Unimog FLU 419 needing a clutch

[Xoloski]

Posting for a friend. He lives near Ft. Huachuca and has 2005 FLU 419, AKA a SEE.
The Mog clutch slips and needs replacement. Unit says only 488 miles but I haven't seen the hour meter.
Is anyone aware of a shop or individual who does this activity in southeast AZ?
Is there a extensive write-up on the process and where does one locate parts?
Thanks for your help....

 

[frank8003]

Arizona listed only one
http://www.mogsrus.com/

found in
http://www.rockymountainmoggers.com/links.html

and this
Thilo Kass - T-Lo's Ultimate Off-Road in the Prescott area. T-Lo's Ultimate Offroad - Unimog and Pinzgauer Sales and Service, mogsrus@gmail.com.

 

[The FLU farm]

To avoid any future confusion, especially when ordering parts, keep in mind that this SEE was apparently rebuilt in 2005, but was made in the late Eighties or early Nineties.
Do have your friend double check that it's actually an issue with the clutch assembly and not something external with the actuation system. It's supposedly something like a 40-hour job to get the trans out, pulling the cab and engine is probably quicker. In other words, make sure he really needs to get in that deep before starting the process.

One place I know of that knows how to fix these things is Couch Off-Road. Not exactly next door, but probably no more than 500 miles away. If nothing else, have your friend call and describe the situation to find out what's most likely to be the problem and take it from there.

 

[peakbagger]

I haven't done it and don't ever want to do one but I sure would make sure the hydraulic clutch system is up to snuff before thinking about a clutch replacement.

 

[Xoloski]

The hydraulic clutch is set for 1/8" free play between the slave cylinder actuator rod and the clutch throw out bearing arm.
It was at 1/2" travel when we first got it. The adjustment seemed to make no difference other that once adjusted the transmission began to grind into the gears as though the the clutch disc wasn't completely releasing. Yet the clutch still slipped upon acceleration. Confirmation by a local and reputable transmission shop confirmed the need to replace the clutch.
Judging by the free play position of the retracted slave cylinder and the travel length of the cylinder itself, there is nothing more to adjust.
Reminds me of the old chevy's that would have a worn out throw out bearing fork...

 

[The FLU farm]

Since replacing the clutch seems to be an absolute pain, I would try just about anything before going that route. Including making the actuation part inoperable, then try driving again and find out if it still slips.
Faced with the situation your friend is in, my approach would be to buy another SEE (ideally with a clutch known to be functional) and swap over whatever parts that are better on the original one. It'd probably be less costly.
Come to think of it, I could use a parts car, so I'd buy the carcass if he decides to do that.

 

[Bikers33]

Check the clutch collar for rust in the bell housing... This is a common problem if the Mog was run through a wash pit before parking it for an extended period. The housing fills full of water then the throw out bearing rusts and seizes up.. 8 shots of grease could help. Check for smooth operation of clutch actuator arm. Clutch pedal lateral movement should be .06", this is done with the eccentric bolt connecting the pedal to the pushrod. Lastly, stupid question but is the master cylinder functioning correctly? A fresh rebuild does not really say much...depends on which type of rebuild it got. Go through everything first before deciding to drop it off at the shop.. Like FLU FARM said.. It will be way cheaper to just bid on another SEE ( with a known good clutch ). Good luck

Peace!!

 

[tennmogger]

Bikers33 brings up an important point. If the bell housing has any fluid in it then the drain plug is in place. The drain plug should not be in place unless fording is expected and would then be there to prevent water entry. If the plug is in, then the bell housing, and thus the clutch, could have been contaminated with water and oil leakage from rear main or front main shaft of the transmission. A contaminated clutch will slip, and it does not take much contamination.

The condition of the transmission not wanting to shift is indicative of dragging clutch (failure to disengage), as pointed out, and is opposite condition of slippage.

Xoloski, you did say a transmission shop has checked it. Obviously they should have caught a drain plug in place, and contaminated clutch, but ya never know. I'm with everyone else, exhaust all possibilities before doing a clutch job.

How many of you guys and gals have heard of Granville King. He wrote "The Jeep Bible", first published in 1985. He was an offroad and Jeep legend who wrote for some off road magazines years ago. His "clutch tuneup" for contamination was to drive the Jeep up against a tree or big pole and let the clutch out. When it smoked it was 'tuned". Of course a little common sense applies but I'd try that before a teardown!!

Bob

 

[Xoloski]

Thanks for the advise.
I'll grease the clutch collar..., I'm guessing it is the grease fitting at the bottom center of the bell housing...
I'll check the free play (lateral movement) of the clutch pedal before engaging the clutch master cylinder.
The clutch slave cylinder appears to move the entire length of it stroke and has the requisite 1/8" free travel before the clutch fork engages the throw-out bearing with the pressure plate.

