Help locating 409/425 Flywheel part number and source

Wes McCallum

Well Known Member
I am looking for the correct P/N for the flywheel on a 64 Impala SS. With 409/425, 4 Speed set up. I am going to need a new one and also looking for a source to purchase one. Any help pointing me in the right direction would be appreciated .

WES
 

MRHP

 
Supporting Member 1
I have one that came off of my 1965 409. Would be the same part, not sure about the same part number though.
 

Wes McCallum

Well Known Member
MRHP,
I would think that they would be the same, sound interesting, is it something you would part with? What condition is it, does it have heat cracks, and has it been resurfaced ?
 

MRHP

 
Supporting Member 1
I will dig it out tomorrow. As I recall it is near new, no cracks, and has never been surfaced. Sure I would let it go. I'll see if I can find it. Brian.
 

MRHP

 
Supporting Member 1
Got it out. Casting number 3789733, date code d 15 4, and ink stamp part number 3758595. Should be surfaced, but is in great shape. P.M. me if you are interested. I will try to get a picture.
 

Phil Reed

Well Seasoned Member
Supporting Member 10
#3729004 is the original part number....10 1/2"....168 tooth. I have an NOS one left. PM me if interested.
 

MRHP

 
Supporting Member 1
I think my flywheel is for an 11 inch clutch. Would still work as long as you used an 11 inch clutch. Phil is correct as usual.
 

Phil Reed

Well Seasoned Member
Supporting Member 10
You are correct Bryan...........stock was 10 1/2" until 63 then in 64 it was 11". But the 552 and 553 bellhousings will take an 11" flywheel.
 

Wes McCallum

Well Known Member
So I am alittle confused, I had read in the Tech material that the flywheels for the 348 & 409 were the same. I know the clutch in my car is an 11 inch, but the original was a 10 1/2. So what am I looking for exactly?
 

La Hot Rods

Well Seasoned Member
Supporting Member 15
If you want to put some miles on it go for the 11 inch if you want to race it go for a SFI steel flywheel.
 

Wes McCallum

Well Known Member
Bryan,
Once I get this sorted out I will know what I need. I'm not racing just a driver, but having a problem with shuttering and hard to push in when it gets hot.
The one you have is a 168 tooth right? Please send a pic when you can.
 

threeimpalas

 
Supporting Member 1
A 168 tooth flywheel will be the same OD regardless of whether a 10.5" or 11" clutch was used. Which pressure plate pattern it's drilled for will be dependent upon the clutch size. Some will be drilled for both. Are you set on having a numbers correct flywheel or do you not care so long as it has the correct balance and fits?
 

62impala409

 
Supporting Member 1
Bryan,
Once I get this sorted out I will know what I need. I'm not racing just a driver, but having a problem with shuttering and hard to push in when it gets hot.
The one you have is a 168 tooth right? Please send a pic when you can.
I had the same shuddering and hard to push in clutch pedal when hot! I forgot to put grease on the transmission splines and on the I D of the throwout bearing when I assembled the car. The clutch pedal was always extremely hard to push in after driving the car awhile. the parts were metal on metal! After the grease job, the clutch was smooth and easy to push in. This information is in the GM shop manual under clutch. I believe they call for wheel bearing grease on the splines. Wipe a small amount on and wipe the excess grease off. BTW, I have an 11" clutch on a late 60's 168 tooth flywheel.
 

Wes McCallum

Well Known Member
Mike, Just as long as it is the proper set up for my car. Bryan has a flywheel which was off a 65, using a 11 inch clutch which he feels would work fine.
 
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