Cneterforce said that they dont have a flywheel that will work with an externally balanced BBC for a T56..THey said that the only way for it to work is if I internally balance the 496.

 

Ouch, looks like it's coming apart for a rebalance. I know they don't make any counterweight plate that can bolt onto a flywheel, i tried it when hunting for the 383, but ended up having to cough up the dough for a Centerforce flywheel.

Odds are if they don't make it, it doesn't exist.

 

Hasn't changed since what I told you last time you posted this.

https://www.thirdgen.org/forums/engi...-pre-90-a.html

Get yourself a CF 700107 or 700170 (for internal or external-balance 2-pc RMS SBC, respectively); and take it to your local balance shop, and have them change the unbalance to the correct amount for the 454 (or whatever it is).

 

lol I panicked.

stupid question:do they need to balance the internals or can they just convert the flywheel into a 454 balance?...

/me still hopes this will work without having to balance the internals

 

I'd think they'd need your crank, or some other 454 crank close to yours to simulate the bobweight when converting the flywheel, no? the

 

I wonder if they could just match it up to a 454 flywheel..crap

 

Keep in mind, that the factory doesn't "custom" balance ANYTHING as an assembly; they have flywheels and flex plates sitting on the shelf that are already prepared, and they just bolt them up, and they are correct. Why it is, that in the world at large, that balance shops don't "get it", I'll never figure out.

If a motor is set up to the stock balance spec, then external parts with their balance set up to the stock spec, will interchange directly. That's the CORRECT way to balance a motor: set it to where it requires EXACTLY the "unbalance" that a stock one requires. Then, just like the factory, YOU can go to the shelf, any shelf, and pull a STOCK part, and slap it on there, and it will be right.

They don't need your crank or any of that, AS LONG AS ALL OF IT IS SET UP TO THE STOCK BALANCE SPEC.

Alot of us continuously preach about balancing, and when you get it done, that you should NOT allow your shop alter the flywheel or the damper from their stock settings. This is the reason why.

If your motor is balanced to the stock 454 spec, then you CAN take one of the flywheels I mentioned, and match its balance to a 454 flywheel, and all will be good. On the other hand, if someone did themselves a favor at your expense and "balanced" your motor by hacking on your existing flywheel, then you CANNOT do it quite so easily.

Hopefully, your motor is balanced to the stock spec, rather than some "custom" hack job, and it will be easy for you. Otherwise, the balancing shop will need your entire rotating assembly, out of the engine, in order to get it right.

If your motor is internally balanced to THAT stock spec, then the 700107 will work.

If your motor is externally balanced, I think you'd be alot closer if you started out with the 700170.

 

good stuff..A couple guys told me that the SBC will work as long as the clutch would match in diameter.I heard the same thing as what you have said too.THanks for assurance

 

Good luck!!!! The same swap may be in my future someday.

 

That balancing THEORY only applies if your using 454 factory crank, 454 factory rods, and 454 factory pistons. If any of those change ie. larger bore, different length rod, then none of that belief applies, because the bobweights are not accurate to the mass rotating around them.

Thats what aftermarket balancing is for.
If daz is running a 496, then he's altered from stock and his bobweights are not accurate. Although it is safer to be overweight on the bobweight than underweight. It would be a shame to have a crank break.

 

Right; except that, it's quite easy for a balance shop to restore the whole thing, 496 or whatever, to THE STOCK 454 BALANCE; rather than some "custom" one-off setup that you can't just interchange parts with.

"Bob weight" is the term used to describe the effective mass of the piston/rod assembly. Neither over nor under is good. Either way, it will vibrate and overstress the crank at high RPMs.

 

true, but studies show that if a variance of 1-2% can't be helped, which comes down to milligrams, then having a bobweight heavier than the rotating mass is better. This is just what i have read though.

 

The problem I think its the thickness of the bellhousing.

weir hot rods sell a bellhousing for it but its not cheap..Its probably better to get a new aftermarket tranny from Tremec

 

???? ....everyone I know is running a regular sbc/bbc(for their respected motor) flywheel. Are you getting some odd-ball CF clutch that doesn't bolt in the standard 11" or 10.5" clutch pressure plate holes in the flywheel?
- SBC flywheels will NOT work unless you use a 400 flywheel. All other factory sbc's were internally balanced, therfore did not have the balance weight on the flywheel.

thats what 1/2 the T56's in non-factory cars are.

 

Internal/External balance has nothing to do with recipricating weight balance of the rotating assembly.

The crankshaft has counterweights to offset the throws of the crank. Normally, there's enough space inside an engine for these counterweight however on a few engines 400 SBC and 454 BBC, the increased stroke of the crank doesn't allow enough room inside the engine for all the weight on the counterweights so the extra weight is moved outside onto the dampener and flexplate/flywheel.

When you get an engine balanced, all the machine shop is doing is adjusting the counterweight weight to compenstae for the weight of the rods, bearings, pistons, rings, etc.

