Will a 6.9L flywheel work on a 7.3L?

[5.0ohsoslow]

Will a 1983 6.9L flywheel work on a 1992 7.3L? The 7.3L was a former auto.

 

[towcat]

no problem.
these are internally balanced motors with a wide tolerance for various flywheels/flexplates hung off its butt.

 

[5.0ohsoslow]

Thx, the 6.9L has shorter flywheel bolts? The 7.3L Threads start around 3/4 of an inch in the crank! There for the 6.9 bolts will not start. Can I just use 3/4 in. longer grade 8 bolts?

 

[david85]

these are internally balanced motors

Always wondered if they were internally balanced. Does this mean I can take off the flywheel and turn it one notch on the bolt circle to solve the intermittent starter grind problem?

Wish I knew that a few months ago. Better late than never I guess.

 

[towcat]

Always wondered if they were internally balanced. Does this mean I can take off the flywheel and turn it one notch on the bolt circle to solve the intermittent starter grind problem?

Wish I knew that a few months ago. Better late than never I guess.

nononononono....NO.
you can certainly heat up the ring gear and slip it off the flywheel. reposition/reclock the teeth and drop it back on.
if you look at the backside of the flywheel, there is a weighted section that is consistent in the location for other flywheels.

 

[david85]

nononononono....NO.
you can certainly heat up the ring gear and slip it off the flywheel. reposition/reclock the teeth and drop it back on.
if you look at the backside of the flywheel, there is a weighted section that is consistent in the location for other flywheels.

Ah, ok so the flywheel itself does have a counter weight in it to balance the engine. The flywheel on my truck is carved out of a single piece of cast iron, teath and all so I guess I'll just have to live with it or replace it some day.

 

[5.0ohsoslow]

The 6.9L crapped out in my truck so i am doing a 7.3L swap. The 6.9L was a 4-speed and the 7.3L was an auto. I tried to reuse the 6.9L flywheel bolts and the flywheel on the 7.3. But the bolts would not even start in the treads on the 7.3L. I did some measuring and the bolt are too short around 3/4in. I just wandered what type of bolts to get and where to get them.

 

[k_williams1982]

Don't know about around you, but anytime I need any bolts/nuts/washers/etc. around here, I go to NAPA. They have a great selection and can help you out easily.

 

[DeepRoots]

plus it seems like you could only put the flywheel on one way on account of the one mini hole with no bolt in it.

 

[Agnem]

Thx, the 6.9L has shorter flywheel bolts? The 7.3L Threads start around 3/4 of an inch in the crank! There for the 6.9 bolts will not start. Can I just use 3/4 in. longer grade 8 bolts?

I would NOT recommend doing that. Go to Ford and swallow the pain needed to by the factory bolts. When you consider what they do, it's worth it being able to torque them to spec, and know that you will never have to worry about them again.

 

[hesutton]

I did some measuring and the bolt are too short around 3/4in. I just wandered what type of bolts to get and where to get them.

The 6.9's flywheel is thicker than the 7.3's automatic's flexplate. You need to do one of two things......
1. buy new flywheel bolts (ford). Best option in my opinion.
2. use the ones from the 6.9 (with thread lock/sealant).

Heath

 

[85hauler]

Thx, the 6.9L has shorter flywheel bolts? The 7.3L Threads start around 3/4 of an inch in the crank! There for the 6.9 bolts will not start. Can I just use 3/4 in. longer grade 8 bolts?

the bolts from the 6.9 should work. Did you take the flexplate adapter hub off the end of the crank before putting the flywheel on?

 

[5.0ohsoslow]

The difference is the crank on a 1983 6.9L the threads start right off the bat. On a 1992 7.3L the threads on the crank start around 3/4 of an inch back. What is a good place to get the bolts online? Will 7.3 manual flywheel bolts work?

 

[5.0ohsoslow]

The flexwheel adapter hub? Is is just pressed on? I did not look that close? I was getting dominated by that flywheel!

 

[hesutton]

I did not look that close? I was getting dominated by that flywheel!

I've been there and know exactly what you're saying.

Heath