Brakes on 1855. something aint right?

[bison]

I am rebuilding an 1855.
I done the reared and transmission and am now in the process of putting the brakes together.
You can see in the pics that the brake piston had been riding against the bull pinion(with brake applied) but even with new brake discs there is only 1/16 clearance left between a fully retracted brake piston and the pinion with all brake parts in place
What am I missing here?



 

[rrlund]

Was there supposed to be thin shims in there between the cover and housing or was that just some of the late ones with a mechanical actuator?
 

[Dieseltech]

Are you sure the discs are the right thickness? If too thin that will cause the trouble you have.
 

[IanC]

Have you backed out the adjusting screw for the parking brake actuator?
 

[mkuhns]

Did someone machine the outer or separator plates too thin? That is about all it could be. I see the piece of fiber glued to the piston, so that isn't it. I would compare parts with the other side.
 

[bison]

[gary66]

did brakes on my Truck and although the pistons were retracted as far as
they would go, they couldn't go all the way...new calipers were required.
I know this isn't the same, but something that old could be doing
something similar. If not I'd say wrong parts, these things can't be
complicated and loose is how I'd expect them to be.
 

[Tractorcedric]

I have not done one of these for a long time! I suggest that you go to agcopartsbook online and look up the 1855. Page 113 items 28 and 34. Maybe someone else has miss matched these parts? Could change how many shims are under the housing.
 

[bison]

[Tractorcedric]

That's good that you know that no one else has been into it. Just curious does the parts book you have show two different inner bearings depending on serial number of your tractor. Maybe it got miss matched on the assembly line if it was close to the serial number break. From the picture on the net I am not sure were part 34 goes? Looks like some kind of spacer. I know what you mean about the shims under the housing as they are how you set the preload on the ring gear carrier. But different bearing sets may have a different overall thickness. A thicker bearing set would require more shims and give you more clearance. I have seen brake disc so worn that the piston came out of the bore enough to let the oring leak. But I don't remember if it had rubbed on the bull pinion. Question, If you place a straight edge over the brake housing and measure the distance to the bull pinion. Is it the same on both sides of the transmission? Just trying to help.
 

[wilma]

Have you removed the piston from the housing? I had one that the stem for the parking brake part of the piston broke, although everything was still in tacked and not leaking, it created a situation like what you have by increasing the overall length/height of the piston
 

[bison]

# 34 is an fiber insulator that goes between the brake disc and the adjuster plate.
The 0 rings in the piston housings have been replaced and everything looks fine in there.
Bull pinion face to end of housing distance are within a couple thou of each other.
Differential carrier and crown/pinion backlash have been reset to factory specs which required removal of 1 shim each side.

AFAIAC the only way to increase piston travel is to machine the face of the piston back a bit where it contacts the bull gear but there ain't enough meat Imo to do that safely without risking piston integrity.

I'm at a loss.
 

[bison]

# 34 is an fiber insulator that goes between the brake disc and the adjuster plate.
The 0 rings in the piston housings have been replaced and everything looks fine in there.
Bull pinion face to end of housing distance are within a couple thou of each other.
Differential carrier and crown/pinion backlash have been reset to factory specs which required removal of 1 shim each side.

AFAIAC the only way to increase piston travel is to machine the face of the piston back a bit where it contacts the bull gear but there ain't enough meat Imo to do that safely without risking piston integrity.

I'm at a loss.
 

[Tractorcedric]

So are both pistons hitting the bull pinions? I must be looking at a different parts diagram than you. Part #10 is the friction disc bonded to the piston in the drawing I am looking at. I have tried to load the drawing I have and it won't load. It is at agcopartsbooks.com. I would sure like to help! 8zero1-55four-68eight6 Dennis
 

[bison]