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Flywheel differences

Discussion in 'Manual Transmission & Clutch' started by Frankenchevy, Oct 27, 2020.

  1. Frankenchevy

    Frankenchevy Lying Dog-Faced Pony Soldier

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    I picked up this bell housing for my upcoming nv4500 swap from advance adapters. The bell housing allows for the 1996 & up nv4500 to utilize 85-87 slave cylinder and clutch components.

    B1B882D4-F152-493A-A9E7-DD4A0BDD98F7.jpeg

    QUESTION IS:

    As mentioned, the bell housing is designed to be used with 85-87 clutch components. However, I have an L31r vortec engine from a 96-99 pickup that I bought new from GM about a year ago.

    IIRC, the 96-99 vortec 350 is internal and external balanced and uses a different style flywheel than other 86+ 350s which are externally balanced only. I know they all went 1-piece RMS in 86, but I might be making up the rest of it in my head.

    Long story short, is there a difference in a flywheel for a 1986 350 and a 1997 350? Just trying to figure out what to order...

    most accurate answer wins all my Halloween candy.
     
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  2. Nonstop

    Nonstop Full Access Member

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    According to Rock Auto - it is the same flywheel from 86-98.

    Better not be the leftover sucky candy!
     
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  3. bucket

    bucket Super Moderator Staff Member

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    I thought this was discussed already? Maybe I'm going nuts though.

    But yes, it's the same flywheel from '86-'98. The engine balance is the same. However, if you are looking it up by application for a vortec truck, it has to be for a 1/2 ton truck to get the same flywheel. The heavier trucks obviously got the 4500 trans.
     
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  4. Frankenchevy

    Frankenchevy Lying Dog-Faced Pony Soldier

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    I think you’re correct. I’m the one who’s losing his marbles.
     
  5. idahovette

    idahovette Full Access Member

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    You two playing "Keepsies"
     
  6. Frankenchevy

    Frankenchevy Lying Dog-Faced Pony Soldier

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    I haven’t shot marbles since cub scouts. I remember asking if there was an achievement patch involved and immediately losing interest after finding out there wasn’t.

    I need the patches Perry!
     
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  7. idahovette

    idahovette Full Access Member

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    Can't have em, I lost em.....Can I have one of your truck washing patches????.....LOL
     
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  8. SquareRoot

    SquareRoot Full Access Member

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    Frankenchevy-

    You and I are in the same boat right now. I'm planning to swap my 400 for my 4500 in the next two weeks. I've been putting it off until it cooled off here. Initially I was going to swap the trans and tcase together, all at once along with the pedal assembly. I've got a round pattern 205 with twin sticks ready to drop in behind the 4500. I have been hesitant because I'll need the driveshafts redone and until its all bolted in I cant predict what that will involve. I have a 2 piece shaft out of a burb and a carrier bearing mount but it will still require some thought.

    I've been following your posts and I recently read that the 4500 is the same length as the 400. WHAT! That being the case, I'm going to just swap the trans and pedals for now and run it with the current 208. Once I work the bugs out, I'll revisit the 205/twin-stick swap.

    I've pulled the dash, dropped the steering column and removed the pedal assembly a few times. I know the process by memory and I know thats a days work just right there (in my case anyway with my Vintage Air, Dakota Gauges, Stereo Mods).

    I'm also swapping over to hydroboost this time. I just got a seal kit for it since mines been sitting for a few years.

    FYI, I've got a 93 NV 4500, AA bellhousing, external d/s slave. I bought the trans from a guy who had it rebuilt and wrecked the truck shortly thereafter. It also had a new flywheel and 12" clutch. My engine is a GM crate "non vortec" 350 so the flywheel wont bolt to my engine so I bought a new one for a gen 1 engine. The 12" clutch bolts up fine and fits inside the AA Bellhousing.

    I bought all new LUK brand master cyl, line/hose, slave cyl for a 93.

    I will setup my pedal assemblies on my workbench tomorrow so I can compare them and try to help you with pics and measurements on how we can get set up correctly with your pedal situation.

    Keep posting on the swap and we can help each other get thru this together. :favorites13:
     
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  9. Frankenchevy

    Frankenchevy Lying Dog-Faced Pony Soldier

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    @SquareRoot

    I’m keeping the 208 as well. Seems pretty straightforward. With my cross member, I’ll have to make a roughly 4” perch to reach the mounting points on my 96+ nv4500 from what I’ve read. My rear driveshaft should be good, which is nice since I just had a new one built. I’m going to have a new front DS built. My ORD springs are going to locate the axle 1” forward and it needs to be rebuilt anyhow.

    I can’t start mine till next week sometime. I’m dropping it off to get the axles rebuilt.

    Which flywheel and clutch are you going with? I’m leaning towards a Centerline billet flywheel and McLeod clutch. I’m also leaning towards LuK components for the clutch hydraulics.
     
  10. SquareRoot

    SquareRoot Full Access Member

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    @Frankenchevy

    All my parts are new LUK.

    Why a new front shaft?
     
  11. Frankenchevy

    Frankenchevy Lying Dog-Faced Pony Soldier

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    ORD talked me into relocating my axle 1” forward. Not to mention, it the original driveshaft. Only has 65,000 miles, but 35 years old and the CUCV shafts are non greasable.

    You have p/n for the LuK clutch, pressure plate and flywheel you purchased?
     
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  12. SquareRoot

    SquareRoot Full Access Member

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    Alternate/OEM Part Number(s): L04902, LUK 04902.

    https://www.rockauto.com/en/moreinfo.php?pk=4697655&cc=1408328&jsn=1168

    Copy on the front shaft.
     
  13. SquareRoot

    SquareRoot Full Access Member

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    Screenshot_20201029-125254~2_copy_540x795.png @Frankenchevy

    So I've done some research on the 400/4500 trans case lengths. The 400 case is 25 inches from front to rear mounting flange without any tail housing as the t-case bolts directly to the case. (2 wd versions have several different tail housing lengths).

    The 4500 has an overall length of 25.17 inches.

    So this makes sense they will interchange and bolt back in the original location except for the trans mount spacer that's needed.

    However, this is where I'm confused and cant recall the 400/208 mounting "foot"? Doesn't the foot go between the trans and t-case and take up about 1.5 inches? If so, that piece being eliminated will result in the driveshaft being the same distance shorter. The shaft may still fit but it wont be fully engaged if I'm thinking about this correctly.

    What say others?
     
    Last edited: Oct 29, 2020
  14. SquareRoot

    SquareRoot Full Access Member

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    Here's another pic from a thread I found. This is the adapter that's no longer used. I'm just having a hard time getting the math to work. Lol. I just don't want any surprises once I get it torn apart. IMG_20201029_130650406.jpg
     
  15. Frankenchevy

    Frankenchevy Lying Dog-Faced Pony Soldier

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    Correct, the 400 to 208 adapter goes away. The 208 bolts directly to the back of the nv4500. So in my head, yes you are losing the space the adapter took up in your rear DS and also may need to shorten your front one.

    also, if you have the flat crossmember like I do, you’ll need to make a 4” spacer out of 4x square steel stock. If you have the W style CM, I’ve been told it bolts right up.
     
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