Truck---> 1988 F-350 7.3 N/A 5-speed 2wd dually w/ 54k miles.

At idle, the truck makes a clunking noise in the bell housing area with the clutch out. When the clutch is in, the noise goes away. Typical throwout bearing symptom from what I've read and based off of some experience, so I've gotten all the stuff off to drop the tranny; starter, exhaust, drive-shaft, etc.

With the amount of miles on the truck it seems odd to me that anything is wrong like this, but I guess it could be worse. My question is where should I/ can I get a new throwout bearing? I don't want to be back in there again anytime soon, so I don't plan on cheaping out here. Also, anything I should replace while I'm in there?

And lastly, regarding the DMF; it's original to the truck, and I plan on keeping it that way, but it has about 5/8" of free play. With this low of miles, I assume it should be good but I've read 5/8" of play is beyond spec. Clutch has never slipped and besides the usual minor chatter sometimes, it's worked great. Shifts super smooth. No problems. Any input on this as well?

Any help is appreciated and thanks in advance!

 

Usually the throw out bearing rattles when clutch is out. Makes grinding noise when pushed in. Also the starter doesnt have to come out. You can buy a throw out bearing at about any parts store. The hydraulic clutches on these keep the throw out bearing in contact with the clutch fingers at all times there is no free travel meaning it runs all the time. Also the zf-5 is known for gear roll over noise when in nuetral and the clutch out.

 

Thanks for the response. I'm not getting rollover confused with the noise that's happening if that's what you were thinking.It's much different and the truck mainly does it when it's been driven for awhile. One thing to note is that when I'm in any gear and I'm taching below 1400 RPM you can tell it doesn't run as smooth as it should. It's hard to explain what happens, but I know for sure it's not the motors fault; it's whatever the problem is in the bellhousing.

And I did not know about the bearing always being in touch with the fingers so thanks!

 

Ok let's get a little clarity--
By "clutch out" do you mean:
"clutch pedal out" or "clutch disengaged"?

Do you have a transmission jack? These babies ain't light! I did my SMF conversion a few years ago and would have been pretty screwed without the jack. I used an engine hoist through the floor hole for an M50D in my F-150 years ago and it was a major PITA.

Replace while in there: throw out bearing, pilot bearing, and if you are leaking from the rear main seal do that too. Also kind of a PITA cause if you get too rough with it you ruin a $50 seal and have to get a new one. (The pilot bearing can be tough, I think there is a puller you can rent at parts houses.)

I would NOT grab just any parts store bearing. Get the best you can find, hopefully other guys can chime in with good bearing brands. I want to say Timken is good but don't quote me on that just yet.
(I've had a cheap parts store TOB die on me in short order, never went the cheap route again and it's paid off)

As for the mileage, do you know the original owner?? If not I doubt a 30-year-old pickup has 54k on it. But even if so...that's a lot of sitting around doing nothing, which will cause metal parts to rust. No surprise there, everything fails eventually.

Where are you measuring the 5/8" free play?

Edit: the starter can stay as said above. For some reason the dumb manuals say to pull it...

 

By out I mean clutch pedal out; so clutch engaged. And no jack, but I'll rig something up somehow or just go buy one. We've got 4 IDIs so it'll probably come in handy some time.
And thanks for the tip as far as pilot bearing and rear main. I don't think it's leaking bad but every one I've seen leaks at least some so may as well just get it.

And yes the truck has 54k on it. Don't know the original owner, I'm the third. Guy I bought it from bought it with 34k on it in 20(11?) from a guy who owned a Ford dealer in Indiana. Didn't use it much obviously but with that comes leaky seals and such. Got the manuals and all the sales things. Lucky find on my part.

I hope someone can point me in the right direction as far as a good bearing. Local Ford dealer came up with nothing and like you and I said I'm not trying to cheap out on it.

 

And I'm measuring 5/8" from the back part of the flywheel (closest to rear wheels) and the front section where it bolts to the crank. The 5/8" is the play between the two sections when you rotate the rear one.

