On a 3800SC / Getrag swap a modifed flywheel must be used. The two approaches seem to be modifcation to the original flywheel or using a mid 90's 3800 F body flywheel and machining to .840" final thickness that requires removing about 1/4"off the face. ( about 5 lbs of material) The later appraoch makes the most sense to me, but the worrysome part is the amount of machining needed to get the F-Body cast flywheel down to the necessary thickness. It seems to amount to a machine shop charge of $200 or more. Anyone found a more cost effective solution?

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87GT 3.4 Turbo- 0-60 5.2 seconds
2006 3800SC Series III swap in progress
Engine Controls, PCM goodies,
re-programming & odd electronics stuff
" I'M ON THE LOOSE WITHOUT THE JUICE "

I've found a non automotive machine shop with a lathe big enough to turn it down for about $100 but after that I still have to take it to an automotive machine shop for balancing. It's not ideal but it's better than being charged $90/hr to let the flywheel sit on a resurfacer until it gets to the proper thickness.

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Alan Frazier

'84 2m4 project car
'86 GT-'92 3.4 TDC 5 speed(sold)

our machine shop is a well known v8 builder, and he did it fairly cheap. I really dont know what he did specifically, other than spend a decent amount of time balancing it.

IIRC it was about $130 in machine work.

The 3800 flywheel is cast steel and not the easier to machine billet steel. Machine shop work around these parts is very expensive plus Autozone wants $258 for an F body 3800 flywheel. As for balancing, it shouldn't be a real big problem as the 3800 uses a neutrally balanced flywheel. If you add up the total cost of making a 3800 swap flywheel it can amount to one expensive proposition. Going out to the boneyards today to see what I can find.

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87GT 3.4 Turbo- 0-60 5.2 seconds
2006 3800SC Series III swap in progress
Engine Controls, PCM goodies,
re-programming & odd electronics stuff
" I'M ON THE LOOSE WITHOUT THE JUICE "

I have looked for pictures of these "balanced" flywheels forever but didnt found em, found one but it appeared machined wrong later. I also sent that pic to the machinist and he came back to me saying it didnt make sense...
I sent a 99 camaro flywheel and the flexplate of the 98 GTP donor engine as a guide for balancing.
Turned down to 0.840 and two holes were drilled for balancing, hope this is done right..

quote Originally posted by Dennis LaGrua: As for balancing, it shouldn't be a real big problem as the 3800 uses a neutrally balanced flywheel. If you add up the total cost of making a 3800 swap flywheel it can amount to one expensive proposition.

My 3800 SC series 2 is externally balanced and I assume the rest of them are as well. Check this out for reference http://dtcc.cz28.com/tech.htm

It took me a while to find a machine shop to turn down the flywheel for a reasonable price. The trick is to try regular machine shops that don't usually deal with automotive parts, they won't make a big deal of it. If all else fails Loyd can sell you one for a good price.

www.rockauto.com has them dirt cheap.

At autozone, you can buy a 3800 flywheel and use any random flywheel for a core charge usually because they have highschool kids working there most the time.

Go to Advance Autos site ( www.partsamerica.com ) they offer the flywheel for $50.99 w/ $40 core.

[This message has been edited by goatnipples2002 (edited 07-21-2007).]

I know nothing about 3800 swaps, but have you thought about using a 1/4" spacer between the block and tranny and keeping the camaro flywheel unmodified?

Should only require longer dowel pins and a simple spacer.

This could cause issues with tranny mount to engine mount spacing vs. the non-spacer setup.

quote Originally posted by fieroguru: I know nothing about 3800 swaps, but have you thought about using a 1/4" spacer between the block and tranny and keeping the camaro flywheel unmodified? Should only require longer dowel pins and a simple spacer. This could cause issues with tranny mount to engine mount spacing vs. the non-spacer setup.

