6.9 + ZF5 owners please post your flywheel and clutch type

[hce]

Had both flywheels on a balance machine by themselves. If the engines were internally balanced, I would not of spent 4 hours on the balancer changing the imbalance of a 7.3 flywheel to a 6.9. It may not be noticable but It would always be in my head that the engine was off balance.

 

[franklin2]

Had both flywheels on a balance machine by themselves. If the engines were internally balanced, I would not of spent 4 hours on the balancer changing the imbalance of a 7.3 flywheel to a 6.9. It may not be noticable but It would always be in my head that the engine was off balance.

I have one question that will give credibility to the 6.9/7.3 balance theory; Will the flywheel bolt on only one way or many different ways? It would either have a dowel pin to set it in the correct position, or it will have a bolt hole in a oddball spot like the small Ford gas engines do. I had mine off once and can't remember how it was, but if you can bolt the flywheel on anyway you feel like it, then it doesn't have anything to do with the balance of the engine.

 

[dunk]

So there is a difference in the balance of 6.9 and 7.3 flywheels... That being the case, what flywheel and clutch should I use for a ZF5 on a 6.9? Was 87 a legitimate 6.9 + ZF5 year? If so should I get a flywheel for an '87 with 6.9 and ZF5? Those seem to say 5 speed but are about $750-ish and I think may be dual mass... Which I don't want.

So I just get a 7.3 regular flywhell and bring it along with my 6.9 C6 flexplate to a balance shop and have the 7.3 single mass flywheel matched to my C6 flexplate? Is there anything off the shelf that's the correct balance for a 6.9 and will work with a ZF5? Will an earlier 6.9 4 speed flywheel work with a ZF5? Or are there differences in bellhousing depth or size that prevent this from working?

I'd imagine if there are people running 7.3 flywheels on 6.9 engines the difference in balance can't be terribly much or we'd be hearing of failures, either flywheels or main bearings, but even with the fairly low RPM these engines spin I don't want to just slap it together and have a rough engine and have to worry about it.

 

[franklin2]

So there is a difference in the balance of 6.9 and 7.3 flywheels...

How do you figure that? I don't think we have nailed that down yet. Apparently the guys in the know haven't dropped by yet.

 

[hce]

How do you figure that? I don't think we have nailed that down yet. Apparently the guys in the know haven't dropped by yet.

Don't listen to that guy that had both on flywheels on a crank balancing machines accurate to half grams.

 

[ksingltn]

I had the stock 7.3 DMF behind the 6.9 when it was in my truck. No issues other than the noise from the fact that the DMF was worn out and the 2 halves moved about 15 degrees in relation to one another without any resistance.

 

[hce]

The best flywheel would be one for a 87 with a 6.9 and zf. Luk use to list one, due to lack of demand for a one year oddity it no longer exists. If were to have southbend build a clutch and flywheel setup they would change the balance. Having access to a crank balancer I went the cheaper route and matched a single mass 7.3 flywheel to a 6.9. Neither were 0 balance. Obviously from what others have done the engine does not feel to vibrate. I have also read other that have noticed a slight vibration at 2200-2500. Ive experienced wrong flywheels on ford small blocks and wrong crank in Chevy small blocks. Both liveable if you kept rpm under 2500, after switching to the correct balance of parts they were just smoother everywhere. Decisions yours if it for short runs throw the 7.3 flywheel in it. If you doing extended trips where fatigue is an issue, balance a 7.3 to match the 6.9. If anyone tells you the are zero balance look at the 1/2" x 2" boss cast into one side of 7.3 single mass flywheel and the section machined out on a 6.9. And yes the flywheels only go on one way.

 

[Kevin 007]

As for the one year 1987 6.9/zf clutch kits, "New Generation clutch" makes em, including the flywheel which is listed as 12'' heavy duty w/o dual mass option. So im going to assume that it is labled properly. This is the kit im going to purchase as I can get it local. .....soon, the trans swap will finally happen.......

 

[dunk]

I don't see a web site for a company or product line called New Generation though I see some branded as such for sale on Amazon and other places. Do you have a website or catalog link for them?

I see this site for AMS Automotive comes up http://www.amsautomotive.com/new-clutch-kits. They have clutches listed but all the single mass clutches and flywheels seem to be for 1 1/8" input shafts whereas the 1 1/4" input setups are listed as dual mass. It's my understanding the diesel ZF5 is 1 1/4" input.

I'm going to see if South Bend can get me a clutch setup for this combination, maybe someone knows of another off the shelf option though. I definitely do not want a dual mass flywheel though so that leaves the excessively expensive stock replacement options for an '87 out. Hopefully someone offers a single mass setup for this combination.

 

[franklin2]

Don't listen to that guy that had both on flywheels on a crank balancing machines accurate to half grams.

I am not doubting you had you flywheel drilled for some sort of balancing. I am still not sure how they balanced one flywheel to match the other if there is no reference point. In other words,, if the flywheel can be bolted on any way you please on the back of the engine, what is the point? I have done a little bit of research, and so far nothing I am comfortable with except that both the 6.9 and the 7.3 take the same part number crankshaft. They have the exact same crankshaft installed in both engines.

