Gear rollover much louder than expected...6.9 w/zf5

[fiverpuller]

I knew I would hear some but holy cow! I have a 6.9 engine/flywheel with the zf/5 using a springed friction disc. Question: could this be making more noise than other smf's because the flywheel weights 23lbs less? I am thinking so but curious if there is anyone else out there with this combo? I am only using atf for now...will consider other options to reduce noise and protect the fragile zf.

My t19 had some rollover when grunting hard at about 700rpm. But this one grunts all the way up to 1200 and seems a bit louder. I know there has been many posts about rollover but anyone have the 6.9 flywheel with a zf? Didn't the '87 6.9 have a solid fly with the zf5?

 

[Agnem]

Nope. ZF's mated to the 6.9 in 87 had the DMF. Gear rollover noise is a real ******. Try putting 2 gallons of 30wt. oil in the ZF. It helped the Lady Moose alot, but don't expect a miracle.

 

[wwwabbit]

Yep! welcome to the club I don't even have the springed clutch. Mine has an extra loud "gear rollover" noise from 40-60 km/h in 4th... I think that is part of the "getting tired trans" part more then the rollover noise, but it's loud enough that you can't easly talk over it in the truck... you need a good shout to be heard.

 

[Pacific]

You guys must have really bad ZFs or I'am partially deaf because I have the LUK single mass flyhweel behind the 7.3 the shifter boot is a aftermarket one its not even screwed to the floor I can see daylight. The transmission has almost 328,000kms 203,819 miles which were hard kms/miles because the truck was a company truck for 2 companies. The first company that owned the truck either used it for a welding truck or a dump truck so it was grossed to 15,000lbs most of the time. Most P/U trucks never gross that for 90% of its life the ZF in a F-Superduty sees alot more stress.

When I bought the truck the engine was blown the flywheel sheered off the crank shaft bolts so the flywheel's full weight hung off the input shaft. The guys that pulled the transmission out (before I owned the truck) damn near killed themselves because they didn't realize the flyhwheel wasn't attached to the engine.

The only gear roll over noise I really notice is in reverse and in first gear at low rpms. At highway speeds the truck spends most of the time in Overdrive because 4th gear is too low. If I can't pull the hill in OD then I can't do the speed limit its crawling in 4th with the engine screaming at 2800-3000.

I hear more tire howl and engine noise more than I hear the transmission I heard more noise coming from old NP435s and T-18s in my old gasser trucks.

Personally I can live with a little extra noise over paying 1100 dollars for a dual mass flywheel and another 300 for the clutch then put up with a heavy pedal pressure that screws up the firewall.

 

[The Warden]

I have a 6.9 engine/flywheel with the zf/5 using a springed friction disc. Question: could this be making more noise than other smf's because the flywheel weights 23lbs less? I am thinking so but curious if there is anyone else out there with this combo?

I have but one question...HOW?

When I did my ZF conversion, one of the first things I found was that the T-19 flywheel that was originally on my truck was considerably narrower than an appropiate flywheel for a ZF5 would be (I think that the T-19 f/w was half the width of the ZF f/w). I actually thought at first that this wouldn't be a problem. I was then told that using the T-19 flywheel with a ZF, IF you could get the ZF pressure plate to go onto the flywheel (IIRC, my T-19 pressure plate has 6 holes while my ZF pressure plate has 8), would result in various issues (don't remember the specifics with my brain running the way it is at the moment; hopefully someone will chime in and remind me)...

I wouldn't be surprised at all if this was a direct cause of the rollover noise issues you're dealing with...and I'm surprised that you're not having any driveability issues...

 

[fiverpuller]

Well...was going to do a mini write up on this but I will tell my secrets now. First...the 6.9 fly is about 3/4" slimmer. The 6.9 pressure plate will not work since the t19 uses a different throw out bearing. The 7.3 pressure plate (Luk) I had bolted right onto the 6.9 fly with 6 bolts. Now I had to look at the critical dimensions. The idler bearing in the fly is located at the exact same spot on both. So then I had to check the location of the friction disc splines. The splines on the dmf clutch go towards the fly since it is farther from the idler bearing...if that make sense. Whereas the springed clutch has the longer splined (springed) side going to the transmission. So the end result was the springed clutch splines on a 6.9 fly are 3/16" closer to the fly. I found the wear marks on the zf input shaft and found 1/4" of splines left. Also noted there was enough unused shaft on the t/o bearing area. I was worried about the throw of the lever arm. It had been way far foward before. It ended up just past center with the 6.9 fly and the slave cylinder was much easier to install. Bottom line... things moved a little but everything fits fine and it's the smoothest clutch I have ever ran.

 

[geneluo]

i also have a luk fly and clutch with a zf5 behind the 6.9 and i also get a lot of rollover noise

 

[fiverpuller]

So is that the same flywheel that is on the 7.3? Do you know how much it weighs? I will have to take some video of the noise to post and compare. I guess the rollover won't cause any short term damage but over the years it is bound to wear something out faster.

Has anyone tried some fancy atf like redline? And for the 30wt...is that synthetic or regular motor oil? I will have to change my driving habbits a little to stay away from 1000rpm...but it's hard not to lug when stuck in traffic...which is everyday in this town. Man...what happened to the days when the fwys weren't jammed?

 

[Agnem]

That's regular 30wt. motor oil I'm using. All the industry guys say the noise will not harm anything, but I agree that it "sounds" like it sure would. If I read that write up properly, what you ended up with was a 6.9 flywheel, and a 7.3 disc and LUK presure plate, with no modifications needed. That's good info if correct, and I'll add it to the FAQ.

 

[fiverpuller]

That is correct Mel. Everything is working fine besides the rollover. Very smooth pedal operation and engagement. I should have noted the part numbers...but here is what I have (all 11" parts):
Stock 6.9 flywheel
Valeo clutch disc with 4 springs
Luk pressure plate

One note...these things might have to be ordered seperately. I am not sure if you can get a 7.3 clutch kit with the springs. And I think the springed luk kit is 12"?

I think any 11" zf pressure plate would work. But I am curious what clutch disc others are using on the lucky mod? Since the 7.3 fly is so much thicker...it looked like my Valeo disc would run out of splines on the input shaft with a 7.3 fly? Must be a more "centered" spring pack?

 

[Agnem]

I think the Lady Moose has the same disc as yours.

 

[thunder]

So has any one tried the syn 30 to see if it quiets the noise a little?

 

[Hoss6.9]

I'd try putting some Lucas Oil Stabilizer in there. I use it in everything. Trannies (Manuals of course), Rearends, etc. I Love It! Realy quites them up and keeps running temps. cooler.... I have used it for 12+- years now. And would swear by it!

Hoss....