This seems like one of the harder-to-get parts and processes of a 3800 swap, that should be doable by most competent auto machine shops. But many people seem to have difficulty finding a shop to do it. Let me see if I got this straight, and exactly how you would explain to a machine shop what you need done:

We have an externally balanced engine in our car, and want to swap from an automatic transmission to a manual. The flexplate has a weight on it, which balances it out. The manual transmission we are using has a neutrally balanced flywheel, because that engine was internally balanced. So I need the amount of imbalance in the flexplate measured, and applied to the neutrally balanced flywheel by removing material on the flywheel, creating an imbalalnce, the same amount of imbalance in the original flexplate.

So in order to get this done, you would need to bring the original flexplate and the flywheel to the machine shop, so they can measure the amount of imbalance in the flexplate and machine that imbalance into the flywheel. Plus the flywheel would need to be turned down to a total thickness of 0.840 inches.

Is that correct?

Replace "The manual transmission we are using has a neutrally balanced flywheel, because that engine was internally balanced. "

with "This flywheel is neutrally balanced".

Your sentence really doesn't make sense. It isn't the transmission that is neutrally balanced.

You could have said "This flywheel came from a manual transmission attached engine that was internally balanced thus this flywheel is neutrally balanced", but that would imply that you were talking to a kinda moron. Your guy will already know why flywheels are neutrally balanced or not.

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Also specify that the thickness is from the crankshaft flange to the clutch surface - not the total flywheel thickness.

[This message has been edited by phonedawgz (edited 01-15-2012).]

quote Originally posted by phonedawgz: but that would imply that you were talking to a kinda moron.

You should meet the guys at the machine shops around here. I took in with me, a Fiero rear lower control arm, and they told me they couldn't press out the control arm bushing. Not a rusty one either, nice clean one.

Ah - I see.

May I also suggest you no longer use that machine shop.

quote Originally posted by RWDPLZ: You should meet the guys at the machine shops around here. I took in with me, a Fiero rear lower control arm, and they told me they couldn't press out the control arm bushing. Not a rusty one either, nice clean one.

That WOULD be nice, but small town in the middle of nowhere and all.

"Traverse City functions as the major commercial nexus for a seven-county area totaling over 2,700 square miles" sounds impressive until you get to " The population was 14,674 at the 2010 census"

I always thought Traverse City was bigger than that.

The flywheel doesn't come neutrally balance. The supercharged engine just has more imbalance than the n/a do to the heavier duty internals. I've seen some people on here bolt the flex plate to the flywheel with the weight off sets 180* to each other and then it is neutrally balanced. I don't know how my machine shop did it though.

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Turbo 3800 E85 5spd spec5
11.54@132.7

[This message has been edited by Justinbart (edited 01-15-2012).]

'City' would certainly imply that, wouldn't it? Nope, just a spread-out small town, 90% of the vehicles on the road are pickup trucks and SUV's.

quote Originally posted by phonedawgz: "Traverse City functions as the major commercial nexus for a seven-county area totaling over 2,700 square miles" sounds impressive until you get to " The population was 14,674 at the 2010 census" I always thought Traverse City was bigger than that.

Until summer comes.....then it feels like 50,000 and all the motels are full.

Since I'm doing a 3.8 swap at the moment, I have the same question about flywheels.

I was going to reuse the 2.8 flywheel - 6 holes welded up, 8 new holes drilled and flywheel balanced to 3.8 crank.

Will this work? What should I look out for?

The machine shops I use should be able to do most of the work.

And by the way, 3.8 flywheels are very hard to come by in France! (Which is one of the reasons to reuse the 2.8 flywheel!)

Rafe


PS What reference bolts do you guys use? (Since the flex plate bolts are too short.)

quote Originally posted by Englishrafe: Since I'm doing a 3.8 swap at the moment, I have the same question about flywheels. I was going to reuse the 2.8 flywheel - 6 holes welded up, 8 new holes drilled and flywheel balanced to 3.8 crank. Will this work? What should I look out for? The machine shops I use should be able to do most of the work. And by the way, 3.8 flywheels are very hard to come by in France! (Which is one of the reasons to reuse the 2.8 flywheel!) Rafe PS What reference bolts do you guys use? (Since the flex plate bolts are too short.)

One thing to keep in mind is that the 3800 crank holes are not evenly spaced. There is one that is a few degrees off. For the bolts, search the forums for the ARP camshaft bolts.

Re-balancing is not necessary if you are using an N/A 3800, since it's the same exact thing the flywheel was mated too.

But of course everyone is doing the S/C, so why bother saying this...

Im doing an NA swap so that info actually helped.

quote Originally posted by mattwa: Re-balancing is not necessary if you are using an N/A 3800, since it's the same exact thing the flywheel was mated too. But of course everyone is doing the S/C, so why bother saying this...

