John Deere 2120 Brake Concern

[bigblock76]

Hello Everyone,

I have a JD 2120 with a billion hours on it. I usually have the brake lock on to engage both pedals at the same time but the other day I flipped over the latch as I needed to do some tight turns and I noticed that the right pedal I had to pump twice before it would brake. The first pump goes to the floor and then the 2nd pump engages the brake at a more normal level.

The left side I don't need to pump it.

Is it a seal in the braking cylinder that is gone? Tires are loaded, removing the axle would be a huge job at this point.

Thoughts?

 

[jd110]

Sounds like there is some air in the brake circuit. I would try to bleed it out. The bleed screw is on top of the axle housing. If bleeding helps, I would just leave it be and see if the pedal says good. If it gets air in again in a short time, then most likely the seals in axle housing on brake piston are going bad. If bleeding does not help, The problem is most likely in the brake valve. May just need to adjust stop screws on the pedals.

 

[bigblock76]

Sounds like there is some air in the brake circuit. I would try to bleed it out. The bleed screw is on top of the axle housing. If bleeding helps, I would just leave it be and see if the pedal says good. If it gets air in again in a short time, then most likely the seals in axle housing on brake piston are going bad. If bleeding does not help, The problem is most likely in the brake valve. May just need to adjust stop screws on the pedals.

I'll back off the bleeder nipple and bleed the line and see what comes out. I'll report back when I'm done.

 

[Tx Jim]

Engine needs to be running when bleeding brakes so trans pump can replenish oil level in brake reservoir. IIRC there's an equalizer valve in in brake valve housing that can malfunction causes single pedal to require pumping but when pedals are locked together no pedal pumping is required.

 

[bigblock76]

From BuickandDeere in another thread here: http://www.tractorbynet.com/forums/john-deere-ag-tractors/380019-john-deere-2120-gear-shift.html

Quote Originally Posted by bigblock76 View Post
Ahh well still need to figure out what's wrong with the 2950 linkage and on the 2120 the right brake pedal goes all the way down on first pump so need to bleed that.... always something with these old units.
Left-right Equalize valve in brake master cylinder is leaking.


Which parts are you referring to?

 

[jd110]

The equalizing valves are balls and springs 11 & 12.

 

[bigblock76]

The equalizing valves are balls and springs 11 & 12.

Does it make sense to change the ball and spring? Or is it the seal #14 that needs changing?

 

[DLTTrekkers]

I never replace 11& 12 . Bleed that side . Check condition of hydraulic filter fot brakeliningmaterial and oil for metalfilings that will tel you brakes needs attention

 

[bigblock76]

Using the tractor again today, removed the brake lock to tie both pedals together.. The right side is real bad, but every so often the left side does the same thing. What is causing this if not to change parts 11 and 12? I have bled them today and didn't really see any air coming out.

 

[DLTTrekkers]

When depressing the brakepedal slowly and the brakes fail it is durt in valve 3...replace both

 

[Tx Jim]

Ditto I think valve(key 3) is the problem also. AL70242 Pneumatic Control Valve 69.10 USD 0

 

[Tx Jim]

O-ring(key 14) only seals plug(key 13). If plug isn't leaking o-ring is fine.

 

[bigblock76]

Ditto I think valve(key 3) is the problem also. AL70242 Pneumatic Control Valve 69.10 USD 0

Should I start with this part then? AL70242 Pneumatic Control Valve 69.10 USD

 

[DLTTrekkers]

Order 2xno 2 and 2x no3...remove no 2 and strip valve....clean all . When assemble make sure no 3 do not touch piston and do not use silicon on gasket...there is a small hole in the gearbox casing allowing oil to fill mastersilinder...after assembling remember to adj the pedals with the 3/8 bolts on top...all pedalfreetravel gone plus 1/3 turn tighter...do not try to adj pedals equal ! Lock 3/8 bolts with there nuts !

 

[Tx Jim]

Ditto what DLTTrekkers stated

 

[bigblock76]

I致e ordered 2 equalizing valves. Waiting for them to arrive.

Is there a way to test the brake linings without taking the axle apart to see how much lining is left?

 

[Tx Jim]

No way to check brake lining thickness other than removing final drives.

 

[bigblock76]

No way to check brake lining thickness other than removing final drives.

Is it worth doing giving age of the tractor and unknown history prior to me owning it? Given the horror stories I've heard about the metal getting everywhere and messing up the pump. Is it hard to service other than needing to take an axle off once your inside?

 

[Tx Jim]

Brake linings are relatively easy to R&R once axle housings are removed. IMHO installing cow magnets in the bottom of older JD tractor trans case of this era is a good idea to help limit hyd components exposure to metal fines.