DMF to SF...Lucky mod??

[ttman4]

I'm digging up & compiling info. to do my DMF to SF conversion & have looked & saved all the tec articles I can find.....and as usual I remember some from the past that I can't find now, or have forgot where I put them.

I would estimate mine (FW, clutch, P/plate)has approx ???K miles on it...I don't know, but a lot! & it's been bigtime HOT twice in years past. So hot once the whole road filled with smoke but I had to get'er outa the road. Let it sit overnite & she been running A-OK ever since, till lately. Been playing with my IP again, finished my "RamAir", & couple other "upgrades." Then she slipped yesterday "blowing the smoke out" in 5th gear, but I couldn't make it happen again after that in any gear.
But some questions: '90 CCD 2WD
1. I think I have a 11" clutch...after converting & going to a spring loaded clutch kit, does anybody know if my DMF will/can use a larger clutch & pressure plate, or only can go back with same size setup? Or is more machine work required?
2. I've seen some talk about checking/testing the DMF for wearout & play (1/2"-to3/4"max). I didn't understand if this can be checked still mounted in truck, or only after removal of tranny etc?
3. About 350K miles ago I had the engine out & had the flywheel resurfaced. I don't remember how much was milled off & I don't remember how thick the original flywheel specs call for, but will find it later....unless somebody here knows. I've been told that if a flywheel is resurfaced, there needs to be an equal thickness spacer/shim put between FW & crank to bring back out to original distance.
Last question:
4. Should I just buy several lottery tickets & go buy a new truck, or keep working on this'n? I like working on this one because all my friends, pals, & buddys keep telling me these projects "can't be done!!!"
Besides that, evertime I buy something new I gotta carry it home & start tearing & fixing it to suit me anyway!!

 

[adelyser]

I just went through this with mine. While the Lucky Mod is a great idea, I still needed to use an 11" clutch, only because of the wear in the flywheel. I couldn't find a shop to turn a DMF, so I ended up just buying an entire set from Napa, SMF, 12" clutch, and all. The only time you can upgrade to the 12" clutch is if your flywheel has zero wear from the previous clutch, otherwise you'll have abnormal wear on the outside of the new clutch disc, and your clutch probably won't hold much.

You can check the flywheel play while still in the truck, remove the inpsection plate, put the tranny in neutral, and turn the inner flywheel surface by hand. It should turn only about 1/2".

 

[ttman4]

Then she slipped yesterday "blowing the smoke out" in 5th gear, but I couldn't make it happen again after that in any gear.

Still haven't been able to make it happen again yet. I'm gonna ck my throwout bearing slide today, that's only thing else I can think of now.
I had a TO bearing go out @ 73K in Wyo.....bad scene. Big load, snowing, no shop, no clutch to shift, crank start in gear....finally made it to Denver. New FW, clutch kit, & front input shaft.

3. About 350K miles ago I had the engine out & had the flywheel resurfaced. I don't remember how much was milled off & I don't remember how thick the original flywheel specs call for, but will find it later....unless somebody here knows. I've been told that if a flywheel is resurfaced, there needs to be an equal thickness spacer/shim put between FW & crank to bring back out to original distance.

I still needed to use an 11" clutch, only because of the wear in the flywheel. I couldn't find a shop to turn a DMF,
The only time you can upgrade to the 12" clutch is if your flywheel has zero wear from the previous clutch, otherwise you'll have abnormal wear on the outside of the new clutch disc, and your clutch probably won't hold much.

From what I remember, when I had mine resurfaced before, the machine shop guy got me to take mine apart (pull the small countersunk screws out) & took the F/wheel apart, then he resurfaced it.
I need to find a DMF to look at again. It's been awhile. & I know a little more about how these DMF work than I did back then.
But a question.....Can these DMF be taken apart like I did if they aren't worn out. If I understand, when they wearout & the cushion stuff gives up, you got bigtime troubles? I need to see another one again.
11" vs 12"....if my DMF surface is OK (probably isn't) will a 12" disc & PP even fit on it?
Also I wonder if it's even worth the effort trying to upgrade to a 12" disc when I have it all apart. If I'm able to get more clutch available, I'd like to.
(really, I need an underdrive, or double under lots of time untracking some of my loads, especially in reverse)
I've been measuring & looking again at a little 3 speed under/over seperate box, but that's another story & project.

 

[wwwabbit]

(really, I need an underdrive, or double under lots of time untracking some of my loads, especially in reverse)
I've been measuring & looking again at a little 3 speed under/over seperate box, but that's another story & project.

There is some local guys here (on Vancouver Island) that just came out with a "black box" http://www.northwestfab.com/blackbox.html underdrive unit for 4x4's. I have seen some of their past work and it is solid.

 

[Agnem]

You CAN check DMF play through the inspection cover. As for 11" versus 12", I remember the Moose Truck came with a 12" clutch. When I went to replace it, they gave me an 11" and I came back with "hey, this isn't the right one." They looked into it, and said yes it is. When they changed from the 3 fingered centrifugal weighted clutch to the multifingered presure plate design, they reduce the clutch to 11". I can't say that there is any real difference in normal use. If you were going to pull a sled, I'd worry more about the 12", but an 11" is going to work just as well for you in the long run. Part of the lucky mod involves disassembly of the DMF anyway, so you can take just the clutch surface to your machine shop for resurfacing.