I have a 1990 retired U-HAUL E350 with 7.3 IDI and C6. I converted it to a motorhome. I am putting a ZF5, BW1356 or NP205 and Dana 60 on it. I got a donor vehicle drivetrain I believe is a 89. It has a IDI of unknown year. I plan on using the flywheel and resurfacing it. The clutch disc measures 12 1/4". I plan on replacing the clutch disc and pressure plate. I want to know which clutch to purchase. My plans for the motor will be a rebuild, Banks turbo, a slightly better cam and exhaust. It,s in a 9,000 lb rig shaped like a brick, not a hot rod but, still I don't want a clutch that will give out. I'm new to the IDI world so I would love some input from people who know more than I do. I am a machinist by trade so any necessary adapters I can make. Thank you all for your replies.

 

I have a LUK clutch and I am happy with it, have gone the SMF conversion, the only anoying part is the gear rollover.

 

Now, the flywheel I have has the bolt pattern for the 12 1/4" clutch pressure plate. To my understanding that is not the stock bolt pattern?

 

All Dual Mass Flywheel clutches I've seen are "11" inches. Single masses I've seen are listed as "12". It might have already had a Single mass put on it

 

LuK SMF is the way to go.

 

Cool thanks, It is a single mass clutch set up. I'm just thinking that since it's a heavy rig and it's not aerodynamic a stock clutch would probably not suffice. Also, when I purchase a clutch is there certain years that are 12"?

 

Does the LUK SMF feel normal or does it make the clutch pedal harder?

 

It feels better than normal. It is super smooth and linear, with LESS pedal pressure.
I have the same driveline setup you have, including 4.10's. Love this clutch. For me there is almost zero gear rollover but each pickup is different.
While you're doing all this I highly suggest filling the ZF with Redline MTL(manual transmission lube). Has friction modifiers that keep the synchros healthy for a LONG time and let's you shift super smooth, even in cold weather. Its night and day to the gear oil some people run. (ZF has a big fat chart of approved lubes and it's staggering how wide the range of stuff is, all the way from 75w gear oil to synthetic ATF)

 

Not wnt to hijack the topic but I would be interested in that lube chart for zf5, I can not find it anywhere. I want to experiment with different oil.

 

Thanks for the info.
ATF is what came out of the tran. The transfer case was almost empty, about 1/2 qt. came out. I do plan on rebuilding everything before it goes into the U-HAUL because that thing has to be reliable because if it breaks down it will be far from home.

 

It seems silly to me to run ATF in a gear box. I was going to look into something else.

 

The general rule is if the case is aluminum or magnesium, it usually needs ATF. If it's steel, it probably needs gear oil.

In the case of our trucks, ATF in both the transfer case and transmission. If you put gear oil in the transfer case, YOU WILL DESTROY IT. In the transmission, I guess it can handle other stuff, but I would still use synthetic ATF, mercon or equivalent.
To prevent/reduce gear rollover noise, add an extra quart to the transmission, through the shift lever hole.

 

Toyota's run 90w gear oil in aluminum transmissions and transfer cases.
Don't get me wrong, I'm not trying to argue you, just the first thing to pop into my mind.
I will probably use what it calls for as far as oil.
The transfer case I'm still undecided. The BW1356 is chain driven and has rear output slip yoke. NP205 is a much better case but, this isn't really an off road rig so the 1356 would probably be good enough. The rear output I can modify to have a fixed yoke.

 

x2!!! I love the LUK smf in my '88. There is I think a south bend smf in my '93 and I HATE it, feels worse than I remember the stock dmf in the '88 before I swapped it. When I eventually tear into the '93 it will be getting a LUK clutch and pressure plate (flywheel too if needed?)
This is not a TOYota, the ZF is a well engineered transmission with tight tolerances and small clearances. A heavy weight gear oil is too thick and will screw with the shifting. That will cause excessive wear on the synchros, and can starve the bearings causing more damage. The engineers knew what they were doing when they specced ATF, same goes with the transfer case.

After quite a bit of research I'm running mobil 1 synthetic something in my ZF5. It was recommended somewhere to keep gear rollover quiet, turns out that didn't work, but it shifts well and unlike gear oil is thin enough to shift well. I had swapped to Redline MTL in my old VW jetta and that shifted awesome, I hadn't really thought of putting it in my ZF5, though its a good idea, just a bit pricey for the amount needed.

BTW, there are fixed yoke BW1356 units, I want to say Bronco's had them? I would also prefer the fixed yoke, but have very little trouble with the 1356 in my truck. There was a small issue with the linkage inside popping out of place, but the only effect was it wouldn't shift out of 2wd, and was easy to spot and fix when I popped the case open.