88 TA GTA

Hi For those that have an older block and installed a 6 speed tranny I was Wondering your thoughts on which works the best.

There are 3 companies that I know of that make a flywheel to bolt the 93-97 LT1 T56 6 speed tranny to an 85 an older block w/ the 2 piece rear main seal.

Centerforce Steel flywheel 700107 $425

Ram aluminium 2555 $408

McLeod 64033-00-07 $ not sure this is the correct #.

I would think go aluminium, but not sure...

Thanks in advance!

black1990RS

what are your plans for the car? daily driver or strip only?
if you want it streetable i liked the centerforce because its weight keeps momentum up. the aluminum will allow you to pull RPM much faster but is to to good for the street

sofakingdom

iTrader: (1)

I have the CF.

It's HELLA heavy. It makes the engine NOTICEABLY more sluggish revving than the stock 305 one I had on it before. That might be OK in some situations but I don't think it's necessary in mine.

If I had it to do over, I might use an aluminum one.

If you have even worse (lower number) gears than my already pitiful weenie stock ones (3.73) as I suspect you do with that 9-bolt, you will probably want the heavy one because the engine RPM will be held so low all the time. OTOH if you have gears that are a better match to the T-56 to begin with such as 4.10, the aluminum will probably be better.

88 TA GTA

Thanks, appreciate the feedback.

I plan for a daily driver.

I have come across another made by Spec and its much cheaper
Steel: SC66S = $279 (NY Performance Shop) $359 on their site
Aluminum: SC66A $ $359.00 on their site
The cool thing about this is that is has a weight that you can add depending on how the motor is balanced.

From what I was told (same as above), its better to go with steel for a daily driver as the alum. doesn't hold the momentum/power of the motor due to less mass.

I'm not sure what gear ratio I have, it did rev high on the highway w/ the 700R4 - 70MPH =2750RPM

John in RI

iTrader: (167)

I've only used the Centerforce - and have no complaints.

P.S. with a 350, auto, and BW rear doing 70 reading 27xx RPMS....... You've got a 2.77 gear ratio.

88 TA GTA

Thanks! I think I have some pics of the gear codes, when I changed the axle bearing...just have to find them.

NufNuffZ28

iTrader: (10)

Im in this delimma right now. My build got switched up to now include a T56 that I couldn't pass up. Includes a VERY good Spec 3 clutch(know this as my friend and I put it in for the guy), but no flywheel.

700rwhp TPI car with a Vortech SC..... centerforce one?

Oh yeah, my car has 2.73 gears and 27" tall tires on 19" wheels. I'll never get to use 6th until I change gears!

black1990RS

yeah you are definitely going to want those gears changed. gas mileage will go up but you will have a large power decrease. i actually have a couple of the centerforce flywheels left over . mine is the 9 bolt with 3.45 and it is a pig

88 TA GTA

Have you used any of the clutches above? What do you think works best?

Thanks!

Jaxom

I've been running the Centerforce flywheel and Spec clutches for 8 years. I started out with a stage 3, but decided to drop to a stage 2 when I pulled the powertrain to swap it into another car. The stage 3 was just a little too much for me in a street car and had some mild chatter at low speeds, more so when backing. I have NO complaints with the stage 2 in a 375ish HP street car. The flywheel is indeed VERY heavy and no-load revving is a little more sluggish than I'd like, but I don't run around kicking the throttle all the time anyway.

Also FWIW I run a 3.70 9-bolt in the rear and turn around 1800rpm in 6th at 80mph. The majority of 9-bolt rears were equipped with 2.77 gears, and if that's what you have they'll make you miserable. I had a peg-leg 2.73 10-bolt behind my T56 for the first six months or so and it was truly a dog. 6th gear was essentially unusable.

jmd

iTrader: (4)

that's for ~26" tires and a 1:1 gear (third in a 700-R4, fourth in a T5,) not overdrive.

black1990RS

im running a stock clutch now which i could truly do without i am looking into a ram clutch ive heard some good about them for there price just need to come into some more cash. im also working on swapping a forth gen 10 bolt posi with 4.10 here in the very near future

88 TA GTA

I'm talking in overdrive with stock tires 245/50/16's, I always thought it rev'd high for a 350, thought maybe 373's or 411's...

88 TA GTA

Thanks - i'm going to have to find those pics I took a few years back to confirm...

BlueChevyZ

iTrader: (1)

if you plan any track time its best to use the steel flywheel, if its all street driven then the aluminum will be ok..

88 TA GTA

Thanks Going to call Ram tomorrow as they say there aluminium is "streetable"

InfernalVortex

iTrader: (4)

Then how come factory LT1 flywheels are steel?

Ive always heard the exact opposite.

I have a steel flywheel in mine (Mine is a 1 pc RMS engine though. so its not applicable to the thread)

Jaxom

The concept is still applicable...only the part numbers are different.

In my experience, aluminum flywheels are best suited to autocross and rally racing where there are a lot of sudden gear/rpm changes and the engine needs to be able to rev up and down quickly to accommodate that. For drag racing or a street car, there's no real need for a lightweight flywheel, and using one could make it more difficult to get a good idle quality out of the engine.

88 TA GTA

Thanks - I was thinking for the weight - the Centerforce is 34 LBS. The lighter the easier for the motor to spin, but the less mass is the issue....

Anyway Ram said they have sold many for street apps and they haven't had one come back, zero issues....

Think I'm going w/ the Spec steel FW.....

stark

hey there, the cost of these 2 piece rms fly wheels for a t56 is killing me,any chance i can have the name and or number of that shop you found one at for 240?

stark

any chance you have any of those center force flywheels left?

stark

bump