Flywheel attachment question

C

cjc56

Senior Member
I have a 56 tbird that has a air cooled Fordomatic. The flywheel is a 1/4 inch thick plate with two flexible flanges ( three holes in each) attached to the outside edge of the flex plate. They set opposite of each other on the perimeter at 12:00 and 6:00. the plate attaches to the crank shaft with three 1/2 bolts(fine thread) and the manual says they should be torqued to 75-80 lbs. My question is this: Should these bolts have lock washers? The used bolts that I have also had lock washers with them but with the lock washers under the head, the threads of the bolts do not fully extend thru the crankshaft plate. With the manual calling for 75-80 lbs torque, this seems a little extreme when only approx 7/16 inch of the bolt's threads are engage. Any advise welcome!!!
 
With clean threads, and a drop of oil on the bolt where some gets on the flange, no lock washer is needed.
 
Are you saying that you are only using three bolts to bolt the flywheel/flex plate to the crankshaft flange? There should be six bolts.
The torque/tension is as the manual states.
 
I have run Y blocks for over 20 years... and daily drivers to boot, building several 292's and now a 312. No lockwashers needed - get rid of them. You want all of the thread in the crank flange that you can have WITHOUT COMING THROUGH to the other side lol.
 
I noticed that some people are using the newer flex plate on the 56s, that came standard on the 57. In fact most of the vendors like CASCO carry only the newer kind. This newer one has convert mounting bolts at 4 corners (12, 3, 6, 9:00) of the flex plate. I think that it is thinner also. What is your opinion of the advantages of using this newer version over the originial one that has torque converter mounting points just north and south (12:00 and 6:00)?
 
The rivets that hold the mounting 'ears' become lose over time and cause a clunking sound similar to a rod knock. Check your 'ears' closely.
The later flex plate does away with this problem.
 
cjc56 said:
I noticed that some people are using the newer flex plate on the 56s, that came standard on the 57.
Click to expand...

I wouldn't try using a '57-up flex plate on a air-cooled '55 or '56. Think about it. You would be pulling the converter hub forward in the front pump at least 1/8 inch. Seems to be the dogs at the back of the converter hub would be barely engaged in the pump. Just my two cents.
 
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