I was just searching around looking for the IDI 7.3L compression ratio, when I bumped into a thread where it mentioned the 6.9 got a solid flywheel. Im not familiar with the similarities between 6.9L, 7.3L IDI and 7.3L PSD, but I have a 96 PSD w/ZF5 and a 'on the last leg' DMF...question is, can I swap mine for the 6.9L IDI solid flywheel?

 

If i am not mistaken you can I have an extra idi laying around i can take a pic and measure it for you if u want.

 

yeah if you can measure the diameter of it and any other measurements Ill see what I can dig up tomorow.

 

On looking on fordpartsonline I find the 94-97 flywheel compatable probably due to turbo specs.

There was consideration of making the DMF into a solid, be advised there may be noise in the ZF afterwards associated with this mod. The DMF was installed to absorb shock in the drive line eliminating it COULD cause problems.

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NOW FOR THE FIX


Changing a Dual-Mass to a Single-Mass Flywheel


When taking out the flywheel be careful as this thing is heavy, around 65lbs

One thing if for any reason you have any concerns don't try this . This is at your own risk, Mel Agne has done this conversion and so far it has worked out great, I have not put this in my truck as of yet but have it ready as my flywheel is making noise and I have this ready when I do change the clutch out I will change this out also. I am not afraid of using this fix, I feel really safe doing this to my truck.

I strongly suggest you drill out the bolt holes on a GOOD drill press to make sure the holes are straight. It would not be a bad idea to check the balance after putting it back together before installing it.

There is a guy on E-Bay that has made a DMF hub that dose the very same thing I have done and he wants $200 plus shipping for the hub, that is where I got my idea and tore a flywheel apart and discovered this trick This fix will cost you whatever the price of the 6 grade 8 X 2" fine threaded bolts & lock nuts and about an hour of your time drilling out the holes and bolting it all back together once you have the flywheel out.

After removing the flywheel take it all apart and I do mean all apart, remove everything, springs, friction plates and take the hub that bolts to the crank off, 2 small countersunk screws and remove everything in there also, there are some friction plates in it also.

The part that the pressure plate bolts to, the clutch plate, has 6 holes in the center that also bolts to the flywheel hub, this hub has 6 blind threaded holes that needs to be drilled all the way through I drilled them out to 3/8 even though they were threaded, I thought 3/8 X 2" fine threaded grade 8 bolts would be the right size and would match the holes in the ring gear plate better. , becareful when removing the hub plate that has the blind threaded holes as it is mounted to a center that is a roller bearing and you might pull the bearing apart. If indeed you do pull the bearing apart you will need to put the ball bearings back in as to line up everthing. Don't worry about the bearing as it will serve no purpose after you bolt the whole thing together.

If you notice on the plate that has the ring gear there are 9 holes drilled through it. 6 of the holes are smaller and will almost line up with the 6 in the hub you just drilled, you now have to drill the holes in the ring gear plate to match the ones in the hub you just drilled. I did this by bolting the 2 part hub back together on the ring gear plate so the clutch plate would line up true and then put 3 smaller diameter bolts, 5/16" bolts through every other hole I drilled out in the hub and through the smaller holes in the ring gear plate to line every thing up. I ran a 3/8 drill down to drill out 3 of the holes in the ring gear plate, I then put the 3/8 bolts in the 3 holes I just drilled out and tightened them then drilled out the other 3 holes. I put all grade 8 bolts in and used lock nuts, but do not use the ones with plastic in them but all metal locknuts, tourque the nuts to 40 lbs.

The 9 bolts that bolt the flywheel to the crankshaft also goes through the ring gear plate and the clutch plate, the hub now bolts to the ring gear plate so everything is bolted together to make it a single mass.
No more noise and you can still use you stock clutch setup. Hope this is of some value to you. Let me know if you use this and how you like it.
If you have any questions please fell free to ask.

Info re clutch too...........

