Heard a SNAP when turning on pavement with diff lock

[Piston]

I didn't realize it but the cotter pin that holds the lever for my rear differential lock had fallen out. Strangely enough, when the lever becomes disconnected from the linkage, the differential gear is always engaged? I would think the 'fail safe' mode to this would be that if it breaks, it is always disengaged?

Anyways, I didn't notice right away and my rear diff was engaged for probably 45 mins of use. I was on soft dirt doing some boxblading and I think since the soil was soft, it didn't make too much of a difference with the way the tractor turned/felt. I then drove down the road for about 300 yards, and turned into my driveway, that is when I noticed it was hard to turn! I have my rear's filled and had good traction on the pavement obviously. Well when I turned into the driveway, I heard a loud SNAP! I was scared to death that I just broke my axle in half or something. I stopped right away and looked down to see the rear diff lever in the 'engaged' (down) position. I got off the tractor and looked underneath and saw the linkage disconnected. I noticed a tiny amount of fluid on the rear end housing, but I believe it was there for a while and haven't noticed anymore since.

I fixed the linkage and carefully tested the tractor out. I was able to use the tractor as normal for another few hours without noticing any ill effects. I'm wondering if I did some damage that I don't know about yet? If not, what in the world was that large SNAP sound?

I barely ever use the diff lock and at this point I don't want to use it anymore. I tried it out and it doesn't seem to stay 'locked' when I'm using it, almost as if it's skipping. When I am not using it it seems perfectly normal.

Any thoughts? Do you think I broke or seriously damaged anything? What should I do at this point?

 

[Gator6x4]

Explain: I barely ever use the diff lock and at this point I don't want to use it anymore. I tried it out and it doesn't seem to stay 'locked' when I'm using it, almost as if it's skipping. When I am not using it it seems perfectly normal.
___________________________________________________________________
Differential locks are not designed to be engaged all the time. All I have used required activation when needed and when the foot was removed they would automatically return to the disengaged position to wait for a time when needed again.

The four wheel (4WD) activation lever will remain in the activated position until disengaged.

 

[Verticaltrx]

It is possible that in it's unhooked state it was only partially engaged. When you loaded it real heavily it popped out of engagement. Definitely not good for it, but it might not of hurt anything either.

If it seems to function normally I wouldn't worry about it too much. Maybe change the hydraulic/transmission fluid, and clean the transmission strainer to make sure there is no metal in there. If it's all good I wouldn't worry about it and consider yourself lucky.

 

[Piston]

What I mean is, when I do use it, as in step on the lever when I need a little extra traction, it doesn't seam to stay in constant engagement.

It almost seems like it will skip gears or something for a little bit, and then engage, and then maybe skip a little and reengage. I would think that I step on the pedal, it engages, and then both rears are locked, and when I get out of the area where I needed extra traction, I let off the lever and it disengages?

I am talking about using it for maybe 10' or so. But now I am afraid to use it at all because I'm worried about damaging something if I haven't already.

 

[AchingBack]

#1. You should not apply the differential lock pedal while turning the wheels.
#2. Once both wheels are engaged, you should remove your foot from the pedal.

It sounds like you broke the mechanism that disengages the lock. Check a shop manual for a parts breakdown, and instructions.

 

[toddbiss]

#2. Once both wheels are engaged, you should remove your foot from the pedal.


You would actually want to keep your foot on it until you do not need the diff-lock....

 

[General Lee]

#2. Once both wheels are engaged, you should remove your foot from the pedal.

I thought one has to leave their foot on the pedal to keep the diff lock engaged and remove the foot when your done needing diff lock??

 

[slowzuki]

My Kubota I really have to put weight on the pedal to hold it engaged and if the linkage is maladjusted it will skip unless I really stomp on it. Same as the international I had before. The pop might have been it popping unlocked, the old IH would make a real bang unlocking on a hard surface.

Since getting the Kubota I hardly use the difflock, just pop it in 4wd and go.


Edit yes you need to hold the pedal as long as you want diff lock engaged.

 

[Rustyiron]

I thought one has to leave their foot on the pedal to keep the diff lock engaged and remove the foot when your done needing diff lock??

When the diff lock is engaged, it stays engaged until the load difference between the wheels is close to equal, so if you have a short area that might require diff lock, yes, step on it until you feel it engage and release it. on the other hand as you say, if there is a longer area that needs diff lock, with maybe a "dry" spot in there, there's no harm in staying on the pedal, this might actually be slightly better on the tractor with less engagement.
All in all it's a minor point but definetly a no no on solid high traction surfaces and only a concern when making a tight turn.

 

[BotaBigot]

Most likely "snap" was diff lock disengaging...it's a low-tech way of "locking" the rear diff so both axles rotate as one...stepping on lock pedal pushes a pin thru carrier housing into hole in side gear...blocking differential action. The hard-to-engage or "jumping" experienced when stepping on diff lock pedal is fact that side gear has to rotate until pin and hole align. Linkage has return spring to keep lock disengaged under normal operation...keep pedal depressed to keep lock engaged...sometimes when pedal released, lock remains engaged until tractor travels far enough in straight line to relieve strain on pin/differential gears.

Chances are OP didn't do any serious permanent damage...possibly some pin wear. Like 4WD, diff lock is intended to improve traction off-road. Unlike 4WD, diff lock only for straight-line traction.

 

[rmk700]

Probably not the case, but make sure your lug nuts are tight.

 

[Piston]

Im not ad worried anymore that I did some major damage. It makes sense that it was just the diff lock disengaging when I heard the snap. Thanks for the replies everyone.

 

[Piston]

Probably not the case, but make sure your lug nuts are tight.

Actually I checked those after buying the tractor and found that two of them were finger tight. Good reminder to keep an eye on them!

 

[chiefchicken]

I'm willing to bet dollars to donuts that your diff lock no longer functions properly regardless of pedal position. If possible, safely jack up the rear of the tractor so one wheel is off the ground. With the engine OFF and the gearshift lever in neutral, rotate the raised rear tire by hand, it should spin freely. Then, continue to rotate the tire while pressing down on the diff lock pedal. When the diff lock pin goes into place, the raised wheel should no longer be able to be turned. If you can still turn it, you have some broken internal parts. Because you stated that you have no need to use the lock in the future, this may not be a problem you have to fix. I would recommend changing the fluid and filter though.

 

[cisco]

Differential locked (1) turn and (2) pavement don't work well. My differential lock (which involves the rear wheels of a 4WD tractor) only stays engaged when I'm more or less standing in the pedal, useful when I'm in a bog and considering using the FEL to get out but otherwise..... Those vehicles have a true differential lock, say a 4WD Toyota 4runner, state in no uncertain terms that such must be used at slow speeds and only when going more or less straight forward or back, as in getting out of a snowbank, otherwise the warranty on the transmission is void, and I don't blame them - common sense.

 

[638]

It's broke! Loud snapping noises from the rear end when driving on pavement with the diff. lock engaged means that something broke.

 

[crazyal]

I remember a friend telling me he had to repair the diff lock on his 7800. Not sure if it was from not letting off the hst pedal so one wheel was spinning as he stepped on the lock or if it was from having it locked in on hard pack surfaces. Either way he said it wasn't just a snap and it broke but it just kept breaking off the ends of teeth (or something inside) until he finally wore them down to the point the diff lock no longer worked.

I think I might drain the oil and take a look for broken metal in either the filter(s) or oil.