Clutch failure on trail. Need help.

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hatzlibutzli
Germany
Posts: 23
Joined: Mon Dec 28, 2015 11:47 pm

Re: Clutch failure on trail. Need help.

Post by hatzlibutzli » Fri Jul 03, 2020 2:26 am

could bring a spare disc since a clutch swap is 100% doable in the middle of nowhere with just the on-board toolkit
That is what I always do, when going to remote areas like North Africa without spare supply available. The additional weight in bearable. And you need the suitable spare, since there is no way for an improvised replacement. The experience shows, that only the spares you don´t carry with you fail ://

Greets ... Simon

Joeri
Belgium
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Joined: Sun Jan 05, 2020 11:09 am

Re: Clutch failure on trail. Need help.

Post by Joeri » Fri Jul 03, 2020 8:17 am

And do you know the reason why this happens ? No....tis water that goes in to that hole when doing deep water crossings....it makes the clutch liner wet and after that when using the clutch a lot ( like on trails) the clutch becomes hot so it litterly makes the disc explode , this is why theres no warming...it just happens and theres no clutch annymore. :mrgreen:
Had the same problem when driving the croatia trophy in 2003....pulled the tranny out on the spot....same damage like in the picture above.....a croatian guy we met drove us to a farmguy where we took the liner off a clutch from a international tractor cut it on size and riveted it back on the pinz disc.....I drove the whole trophy with that disc :mrgreen: :P

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rmel
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Re: Clutch failure on trail. Need help.

Post by rmel » Fri Jul 03, 2020 8:34 am

Wow ! That's a mighty impressive failure, ground to dust.

Well I'll be taking a good but used disk with me on the
next trip rather than sitting in the spares pool -- darn
good suggestion.
Puller: 71' 710K 2.7L EFI aka Mozo
Follower: Sankey MK 3, 3/4 Tonne
Rescue Pinz: 73' 712M

Driver: Ron // KO0Q

ChickenPinz
United States of America
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Re: Clutch failure on trail. Need help.

Post by ChickenPinz » Fri Jul 03, 2020 10:37 am

Joeri wrote:
Fri Jul 03, 2020 8:17 am
And do you know the reason why this happens ? No....tis water that goes in to that hole when doing deep water crossings....it makes the clutch liner wet and after that when using the clutch a lot ( like on trails) the clutch becomes hot so it litterly makes the disc explode , this is why theres no warming...it just happens and theres no clutch annymore. :mrgreen:
In this case, the truck hasn't seen water immersion in any recent past.
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ChickenPinz
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Re: Clutch failure on trail. Need help.

Post by ChickenPinz » Fri Jul 03, 2020 10:43 am

rmel wrote:
Fri Jul 03, 2020 8:34 am
Wow ! That's a mighty impressive failure, ground to dust.

Well I'll be taking a good but used disk with me on the
next trip rather than sitting in the spares pool -- darn
good suggestion.
Yep. Nothing left of one side of the disc. Even found a few chunks wedged in the spring tines.

The flywheel side has 4.0mm of material remaining and dust grooves still visible. Not sure what the original material thickness was.
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ChickenPinz
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Re: Clutch failure on trail. Need help.

Post by ChickenPinz » Tue Jul 07, 2020 7:16 pm

ChickenPinz wrote:
Fri Jul 03, 2020 1:34 am
I don't think the drain hole on the underside is going to help much. It's only 5mm and likely very little clearance on the inside. Your best inspection point is to remove the two nuts over the slave cylinder ball-and-socket joint.

All that being said, it wasn't particularly obvious that the failure had occurred on my truck even after half the disc had disintegrated. You might be able to stick a borescope in there, but it's not clear that there would have been any visual warning signs.

The transmission was just out within the last 100 miles or so, and both Jim and Andre saw it and neither saw anything that looked wrong at that time. My take from that is: There are no visual early warning signs. And there was no hard use of the clutch anytime from when Jim/Andre saw it until it failed. Oh, and the truck has about 50,000km/1500hr on it.

All that being said, if you're really worried about a failure on the trail, you could bring a spare disc since a clutch swap is 100% doable in the middle of nowhere with just the on-board toolkit. Me? I'll just make sure I'm with pals who could leave me some water and whiskey while they drive back to civilization to return with a new clutch.
Right now the feeling is this failure was a combination of 40yo disc + overspeed, but I've started a separate survey to collect data on if this is just an old disc issue or if it is a risk with new discs. FWIW, it's not a failure I've seen come up on other 4x4 forums.

This was my first time removing the transmission, clutch, and flywheel on a Pinz, and I wanted to share a few thoughts from an experienced mechanic but one new-ish to the Pinz. Much of these bits of advice and observations have been echoed by others before me:

- You can do this whole job from inside. In the future, all I'd do on the outside is to stack up cribbing to support the rear of the engine, and position another stack about a cm below the transmission to rest it on.
- Inside, put a 5ft 2x4 across the transmission area, and a ratchet strap under the transmission as a *safety* strap. On installation, don't make it snug so you have room to wiggle the transmission back into the pilot bearing alignment. That last part is why I suggest keeping that cribbing slightly low so you have wiggle room.
- After unbolting the driveshaft from the transmission, it steel wires up nicely to an inspection cover hole.

- Do not attempt to replace the clutch disc without an alignment tool as it's a close fit to the pilot bearing. I'm keeping that tool in the truck now in case I need it on the trail.

- If your clutch disc frags, you really need to pull the flywheel to get all the pieces out.
- The flywheel bolts came off with about 5s of MAP/Pro torch heat and a 500ft-lb impact wrench -- both were required.
- Torquing the flywheel bolts was fine with a 2ft bar and spinach.
- Clean up (de-glaze) the flywheel surface with a red 3M pad.
- Pulling the pilot bearing out of the crankshaft was easy with a J-hook bolt and a Vaughn Superbar. To replace, just tap in gently with a large socket as the flywheel installation will push it into place later.

- I just left the slave cylinder push rod float -- it never got on the way and I didn't pull it out of the boot.
- Give that starter drive a little lube while things are open.
- And...you might as well clean up all the years of gunk while things are apart -- you'll thank yourself later for that.

And most importantly, when you go for that first test drive, remember to take the reduction box out of neutral so you don't scare yourself! :)
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4x4Pinz
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Re: Clutch failure on trail. Need help.

Post by 4x4Pinz » Sat Jul 18, 2020 7:59 pm

such a funny thread. I can not tell you how many fj40 guys have had the clutches explode when going down hill. We used to teach them to place the transmission in desired gear at top of hill and place their foot under clutch pedal. Too many times they would start down and then push the clutch pedal in as engine speeds became high and tried to brake which would cause the disc to explode or they would release the clutch near the bottom of the hill without bringing the engine back up to speed and that would explode the disc. We have a guy here in the pinz club (former fj40 guy BTW) who has blown up so many clutches on the trail that we now just carry extras with us as it is quicker to change then try to recover.
Only way I know to check a hydraulic clutch health is to periodically place the truck in second gear on flat ground while holding the brake, let out the clutch. This should kill the engine immediately. if the clutch is slipping it will take a second to stall the engine.

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