Section for komatsu d20,21 and similar grey market dozers

[petepilot]

its already started seizeing bearings suggest you not restart it

 

[dcara]

Of course your right but the urge to do just another few minutes on it before more bad weather set in was strong. Also I'm thinking that I need to get at least the head cover off and pan dropped so I can see where the leak is or is not coming from during the pressure test. Doing the test without at least that done will only tell me what I already know. That there is a leak somewhere.

 

[Buchan]

New here. I have currently read about 3/4 of the posts. I have experience with small and large Allis Chalmers (HD6 & HD21), but these are a different kettle of fish with the fixed truck frames, steering and drive mechanism of the D21A-8.

Up until a week ago I was unaware that these little machines existed. They were never imported into Oz as new, and are now being imported second hand from Japan. I an was contemplating a small Korean 4wd tractor/loader, but have hesitated/ as the country is steep in parts, rocky in parts and covered in fallen timber. I have some minor earth works to do and a heap of manuka scrub to clear out from under mature forest trees.
I am now looking to purchase a D21A-8, with 2100 hrs. I have uploaded some images of the track gear/sprocket, and am curious as to the life left in them especially the pins. I am told that the tracks are SALT tracks. The rest of the machine looks tidy enough. I have yet to touch it though. If I make the effort to drive it ( it is 2000kms away), is there anything I need to note wrt the drive engagement and steering that would give me any warnings to steer clear.
Thanks in anticipation.
Donald
tracks

 

[epirbalex]

New here. I have currently read about 3/4 of the posts. I have experience with small and large Allis Chalmers (HD6 & HD21), but these are a different kettle of fish with the fixed truck frames, steering and drive mechanism of the D21A-8.

Up until a week ago I was unaware that these little machines existed. They were never imported into Oz as new, and are now being imported second hand from Japan. I an was contemplating a small Korean 4wd tractor/loader, but have hesitated/ as the country is steep in parts, rocky in parts and covered in fallen timber. I have some minor earth works to do and a heap of manuka scrub to clear out from under mature forest trees.
I am now looking to purchase a D21A-8, with 2100 hrs. I have uploaded some images of the track gear/sprocket, and am curious as to the life left in them especially the pins. I am told that the tracks are SALT tracks. The rest of the machine looks tidy enough. I have yet to touch it though. If I make the effort to drive it ( it is 2000kms away), is there anything I need to note wrt the drive engagement and steering that would give me any warnings to steer clear.
Thanks in anticipation.
Donald
View attachment 189609 View attachment 189610 tracks

I have seen where Japanese new machines sold used here advertised having had a geiger counter run over them . Heaps of Japanese new sold used into NZ across the Komatsu range . Suggest you ask your closest Komatsu dealership if they will supply parts for it .

 

[burnerlief]

Hi, I'm new to the forum. I have a D20 A5 that I'm having a problem with. I start it up and drive it for a bit and then the left track starts to bog down and eventually will lock the track. If I wait a few seconds it will release but will slowly lock up again over a few yards of driving. This will go on and on over and over for quite a while (10 to 15 minutes) and then it will stop happening and the unit will run fine the rest of the day. The problem only seems to happen when I first start it up. I've checked and adjusted the linkages - everything is set up right. Any ideas? Is it a sticky hydraulic valve?

 

[tantoy]

Hi, I'm new to the forum. I have a D20 A5 that I'm having a problem with. I start it up and drive it for a bit and then the left track starts to bog down and eventually will lock the track. If I wait a few seconds it will release but will slowly lock up again over a few yards of driving. This will go on and on over and over for quite a while (10 to 15 minutes) and then it will stop happening and the unit will run fine the rest of the day. The problem only seems to happen when I first start it up. I've checked and adjusted the linkages - everything is set up right. Any ideas? Is it a sticky hydraulic valve?

Maby that brake is too tight, try loosing the adjustment bolt for left brake band?

 

[burnerlief]

Maby that brake is too tight, try loosing the adjustment bolt for left brake band?

I can try that. The weird part is that it stops happening after a while and runs perfectly fine until the next time I start it up after its been sitting. -- I'd think if the brake band was too tight, it would get worse after the machine warmed up, but maybe not.

 

[DoubleK]

