3.9 g6 GXP flywheel

[NateD4]

Pocket Rocket,

You either didn't understand my post or....

The dual mass allows them to run higher power engines with less possibility of damaging the transmission. In the case of the F40 290 Ftlbs instead of 180 as the old 282s were rated. Of course part of this was due to a redesign. Bottom line is that GM is now selling cars that are FWD and putting down almost 300 ftlbs to the ground while still giving a 100K warranty. This is good news for the hot rodder as we not have a decent trans to use.

[NateD4]

Joeseph,

I have a G6 dual mass here. I'm still determining if it needs a rebuild or whether I should replace it with an aluminum unit. I really see nothing horribly wrong with its design except the friction limiter and potentially coil binding the springs inside. I can get around the latter problem by adding a second set of shorter springs to prevent the complete coil bind at high torque outputs.

[robertisaar]

IIRC, GM has always rated it's transaxles based on the torquiest engine it was attached to and with the highest GVWR it was installed in.

284s can take mountains of power without failure, but they were only hooked up to the ~220 lb/ft or so that the 91-93 LQ1s generated.

[NateD4]

Jdaniels,

I'm looking at a ClutchNet 6 puck ceramic with a 2400 lb pressure plate. They tell me it'll handle 550 Ftlbs. Now the problem seems the flywheel.

I wish I would have known about the group buy for the flywheels. I think I got the exact same cost from Clutchmasters when I e-mailed them.

It looks like I can replace the rivets in the flywheel pretty easily. If that is the case I can rebuild with a different friction material OR higher preload on the torque limiting ring. IF it takes that much effort it might be worth my while to have my machinist make me a flywheel from scratch.

As to the GXP. I'm in the process of a buildup with 80 mm throttle body and ported exhaust ports with custom headers.

I'm also considering the option of doing a turbo setup with proper bottom end (hence my question about anyone looking for head and main studs).

[Joseph Upson]

IIRC, GM has always rated it's transaxles based on the torquiest engine it was attached to and with the highest GVWR it was installed in.

284s can take mountains of power without failure, but they were only hooked up to the ~220 lb/ft or so that the 91-93 LQ1s generated.

Yeah, the 5 speed "Getraggedy" has been setup behind 350s, Northstars and 3800 SCs for years on the Fiero forum and the failures are for the most part with the owners that are racing them. Not bad considering the trannies used are OE originals that are already worse for wear given their age. The 4 speed Muncie however is said to be the strongest of the pre F40 bunch though. Some have even put the Isuzu tranny behind a V8 in the Fiero but I liken that to putting ice in a blender.

Eliminate clutch dumping and I doubt there's any need to feel the dualmass flywheel is important for anything more than ease of driving since manual tranny failure to my recollection has never been a GM issue. The problem with the F40 (1st year in the G6) was corrected in the second year. At least once or twice a week I have trouble finding 1st gear that sometimes seems to have merged with reverse.

[Joseph Upson]

Jdaniels,
I'm looking at a ClutchNet 6 puck ceramic with a 2400 lb pressure plate. They tell me it'll handle 550 Ftlbs. Now the problem seems the flywheel.

I wish I would have known about the group buy for the flywheels. I think I got the exact same cost from Clutchmasters when I e-mailed them.

It looks like I can replace the rivets in the flywheel pretty easily. If that is the case I can rebuild with a different friction material OR higher preload on the torque limiting ring. IF it takes that much effort it might be worth my while to have my machinist make me a flywheel from scratch.

As to the GXP. I'm in the process of a buildup with 80 mm throttle body and ported exhaust ports with custom headers.

I'm also considering the option of doing a turbo setup with proper bottom end (hence my question about anyone looking for head and main studs).

I liked the idea of head and main studs but I question the efficacy in this application except for the most extreme build for the following reasons:

Relative to the previous boosted performance levels of the iron head motors, the aluminum head motors have an inherently stronger bottom end as is with steel main caps and cross bolts.

In the case of the 3900, it comes stock with an Multilayer steel headgasket and torque to yield head bolts, two components that individually produce better gasket sealing and make for a synergystic combo.

There's nothing wrong with modding the dualmass flywheel if you have access to the resources but the weight alone makes it unattractive. With the clutch and pressure plate attached you're at approximately 40 lbs of rotating mass. The stock G6 pressure plate has 2000 lbs of clamping force. I started with a $57 heavy duty Fiero style pressure plate with ~1950 lbs of clamping force and had it modified to about 2350 lbs with additional straps added.

I should be swapping in the stock motor at the end of the month to assess the damage I did to the forged motor and at that time will hopefully be able to get to the bottom of the noise I'm hearing on clutch engagement. I believe I mentioned here it sounds like loose rivets in the clutch disc.

[NateD4]

Joseph,

Can you get me an audio recording of the vibration at idle and the modifications done to your engine?

I'm looking into an aluminum dual mass flywheel but need to know the frequency of the vibration. I should be able to pull this from a half way decent recording.

Then I can investigate a way to retune a flywheel to the proper frequency range.

[pocket-rocket]

Actually the importance of the dual mass flywheel over conventional has to do with the ability of the flywheel to reduce the total torque experienced by the transmission. It does this by absorbing a pulse and then releasing it over a longer period of time. It thereby exposes the transmission gears to less total torque. This allows the designer to design a gear which sees less extreme stress fatigue cycles. This then allows them to be less conservative on their designs. So they can either make the gears with less metal or they can up-rate the torque they can handle all the while still offering the customer a 100K mile warranty..

The explanation makes perfect sense. The dual mass is a "buffer" between the engine and tranny so they can make a weaker tranny, basically, cutting corners for more profit. The 284 may be rated at less than 300 ft.lbs, But I highly doubt it has a harder time handling higher loads than a newer transmission.

