redbird8628

iTrader: (1)

my 2.8 just died so i decided to take this chance to swap in a 3.4, i found one from a 94 firebird, the guy at the junkyard says its a complete motor with the flywheel, so my question is, For what motor should i order the clutch for, my 2.8 or 3.4, the 3.4 has a 9 11/16"-26 spline by 1 1/8" and the 2.8 has a 9 1/8"- 14 spline by 1 ", i know i need the 14 spline, but will the pressure plate bolt to the flywheel?

redbird8628

iTrader: (1)

anyone?

2_point8_boy

Just order a new clutch and new flywheel for a 2.8, that'll get you brand new stuff that you won't have to worry about changing soon or fitment.

Drew

iTrader: (58)

BBZZZZZZZ!!!!! Wrong answer.

The 2.8 is externally balanced, the 3.1 and 3.4 are internally balanced. You need to use the 3.4 flywheel or a 3.1 flywheel and whichever clutch will fit the input shaft on your transmission. Even if you have to have a clutch disk custom made it shouldn't be too difficult.

On my carbed 2.8 I used a clutch disk for a 3.1 with the stock 2.8 flywheel and pressure plate. Technically the 84 2.8 used a larger diameter disk but the smaller 3.1 disk lined up with the pressure plate in such a manner that all the friction material was applied to the pressure plate and flywheel when it was engaged.

You might be able to use a 3.4 pressure plate (which would bolt to your 3.4 flywheel) and a 2.8/3.1/etc disc that will mate to your transmissions input shaft.

Drew

iTrader: (58)

Forgot to mention, if you do use a 2.8 flywheel on a 3.1 or 3.4 it'll shake the fillings out of your teeth and if you run it that way for very long it'll probably cause internal engine damage.

TechSmurf

Yeah.. for the love of *** please don't slap a counterweighted flywheel on the 3.4... we've had enough of that already.

IMHO just use 3.1 parts. There's no question as to them being neutral balanced and definitely designed for the thirdgen clutch system.

The_Raven

BZZZZZZZ, wrong again.

Not ALL 2.8s were externally balanced.

After 1987 (some say 1987.5), they became internally balanced, which is the flywheel needed.

Interesting tidbit of info:
The pressure plates are al the same size for the 660s, RWD FWD, doesn't matter, the flywheel is slightly larger in overall diameter for the RWD than the FWD. The discs will work accross the board.

I've had many of these variations apart, FWD and RWD. Using the 3.4 flywheel may be possible, but have read that the 3.4 uses a thicker flywheel than the 2.8 or 3.1, this is one combo I have not had a chance to have apart.

Short of that, a machine shop can remove the counter weight from a weighted flywheel.

Drew

iTrader: (58)

While that is certainly possible (since I haven't personally inspected every 2.8 ever produced) its enough of a concern that I wouldn't use 2.8 parts in this situation since it would open up the possibility of needless destruction.

The advice I was correcting said to use a new 2.8 flywheel and clutch set. It didn't specify the need for a flywheel matched to the engine. That was what I was trying to get across. By your own post you say 87-later are internally balanced, since the person asking the question of what to use lists an 86 Firebird in his/her profile I don't see how the 87-later 2.8 applies. I stand by my original suggestions and point out that the information I gave might not always apply, in this situation it would certainly seem to.

redbird8628

iTrader: (1)

thanks for the help guys, yea, i knew not to use the 2.8 flywheel, once i get the 2 motors side by side, i'll see if my 2.8 pressure plate can bolt to the 3.4 fly wheel, if not, im gonna hafta mix a 2.8 disk witha 3.4 pressure plate. thanks again

The_Raven

Gah, the post said that all 2.8s are externally balanced which is BLATENTLY FALSE!

So using a 2.8 Flywheel will not be a problem IF it's from an '87 and newer 2.8. That's what I was getting at, I kinda figured the rest would be implied about still needing to switch due to the OP owning an '86.
Does it really need to be spelled out letter for letter?

Oh and there will be NO need to mix 3.4 and 2.8 clutch parts, re-read my post about the clutches, the pressure plates are the same from '82 to '95 (last year of a manual trans equipped 660, which was the F-body).

Drew

iTrader: (58)

I enjoy a healthy debate, but seriously who are you trying to convince? I don't care if 87-up 2.8's are internally balanced since I don't own one, and neither does the guy who posted this thread. If he's got to buy a flywheel why risk a 2.8 flywheel when he might be given one that's for an externally balanced engine? I admit I didn't know that 87-up 2.8's are internally balanced, what more do you want?

BTW you contradict yourself...

Originally you said -
Indicating you don't know if the 3.4 flywheel will work with a 2.8 or 3.1 clutch kit.

Now you're saying - Indicating that you know for a fact it will... So which is it, Pootie?

I think the original poster has enough information to get his project finished, if you feel you have more to offer him then by all means continue to contribute. If you want to debate with me, I'm sorry my schedule is full. Please make an appointment with my secretary and I'll get back to you.

The_Raven

Comprehension pwns joo....

The FLYWHEEL is the only part I am not 100% sure about, the clutch on the other hand I know for a FACT is the same all the way through. There were mild differences in diameters of the clutch disc, but all use the same pressure plate.