Your decision on which flywheel should be made with great care..About a year ago I replaced my dmf with the LUK clutch and flywheel from Southbend Clutch In Indiana. With the new clutch they sent, was some info papers that I found very informative.."1. The DMF has a free travel section that reduces gear rattle in neutral. 2.The DMF has a series of damper springs on the backside of the flywheel that isolate damaging engine torsionals from the transmission and drive train. The series dampened clutch used with solid flywheels also has design elements that protect the transmission from damaging engine torsionals and reduce gear rattle. Series dampened clutch dics do NOT have a slip joint for spike torque protection. These dics are designed to fail and will fail if torque spikes exceed the rated torque capacity of the vehicle." Examples of conditions where vehicle torque ratings can be exceeded are;1. towing loads heavier than the rated vehicle load capacity. 2. High speed downshifts. 3.Coasting down hill with the transmission in too low of a gear. 4. Increasing the boost pressure on turbo applications."----Rob

 

interesting. I figured if they built the flywheel to dampen driveline vibrations, a sold flywheel would indeed kill bearings sooner. Now im kickin myself for not buying that DMF for $75 outta the paper.

 

I'm sorry, I'm lost. What is this dual mass flywheel, and why might you want to get rid of it?

 

the DMF is a 2 piece flywheel. Like two flywheels joined together with springs, and other things maybe? (not sure) but the springs wear out and/or break causing play between the 2 parts, which is not good for your engine, input shaft, and tranny bearings.
It feels and sounds like a loose/broken U-joint when it goes bad. They are designed to dampen drivetrain vibrations caused by the big clunky diesels...but they dont last, and are more expensive than a solid flywheel conversion kit.
The solid flywheel is more desirable for longevity since there are no parts, other than the surface, to wear out.

 

If a solid flywheel is used then the clutch has to have the springs to absorb the shock(s) where as the DMF has the springs and the clutch is solid. There is a free play/rotation maximum between the 2 parts of the DMF. Usually broken or worn springs will cause excessive rotation between the 2 parts and rattling noises. One other area of concern it the center spline attached to the clutch for the input shaft, it can shear rivets or elongate the holes for the rivets holding it to the clutch plate.

 

PLC7.3 in that tech how-to you posted, im not 100% understanding it.... Is he telling you how to mod the DMF to a SMF..effectively by bolting the two pieces together?
I barely understood a single thing about the clutch part at the end, except harder driving will break something. Is it saying the DMF is protecting the engine from the tranny? Oh man the more times I read it the dumber I feel lol.


noone ever answered if a 6.9L SMF will work...ie flywheel to crank bolt pattern, size, ring gear count, if the 6.9 starter will work if the flywheel is a different dimension/tooth count,


GPSMatt, can you measure the diameter of the flywheel? and get a couple pics of it? Im going to compare it to some other flywheels

 

"""""""Is he telling you how to mod the DMF to a SMF..effectively by bolting the two pieces together"""""""

That is correct.....but you will have to put a clutch with springs in it....

Personally I would think hard re the costs of a new DMF VS ZF5.......

 

What years/engines had a dual mass flywheel?

 

does my 88 7.3idi have a dual mass? I hate the clutch on this thing. Hard to get smooth shifts.

 

do they make a rebuild kit for the DMF? with upgrade pieces...you would think someone would design such a product since the DMF is a troublesome area.

 

From what I've read so far the manual transmission 7.3s, both IDI and PS, do have the Dual Mass Flywheel. The last year of the 6.9 with the Zf 5 speed manual may also have it. Correct me if I'm wrong.

 

87 6.9 with the ZF5 had a dual mass flywheel.
All of the ZF 5 equiped trucks had them.
I have run a 6.9 flywheel and clutch disc behind a 7.3 turbo motor with my 4 speed without problems, it bolts right up. (same crankshaft in the 7.3 and 6.9 motors)
I think the bearings the dual mass is actually trying to protect is in the rear axle, pinion bearings if I remember right.

I have seen dual mass flywheels with no springs left in them which made the truck feel like it had a couple of pistons out of it while it was idling. You can not resurface them, they cost about 800 dollars just for the flywheel from Ford. What is there to like about them?