Before the clutch slave was adjusted there was 1/2" movement. The manual called for adjusting the slave by loosening the lock nut and then extending or retracting the length of the push rod the necessary amount to obtain the 1/8" of free play.
There also exists slots in the slave cylinder mounting surface that allows the entire slave cylinder to move up or down in order to obtain the clearance. I used to slots to get the 1/8" free play.
After I did this, stepping on the clutch resulted in the clutch not disengaging completely and the the trans would grind going into gear. I would have expected the opposite effect, an easier gear engagement...
It'll take me a while to get to these things, then I'll report back...

 

[The FLU farm]

After I did this, stepping on the clutch resulted in the clutch not disengaging completely and the the trans would grind going into gear. I would have expected the opposite effect, an easier gear engagement...

That sounds like Bikers33's assessment may be correct. You might have lucked out here.
I put it on the list to check the drain plugs on mine today.

 

[Xoloski]

Reporting back.
The only grease fitting I could spot was about 18" rear of the clutch housing.
I greased this to no avail.
I do find it odd and unexplainable that I moved the entire slave cylinder down to acquire the desired 1/8" of free play between the the slave cylinder push rod and throw out bearing activating lever. Then when the entire slave cylinder was relocated to the highest position on its mounting slots, the 1/8" clearance remained. I would have expected the distance to grow as the throw out lever remains stationary while the slave cylinder moves away from it.
I did get an estimate of between 3 to 4K for the repair because of the labor intensive process of replacing the clutch.

 

[UnimogMP]

Dear Xoloski, I'm having the same problem...
Recently my clutch gave out, turned out the master cylinder developed a fissure on the seal, replaced the master cylinder and worked fine for a while, but recently, when driving uphill on a highway, the clutch starts slipping on 3rd and 4th (14th, 15th and 16th) above 2,000rpm with a warm engine, once it cools down it works fine, I'm guessing when I put together the new master cylinder I disregarded the eccentric screw adjustment in the pedal, I'm hoping that's the only problem, What ever happened in your case?

Regards!
MP.

 

[Sgt Jiggins]

MP,

I'm curious to hear what you learn about this situation as well - it's only happened once for me, but it seemed to be heat-related at the time for me too. Unfortunately, because I was unable to replicate is since, I've never been able to figure out what was going on.

Thanks,
SJ

 

[UnimogMP]

BTW, my FLU was running super hot the first time it happened, close to 230F, bad thermostat, bled the clutch line and greased the clutch lever, replaced the thermostat and much of the coolant (couldn't find the engine block drain because of course), and it just happened again at around 200F.

 

[Speedwoble]

The clutch throwout bearing slides on a tube surrounding the transmission input shaft and it is not unheard of for it to rust to that tube or otherwise have difficulty moving. I could believe that, when warm, that tube expands and makes it difficult for the throwout bearing to completely release. Consider trying to get access and lubricate the throwout bearing as it slides on that tube.

 

[UnimogMP]

SJ, I tried adjusting the clutch pedal via its eccentric screw and could not get the 1/8th freeplay on the clutch lever/slave cylinder so I adjusted the slave cylinder screw directly, hard to reach with the cab down, (10mm wrench for the screw and 13mm nuts on top (locker and base)), The slave cylinder had zero free play, it was probably disengaging the clutch when running, I still have to take it out on a highway to see if its been fixed, hope to do so this weekend, will post results. Now I have a priming issue, it used to hold its prime for weeks but now its losing it in a couple of days, found that the line connections on top of the diesel pump are bleeding slightly, surely letting air in and diesel drian back to the tank?, I hope its just a tightening solution.

Regards.
MP.

 

[The FLU farm]

Now I have a priming issue, it used to hold its prime for weeks but now its losing it in a couple of days, found that the line connections on top of the diesel pump are bleeding slightly, surely letting air in and diesel drian back to the tank?, I hope its just a tightening solution.
MP.

New sealing washers are dirt cheap.

 

[UnimogMP]

SJ, I took it the same highway today, clutch worked perfectly, I guess the clutch lost its adjustment either when I changed the master cylinder, or by my abuse or just the 30 years since it was originally adjusted.

Regards!

 

[UnimogMP]

Dear Bob, my clutch is acting out again, I looked under the housing and there was a drain plug ‘plugged’, I took it out and it drained about one liter of oil, the first part was mostly ok, looked like diesel motor oil and the last came out like guk, and its still dripping, I’m gonna check tomorrow for how much it drained and engine and trans levels, question, have you seen the housing drain plug? Is it a standard mag-plug on the back of the housing near the trans pan? I can only see four, the engine pan, the trans pan and transfer plug and this guy.

Thanks and best regards!
MP.

 

[tennmogger]

MP, You may have found all the drain plugs. I really do not know the transmission setup in the SEE mogs but a typical 406 mog transmission of that era has three drains, two on the transmission and one in the cascade case ahead of the transmission, plus the one in the clutch/bell housing. Guess that's five. The transmission, cascade and "transfer" (actually part of the transmission) all fill together in the transmissions I have serviced.

For your fluid-filled bell housing, after it drains a while you might want to use a garden sprayer with degreaser in it and spray out the housing best you can. Maybe have a second person operate the clutch while spraying. The purpose is to get the oil off the friction material, of course.

You will probably never need that clutch housing drain plug put in.

Bob