I have done some reading in earlier threads and different diesel forums, and it's always the same thing; "We don't really know, but I have been running my E4OD or my zf behind my 6.9 with 7.3 components for years with no problems".

 

[dunk]

Ugh, the plot thickens. My understanding is there are 3 different cranks. One was a very early minor revision of the first and essentially identical. Then a later 3rd revision but not sure if that was same year the 7.3 was released or not. If all the 3 cranks are interchangeable regardless of 6.9 or 7.3 then it makes no sense for the flywheels to be different imbalance, unless the flywheel and balancer on the front are matched and both must be 6.9 or 7.3.

This is my first IDI so I've never had one out or a trans off one, never seen a crank or flywheel so don't know. But I've heard both ways that they can be bolted on any orientation and also that they are keyed like a gas engine flywheel and can only go on one way. Looking at pictures IIRC I see 9 bolt holes in the flywheel which would indicate it only goes one way. I may be wrong. So which is it? Can the flywheel only go on one way or can it go any orientation? If it can go any orientation then why do we have one guy here saying he had a 7.3 flywheel balanced to match his 6.9 flywheel. If he did there must be a reference and there must be a significant or appreciable different in balance unless he got a part way out of tolerance on one or the other. He is also saying they have significant material on the backside offset, and I've only ever seen that for balancing purposes on an external balance engine.

Clear as mud, I'm pretty confused. Wish I had a spare of each engine sitting here to look at.

 

[hce]

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One of the 10 holes is smaller then the other, It is near the machined out area. 9 bolts hold on the flywheel. So how did I reference and keep reference. Placed two unmolested drill bits that the shank end fit tight into two of the flywheel mounting bolt holes. Then placed a straight edge against the drill bit shanks and scribed a line. I then repeated this process on the other flywheel using the same bolt holes. I was able to keep track of which bolt holes by counting from the smaller. Flywheel was mounted in the flywheel arbor (arbor for lack of a better term) for the balancer and the arbor was marked where the line on the flywheel was. Also flywheel arbor and magnetic end of driveshaft for the position sensor was also marked, this way position was held between the two flywheels. Mounted 6.9 flywheel noted amount of imbalance and position. Unmounted 6.9 flywheel mounted 7.3 and proceeded to match the imbalance. Sorry I did not take pictures of the process or write the numbers down for posterity sake. I did at one point mount a 6.9 flywheel to tire balancer. Tire balancer read 1.5 ounces at 7 inches from the center or 10.5ozin of imbalance, I have pictures of this but do not put much into it other then it shows imbalance.

 

[Kevin 007]

I don't see a web site for a company or product line called New Generation though I see some branded as such for sale on Amazon and other places. Do you have a website or catalog link for them?

I see this site for AMS Automotive comes up http://www.amsautomotive.com/new-clutch-kits. They have clutches listed but all the single mass clutches and flywheels seem to be for 1 1/8" input shafts whereas the 1 1/4" input setups are listed as dual mass. It's my understanding the diesel ZF5 is 1 1/4" input.

I'm going to see if South Bend can get me a clutch setup for this combination, maybe someone knows of another off the shelf option though. I definitely do not want a dual mass flywheel though so that leaves the excessively expensive stock replacement options for an '87 out. Hopefully someone offers a single mass setup for this combination.

I do not have a website or book for these clutches. Lordco Auto Parts (canada) stocks lots of NG clutch and hydraulics. I have used many slaves and masters before with luck. I to have searched online for a NG site....cant' find squat. Im sure its all a product of China.

 

[dunk]

Interesting. Clearly one hole is smaller so the flywheel can be keyed to a particular orientation to the crank. Also clearly there is a significant amount of material removed for balancing. Typically a neutral or zero balance piece will be cast symmetrical and have holes drilled to balance it, not milling out a large chunk. And of course that flywheel did have a significant imbalance when tested for it.

Interestingly here is a 7.3 IDI flywheel on ebay... It does not seem to be keyed with a smaller bolt location, though there is a small hole like for a dowel or to indicate orientation. Unfortunately no picture of the back side to see if it appears zero balance or has an imbalance.

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http://www.ebay.com/itm/87-88-89-90-91-92-93-94-FORD-F250-F350-7-3-DIESEL-FLY-WHEEL-/271405645156

Also this 7.3 flywheel (assuming image is correct) certainly appears to have an imbalance and it would be in approximately the same location as the 6.9 flywheel hce posted that was milled on the backside for imbalance.

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[dunk]

From: http://www.dieselpowermag.com/tech/ford/0703dp_international_diesel_engine/

"External balance weights in the flywheel and a vibration dampener were required to keep the overall engine size within that of a gasoline engine and to limit the scrap rate during manufacturing."

Of course no mention of how much external weight or any changes from 6.9 to 7.3.