I for one would rather simplify the swap not make it more complex.

quote Originally posted by fieroguru: I know nothing about 3800 swaps, but have you thought about using a 1/4" spacer between the block and tranny and keeping the camaro flywheel unmodified? Should only require longer dowel pins and a simple spacer. This could cause issues with tranny mount to engine mount spacing vs. the non-spacer setup.

To me this actually sounds logical. How is this any different that a small block chevy swap? Don't they use at least a 1/4 inch spacer?

quote Originally posted by fieroguru: I know nothing about 3800 swaps, but have you thought about using a 1/4" spacer between the block and tranny and keeping the camaro flywheel unmodified? Should only require longer dowel pins and a simple spacer. This could cause issues with tranny mount to engine mount spacing vs. the non-spacer setup.

There was a guy locally that was using this approach on a S1 swap but I think he sold it before it was done. I done see why it wouldnt work just the same and be alot cheaper.

Cost of machining flywheel vs. cost of custom-making a 1/4" transmission-sized spacer though?? Somethin tells me that's not going to be cheap unless you DIY, but even the 1/4" aluminum plate stock in that big a size will be a few $$..

The flywheel approch is really easy, its just a shame shops are trying to rip you off. I honestly spent next to nothing on my flywheel, It was so low I dont even remember the price excatly.

quote Originally posted by Riceburner98: Cost of machining flywheel vs. cost of custom-making a 1/4" transmission-sized spacer though?? Somethin tells me that's not going to be cheap unless you DIY, but even the 1/4" aluminum plate stock in that big a size will be a few $$..

Since this would merely be a spacer (no bolt pattern change) with the dowel pins providing the needed precision there are 3 ways to go about making this spacer.
1 - just use machined washers at the bolt locations. This will leave a gap in between washers, but this is super simple. You could then fill the gap with silicone
2 - use a multi part spacer with 3 to 4 pieces of 1/4 x 2" aluminum and drill the needed holes
3 - go full bore with a larger 1 piece spacer - requires the most cutting and largest investment in material.

[This message has been edited by fieroguru (edited 07-22-2007).]

another approach is have an aluminum one made up. Ive driven a few 3800SC with one and it makes a big difference.
Joe formally of Racetec can still get them made up

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87 Fiero GT 5sp with Vortec L35 4300 Turbocharged V6
Bully Stage 2 clutch
Syclone intake manifold and engine management with Moates adapter and chip burner
Air/water intercooler and Devil's Own progressive water/alky injection
50lb injectors, 3 bar map sensor, Walboro fuel pump and Jabasco Intercooler pump
LM1 wideband on custom manifolds and 3" stainless exhaust system
T31/T04B S4 turbo with a Super T61 in the box
S10 caliper conversion.
Murphy's Constant Matter will be damaged in direct proportion to its value
Murphy's Law of Thermodynamics Things get worse under pressure.
Arthur C. Clarke "Any significantly advanced technology is indistinguishable from magic"

quote Originally posted by vortecfiero: another approach is have an aluminum one made up. Ive driven a few 3800SC with one and it makes a big difference. Joe formally of Racetec can still get them made up

On paper, the alum flywheel would be worth the money. Might help save the transmission by reducing rotating shockload.

Priced used 96-02 Camaro 3800 Flywheels at my local junkyard and they can be had for around $50.00. So far the best machine shop cost that I can get is $150 -$200 for the milling and the balancing. That's $200-$250 which seems high so we are still looking around for a more cost effective solution. Has anyone tried using a Fiero flywheel and redrilling for the 3800 bolt pattern? Probably not the way to go but it has been done before.

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87GT 3.4 Turbo- 0-60 5.2 seconds
2006 3800SC Series III swap in progress
Engine Controls, PCM goodies,
re-programming & odd electronics stuff
" I'M ON THE LOOSE WITHOUT THE JUICE "

quote Originally posted by Dennis LaGrua: Priced used 96-02 Camaro 3800 Flywheels at my local junkyard and they can be had for around $50.00. So far the best machine shop cost that I can get is $150 -$200 for the milling and the balancing. That's $200-$250 which seems high so we are still looking around for a more cost effective solution. Has anyone tried using a Fiero flywheel and redrilling for the 3800 bolt pattern? Probably not the way to go but it has been done before.

