flywheel questions
 

Many of you know that i did a 5-speed swap a few months ago. My donor truck was a 91 and my driver is a 94 factory turbo. I was just told lately that the flywheel for a 94 factory turbo is balanced different than a N/A truck. It makes no sense to me but i have a vibration above 2500rpm and thought just maybe this could be the problem. Anybody know if there is a difference in flywheels?

The factory turbo engine has larger piston pins, which means the piston assembly weight is different than tha NA engine.
I believe that IDI engines are externally balanced by weighted harmonic dampeners and weighted flywheels. This means that flywheels & dampeners shouldn't be swapped between the 6.9 & 7.3, and would also mean that the factory turbo dampeners & flywheels are differently weighted than the NA 7.3s...

Will driving with this setup cause premature tranny or engine failure until i can get the right flywheel. I am really surprised this never came up with all the questions i asked during the swap.

Does anybody have a part number for this, everything i find is for 88-94 non turbo

What is the difference between F and K code trucks, both show turbo charged

does anybody know what the difference is between these two flywheels and if this is what i am looking for
Sachs NFW1069 - Flywheel | O'Reilly Auto Parts
Sachs NFW1067 - Flywheel | O'Reilly Auto Parts

I cant find to much diffeance expect the secnd link fits more applications. Could be the spring rates or tooth count. Couldnt find those specs though

K is `94 factory turbo, F is Power Stroke.

Jamye You have to remember tha there were 3 different versions of the 7.3 in 94. As far as I know both the NA and turboed 7.3 IDIs take the same flywheel, but the 7.3 powerstroke flywheel is different, and won't work on the IDI. Is that where the confusion is coming from?

I do understand the three different motors for 94. However i am now learning the motors are balanced different for the factory turbo and the N/A so the flywheel has to be different. I know that my truck is K code but every flywheel i find says 88-94. ???????

I just bought a 7.3 idi and the guy I bought it from took the after market flywheel that was on it and put it on his 6.9 with no prob he did say something about haveing to use the aftermarket clutch and pressure plate as they are a different size than the ford one but myself I do not Know.Thats just wat was said .

For reference, this is the origin of my question to Jayme Duty, since I'm doing this swap soon. This is from the Ford manual supplement for the 94 turbo modifications:

https://www.ford-trucks.com/user_gal...id=242075&.jpg

Nothing I had read before said anything about different flywheels for the factory turbo. I never really thought about it until your 1st. post in this thread, but it makes sense.
Now, how much difference it makes is a good question. I've read of people interchanging 6.9 & 7.3 flywheels with no problem, & I'd have to think that the difference in piston assy. weight is greater there than the difference between the 7.3 NA vs. Turbo.
The O'Reilly links are disapointing. Based on the engine code, they claim that both flywheels fit IDI's and Strokes... You might contact Sachs directly, with their part numbers. You might get better info there.

Good luck man!
Phy

Thanks for all the tips, i will contact ford and sachs today to see what i cant find out. is there anyother parts you guys would change out while i have the tranny out again. the clutch is almost new (10,000miles) so am not worried about it.

Northern, Good info, that is the first that I heard of that, but it makes sense. You learn something new every day.
I agree with Phy on the Orilley's links, if you do a search for a 96 flywheel you come up with a different number than what they say a 94 stroke takes, but they should be the same.

I do notice now that they say the vibration damper cannot be interchanged, but they don't say that for the flywheel. They also say that the differences are not discernable, unlike for the damper.

To me it seems that if the differences are not even visible and it fits on the same transmission and engine mounting it shouldn't make a big difference, but the 3D dynamic physics engineering they did to create it are beyond me... that's why I switched to mining!

Jayme, have you brought your engine to speed while in neutral? Seems to me if the engine was unbalanced it should vibrate even in neutral, since the damper and flywheel are spinning.

I bet they mean not decernable visually by the average mechanic.

Good idea, ND! If this is done with the clutch in & in gear, then the clutch disk and trans input shaft wouldn't be spinning, thereby eliminating them from the equation. If you don't have the vibration in that condition, put it in neutral & let out the clutch. If the vibration appears, then it's in the clutch disk or front of the trans. Did you install a new pilot bearing?

As far as other parts to change, I always put a new throw-out bearing in. Mr. Murphy is my personal guardian angel, and he makes sure that if I don't, it goes out within a week of my putting it back together...

Let us know what you find out from Ford & Sachs.

Phy

Jamye, did you use the original dual mass flywheel off of the 91, or did you use a single mass conversion? If you used the one off of the 91 it could be crapping out, and giving you the vibration you are seeing. This happened on my 97 Stroke, and it cost me a tranny as the bell cracked from the vibration.

Honestly i don't know the difference between dual mass and single. The PO of the 91 had a new clutch and throw out bearing installed 7000 miles before i got it. I put 3000 miles on it before parting it out due to registration issues. There fore i just swapped everything thinking i should be ok. And no did not install a new pilot bearing. Also if i am sitting still clutch in and in gear or in neutral and rev to 2500 i get just a very very little bit of vibration that isn't really even noticeable.

