B7100 loader cracks

[charlz]

Pretty much since I have owned it I have known some old welds on my loader were cracking. Never seemed like there was a good time to repair but now it is getting bad enough I want to fix it before it fails.

Notice in this pic that the loader sags on one side, this is the side of the cracking. I have done the whole check the tire pressure, loosen all the bolts and try to level etc. No doubt pins are worn etc. but something really lets that side sag and when you dig into the dirt it dives right in.



I am wondering if the cylinder on that side is weak? Is it possible for a dual-acting cylinder to just pass fluid internally and not leak at all? I am thinking yes and that could be what is putting extra stress on that side of the loader.




The cracks are where the cross member welds to the loader arms. Both sides have been heavily welded at some point in the past. Only one side is cracking. I am not so sure the loader frame was not repaired 'square' and that is causing some of the problem.


Bottom inside:



Little further back view



Way back view:



Outside of loader arm looking in:


So I am thinking of:
cutting the cross member out completely

welding up and grinding down cracks in the loader arms

reinforcing the loader arms with a plate that extends fore and aft along the loader arm a few inches past the cross member, plug and edge welded

welding in a new cross member to the new plates.


Anybody have any different suggestions? Should I go ahead and repack both lift cylinders while I am in there? Ideally I would like to get this fixed right AND back in service fairly quickly.

Thanks!
Charles

 

[Egon]

That is a nice loader grin. It must know it will getting some attention!

I am sure your idea will work well.

On the loader on my B7100 HST almost every factory weld has had to be redone. The bottom of the bucket has almost worn through and has had to have a new plate welded on. The cutting edge has been replaced with a much sturdier one and reenforcement has been added to the side leading edges of the bucket. Two extra support plates have also been added at the points I bolt on my forks. The joystick components have also been replaced twice.

I treat it very gently!! So it must be the rock harvest that wears on it!

I've got just about 3000 hours on mine now.

 

[charlz]

I had some time to work on it this morning so I dropped the bucket, pulled the lift arms off and cut out the cross member. Have to say that dropping the bucket and arms went much faster than I thought it would. For some reason I thought the pins holding in the various pins were tacked in but they were not so that made it much faster.

Here is the loader off the tractor and on the shop floor:


I could pull all the hydraulics off it without having to disconnect all the hoses/hardlines:


After cutting out the cross member I cleaned it up and ground it down to get a look at the cracks. The damage to the side arm is pretty bad, looks like I caught it just in time:


You can just barely see in that photo that the crack also runs across the top, maybe 1/2 inch of material there that is holding the piece in. The other side also had some minor cracking, nothing like this side. Tomorrow it is off to the steel store for material.

 

[kennyd]

Is it possible for a dual-acting cylinder to just pass fluid internally and not leak at all? I am thinking yes and that could be what is putting extra stress on that side of the loader.

Yes, that is very possible.

Should I go ahead and repack both lift cylinders while I am in there?

Absolutely! Why wouldn't you...I would also do the curl cylinders and then you know everything is 100%

 

[charlz]

Made some progress yesterday and today. I vee'd out all the cracks and welded them up. Then I made the reinforcing plate:



The 'wings' are because some of the cracks ran along or across the radius of the bend in the loader arms. This will not only allow me to bridge the 'window' of where the old cross member was welded in but tie the top and bottom of the loader arm in as well. I made it pretty long as the metal where the cross member tied in was pretty thin sounding and probably not in the best of shape from previous welding. Since the arm is tapered I couldn't just use some C channel or the like.

I welded in the plugs and along the ends, the middle plugs are right where the cross member will be tying in. With a little heat and persuasion I bent the wings around the top and bottom of the arms. I will stitch weld along there tying into the weld which holds the two halves of the loader arms together.







Some of my welds could have been a little better, I am still getting used to this new (to me) MIG. Hopefully tomorrow I will make some progress on the other arm. I also have the packing kits for all the cylinders on order and they should be in tomorrow or Friday.

 

[Egon]

Nice looking work.

 

[charlz]

Nice looking work.

Thanks! Those are some big rocks in your other post! How much weight do you think you have picked up with your loader? I know its rated at 500lbs but I tested mine with pellets and ran out of space in/on the bucket at about 800 lbs

 

[charlz]

I got the second arm plated and then took a break from welding to repack the cylinders. The repack kits were about $16, one per cylinder. Pretty easy with the cylinders laying on the floor, took about 15 minutes each with the hardest part being getting the snap ring out. The curl cylinders had been repacked at some point but the lift had not, the o-rings etc. were pretty brittle in those.

I need more pipe clamps to be able to hold the loader all together for welding in the crossmember so a trip to HF is in order today

 

[Egon]

Chances are that rock was around the 400 pound range as I could lift it but really didn't want much more.

 

[charlz]

I wanted to post back here and let you know I did finish this project

It took some messing around to make sure the new cross member was in correctly and the whole assembly was square. Clamping, measuring, remeasuring etc etc. I had taken measurements at certain places and ended up cutting boards to those lengths and clamping them and the new cross member in place, checking square corner to corner and welding it up.

Due to the amount of material replaced I decided to paint the arms and cylinders. Here it is back on the tractor....dirty of course since I had to try it out



And some close ups of the new cross member and side plates I welded in:







I used the Van Sickle 'AC Orange' as that is supposed to be the closest match to the old Kubota color. Their Gloss Black for the cylinders. Couple coasts of their primer underneath. The stuff goes on slowly, lots of light coats and takes _forever_ to dry. The paint is still soft as you can see in the photos from the assembly damage even though we have had weather up into the low 100's. Might get around to going back and touching up the areas I scratched putting it back together.

Works perfectly, the bucket is level and it no longer 'digs in' on the one side. I am more than happy with the results even if it ended up taking a lot longer than I wanted. I finally had to just get it together as projects where piling up. Most require the loader or the weight of the loader. It steers real easy with no loader on the front and an implement on the back