Repeated Damage to Bottom Plate on front Axle Assembly on 3120,3320,3520 &3720??

[OzGrasshopper]

Hi to all 3,000 series owners, i was wondering how many other people have had damage done to the round disc plates that are on the lowest flat point of the front axle assembly wheel hubs. my 3120 is approaching 900hrs, & i do a fair bit of ground leveling with this tractor, but to date have dented 6 of these plates, when small rocks or sticks come up under the bucket and hit the bottom of the front axle assembly. these plates are made out of very light material, & when bumped, easily cause the loss of front axle fluid. Usually the first u know about it is when u come out and see a oil leak on the floor on the inside of either front wheel.......its very annoying & u have to drain all the fluid out of the front axle b4 removing the damaged plate. i can't for the life of me understand why these plates r made of such soft material??? anyone had similar experiences, cos i recon JD should look at this as a very poor design aspect on an otherwise outstanding tractor?
cheers OzGH

 

[JD755]

Re: Repeated Damage to Bottom Plate on front Axle Assembly on 3120,3320,3520 &3720??

If they are like the 4300, then yes lots of discussion on it.

http://www.tractorbynet.com/forums/john-deere-owning-operating/173775-another-4300-design-flaw.html

 

[OzGrasshopper]

Re: Repeated Damage to Bottom Plate on front Axle Assembly on 3120,3320,3520 &3720??

Hi JD755, yes thats the same part on different model - surprised Kubota also has same plate, but theirs looks a bit stronger - mine is made from very light material - i just for the life of me can't work out why it can't be of a thicker material - 3 i've "damaged" have just been the smallest of dents that just break the seal enough for oil to leak - this is on the lowest part of the tractor?? i'm sorry but for those whose say operator error, i ask one simple question, why have a FEL thats so strongly built, to go on a tractor that easily handles that loader, but is obviously going to have trouble if it gets hit with a stick, rock, or hard clod.....its not a lawn mower its a strong little tractor with a bucket designed for moving earth!!!
why can't that plate be made of a stronger material and that would be the end of it?? we often use the tractor to clean the edges where chain digger has been & use tractor to back fill sand to sit poly pipe in trenches - the size if the tractor is ideal for that task as it can turn very tight and the bucket on FEL is ideal to judge the tipping of sand into the trench, but repeatedly we have this plate damage - once or twice in 900hrs i can accept, but a lot of the time the objects that have done the damage go un-noticed - now we constantly look out for odd shaped rock that might get "leavered" up by the tyre - the rock might even have 3" or 4" clearence, but if its a flat bit of rock, pressure on edge might just flips it up enough to bump the plate.....damage done.
why have such light plate on the lowest 2 points of the tractor...must be a reason or is it simply something designers don't realise is not practical in the field??? cheers OzGH

 

[Glen Watkins]

Re: Repeated Damage to Bottom Plate on front Axle Assembly on 3120,3320,3520 &3720??

Sounds like it is a flimsy piece of steel that should be redesigned. Anyway you can have it beefed up to be able to take an occasional hit?

 

[AKfish]

Re: Repeated Damage to Bottom Plate on front Axle Assembly on 3120,3320,3520 &3720??

With a little bit of "seat of the pants" work with a plasma cutter and welder and some 5/16" flat plate - I can imagine a workable solution.

Extend the plate out to the edge of the hub and bend or weld it at a right angle up onto the axle hub. The face of the plate would be attached to the bolt pattern on the axle. Drill it out to accomodate the wheel bolts.

Might have a problem with mud, debris accumulating between the plate and the bottom of the hub - drill a couple of holes in the bottom of the plate to allow dirt etc. to fall thru and drain.

Some bending or sculpting of the plate to follow the contour of the hub would even lend a more "professional" look to the job.

AKfish

 

[defed]

Re: Repeated Damage to Bottom Plate on front Axle Assembly on 3120,3320,3520 &3720??

i was the one complaining about it on the 4300...glad (well, not really GLAD) to see that i'm not the only one!

on mine, one cap appears original and a little heavier, and ALL steel. the new replacements, and the one that i ruined, is only steel in the center with just a rubber lip around the edge, allowing it to be VERY easily pushed in.

i was going to look into making a heavy replacement or at least a shield for it, but never got to it. probably would be easy enough to machine one on a lathe w/ a nice thick lip to prevent it getting pushed in, and heavy enough to not get deformed when hitting something.

 

[OzGrasshopper]

Re: Repeated Damage to Bottom Plate on front Axle Assembly on 3120,3320,3520 &3720??

Hi all, No Glen its a very difficult place to mount a guard as the hub turns with the wheel. the local JD mechanic looked at mounting a guard off the wheel hub studs, but if you hit something really hard, the studs could break off on the wheel hub then there would be huge problems.
yes AKfish we r looking that way, but why on earth is that plate made from such soft material - hard bit is engineering around the cast hub. i wondered if the plates is made light, to be like a "welsh plug' in an engine to allow some heat expansion of the hub?!?
yes defed i saw the thread about ur problems, as per above what is the reason for the lightness & if u put a lathed up one in, would it cause problems with the hub when hot?!?
remember the sales brochure for this series tractor shows a chap carting bucket loads of huge rocks around - if any rock that big hit that hub it would be dry in 2 mins!!!!
thanxs to u all for ur interest - cheers OzGH

 

[JD755]

Re: Repeated Damage to Bottom Plate on front Axle Assembly on 3120,3320,3520 &3720??

Going back to the picture I posted in the referenced 4300 thread, I can only assume they added the hole to make it easier to repair. Of course adding the hole made it much more likely it would need repair. Sort of a self-fullfilling prophecy by the designer.

 

[defed]

Re: Repeated Damage to Bottom Plate on front Axle Assembly on 3120,3320,3520 &3720??

yea, it is VERY easy to get the thing apart w/ that hole. i replaced a knuckle seal and you have to pull the spindle gears and bearings out the bottom.

don't know about heat expansion of the hub. in the problems i experienced, the part that gets pressed into the hub is fine, but the outer lip (on the new ones) is just a rubber flap, which doesn't stop it from getting pushed in quite easily. if just the outer lip were thicker, it would help. and the outer lip wouldn't have to extend all the way out to the hub walls, since the center of the cap is what holds it in place w/ the interference fit.

 

[OzGrasshopper]

Re: Repeated Damage to Bottom Plate on front Axle Assembly on 3120,3320,3520 &3720??

yes JD755 & defed, i can see the lodgic of having the plate there, very helpful to access the spindle & bearings = good design.... BUT why have such a filimsy insert........thats the bit i just don't understand. i would have thought a thread on the inner hole of the hub and then a decent thick plate with a threaded shoulder that u could screw in and out would have been a perfect bit of design work & of no great cost if down when at assembly stage? i think i might even e'mail JD and see whats going on here cos its the only part of the tractor i continually have to worry about.....cheers OzGH