"new" ZF - Bad Vibration at idle - Very Concerned

[84TD]

I was wondering the same thing. I was also wondering if the camming damaged your trans bearings at all and if my case sounds similar.

 

[79jasper]

It could definitely screw up the input shaft bearing. If you have the trans out, it'd be easy to check.

 

[hesutton]

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Got the kit from South Bend Clutch, but the flywheel isn't their casting. That flywheel is in a lot of SMF kits for these IDI's. It has a cast-in counter weight on the engine side of the wheel. The balancer had to drill three 1/2 inch holes about 3/4 of an inch deep at the base of that counter weight area to get it corrected.

Heath

 

[Dieselcrawler]

When I pull my engine to reseal/ install new pan I am going to get mine balanced. I have a very slight hormonic vib around 1500-2000 rpm.

Jon, have Brandon balance that flywheel he got. Just to be sure. He has the same kit I got.

 

[84TD]

Ok I called LUK directly and their support department told me that the 7.3 idi has external balance on the flywheel and the 6.9 has a neutral balance and the flywheels are not interchangabl. Furthermore they do not and never did make a 6.9 flywheel so if you had a 87 with a DMF they could not help. I though that have read in multiple threads that they were both neutral balance and were interchangable.

I am now wondering what flywheel setup all the 6.9ers are running. I have found multiple threads on multiple boards with vibration issues after a ZF was installed on a 6.9l, I am wondering if flywheel misinformation is the root cause. I am pulling the flywheel and bringing both new and old to a machine shop tomorrow to get to the bottom of this.

 

[cpdenton]

I'm interested to see how this turns out. I swapped in a zf behind my 7.3. I went from one of those really thin flex plates with the spacer in between, to a heavy flywheel. I never had it balanced or anything, but I also do not have any vibrations. This will be good information to have available to us.

 

[hesutton]

Ok I called LUK directly and their support department told me that the 7.3 idi has external balance on the flywheel and the 6.9 has a neutral balance and the flywheels are not interchangabl. Furthermore they do not and never did make a 6.9 flywheel so if you had a 87 with a DMF they could not help.

They are incorrect. The only difference in the rotating internals between the two are the pistons. The crank, rods, wrist pins are the same. How does that make the 7.3 externally balanced and the 6.9 neutral balanced?

Heath

 

[riotwarrior]

Wow, interesting thread,

Glad I'm reading this as there is some good info, I'll be watching this for the outcome.


Al

 

[84TD]

I also think the tech at LUK is incorrect. I called 2 different machine shops today that balance rotating assembly's and both told me 6.9 and 7.3 are both internal balance. I also talked to the intl truck dealer and he lists the same PN for a 17in flywheel for the 6.9 and 7.3. Its just freakin me out the the manufacture of the flywheel told me what he did.

Maybe I got the 1 out of 1000 bum flywheel? I got mine back out tonight, if you look at heaths wheel compared to mine it looks very similar yet I have 4 holes and they are not even lined up with the counter. I get me new one tomo so I will see if the holes are different.

 

[bigoilburner20]

check your ujoints but the whole idle has got me a lil messed up but my truck just got a new ujoint vibrated real bad at low speeds then hummed after 50mph

 

[hce]

Both fly wheels have imbalance in them. Had the 6.9t/19 and a 7.3/zf5 on a crank balancer, and there is a fair bit of difference between the two. When I talked to southbend, before doing the swap, they told me there was a difference between the 7.3 and 6.9 flywheel. See that big wedge shape on your flywheel below the drilled holes, that is the balance weight.

 

[icanfixall]

Every crank in the 6.9 and 7.3 non turbo engines are the same. They even have the same part number. Even the rods have the same part number. The turbo rods have a larger wrist pin size. They are 33mm compared to the non turbo 28mm pin size. Thats all the internal differances there are. Bearings are all the same.. Cams are all the same. Valve springs are the same. even the intake and exhaust are the same. I'm betting the flywheel was drilled off center so it cams and shakes the hell out of things. Please remember to use a thread sealant on the crank bolts that enter the crank flange. they enter the oily side of the pan and oil will leak out past the threads. Any sealant is better than no sealant. I use blue loctite and 47 lbs torque.

 

[84TD]

So are you saying they are different?
I think I will call southbend tomo and get their take.

 

[84TD]

@icanfixall That is exactly what the machine shop told me today so I do not see how there could be a difference in the flywheels balance, other than that they just happened to change from the t-19 to ZF at the same time so there is no official solid flywheel for a ZF+6.9

Both fly wheels have imbalance in them. Had the 6.9t/19 and a 7.3/zf5 on a crank balancer, and there is a fair bit of difference between the two. When I talked to southbend, before doing the swap, they told me there was a difference between the 7.3 and 6.9 flywheel. See that big wedge shape on your flywheel below the drilled holes, that is the balance weight.

I see the counter but I think its a universal casting and they drill the holes to counter the counter if you know what I mean. All the pics I have seen of the 7.3 SMF have it and also have weight removed.

 

[90idi4x4]

Check u joints and if its a 10.25 rear check the pinion nut. Had what i thought was transmission problems but it was rear pinion nut. When it loosened it smoked the u joint and i think the tcase also.