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Flywheel question for those with manual transmissions


carkhz316

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I've machined down 2 RhinoPac brand flywheels in a row now and both have a couple dime sized spots with tiny champagne bubble sized air bubbles in the clutch face of the casting. Will this hurt my stupid expensive Spec clutch? I can't see it being much different functionally than a drilled and slotted brake rotor. What are your thoughts? Is it safe to run or should I return it as a defect as I did with the first one?

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I'm finishing up (trying to) my 284 swap into my Monte and yes they are new, but have to be machined down to .84". This takes just over 1/4" inch of material off the original thickness. Both have been brand new (1st from Rock Auto, 2nd from Amazon). I'm thinking I'm going to cave and just buy the AC Delco one on RA this time.

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ahh, casting porosity.... this has made me a lot of money since the age of 19, i sorted a lot of parts to certify them as good/scrap, if i had to guess i'd say Rhino went through the same process and called them good enough.

 

it doesn't look that bad and i doubt you would have trouble with them. that being said, i wouldn't be too happy about receiving two of them that looked that way.

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If you take 1/4" off a 284 flywheel, and shift it at 6K rpm, I promise itll fly apart. These flywheels are not that thick to begin with. Get a new one, make sure its flat ( do no surface the flywheel ) clean it up, then put it on. No need to machine it, especially 1/4" of machining. I didnt even think you could take 1/4" off these flywheels..

Edited by 19Cutlass94
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Shouldnt matter really. Only flywheel that'll work is a 282/284 flywheel, since a 3800 ( w-body ) never came with a 5spd. So you should be able to bolt it on and go. Ive got a brand new spare sitting in the trunk of my car, and its nowhere near .84".

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If you take 1/4" off a 284 flywheel, and shift it at 6K rpm, I promise itll fly apart. These flywheels are not that thick to begin with. Get a new one, make sure its flat ( do no surface the flywheel ) clean it up, then put it on. No need to machine it, especially 1/4" of machining. I didnt even think you could take 1/4" off these flywheels..

I should have clarified that this a stock F-body 3.8 flywheel. It's original thinkness is somewhere around 1.10". In order to bolt a 284 up to a 3.8, it has to be machined down to .84" At this thickness, there is still plenty of flywheel left.

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Shouldnt matter really. Only flywheel that'll work is a 282/284 flywheel, since a 3800 ( w-body ) never came with a 5spd. So you should be able to bolt it on and go. Ive got a brand new spare sitting in the trunk of my car, and its nowhere near .84".

Trust me, this will work. It is how it is done as there are dozens, if not hundreds of Fiero, Grand Prix, and other car guys that have successfully bolted a 282/ 284 to a 3800. My concern is the porosity in the flywheel face an issue in any application?

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ok ya, makes sense now. In that case, yeah Id get another flywheel. You want your surface of the flywheel to be completely smooth/flat. Youll ruin a clutch disc quickly if its not.

 

I think I was just confused on what engine you were using.

Edited by 19Cutlass94
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Sorry about that. My mistake that I didn't mention that in the first post. Ya, it's going in my 98 Monte Carlo Z34 with a top-swapped 3.8. I'm actually almost done. I'm just waiting on a shifter bracket from another member on here, and that's about it (along with the flywheel). The rest of my interior is done and the engine/ trans are ready to drop back in as soon as I get the flywheel fiasco sorted out. RA just knocked the Delco, and another brand, Brute Power, off their list of flywheels available, so it may be a 3rd time's a charm with the Rhinopac one. I just can't find anything about casting defects like this on google or anywhere so far, and I don't have much experience with manual transmissions.

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No worries man.

 

If theres a casting defect in a flywheel, never use it. Those things do serious damage. Do you have a GM part number for it? I could probably find one for you. Not sure how much your willing to spend on it though.

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Well, this is a project with no set budget, so it's not a big deal on price, though I was banking on staying under $100 with the aftermarket flywheels, but if I have to step up for a quality one, then so be it. I have no GM part number at the moment, and I can't even grab the number from the AC Delco one as they wiped it from RA. (It was still there until last week)

 

Edit. Here's the GM part number: 12576459

Edited by carkhz316
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