M818 throwout bearing failure (bigtime!)

[70deuce]

On a short trip my clutch pedal went to the floor with no resistance. It appears the throw bearing had seized and collasped into itself on the carrier. Got to use a good friends cool transmission hoist/winch that is placed on the cab's floor over the tunnel. There was a post sometime back on the use of this real cool piece of equipment and there was difficulty using it. This hoist worked fantastic. The cable pulley is on 4 good size roller bearings and can be moved on the shaft very easliy with a 5 ton transmission hanging off it. I lowered the tranny about 18" which was enough by far to get in and pull out the carrier and old bearing. Had to use a drift to pound off old bearing. Carrier was undamaged and popped new bearing on and cranked the tranny back up and on. Took me 3 hours to unhook everything , drop the tranyy and get the tranny bolted back in. That hoist makes it one man job and easy to do it. Big thanks to Mike H for the use of his cool hoist.

 

[70deuce]

Also, you guys with 5 tons might want to check the front drive shaft mounting bolts on the transfer case end. Mine were installed with the head facing forward (threaded ends toward t-case) . A few of the bolts were about 1/4" longer the the others. The longer ones shaved the bolt head down on the air solenoid that the arrow is pointing to. In the picture all bolts have the threaded side facing forward. Something you might want to check. And I didn't paint the transfer case white. Came that way

 

[Gamagoat1]

Good to see ole "Optimus Prime" back on the road.

Glad the bearing failure didn't get to the clutch fingers..

 

[Pappa-G]

I just pulled my 818 around to change my T/O bearing today. Just my luck no fancy transmission tool hoist thing and no air tools, I'm betting it takes longer than 3 hours.

 

[scrapdaddy]

Good job! It's a nice feeling when everything goes right. If you still have the transmission lift, could you take some more pictures of it. I would like to make one like it. I use something on the same order, but way less cool, Thanks

 

[Gamagoat1]

Here are a couple of pictures. If you need more holler. If you have a copy of TM9-2320-211-35
you'll find it there.

 

[bulldog_mack13]

ahhh glad to see Mike helped you out with the nice peice of machinery Phil. Gets me thinking about the 818 here.

 

[Gamagoat1]

Hey Jay,

Phil did all the work, I just provided the winch.

 

[73m819]

when i had the clutch take a dump, i put a pipe though the back window and the front window with a come-a-long hanging from it, another come-a-long used to pull the trans back, then repositioned it to pull the trans back to the engine. this set worked great, it was a one man operation

when i changed the xcase i used the inner tow bar leg

 

[Pappa-G]

when i had the clutch take a dump, i put a pipe though the back window and the front window with a come-a-long hanging from it, another come-a-long used to pull the trans back, then repositioned it to pull the trans back to the engine. this set worked great, it was a one man operation

Thats what I was told by one of the guys at the CSMS. "Just stick your tanker bar on the window sills and hang your come-along from that." Tax dollars at work. - I love those guys!

~ Pappa-g

 

[scrapdaddy]

Thanks Gamagoat, I didn't realize it was a government tool. I use a set of tall walk broad jack stands and heavy pipe,etc.

 

[msgjd]

On a short trip my clutch pedal went to the floor with no resistance.

I realize this is an older post, and now that I am elbow-deep in a T/O replacement i am surprised there's hardly anything on SS about the subject.. i was looking for some "cheats" or helpful info and to refresh my memory.. It's been 40 years since seeing a 6x6 tranny drop at an OMS where they used a modified crowbar with rolling chain hoist, and 30 years since doing it myself with a tranny hoist I no longer have.. ..

I was hauling about 45,000 of hay and about 2 hours left to go with one of the M818's when the pedal hit the floor while leaving the largest town along the route.. Luckily there were only small towns, a few lights, and a half-dozen stop signs left to the route with little to no traffic.. As many know, floating gears with a roadranger is a piece of cake, but the spicers in our mil trucks are stiffer, broader, not as forgiving.. Between that fact and using the transfer case to make easier & closer shifts, it made things rather busy ... Also timing roll-through's just right at lights or signs, or else be forced to stop and then get it rolling in low range with the starter... Fun fun fun but made it with no issues other than elevated stress level at intersections.. .. I suspected a linkage issue but instead found the T/O very stiff and had extreme free travel.. Odd, because it was greased every spring.. There was never any noise and had adequate free play.. I will know its story soon enough.

I recall the OMS shop would loosen the back of the cab canvas and lay a heavy round bar on the rear deck and out through an open windshield.. It had tab rings welded on it so it wouldn't slide front/rear even if it rolled sideways.. They used a small chain hoist below a pulley wheel that fit the bar, thus the pulley easily rolled and the tranny lowered/lifted.. Here we go !! .. PS, that tool you borrowed is quite nifty, especially for those who have a hardtop truck

 

[msgjd]

O..M..G... WTF !!!!! Well, the tranny is down.. Not happy to see a like-new clutch pack in the M818 with failed T/O bearing and chewed up PP fingers .. I bought this truck direct at an army base and there is no grease fitting on bearing... So,,,,,,

After Action Report: What have I learned? .. I have mistakenly fallen for a misconception that the shaft and T/O bearing on the M809-series gets grease via the carrier similar to many Class 8 civilian rigs.. It apparently does not..