 

I'm not sure... but I think that means it's junk? I'm pretty sure the two sections have springs that are supposed to take up all the freeplay(so they only rotate under load, as a shock absorber).

SMF time!

 

On both my other truck (59k miles) and my brothers (63k miles) there is free play, but not as much as this one. You can even tell there is by when you shut the truck off, you'll hear a clank followed by another subtle one occasionally and I assume that's the DMF having some play. I want to keep it DM even tho they're ~$800 at least for a new one.

Amd thanks for the time guys. Appreciate it

 

Uh... Why?

SMFs are far stronger, don't grenade and take out your transmission like the DMFs do.
They are also cheaper.
Everyone around here that I know of who has replaced a clutch has gone the SMF route.

I'm not sure of any downside aside from a little more noise... which can be remedied with 1 extra quart of ATF in the transmission.

 

Factory they had them, and I do believe Ford had a good reason for them. They also slip deliberately to avoid damage to your power train, and ZF-5s being aluminum cased, I think it's a good idea to reduce the shock load if possible.
I do see your points on the SM tho, and a lot of people evidently do too since they buy them. I like things stock, original and factory. That's how I've always been.

 

Which would be good... If they didn't explode and shatter bellhousings rendering the entire transmission useless.
Seriously, look it up.

And yes, Ford used them for the ZF5's. Not for the previous T-19, though.
And I know that the ZF5s are much stronger than we like to give them credit for... When Justin was running 800-1,000 ft-lbs of torque into one(400+HP), he was having a little trouble with his clutch handling the power, but the transmission held just fine.

I've actually only heard one story about ZF5 housings cracking, so I'm guessing that it's probably pretty rare.

Eh... you do what you have to do; I just think it's an expensive mistake. A DMF is quieter than a SMF, and that probably made some Ford engineer happy... I'd prefer my clutch to /not/ explode randomly, even if it is a little louder.

 

Tranny held just fine; for how long is the real test. We could go back and forth all day haha both have pros and cons. Considering how many trucks left the factory with DMF and how many have blown up, it's probably like cavitation issues, right? I'm assuming it doesn't happen nearly as much as its hyped up to be. Knock on wood.

I'm going to look into it, because I actually have a SM in the cellar that only has ~10k behind it. Last thing I want is rollover noise, and IIRC I read somewhere that the right kind of SM nearly eliminates rollover.

Thanks for for the input too, doesn't fall on deaf ears

 

noise while the clutch pedal is pressed down indicates bad TOB ..

noise while the clutch is not pressed down indicates bad Pilot Bearing ..

though you'll want to replace them both while your in there ..

i think you need a puller to yank out the pilot .

I cut mine out carefully but you'll want to use a puller ..

I'm not sure if the ZF is Greasable Like my T19 ..

it may not be , but here's my normal T19 TOB Maintenance ..

Throw out Bearing

 

Thank you! Any Source on where to get the pilot? Or even the throwout?
May just stick a SM after all in there
I appreciate it guys, lots of helpful people on this site.

 

Lets see...
I know you can get throwout bearings at Autozone; not sure on the overall quality, but they seem nice enough. I'm thinking they work for both DMF and SMF, as the fingers are basically the same here. It's supposed to self-center as well(the "head" of the throwout bearing slides around the "body" as well as spinning) which I *think* is a nice feature.

While you are in there, you definitely want to look at the clutch fork. This is what activates the throwout bearing.
The 'fingers' grabbing the throwout bearing get worn and loose; it also pivots on a half-ball attached to the inside of the bellhousing which also can have issues.

In the past, I have had issues with the clutch fork bouncing around in neutral and rattling; at the time, I wasn't sure quite how to solve the problem, so I just attached a spring that held it "up" or "down"(noteushing the clutch moves it "in" or "out"), and that took care of the rattling. The proper solution was probably replacing the clutch fork itself.

As far as gear rollover... If I put the truck in 2nd, and let it idle(800 rpm or less), I hear a noise like gears meshing together. Keep the RPM above that and it goes away(in gear). Out of gear, I've never heard any gear noises, just a rattling clutch fork(or ratting rest of truck, depending on how out of balance everything else is <_<).