If you are using a series III 3800 n/a it will need to be balanced.

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Turbo 3800 E85 5spd spec5
11.54@132.7

quote Originally posted by Englishrafe: Since I'm doing a 3.8 swap at the moment, I have the same question about flywheels. I was going to reuse the 2.8 flywheel - 6 holes welded up, 8 new holes drilled and flywheel balanced to 3.8 crank. Will this work?

NO. Too many things can go wrong trying to modify a 2.8 flywheel to work on a 3800. And the last thing you want is the flywheel coming apart at 6000 rpm when you consider that flywheel is right behind your back and head in the car. Get yourself a 3800 Series 2 manual trans flywheel (from a 1996-2002 Camaro/Firebird 3800) and then do what you need to do to it to make it work in the Fiero swap (For Fiero 4-speed muncies and 5-speed getrags: machine down to 0.840" overall thickness + balance match to the OE flexplate you pulled off the 3800 engine you are using; if the balance is different).

quote PS What reference bolts do you guys use? (Since the flex plate bolts are too short.)

Some people have purchased SBC camshaft (or something like that) from ARP and used those. I've heard horror stories of these coming loose on people (probably due to the fact they were not torqued correctly), so I can't recommend anyone uses them.
Some people have used just plain old Grade 8 bolts you can get from the hardware store (here in the USA). But I've heard horror stories of these snapping off after installation (after the engine had been running), so I can't recommend anyone use these either.
Some people have been able to find Grade L9 bolts, which some have suggested are the same grade bolts as the factory used.

I just order new ones from the factory for the 1996-2002 Camaro/Firebird 3800 manual trans flywheel every time I do one of these swaps. Part number is: 24505092, you'll need 8, and list price on them is about $4.25 each. If you get the factory bolts, then you can torque them to factory specs (11ft/lbs - 1st pass; then turn an additional 50 deg in the second/final pass) and eliminate the guesswork. If you use different bolts, you really should contact the manufacturer of those bolts and find out what THEIR recommended torque spec if for their bolts (and not use the GM factory torque spec).

Now, I do want to warn people on here about something I ran into with aftermarket flywheels. I just completed a 3800 Series 3 SC 5-speed Fiero swap not too long ago where we had an issue with some aftermarket flywheels. The 1st aftermarket flywheel was supplied by the customer - he purchased it (I think online) some time before he brought his car to me to have the swap done. I noticed when I first inspected this flywheel that the manufacturer had drilled an excessive amount of "final balancing" holes in it; but aside from that, it looked fine. But when the machine shop turned it down to the 0.840" overall thickness, we found out why the factory had to drill all those holes... There were a lot of voids in the casting that showed up after it was machined down. It was so bad it covered about 1/3 of the flywheel. The machine shop advised us that they would not recommend we use this flywheel because there was no telling just how deep the voids in the casting were, and these voids could compromise structural integrity of the flywheel. So, in a nutshell, fearing a potential safety issue using this flywheel; we ordered another aftermarket flywheel from a different manufacturer. When the 2nd aftermarket flywheel showed up, it had casting voids (imperfections) in the surface of the flywheel you could see before we even had it machined down. So we immediately sent that one back for a refund. The 3rd flywheel we ended up using came directly from GM parts; but, we were told it was one of about three left available in the country, because they have gone out of production. The GM flywheel had the best looking casting, by far, compared to the other two aftermarket flywheels I inspected.

Bottom line is this: inspect your flywheel when you get it before you have any machine work done to it. Check to see how many final balancing holes the factory had to drill into the face of it. There should only be about 2 or 3 final balancing holes drilled into the face (I'm pretty sure this is what the GM flywheel had in it). The other flywheels had more (the worst one had 7). An excessive amount of final balancing holes can be a sign that the casting is probably crap and has a lot of voids in it. Also make sure you inspect your flywheel closely after it is machined down for voids in the casting as well. There can be a very few imperfections, but you don't want a lot at all and I certainly wouldn't use a flywheel that has a lot of imperfections/voids in the casting.

-ryan

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OVERKILL IS UNDERRATED

Custom GM OBD1 & OBD2 Tuning | Engine Conversions & more | www.gmtuners.com

[This message has been edited by Darth Fiero (edited 01-16-2012).]

Not to highjack this thread, but what are you guys doing for a pilot bushing in the end of the 3800 crankshaft when using a 5-speed trans? The ID of the crank measures .825 and the pilot of the input shaft is .750.

Thank you

Kevin

quote Originally posted by 1988 Formula: Not to highjack this thread, but what are you guys doing for a pilot bushing in the end of the 3800 crankshaft when using a 5-speed trans? The ID of the crank measures .825 and the pilot of the input shaft is .750. Thank you Kevin

There is no pilot bushing. We get the getrag rattle instead.

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Turbo 3800 E85 5spd spec5
11.54@132.7