Yet , since the pedal adjustment has always had slightly more slack than "IAW TM" since I bought it, I question the quality of the bearing, or maybe it was poorly packed, or got heated and grease ran out, someone maybe rode the clutch (it's a winch truck) , or maybe it's just not the right bearing for M809's.. Many maybe's and haven't time to investigate..

But the facts of the matter is it's a like-new clutch pack and maybe 1000 miles of my ownership... I know that some commercial rigs have a fitting 1-each upon two flex tubes for the shaft and the bearing separately, and my FLD120 has one fitting that does both... Anyway, the bearing is stiff, still turns , and the fingers are almost ruined. This should never had happened with a new clutch pack, and strangely, it never squealed or chattered until the day I lost pedal

 

[Floridianson]

Do not know why your throw out bearing went bad. Myself whenever I did a clutch throw out bearing replacement after pedal adjustment I would take off the cover off the bottom of the bell housing and with the engine running look up in there with a flashlight and make sure to throw out bearing is not resting on the fingers and not spinning.

 

[msgjd]

I would take off the cover off the bottom of the bell housing and with the engine running look up in there with a flashlight and make sure to throw out bearing is not resting on the fingers and not spinning.

yep, that has been my standard procedure since a teenager when adjusting or replacing a T/O.... But this truck had a little bit more play in the pedal than according to spec ever since I bought it, it disengaged clutch fully, thus I never bothered to tighten up the play and never bothered to look for anything more than the grease fitting .. Looking at it closer today and the depth of fines slung around inside the housing, I believe the T/O was toast before I bought it , and I did a helluva job finishing it off Hooray for me ! .. Now where the heck is my pilot tool? I have a PP (and T/O) to replace... You can bet I am gonna hand-pack the new bearing .

 

[msgjd]

Took a little time out from another task to get a good look at the T/O bearing etc. in the daylight , it was getting dark when I dropped the tranny yesterday .. I see today the bearing is the correct one and sure enough the grease fitting is only for the yoke.. Well , somewhere awhile back here on SS it was mentioned to double-check NOS GI-surplus T/O bearings before installing them, as the grease could get dry, stiff, or leak out during long-term storage

So I have this shiny NOS GI-surplus T/O bought as a spare about a year or so prior to buying this particular M818 .. Pulled it out of the wrap and the grease was stiff and bearing felt loose as if grease had been warmed out of it, which explains why there was a circular wad of grease in the wrapper along the jointed face of it , the other face was clean as a whistle.. As mentioned yesterday, the failed bearing still turns and seeing it today in sunlight clearly it had been hot more than once.. Most of the balls were dry as a bone and sitting at the bottom of the bellhousing .. Somebody apparently didn't give the army mechanic the memo about new "old" T/O bearings.. Or they just didn't give a shite ...

It's a shame for the fingers on a like-new Lipe PP to be ruined .. I have replaced fingers on smaller dozer steering clutches and other smallish clutches, but never a heavy truck clutch like this one. Not even sure if it can be done in a vise or press without special tools as well as resetting/readjusting the finger height. Has anyone out there replaced or adjusted the fingers on their 5T? (edit update: I have dug out an old used 5T pressure plate.. It appears it would have to be put in a press, rivets drilled out and disassembled in order to get springs out of the way to pull the pins in order to replace the fingers.. Dang. )

 

[Mack90]

Can you get new throwout bearings for the M800 series or are we stuck with NOS?

 

[msgjd]

Can you get new throwout bearings for the M800 series or are we stuck with NOS?

I have not searched for any since the time I bought the one I 've had on hand for several years... Someone else will sure pipe in on availability if they know, and whether greaseables are available

 

[msgjd]

Unfurled the NOS T/O bearing today to repack it on the advise of someone's post here on SS years ago.. Almost unbelievable that a good 1/3rd to half of it barely had any grease (left half in picture) .. The remaining grease was caked, almost dried out... Due to the amount of grease found on one side of the kraft paper it was wrapped in, it clearly had seeped out over time .. These are considered sealed bearings but they are not "that" sealed .. This discovery inside a NOS GI-surplus bearing I bought around the same year the Army installed a new clutch in the M818 likely is the reason why its bearing failed prematurely

 

[Mack90]

Wow! I am about to pick up the parts for a clutch change. I will definitely be repacking the T/O bearing. I have read that moly grease is common on them. How hard was it to get the bearing open?