Pocket Rocket,

You either didn't understand my post or....

Nope, I think I understood your post just fine. You also have to remember, in the end GM is a buisiness, and in the long run any corner cut to make something cheaper will increase profits, or anything that uses less material costs less to produce as well, also increasing profits.

The dual mass allows them to run higher power engines with less possibility of damaging the transmission. In the case of the F40 290 Ftlbs instead of 180 as the old 282s were rated. Of course part of this was due to a redesign. Bottom line is that GM is now selling cars that are FWD and putting down almost 300 ftlbs to the ground while still giving a 100K warranty. This is good news for the hot rodder as we not have a decent trans to use.

Yes, these transmissions are rated higher, but with your explaination in hand, it only makes sense to use a key piece of the puzzle, the dual mass flywheel. But why would I want to use that? All I see all over youtube is people with stock engines ruining dual mass flywheels. Why would I want to put that in a car with an engine that's going to be modified beyond what these stock cars are seeing power wise? I understand the concept behind the flywheel perfectly, but in the end, I'm not going to use a part that's going to fail behind a stock engine, let alone a modified one when there are a few alternatives that, while somewhat "primative" to todays standards still do the job day after day behind heavily modified engines.

By the way, I also do not appreciate your comment about the miniature motorcycle. Making fun of someone's screen name because they don't agree with why you think the dual mass is so much better is sort of childish. You came here asking:

Has anyone had any trouble with the dual mass G6 F40 GXP 6 speed manual flywheel?

I'm looking at using one in a boosted application.

I gave a response talking about the many dual masses failing all over youtube with stock engines, even in higher end cars, like Caddies and VWs. If you look to make fun of everyone or their screen name when they don't agree with what you believe you should call your ISP and have your service terminated because it's a big world with lots of them out there.

[NateD4]

People are too prissy to drive real cars. They need to be all sleek and tidy and plush and girly. Anyone that doesn't want to deal with engine and drive line noises should only be allowed to buy something like a Prius or an Aveo or something like that, not something with enough power to break stuff. Hence my title, lol.

You said hence your title. Perhaps I misunderstood it.

Also you apparently are not fully understanding the importance of the absorbing capability of the dual mass.

If you remove the friction limiter in the flywheel the mass damping is still critically important. Especially on a high output engine.

It really boils down to the fatigue life of the crankshaft and transmission components.

If touring care how long they last no need for a flywheel at all.

On the other hand my goals are different. I'm looking to put the most power down without blowing the trans up. The dual mass helps remove the shock and harshness which minimizes the fatigue loading the parts see.

It's kind of one of those thing where a 282 can probably handle 700 ftlbs if you don't clutch drop it. But what fun is that? With a properly configured dual mass you could probably clutch drop with no big problem.

[pocket-rocket]

You said hence your title. Perhaps I misunderstood it.

My title (below my screen name) is: Because stock sucks...

Also you apparently are not fully understanding the importance of the absorbing capability of the dual mass.

It's kind of one of those thing where a 282 can probably handle 700 ftlbs if you don't clutch drop it. But what fun is that? With a properly configured dual mass you could probably clutch drop with no big problem.

I agree, that would be no fun and I do understand the importance of the absorbing capability. What's the point of having all of that power if you can't put the hammer down without the fear of your transmission kissing the pavement? My main point is I don't see you doing so with a stock dual mass and are going to have to get creative. In theory the dual mass flywheel is an awesome idea, in theory. So far stock production units have fallen short of making it to that 100k mile warranty mark all over the place. Hopefully you do come up with something that does work and can handle the abuse since it sounds like a costly venture.

[NateD4]

Forgot to add that higher compression and boost change the amplitude of the shock and vibration....


Yes it looks like quite a bit of work might be required to make it work. Though the stock unit with updated parts would probably be sufficient.

I'll have to do some investigating to figure out what it'd take to do in aluminum.

[Joseph Upson]

Joseph,
Can you get me an audio recording of the vibration at idle and the modifications done to your engine?

I'm looking into an aluminum dual mass flywheel but need to know the frequency of the vibration. I should be able to pull this from a half way decent recording.

Then I can investigate a way to retune a flywheel to the proper frequency range.

I can if you really, really want to go through that kind of effort but the easiest way to address it is set your idle rpm at about 1000 and it will go away. It's not so much a vibration as it is a clacking noise. It can get pretty loud (and I do mean loud as in severe rod knock loud) at low rpm so I suppose if you installed a 50 lb solid flywheel it wouldn't be much of a problem.

[NateD4]

My title (below my screen name) is: Because stock sucks...
.

Ah, I see. My mistake.

[NateD4]

Pocket Rocket,

The dual mass is a key piece of hardware... just not the stock form of it. I agree why would I put a 290 Ftlb torque limited device in a modified vehicle. I wouldn't. In actuality thats why I started this thread (I think).

After now reading much about them I'm probably going to set about trying to figure out how to have my cake and eat it too....

I think my first step might be to modify the stock unit with a better friction ring. The second step will be to figure out what RPM the thing is tuned for and then figure out what my mods require and tune an aluminum one for that.

I'd be interested though to know what a solid flywheel sounds like.

The other concern I have is that the torque pulses of a modified or high output engine could play complete havoc on the drive train. I'd hate to put all the work into a 500-600 HP V6 and then blow a tranns up by putting it into a harmonic resonance.

[NateD4]

So that all said I see Aluminum versions of the 2.8 Flywheel are readily available. Has anyone managed to get a decent clutch behind this?

If so do you know the offset numbers for the pressure plate and clutch fingers and clutch spline?

Maybe for now I'll put a solid one in since my first install of this engine won't be pushed more then 350 HP.