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Case 580c Brake Grab

zigblazer

Active Member
Joined
Oct 25, 2016
Messages
37
Location
NE MN
I bought a backhoe in June, just got it fully serviced, maintained, and other repairs done. Almost got the brakes working right. Brakes worked when I got it, for about an hour. Left side quit and I found the hose blew. I've been using it with just the right brake until I took stuff apart to fix it. I replaced the Left hose, and both master and slave cylinders. As soon as I finally finished bleeding both sides and got them adjusted, I blew the right hose. Once everything else was back together I put it to work. Only to find the Left brake grabs hard when backing up. It doesn't grab going forward, only every 10-15 feet backing up. It lets go right after stopping the wheel, but by then it has already jerked, and changed direction.

I'm an experienced med/heavy truck tech. Not an equipment tech. I haven't found anything on it that has been difficult yet, but I don't have the experience to know why it is grabbing like this. If anyone has any insight, it would be appreciated. It does look like the brakes had been off recently, and there is no oil anywhere around the housings. I did replace the rear cover gasket on the axle, besides leaking bad and being low on oil, the gears looked good. I am not sure why, but the diff lock collar is missing. Cover and lever are there, but no collar to engage the diff lock.
 

CMSMOKE

Active Member
Joined
Aug 11, 2008
Messages
42
Location
ligonier, pa
There are broken return springs inside the brake housing on the drum/disc assembly. When they break the slightest drag will cause lock up. There are steel balls that ride up ramps which force the discs outward against the housing. Without the springs holding them retracted...the brakes have a mind of their own.
 

zigblazer

Active Member
Joined
Oct 25, 2016
Messages
37
Location
NE MN
Darn

Well that doesn't sound good. I guess I'll have to take it apart then. I assume you're talking about the disc return springs, G48501. The next question would be, do I need to replace multiple parts, or if the rest looks good, can I just replace the springs?

I backed the brake adjustment off, which did help, but still happened. The replacement lines (I am switching to AN brake lines with adaptors. $46 shipped for both hoses and adaptors, and if they have problems again the hoses themselves are less than $12 each.) should be here today. So I'll take it apart tomorrow and take a look when I go to put the lines on.

Thanks for giving me a head start.
 

zigblazer

Active Member
Joined
Oct 25, 2016
Messages
37
Location
NE MN
Took the left side apart. Found no problems . Everything looks like it is working properly. I didn't think to try spinning the tire with the brakes off, but before I took the brakes off, the wheel would spin forward without a problem and would lock almost right away spinning backwards.

I suspect that the diff lock is hanging somehow. Both wheels spun fine before I replaced the brake cylinders while I still had the diff lock cover off. I'll check tomorrow when I go to replace the lines.
 

zigblazer

Active Member
Joined
Oct 25, 2016
Messages
37
Location
NE MN
Ok, now I'm at a loss. Wheel spins freely, problem must be with the brakes. I'll try cleaning and lubing and see what happens. Springs were tight and not broken.
 

zigblazer

Active Member
Joined
Oct 25, 2016
Messages
37
Location
NE MN
Everything is cleaned and lubed. Freely moving and back together. No grab. Brakes are working perfectly. Nothing was seized, but must not have been moving free enough.
 
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