Here is a long winded story that may provide some food for thought for those who own/operate the D20/21's and have problems with the steering/braking on them.
I purchased a D21-6a around 2007 from a neighboring state. I had a company truck it for me. Started using it to level 72 dump truck loads of dirt. I had never run a dozer before, so I had nothing to compare it to. It seemed to be fine, but was a little tricky to steer.
After a while it got harder to steer. I was starting to look like Popeye from having to pull so hard on the steering levers to get it to turn. Finally took it to a Komatsu shop. They said drive clutches were shot and we had them rebuild it.
After that it ran great. We used it off and on for 3 years and then I got relocated for three years so it sat in the machine shed, not being used.
I moved back and we used it to move some rock piles on the line fence. After that it sat for another year without being used.
Started running it this last summer and it worked great, however the steering started to get bad. It finally got so bad that I would push in the inching clutch, pull the lever in the direction I wanted to turn, and then let out the clutch slowly to get it to turn! Otherwise it would never turn. It got really bad, so I decided it was time to tear into it again. I spent a lot of time online trying to determine what would be wrong, finally figuring that all those years of just sitting around and not being used caused the clutch bands in the steering to rust again and stop working.
I trailered it home, drove it onto railroad ties, and started checking fluids. I started with the transmission fluid and filter. The fluid was at the correct level, but I had never cleaned the screen. I removed the oil, and then the screen. It was clean so I reinstalled it. This was tricky trying to get the o-ring back in place... Ask me if you need a way to put it back together.
I then got ready to change the fluid in the final drives. I removed the filler plug, and oil SHOT out of the hole. Yes, it was definitely the filler hole. I put the plug back in after a 1-2 cups of oil had escaped. I then went to the other side. The same thing occurred!. I then removed the oval inspection cover for the center pinion gear case, and it was full. So, Where was the extra oil in the final drives coming from? I checked all of the other fluid levels, and they were where they should be.
I then looked at some youtube videos, and saw that on most of the D21s, there are about 8 bolt holes on the back of each steering clutch case. In the videos, these holes are empty. Mine had shiny bolts installed in them with silicon. I opened up the brake adjustment covers and found the steering cases full of oil. Since I had not added this oil, it had to have been installed by the shop. So, maybe they made an error by making the dry clutch system a wet clutch system, but it worked! All of those years when this unit sat unused, it should have rusted the clutches and the drums. Often the brake adjusters will rust as well. On mine, I removed the access panels to adjust the brake bands and I was able to adjust them with my fingers, no wrenches needed. So, I tightened them both both until snug and then backed them off 1/4 turn and put it all back together.
That was all it needed. Turns with 1/2 pull per lever, dead stops with both levers fully pulled. Hard turn with one side fully pulled, etc.
I did run this all by Darrin of DMM, telling him what I found. He stated that they were indeed dry clutches...

So, will this work for you? I don't know. What I do know is that I don't use this dozer often or at least run it every month or so, but I'm not worried about doing that since it can't rust out the clutches with all of the oil. Timeline wise, that oil has been in there for at least 9 years.

Good luck!

 

[epirbalex]

Here is a long winded story that may provide some food for thought for those who own/operate the D20/21's and have problems with the steering/braking on them.
I purchased a D21-6a around 2007 from a neighboring state. I had a company truck it for me. Started using it to level 72 dump truck loads of dirt. I had never run a dozer before, so I had nothing to compare it to. It seemed to be fine, but was a little tricky to steer.
After a while it got harder to steer. I was starting to look like Popeye from having to pull so hard on the steering levers to get it to turn. Finally took it to a Komatsu shop. They said drive clutches were shot and we had them rebuild it.
After that it ran great. We used it off and on for 3 years and then I got relocated for three years so it sat in the machine shed, not being used.
I moved back and we used it to move some rock piles on the line fence. After that it sat for another year without being used.
Started running it this last summer and it worked great, however the steering started to get bad. It finally got so bad that I would push in the inching clutch, pull the lever in the direction I wanted to turn, and then let out the clutch slowly to get it to turn! Otherwise it would never turn. It got really bad, so I decided it was time to tear into it again. I spent a lot of time online trying to determine what would be wrong, finally figuring that all those years of just sitting around and not being used caused the clutch bands in the steering to rust again and stop working.
I trailered it home, drove it onto railroad ties, and started checking fluids. I started with the transmission fluid and filter. The fluid was at the correct level, but I had never cleaned the screen. I removed the oil, and then the screen. It was clean so I reinstalled it. This was tricky trying to get the o-ring back in place... Ask me if you need a way to put it back together.
I then got ready to change the fluid in the final drives. I removed the filler plug, and oil SHOT out of the hole. Yes, it was definitely the filler hole. I put the plug back in after a 1-2 cups of oil had escaped. I then went to the other side. The same thing occurred!. I then removed the oval inspection cover for the center pinion gear case, and it was full. So, Where was the extra oil in the final drives coming from? I checked all of the other fluid levels, and they were where they should be.
I then looked at some youtube videos, and saw that on most of the D21s, there are about 8 bolt holes on the back of each steering clutch case. In the videos, these holes are empty. Mine had shiny bolts installed in them with silicon. I opened up the brake adjustment covers and found the steering cases full of oil. Since I had not added this oil, it had to have been installed by the shop. So, maybe they made an error by making the dry clutch system a wet clutch system, but it worked! All of those years when this unit sat unused, it should have rusted the clutches and the drums. Often the brake adjusters will rust as well. On mine, I removed the access panels to adjust the brake bands and I was able to adjust them with my fingers, no wrenches needed. So, I tightened them both both until snug and then backed them off 1/4 turn and put it all back together.
That was all it needed. Turns with 1/2 pull per lever, dead stops with both levers fully pulled. Hard turn with one side fully pulled, etc.
I did run this all by Darrin of DMM, telling him what I found. He stated that they were indeed dry clutches...