Just talked to ford, they said there is a difference, the 94 factory turbo calls for a dual mass and he wants $1400. He said i can go after market and switch to a single. Why is that flywheel over a grand more than oriely's

If the vibration was because of the flywheel, it should've been just as bad when sitting still & reving...
Did you try sitting still & reving with the trans in neutral and the clutch out? If the vibration comes back under those circumstances then the issue is with the clutch disk or trans. A worn pilot bearing could let the clutch disk & trans input shaft be enough off-center from the crank to cause a lot of vibration...
'Cause it's from the Stealership?? :-)

Probably 3 reasons:
1. It was a low volumn production.
2. It a dual-mass flywheel.
3. It comes from the Stealership.

These are from NAPA, the first is a dual mass, the second is a single mass. The dual mass is a two piece design held together with springs and a bearing. It is susposed to dampen the impulses from the diesel detenating by the springs in between the two pieces. The single mas is a one piece design like used on a gasser. The springs are in the clutch plate hub. The 1000 dollar difference in price is why most change to the single mass set up when those dual mass ones go to pot. https://napaonline.com/Catalog/Catal...+50028+2028028 https://napaonline.com/Catalog/Catal...+50028+2028028

For some reason i am just getting this, i guess i don't understand the parts. I thought the flywheel was the metal disk with all teeth on it that is bolted to the back of the motor with nine bolts and what the starter engages to go turn over the motor upon starting. This whole two piece with springs and bearings and what not has got me confused. Is the clutch and flywheel together all one setup. Also after crawling around under the truck some more shaking stuff i noticed some place in the tail shaft on the t-case and wondering if this is where my vibration is coming from. A while back my carrier bearing came lose and caused some extremely bad vibrations and i think this my have damaged the t-case.
phy. Yes i did also let the clutch in neutral and it was the same result. very very little vibration at 2500rpm.

You are right on what the flywheel is. The dual mass has 2 pieces engineered into one piece, in my opinion not a good design. I will not install a dual mass when they go bad. You still have a seperate clutch and pressure plate with both set ups.
If you look at the back side of both flywheels in the two links above you can see the difference with the springs in the dual mass.

for some reason i cant open those pages, just brings up errors

check here for a little explanation on dual mass flywheels:
Capitol Clutch and Brake, Inc.

That pretty well eliminates the flywheel & clutch as the cause...

What about pilot bearing or throw out bearing? if it is not these i think i will throw in my spare t-case this week and see if that helps.

You need to change the flywheel from the donor truck's orginal N/A one to a Turbo-Specific one.

Flywheel:
Heavier engine components change the engine balance and require use of a turbo specific flywheel for manual and auto trannys.

Manual flywheel part number is F3TZ6375A
Automatic Flywheel number is 1816637C1

The part's are actually discontinued. So your going to have to find a used one.

You also have to find out if it's the original dual mass flywheel or it's been converted to a single mass flywheel. DMF's DO NOT like engine modification's. They are designed to work at factory setting's only.

When you pull it apart, you'll be able to see the differences between Dual Mass and Single Mass:

Dual:
http://www.dragcars.com/parts/img/du...0528661524.jpg

Single:
http://shparts.com/6.9d%20flywheel%20002.jpg

As you can tell, the Single is much thinner then the Dual. The only way to tell which setup you have is to just pull it apart.

Yea, its starting to sound like the shake is further back in the system. What about running up in gear with the T-case in neutral? No shakes there would completely clear your tranny of any blame.

Manic, that is what i have been looking for pics thank you. Mine is absolutely a single mass as i had it out a few months ago.
Northern, i will try the t-case in neutral this afternoon and see what happens that is a good idea

Awesome! Ok now you said you reused the N/A's flywheel right? As I posted before you'll need to get a single mass flywheel from a "K" vin truck (turbo IDI). The best part is it won't cost you almost a grand. It'll be more around $300, if that. Hell if you find a good condition used one those usually go for less then $100.

Tried this and with the t-case in neutral, tranny in first and throttle at 2500 i get a worse vibration than just in neutral or clutch in and in gear. What does this mean???

I have been finding them new for $130, i am just starting to wonder if this is actually the problem

I'll put money on it that's your vibration if you used the N/A flyhweel on the Factory Turbo motor. :-drink

Manic how much money are we talking, i like to bet

If the flywheel is the issue, the engine should be unbalanced when revving up in neutral, as the flywheel is spinning. Since this is not the case, the vibration seems to be coming from further back in the driveline. Your suspicion of the T-case damage may be worth following up on.

That being said, Rock Auto has solid flywheel conversions for $124.73 and I verified they have them with part numbers specific to the K model (factory turbo IDI), so I think at that price I'll be ordering a new one anyway.

This is interesting, I just searched flywheels to see if I put any sealer on the flywheel bolts and came across this. I'm doing the opposite of the original poster. I'm putting an older 6.9 in a 93 IDI turbo. I have to use the flywheel of the turbo 7.3. Mine is the dual mass. Kind of nervous about using it now.

Where you at, maybe we need to swap flywheels. But also sounds like it may not be your vibration too.

96, i am in montana