Foton 254 clutch failure?? Gulp!

[succor]

Hello everyone, it's been awhile since I've been on this forum but could be a very sad day for me anyway! 275 hours on my 2006 254 foton. The 3 years I've owned it it has ran fine and consistently for me till recently. I've read through what posts I could find on this forum to possibly no prevail and finding a reputable china tractor mechanic without being to pricey! The other day I started my tractor and went to put it in gear, GRIND! I could pop it into 1st low and it would go with or without the clutch pedal. After awhile of driving I eventually could wiggle the clutch to let go on the drive and shift. Same thing with the PTO, I would push the pedal right to the very end before it would just disengage. OK, it looks like clutch adjust. The funny thing is it never did this before. 2 stage clutch with 6 fingers, I've got the books with the specs with lot's of reading and away I went. Took the loader off and 1st inspection shows a little rust in areas but not severe with some moisture in there. I notice that when the pedal is pushed, I can see the plate move and separate evenly but only about 1mm or maybe 1.5mm; not a lot of movement. Should this open more or is this normal? Next I've adjusted TOB gaps and PTO finger gaps to the book spec with no prevail on clutch movement. I've read about roll pins but in this particular design, it looks like the shaft on the clutch pedal arm that goes into the bell housing goes right through to the other side cause I can see it pivot on the other side when I push the clutch. My guess is this shaft goes through a bushing with two lock pins for the fork to the other side. Inside it looks fine and it looks like it's moving fine but unsure. One post shows a fella with a foton 404 where he marked the clutch arm with very little rotation. Mine moves about the same but it's welded at this point where his just comes off with the roll pin falling out. The fingers and TOB seem to look fine and no grinding or abnormal movement that I can see or feel but yest when I start the tractor, grind! I don't know if this clutch pivot arm comes out but I hazzard a guess no. It has to be my adjustment technique or something has not been done right from the get go and has been failing for 3 years without notice? I've spent 12 hours on this adjusting to spec with no prevail. I sure wish I was missing something at this point as it could save me a few thousand dollars so I'm calling out to the china tractor experts out there for some much needed HELP!!

sigh

Cory

 

[RonMar]

Well that is an unusual failure mode. They usually fail by slipping/failing to fully engage. Moisture inside is not a good sign. Was there any standing water in the bottom. There is a drain hole down at the bottom to allow any moisture that collects to drain away. Sometimes that hole gets clogged, which allows any moisture that collects inside to stay inside which repeatedly coats and recosts all the internal parts with moisture during condensation/evaporation... Where do you keep your tractor, Inside or Outside, covered or uncovered?

This type clutch has pretty tight tollerances, and requires verty little movement to function. Unfortunatly this also means that any debris in the clutch will hinder it's ability to disengage. It only releases the clutch disc enough to slip, it dosn't really let it go or separate. IF the plates have become corroded, and since they have been pollished to bare clean metal by the discs they will corrode the worst, the additional friction this causes is most likley your problem.

I would say make sure the drain hole is clear of debris and that any moisture can drain away. If the side covers are still off, do your best to get things dried off and as much moisture out of the case as possible. heating the case or hot air from a small space heater pumped into the case thru the access holes will evaporate and carry the air out of the case. You say it loosens up and functions with use and when things warm up a little? I would say do this every day, getting the machine up to full operating temp. IF it can stay dry, regular usage should help the discs re-pollish the plates smooth again and shed rust debris.

Good Luck.

 

[succor]

Thanks Ron. 2 winters ago was the worst where the weep hole was plugged with a bit of frozen water in it so it wouldn't crank over. I have plans this year to build a small garage to fit this tractor in to get out of the elements so my fault on this one. Better sooner than later. Yeh, it was pretty damp in there with some rusty spots around the clutch. Everything is moving OK and evenly so no problems there. It sat more last winter due to warm weather and no snow go figure; perfect for a clutch eh! Maybe when I drive it again, got some rototilling to do I can work the clutch a little at a time and like you said, hopefully it can fix itself a bit. The PTO is probably the same thing with rust just not as bad because I can actually disengage it.

Time will tell.