So, will this work for you? I don't know. What I do know is that I don't use this dozer often or at least run it every month or so, but I'm not worried about doing that since it can't rust out the clutches with all of the oil. Timeline wise, that oil has been in there for at least 9 years.

Good luck!

Has it had breather caps fitted , pressure could force the oil into the final drives . Sombody was thinking outside the box .

 

[DoubleK]

Has it had breather caps fitted , pressure could force the oil into the final drives . Sombody was thinking outside the box .

No breather caps were installed. Would be a good idea, tho...
I do feel that the extra oil in the finals came from when they filled the steering cases. I'm not sure those sections are completely sealed from each other. I don't know that the finals shafts coming from the steering cases have good seals and that allowed the oil to flow into them. I do remember the mechanic saying that "someone removed these bolts from the back and all the oil leaked out. That is why the clutches rusted." It didn't make a whole lot of sense to me then, but that explains why they installed new bolts.

 

[epirbalex]

No breather caps were installed. Would be a good idea, tho...
I do feel that the extra oil in the finals came from when they filled the steering cases. I'm not sure those sections are completely sealed from each other. I don't know that the finals shafts coming from the steering cases have good seals and that allowed the oil to flow into them. I do remember the mechanic saying that "someone removed these bolts from the back and all the oil leaked out. That is why the clutches rusted." It didn't make a whole lot of sense to me then, but that explains why they installed new bolts.

You could lower the oil level below the the output shaft , so there would be no loss when the machine sits , through the seals . I changed a Hyster D7D winch brake to a wet one for cooling , it needed a softer brake fibre to grab . The oil I used first still had the band slipping so used kerosine , works a treat and is clean to work on . I'm in the middle of changing over a Komatsu winch from dry / dirty hot to a wet / clean cool one and are hoping the fiber works without changing it , your choice of fiber for the brake bands might need to be addressed next time they are done .

 

[DoubleK]

You could lower the oil level below the the output shaft , so there would be no loss when the machine sits , through the seals . I changed a Hyster D7D winch brake to a wet one for cooling , it needed a softer brake fibre to grab . The oil I used first still had the band slipping so used kerosine , works a treat and is clean to work on . I'm in the middle of changing over a Komatsu winch from dry / dirty hot to a wet / clean cool one and are hoping the fiber works without changing it , your choice of fiber for the brake bands might need to be addressed next time they are done .

Only thing I'd worry about then is that if the machine sits for awhile, the portion of the brake drum and the clutches that are no imersed in oil could rust. I realize that they have been in oil for some time, but wouldn't want to risk them rusting. Darin had mentioned the incorrect fiber of the plates and how they may swell and not be able to release, however, they have been in oil for many years now, 6-8, and all still works, including the brake bands. Maybe I got by with just tightening the bands more than normal so they would grab, but like I had said, I finger tightened them...

 

[Joe C.]

Hello guys, new to the forum. Glad there is a section here for these little dozers. A lot of information on this thread alone. I've read through about a quarter of it and learned alot already. I just purchased a shop manual for my d21a-7 then a day later seen where someone posted a link that had the entire manual in pdf form...free! Oh well.
I am not new to the small dozers as I've owned a pair of Mitsubishi bd2gs in the past. But a couple weeks ago I bought a Komatsu d21a-7 (serial 77794). I knew before purchasing it that only one side was pulling on it. Wasn't sure why at the time but only 1200 hrs and at a great price I was willing to take a risk. Turns out the sprocket nut had worked loose allowing the sprocket to wobble around on the sprocket shaft for who knows how long. So the sprocket and the shaft are both trashed. I can get a sprocket no problem. The shaft seems non-existent. I've called and emailed everyone around. Any help that yall can think of? part #103-27-31311. I seen somewhere that Kent Baugh in Tx had one but no luck there either. Thanks

 

[Joe C.]

Any ideas?

 

[thepumpguysc]

If you cant find one or they're non-existent.. how about sending it to a crank/camshaft rebuilder??
They'll size it up from a "good" portion of the shaft & build it back up to size.. Its worth a try.??

 

[tantoy]

https://www.dmmsales.com/
did you try here

 

[Joe C.]

If you cant find one or they're non-existent.. how about sending it to a crank/camshaft rebuilder??
They'll size it up from a "good" portion of the shaft & build it back up to size.. Its worth a try.??

I’ve hit up all of our machine shops locally but none of the have a spline machine or do splines at all. I may have to send it off to someone. Thank you.

 

[Joe C.]

https://www.dmmsales.com/
did you try here

No I haven’t. But I definitely will now. Thanks.

 

[GuglioLS]

Try https://www.andersonequip.com/web/idb.php
Did a search on the part # you gave, call them to see if they can order it. 1000 bucks!

 

[Joe C.]

I know. $1000 seems high but I'd be happy to pay it if they actually have one. I'll give them a shout. Thanks Guglio.