If the engine is internally balanced, all they need to balance the engine is the crank and all the internal parts because the dampener and flexplate/flywheel are neutrally balanced. If it's externally balanced, they also need the dampener and flexplate/flywheel because they have counterweights on them.

It's not possible to use a 454 crank and have it neutrally balanced into an internally balanced crank. It's just not possible to add the amount of weight to the crank to do it. When I built my 540, the Eagle 4340 stroker crank is an internal balance crank. There's a counterweight added to one end of the crank compared to a normal 454 crank. Using this crank, I had to get a neutrally balanced dampener and flexplate designed for a 396/427.

Since a T56 flywheel is neutrally balanced, this would be your way to go to make the conversion easier

 

...Im still at a loss as to why you need a different flywheel for a T56 than any other manual trans....

 

You've obviously never seen a T-56. One look, you will understand INSTANTLY.

 

maybe a factory T56...I've seen several Tremecs'. - Guessing you're not using the adapter that puts you to a standard bell-housing then. That would explain a lot.

 

The stock T-56 BH is about 1½" shallower than a "standard" one. The BH flange of the transmission is about 12" diameter, almost the size of the flywheel. The trans case has 2 about ½" dowel pins, and there's about 8 bolts that go through the inside of the BH and into the trans case from the BH side, not 4 bolts that go into the BH through little ears on the trans case from the rear. The clutch fork attaches to the front of the transmission, not to the BH. The fork pulls on the clutch, doesn't push. The throwout bearing is part of the clutch, not a separate piece. The T-56 flywheel is considerably thicker than a std one; I'd guess somewhere around 3/8" thicker. The clutch fork moves in the opposite direction from a 4-speed or 5-speed one; the hydraulics mount behind it rather than in front like a T-5, and push the fork frontwards instead of rearwards.

Without the extra flywheel thickness, the special clutch can't work. You can't swap out the special clutch for a normal one because the BH has no provision for a fork. You can't use a standard depth BH because the clutch gear isn't anywhere near long enough, and because the bolt pattern is so unique.

Other than those few extremely minor details, I can't see why it wouldn't bolt up to a std BH and why you couldn't use all standard old-school stuff with it.

Like I said, whenever you go actually look at one, you'll understand INSTANTLY why Daz has to do what he has to do; and why old stuff won't work.

 

(I have a T-5 in now) So let me get this right...A T-56 will bolt up to a sbc(383) but will have to get a 400sbc flywheel... I thought tha 350 and 400 flywheel were tha same?

 

No a 350 and 400 flywheel are not the same. Sorry you thought that. Good thing you asked before putting the one flywheel on the other motor.

The 350 is internally balanced; the 400 is externally balanced. If you mix the parts, you will have the vibe from hell.

Yes a T-56 will bolt up to a SBC. That's what they came behind in the first place.

If you have a 383, the flywheel you need, will depend on whether your motor is internally balanced or externally balanced. If your crank will only accommodate 5.565" rods, then it's externally balanced; and you'll have to have the 400 flywheel. If the motor already exists and is running, then whatever flywheel you have now, you'll have to duplicate that balance setup in a T-56 flywheel. If your T-5 works with a stock 305 flywheel, with no extra balancing done to it, then a 350 T-56 flywheel will work. All you'll have to worry about is whether your motor has the 1-pc rear main seal, in which case the actual stock T-56 flywheel will work, or if it has the 2-pc RMS, then you'll need the 700107 (or equivalent from another mfr).

 

I recommend the Weir Hot Rod Products bellhousing. I actually just talked to him about 5 minutes ago, he just got a new shipment of castings in and is currently machining them for shipment. It is a little pricey, but it also allows you to use "normal" GM flywheel, pressure plates, and clutch parts. His kit includes the hydraulic throwout bearing, lines, backing plate, and aluminum bellhousing.

Weir Hot Rod Products


I have an 84 Camaro with a 383, external balance. I don't have it together yet, as I'm waiting for the Weir bellhousing. Therefore, I can't guarantee these parts all go together with no headache, but I don't foresee any major problems. (Famous last words, I know)



I ended up using the following parts:

Weir bellhousing/kit with Tilton master cylinder

McLeod 11" Diaghram push style Pressure plate pn MCL 360-803

McLeod 26 spline clutch disc pn MCL-260871

Hayes 168 tooth external balance flywheel pn 490-10-132

1996 LT1 T56 transmission bought from ebay for $675. I got a friggin steal on that thing.

 

Yup itz up and running(383). I pretty much used my 327(h-balance, new flywheel that fited on my 327 & 383). Tha 305 flywheel wouldn't work. I think it is a 1pc rear main seal also. Should stay wit my T-5(short thrower) or go wit a T-56 . This site helps alot...smart ppl ask questions...aleast that what I was told..

 

That depends on which transmission you have.

If you have a T-5, use the T-5 shifter. Use a T-56 shifter with a T-56.

 

Any clue what their bellhousing/throw out bearing assembly costs? I already have the flywheel and clutch.

Thanks.