I saw a thread on redoing the 2.8 flywheel and it seemed to be a real catastrophe.

i am not sure if it is a good idea to machine those flywheels thinner. what about the strength of it after? that is sitting right behind you, what happens if it comes apart ? i think a custom made flywheel might be safer.

quote Originally posted by vortecfiero: another approach is have an aluminum one made up. Ive driven a few 3800SC with one and it makes a big difference. Joe formally of Racetec can still get them made up

I looked into this. Last I heard from James (3800sc cavi) and talked to the shop in NS, they were eating the bottom end out of the motors. The flywheels were mis-balanced by about 247grams or so. They thought it was the mounts but turned out to be the flywheel. If you know someone who still makes a PROPER aluminum flywheel, I'd like to know. I didn't know how to get ahold of the guy from RaceTech since they're out of business.

quote Originally posted by Jncomutt: I didn't know how to get ahold of the guy from RaceTech since they're out of business.

Not out of bussiness. Hes in this thread... https://www.fiero.nl/forum/Forum2/HTML/088881.html

I was wondering why a few of you guys worried about the strength of the flywheel after machining? I have never heard about a fiero flywheel cracking or breaking, and we are machining the new one to match. Wouldn't that mean it's just as strong as the fiero flywheel? I know we are putting more power to it, but I've never heard of anyone breaking them. There is a ton of SC3800 fieros out there now and quite a few have manuals.

Just my $.02

Dennis: Definitely don't skip the balancing. They are for sure counterbalancing the engine. Look at how much material is punched out of the auto flexplate on the one side...
I believe I was charged $50 or $75 to balance mine. My machinist/engine builder said they mandrel balance them all the time. Hopefully you can find someone cheaper!

MOBILE

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Member MN Fieros Forever
Self Installed SC3800/getrag. 13 years in Car Audio and Car Electronics Experiance........ 19"s.. w/ 13" Brakes all around.

The problem was solved. Found a shop who did the machining for $130 and the balance was maintained. The machined 3800SC flywheel ends up to be the same thickness as the Fiero flywheel so in theory no loss of strength is experienced. While I did work on a stick swap, I much prefer my auto swap. The stick swap is easier to do but IMO the auto gives an extra measure of strength over the Getrag. .Also the Spec 3 clutch that was used is still chattering after 300 miles. Just wonder if it will ever break in and be completely quiet. .

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87GT - 3800SC Series III engine, 3.4" Pulley, N* TB, LS1 MAF, Flotech Exhaust Autolite 104's Custom CAI 4T65eHD w. custom axles
87GT - 3.4L Turbocharged engine, modified TH125H
" I'M ON THE LOOSE WITHOUT THE JUICE "

There is absolutely nothing wrong with machining the flywheel, its no weaker than a normal Fiero flywheel, not to mention if it came apart, it would have to blow through the tranny case and two to three layers of metal in the firewall. To beable to make it through the tranny case, the piece would have to be rather small, and theres no way a piece that small is going to carry enough momentum to break the tranny case, much less carry enough energy afterwards to go through a couple more layers of metal.

As for the spacing idea, you still have to balance the flywheel even if you shim the tranny out. Also, you are loosing a lot of strength. The bolts arent the only thing that hold the tranny to the engine, there is a LOT of sheer force from the tranny face touching the engine, and the force of the bolts on the tranny case is spread across the face of the tranny, if you had washers in there, all that force would be focused on the area the washer is touching, making it very likely to crack the case. IMO it would be a VERY bad idea. Using an adapter plate is a diffrence situation, as you still have the surface area to clamp to and dissipate the pressure.