Cory

 

[greg_g]

it's welded at this point

A little rust is normal. As long as the weep hole is open, the heat generated by friction is usually sufficient to overcome moisture. But 6 fingered clutches adjust a whole lot different, they don't lend themselves to adjusting through the inspection window in the same manner as their 3 fingered cousins. So I hope you didn't lead yourself astray by trying to adjust it as a 3 finger.

A "welded" clutch release lever however, makes me pause. Please clarify, because this is not what I'd consider normal for a Foton

//greg//

 

[succor]

Hey Greg, what I mean about the weld is the clutch arm that pivots off the pedal by the bell housing. This arm is welded to a shaft which goes right through the bell housing with the fork attached to it. So I believe there is no external roll pin on this clutch pedal arm. I've been very careful for the adjustment and followed the specs exactly. 6 finger is easy to adjust in my mind as long as your careful. External linkage for 2.5 mm gap to TOB first 3 fingers even for main clutch and last 3 fingers for PTO clutch. Nothing looks funny unless like I said something was messed up on install or rust or internal roll pins which I cannot see because rotation looks tight on the fork to TOB. I got it out of the rain and am drying the bell housing. I guess that's all I can do for now.

Cory

 

[greg_g]

Yeah, the 1st three fingers are about the same as with the more common 3 finger clutchpack. But the second set is more difficult to calibrate. It's important that each of the 3 fingers in a set makes contact with the throwout bearing simultaneously. The tolerance between fingers is something like 0.1 millimeter. And I don't have the exact numbers anymore, the clutch data went with mine when I sold it. But I seem to recall the PTO fingers were at least another 6mm or so behind the main drive fingers.

Any chance there's a 2-stage clutch diagram in your owner's manual? Not the exploded diagram in the parts manual, I'm hoping there might be gap specs in your owner's manual clutch diagram. That's where they were for the 9 inch six finger in my 35 horse.

//greg//

 

[succor]

Hey Greg, yeh I have the good ole 2 dimensional diagram of both single and dual stage clutches. The 3 main are 2.5mm +/ - 0.5 and the PTO fingers are 10.5 +/ - 0.5 all from the TOB. It does give the stack heights but no way of actually measuring which is the iffy part. I try to go as exact as I can. When we get some sun, I'll try to get it lose again and so called ride the clutch ever so slightly to see if I can free it. Unless there is something obvious I'm missing, that's all I can do.

Cory

 

[greg_g]

Hey Greg, yeh I have the good ole 2 dimensional diagram of both single and dual stage clutches. The 3 main are 2.5mm +/ - 0.5 and the PTO fingers are 10.5 +/ - 0.5 all from the TOB.

Ok, 8mm difference between clusters (finger sets). Nothing you can do about exacting the stack height unless/until the tractor is split. That's most accurately done on the bench. But understand that the +/-0.5 tolerances you cited above are tied to the bearing gap specs. That is, how far away each finger cluster is from the vertical face of the throwout bearing.

The +/-0.1mm spec to which I referred above is among each of the 3 fingers that comprise one cluster (PTO or main). That's what ensures simultaneous contact of 3 fingers against the bearing face. Non-simultaneous contact results in the TOB pushing the fingers at an angle, which can fail to completely release of the friction disc. On a tractor that's not split, that 0.1mm is what's difficult to achieve on the PTO set. The sequence is to achieve that 0.1mm tolerance before setting the 2.5mm finger gap with the bearing. Assuming a tolerable stack height in the first place - and that this sequence was followed - the 10.5mm gap for the PTO cluster will already be established by default.

//greg//

 

[succor]

Hey Greg I understand, fingers have to touch the TOB at exactly the same time or we got a frizbee going sideways sort of speak. Not a good thing when your only separating clutch faces by a hair. However I think I'm pretty close because when I rotate the clutch the spacing around looks pretty even when it's separated. I try to adjust these fingers ever so slightly to achieve as best as possible.

Cory

 

[greg_g]

Ok, lets get back to your original problem then - grinding. We should start with the obvious first - pedal travel. Check the stop bolt to see if the jam nut may have come loose. It's uncommon, but a stop bolt that's backed out unnoticed will stop the pedal short of full travel.

Then check under the left floorboard for bent or jammed linkage. If that's artificially shortened, it will also inhibit full pedal travel. One guy tore up a plastic pedal bushing, which also served to shorten the pedal travel.

//greg//