Front wheel drive doesnt work

[Walkin Horse]

On side note where did the chain wind up when it broke?

 

[Winmac]

Breaking strength of 3/8 70 chain is somewhere around 25000 lbs according to the web anyway, that's a dirty pull.
I'd expect more severe stresses on the front driveline backing up especially if pulling with loader raised, and unlikely to break at all going forward, anyway it's good there gonna look after you.

 

[Gary Fowler]

That's great, but your statement is still a guess. You haven't seen the shaft in person, haven't done any sort of testing or analysis of the metal, and you still don't know exactly when it broke. That's an awful lot of unknowns to be certain a part was faulty. It's certainly possible, but it's far from a fact. The fact is, that twisting you say should have happened could have happened previously, and that's the reason why it failed this time. Without an analysis of the actual part(s) nobody will ever know for sure what happened.



I put quotes around "normal" because you weren't doing something weird, but even doing something "normal" can put an overload on the running gear if a wheel spins, then gains traction, or vice-versa. Abnormal loads can happen while doing "normal" tasks.

Do I work for LS?....seriously, you're going to really ask that? Uh, no, I don't work for any commercial entity.

I think the LS 5 year powertrain warranty is great. That doesn't mean that every single part of the system is covered under all circumstances. Pulling on a stump and a little bit of wheelspin then getting a bite of traction, or losing traction suddenly, could have overloaded the system, and that doesn't mean the part was faulty, and should be covered under warranty. It's great that they're replacing it for you, but that doesn't mean there was a problem with the part, or that the usage was within the design limitations.

Sure, I'd say the drive shaft is part of the powertrain, but so are the wheels, and they don't warranty them if you dent them on a rock.

It's sort of funny that you're talking about a situation where you were pulling a stump hard enough to break the chain, but think it's totally crazy that a driveshaft broke...which could have already been damaged from something previously. 3/8 grade 70 chain has a working load of around 6,600lbs, and a breaking strength of around 26,000lbs, and you broke it. Breaking a driveshaft in that sort of scenario isn't exactly crazy.

Any tractor should be able to spin the tires when in a low gear and just creeping and the tires weren't lunging as some has said could happen. Engine was idling at a mere 900 RPM, no heavy weights on the front to increase front traction, if fact with a 1500 # disc on the back there should have been very little weight on the front wheel drive assembly.
And as I have said, this is the same tractor that is supposed to hand a turned up engine producing 90 HP.

 

[holeycow]

and possibly even a 97hp tractor too???

 

[k0ua]

Let me add this possibility.
When the chain broke, there was probably very little stress on the front, but in that instant, would not the weight have shifted to the front for an instant? Just a thought, as I am no Mechanical Engineer, but I think something like an instantaneous dynamic force was applied to that shaft. Metal under tension, and quite a bit of it, as the 3/8 grade 70 chain did break, "stuff" can happen.

 

[Gary Fowler]

Let me add this possibility.
When the chain broke, there was probably very little stress on the front, but in that instant, would not the weight have shifted to the front for an instant? Just a thought, as I am no Mechanical Engineer, but I think something like an instantaneous dynamic force was applied to that shaft. Metal under tension, and quite a bit of it, as the 3/8 grade 70 chain did break, "stuff" can happen.

I was just saying the same thing to my brother in law. I think that may be what happened, rather than forward twisting stress, it may have been like a backlash that broke the shaft when it untorqued and retorqured in reverse direction.

 

[SPYDERLK]

One other tidbit, the warranty guy told my dealer that they have had about 10 front drive shafts break on the P series of tractors that go up to almost 90 HP. Mine is the 70 HP version and all identical components to the 90HP version. I can just see the extra 20 HP wreaking havoc with the shafts that wont stand up to 70 HP. The larger versions also have larger tires, so more traction= more stress on the drive train.

One would think that LS would look at those breakages and fix the issue, but if just rejecting the claim under warranty gets them by then why would they ever even look at the problem. 10 drive shafts breaking on one particular model is not normal and for sure not normal on a tractor that has no added weight to the front end other than the FEL.

Edit: I see that LS has a 7040 version at 97HP now. I don't know if it is identical to the 7010, 7020and 7030 though as I didn't pull up the full spec PDF sheet.

Yeah, sounds marginal unless the parts are just faulty.

What diameter is that shaft? I had the one on my Mahindra [1.14" dia] break, but you could see that is was a crack that started and progressed thru about 1/3 of the shaft before it twisted on off. With warranty they probably wont give you the old shaft. Maybe you can get a look at it tho. ... Mine failed at a physical stress riser rather than at a transition from a hardened area.
larry

 

[charles todd]

I agree too that the sudden loading COULD have stressed it. But if it was undamaged prior, I do not see that instantaneous moment of torque loading/unloading in L1 snapping the shaft.

I noticed yesterday, I was discing us some rough ground to level out and some for food plots. I would turn off MFWD to turn and turn it on to pull the 10' disc. Sometimes I would forget to engage MFWD and would toggle the switch. I did not like the thump it makes. SO, I only engage MFWD stopped or moving, but not under load.

CT

 

[Gary Fowler]

Dealer called yesterday and tractor is ready. I will pick it up today and hope to get a look at the driveshaft break and determine size of the shaft also

 

[Gary Fowler]

I agree too that the sudden loading COULD have stressed it. But if it was undamaged prior, I do not see that instantaneous moment of torque loading/unloading in L1 snapping the shaft.

I noticed yesterday, I was discing us some rough ground to level out and some for food plots. I would turn off MFWD to turn and turn it on to pull the 10' disc. Sometimes I would forget to engage MFWD and would toggle the switch. I did not like the thump it makes. SO, I only engage MFWD stopped or moving, but not under load.

CT

I don't turn mine on and off like that to turn but I never hear any sounds when it engages. I don't see any need to do that when on soft ground and it seems that would just be needless wear on the system to do it at each turn.

I did disengage it once after I turned off the engine and heard a bump as it disengaged which let me know that the front wheels were under some tension due to the over run % of the front drive.