My Tractor Forum banner
  • Are you passionate about Tractors? Would you like to write about topics that interest you and get paid for it? Read all about it here!
1 - 13 of 13 Posts

·
Registered
Joined
·
63 Posts
Discussion Starter · #1 ·
Hi Everyone,
I have a John Deere 1640 tractor. It is from the end of the time that they made that model. (1984?) the one without the cab. My brake pedals both left and right go all the way to the floor. This came on gradually over around 10 hours driving. We are mostly just slashing paddocks so not a lot of brakeing. The brakes still work but only just. Give the pedal a few pumps and they work ok.
The hand brake still works but the handle comes up a long way.
So my first thought is they may need bleeding. I found a JD service manual on line and it describes the breaking system very well including how to bleed it. The one vital piece of information that is missing is the location of the bleed valves. I assume they must be towards the rear axel end of the brake lines but I can't spot them.
Any ideas?
 

·
Registered
Joined
·
63 Posts
Discussion Starter · #3 ·
Hi Jim,
The pedals go to the floor if I depress one at a time or if I depress both together.
Thanks for the detailed diagrams, this has helped me find more relevant information in the manual that I have. It is hard to sift through a 1200 page PDF :)

I'll go and hunt around on the tractor tomorrow and bleed the system.

Do you think the symptoms I'm having are what they refer to as "Leak Down" in the manual? I haven't heard this term before but it sounds like it. If I have a leaky valve the process to isolate the faulty part seems quite complicated.
I'm thinking that if it isn't a simple bleed to fix it then it is going to be a service call :(

I'll post the results here.

Thanks
David
 

·
Registered
Joined
·
1,853 Posts
If bleeding won't help then I would suggest getting some 0.375 IN JIC caps and cap off brake lines at brake valve and see if pedals will get firm. If capping doesn't make for firm pedals then some valves in valve housing are leaking. If capping firms pedals then your problem will lie in the axle housings(brake pistons).
 

·
Registered
Joined
·
1,369 Posts
If bleeding fixes problem, there is a kit that can be installed to help prevent air from entering the brake system. In some operating conditions, the oil entering the brake valve can be aerated. The kit AL57412 blocked off oil from the passage between clutch housing and brake valve. It then added external line from the reservoir in front of radiator. I don't think the actual kit is still available, but individual parts could be gotten easily.
 

Attachments

·
Registered
Joined
·
63 Posts
Discussion Starter · #6 ·
That is great information. The brake bleed results were mixed. The right bleed was by the book. A dozen or so pumps of the pedal produced a cup or so of oil out the bleed valve and I could see bubble going past at first and then there were none. I tightened the bleed valve and now the peddle is firm about half way down.
Left hand side after about 3 or 4 pumps of the pedal with the bleed valve open the resistance of the moving oil against the pedal dropped and the oil stopped coming out the bleed tube. Output about 1/3 of a cup. I closed the bleed valve and tried the pedal. It goes about 2/3 of the way down and then is quite solid. I was then Wondering if I was supposed to do this with the engine running so I started it up and the pedals did the same thing. I tried the bleed procedure again on the right hand side and the results were the same.
I managed to get half a turn on the handbrake adjustment screw and that lowered the handle a few clicks so I call that fixed. :)

I can't go for a test drive at the moment as it is absolutely ******* down with rain today.

Any ideas why I get a few pumps on the left pedal with the bleed valve open and then the oil stops coming through?

Thanks again for the help so far.
 

·
Registered
Joined
·
63 Posts
Discussion Starter · #8 ·
Hello again,
All sounds like good advice. I can't see how item #2 comes out?
Is it threaded? I can't see any slots or hexagons.
It is very awkward under there. I might have to pull the floor plate out to get at it.
I might get hold of a parts kit before I pull it apart as I don't want to turn a mostly working tractor into a fully broken one :)
David
 

·
Registered
Joined
·
1,369 Posts
Item 2 is a freeze plug or soft plug. It is a press fit into the housing. The easiest way is to drill a hole in it and then tread a screw into it to pull it out. Or you can take a punch and hammer and tap on one side of it to tilt the plug in the bore. Then grab it with a pair of pliers. Just be aware that you can drive it into the reservoir and can be a hassle to pull it out.
 

·
Registered
Joined
·
63 Posts
Discussion Starter · #10 ·
It looks like I sorted the problem out. Partly it was me getting a better understanding of how the brake system works. I had a second go at bleeding the left hand side. This time depressing the pedal slowly and allowing a few seconds rest between each pump. This allowed me to extract 3/4 of a cup or oil until no more bubbles were seen.
As for the understanding part, if I depress just the left pedal it still goes down a cm or so further than the right. However as soon as I move the right pedal off the stop bolt the forces between the two pedals equalized. If I move the pedals with my hands I can feel an increase in pressure on one pedal as back pressure on the other pedal. This is obviously working exactly as designed and how the braking force is kept even on both wheels.

Thank again guys for your assistance and I hope this information can also assist other people in understanding how this brake system works.

David
 

·
Registered
Joined
·
1,853 Posts
Pollardd
Glad you got it repaired. Sounds as if the equalizing valve in brake valve housing is leaking a little. It's always nice to get something repaired without costing an arm & a leg.
 

·
Registered
Joined
·
63 Posts
Discussion Starter · #12 ·
Update:
Looks like the brakes need bleeding once every year or two depending on how many hours we do in the seat. Not a big deal I can bleed it in 10 minutes now.
Wife thinks I'm a genius :)

David
 
1 - 13 of 13 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top