission or some other means? Thanks! __________________ 1966 Chevy C10 Longbed I'm Bob....ol Curt was my Grandpa The truck was his and he sure as heck wouldn't understand why I took a perfectly good truck and tore it down!

08-03-2009, 05:35 PM	#5
TheDark1 Intentionally Left Blank Join Date: Dec 2008 Location: Broussard, LA Posts: 355	Re: Flywheel vs. plexplate? DIFFERENCE??? Should be sized by engine and starter location. Some engines are internally balanced and others externally balanced. Some starters bolt to the block and some bolt to the transmission, each requiring a different ring gear tooth count. __________________ 1965 C-10 Short Fleet 468/TKO 5-Speed 2004 2500HD Crew 496/Ally Blacked Out (SOLD!!) 1997 Formula WS6 2004 Jeep Wrangler (Sold) 2013 Jeep Wrangler (Sold) 2017 Jeep Wrangler (Blacked Out on 35's) 2011 GMC D-Max Dually Denali 3500HD (Sold) 2015 GMC D-Max Dually Denali 3500HD (Sold) 2018 GMC D-Max Dually Denali 3500HD (Sold) 2020 D-Max Dually Denali on 33x12.50's 1979 GMC Short Bed Step-Side 4x4 350/350 Low Miles

08-03-2009, 06:13 PM	#6
jess66chevy Registered User Join Date: Jul 2009 Location: glendale, az Posts: 192	Re: Flywheel vs. plexplate? DIFFERENCE??? How do I know if I need an "external" or "internally" balanced flexplate?

08-03-2009, 06:44 PM	#7
bigsnookmaster Senior Member Join Date: Jan 2008 Location: St.Petersburg,Fl Posts: 1,268	Re: Flywheel vs. plexplate? DIFFERENCE??? If you have a small block 400,you need an external one. All other small blocks are internally balanced. I believe that 454's are also externally balanced as well. __________________ greg http://community.webshots.com/user/68406Stepside

08-03-2009, 08:21 PM	#8
TheDark1 Intentionally Left Blank Join Date: Dec 2008 Location: Broussard, LA Posts: 355	Re: Flywheel vs. plexplate? DIFFERENCE??? I think BigSnook is right. Stroker 383's are external also. I don't know about the inline sixes though. __________________ 1965 C-10 Short Fleet 468/TKO 5-Speed 2004 2500HD Crew 496/Ally Blacked Out (SOLD!!) 1997 Formula WS6 2004 Jeep Wrangler (Sold) 2013 Jeep Wrangler (Sold) 2017 Jeep Wrangler (Blacked Out on 35's) 2011 GMC D-Max Dually Denali 3500HD (Sold) 2015 GMC D-Max Dually Denali 3500HD (Sold) 2018 GMC D-Max Dually Denali 3500HD (Sold) 2020 D-Max Dually Denali on 33x12.50's 1979 GMC Short Bed Step-Side 4x4 350/350 Low Miles

08-03-2009, 08:30 PM	#9
Tx Firefighter Watch out for your cornhole ! Join Date: Jun 2003 Location: Azle, Texas Posts: 14,162	Re: Flywheel vs. plexplate? DIFFERENCE??? My first answer to the difference is about 45 pounds. Seriously though, inline 6 engines in 230 and 250 size use the same unit as the normal internally balanced small block. 292 has larger bolts, so the holes are too large for small block use. Easiest way is to go to any common parts store and tell them you want a Pioneer FRA100. That's the common flexplate that fits all small blocks but the 400. Expect to pay about 35 dollars. Places like O Reilly keep them on the shelf in stock. __________________ I'm on the Instagram- @Gearhead_Kevin

06-15-2012, 12:15 PM	#10
hungarian1964 Registered User Join Date: Feb 2012 Location: Lacrescenta, CA Posts: 61	Re: Flywheel vs. plexplate? DIFFERENCE??? I installed a 168th tooth (14") on my 68C-10 250 Inline 6, backed with a TH350. That is the WRONG Flexplate, the starter shaft hits it, needs the 153th (12 3/4") Flex Posted via Mobile Device

06-15-2012, 01:40 PM	#11
Tx Firefighter Watch out for your cornhole ! Join Date: Jun 2003 Location: Azle, Texas Posts: 14,162	Re: Flywheel vs. plexplate? DIFFERENCE??? Starters and flexplates have to match. You had a mismatch between your starter which was intended for a 153 tooth plate and the 168 tooth flexplate. It's not that the 14 inch one was wrong, it just didn't match your combo. You can use either as long as you keep the differences in starter in mind when you choose. __________________ I'm on the Instagram- @Gearhead_Kevin

06-15-2012, 02:21 PM	#12
hungarian1964 Registered User Join Date: Feb 2012 Location: Lacrescenta, CA Posts: 61	Re: Flywheel vs. plexplate? DIFFERENCE??? That's great info, but when I go to the autoparts store, they only come up with one starter for my application , what should Zi order?? Posted via Mobile Device

06-16-2012, 06:19 PM	#13
bama63 Registered User Join Date: Jun 2010 Location: gadsden, alabama Posts: 468	Re: Flywheel vs. plexplate? DIFFERENCE??? if your starter bolts to the block the diagonal bolt pattern starter head fits the 168 tooth flex plate and the straight across pattern fits the 153 tooth hope this helps __________________ Due to financial constraints, the light at the end of the tunnel will be shut off until further notice

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