Today I removed the covers over the steering clutches. After removing the brake band springs and all 16 of the flange bolts. the clutch assembly is loose and tries to come out but something is snagging as I try to lift the clutch assembly upwards. I'm missing something and the manual is very lacking in details. Hopefully, someone will have a suggestion or trick to remove the clutch.
The manual is telling me to remove the "clutch pilot" and the clutch will lift out. I don't know what this "pilot" thing is. Can anyone enlighten me? How much movement should the throw out lever have?
there could be some info in the link I posted for you on your last thread about dry clutches
I don't see a link anywhere.
HeavyEquipmentForums first sentence and last paragraph are my writing , link is in the middle of it . On the last comment
I found it! Flushing the clutches brings up another problem. Would that not flush the grease out of the throw out bearing? My clutches are 254 years old and never worked on. I want to take everything apart, clean and replace all discs, drums, springs, and throw out bearings and make the assembly work like new. I noticed about 2 inches of crud in the bottom of the housing that needs to be cleaned out. My problem now is trying to lift the clutch pack up and out of between the flanges.
Thats a lot of rubbish to have there for a closed system , the pilot gear refers to what would have been called thrust control , control probably wrong name for it . Check to see that one or more plates have not leaned over againt a flange , are there dowels catching against the drum . Should come up with a good yank . Sounds like you are not in there too early .
I worked on the right clutch today but still haven't managed to remove it. Maybe if the throw out arm could move a bit more to the left, (center of the tractor) I might have enough clearance. I think I'll try to remove the left clutch and see if it has the same problems.
Hi, just reading along here. Could the thrust bearing be the pilot or thrust control? If your throw out arm is connected to a bearing, could it move further if you disconnected it? cheers
Hi Muzy! From what I can discern, the steering clutch must be removed in order to remove the inboard flange to access the throw out bearing. I think the throw out arm needs to move toward the center line of the tractor and touch the edge of the top opening. I still have over a half inch of arm travel to free up.
I found this thread about a D20a-5. Sounds like he had clutch out, but the links to his pictures says I am forbidden. HeavyEquipmentForums Good luck.
I got it out! It was just a matter of freeing up the throw out arm and moving it farther away from the clutch pak. It's pretty nasty in that cavity and plenty of rust and crud. The parts don't seem to be unusually worn, just years of neglect and contamination getting in from bolt holes that are supposed to be sealed with cork plugs. How do put pics on this post?
I need to remove the flange from the bevel gear shaft. I removed the lock keeper and ready to remove the big nut. Does anybody know what is the wrench size for the big nut?
It's nasty in here! Years of neglect and moisture but I have a beadblaster. I intend to repair and rebuild to like new condition so I won't have any surprises when it goes back together! I had to use a hydraulic press to dissemble this actuating lever assembly. It was badly frozen tight! The brake band had corrosion between the band and linings causing the linings to crack and break apart at the rivets. New parts coming.
Nice thing about having a glass bead blaster!
Still cleaning and prepping parts for the steering clutch overhaul. I've got the nuts off the inboard flanges but they are super tight. I have a spreader bar attached as a puller and considerable strain applied with penetrating oil soaking the shaft. Next I'll use a porta power spreader jaw between the flange and throw out arm to try to move it.
In removing the inboard and outboard steering clutch flanges I used a puller bar to good advantage as shown.
Considering the prices, I took another look at the brake drums. After beadblasting and polishing on the lathe, I saved several hundred dollars! I used a portable 21" belt sander to dress the outside surface. All the internal teeth were perfect.
A little more cleaning and painting this week. Maybe I'm going a bit overboard but, at least, reassembly will be clean. I rigged a sleeve to protect the final drive oil seal and wrapped some rope caulk around the oil seals to protect them during sand blasting. A rinse down with paint thinner and a coat of paint.
Nice looking job! Some people might think it's pointless to paint inside where nobody will ever see, but a smooth painted surface will rust a lot less (hopefully not at all). Rust absorbs moisture and begets more rust, so the bare metal clutch discs and brake drum should last longer in this compartment.
I made a list of gaskets and seals needed and the prices thereof. Since the cover gaskets were 25.41 each I invoked my shade tree skills and made a pair!
I got the last of my steering clutch parts beadblasted and painted. Just waiting on new parts to arrive. In the meantime I cleaned and chased the threads of all those 16 holes in the back of the steering clutch cases. Originally, they were plugged with cork and over the years some of the cork plugs were removed. These holes are a prime source of moisture and dirt entry and future clutch and brake failure. Pressure washing doesn't help either! I purchased some M18-2.5 bolts, applied pipe dope on the threads and torqued them in place. Along with new gaskets and seals, my clutches should remain clean and free for many years to come.
Before ordering new steering clutch springs I decided to check the originals. Not having the Komatsu specs for these springs I decided to make a comparison test. Free length was 2 13/16" on all of them, compressed to 2 1/4" they all read 85 lbs. Since they all read the same I feel confident they are good to run.
The service manual for 6 series gives a free length of 70.6mm, compressed 51mm with 60 Kg force. That works out to 2.77", 2.01" and 132 lbs. The spring part # is the same for 6 and 7 series, so these numbers should work for yours. I think you're right that matching is more important than absolute length. I've wondered about those corks from the beginning--why wouldn't they have put the bolts in and left maybe one small vent? Maybe they wanted the steering clutches to breathe, like a fine wine.
I reset my tester to 2" and rechecked the springs. All tested at 130-131 lbs except for one spring came in at 128. I think that will work nicely. Thanks for doing the math for me! As far as venting the steering cases, I'm going for the sealed version. Maybe put a couple of desiccant bags in for good measure. My way of thinking is 'no vent, no moisture'.
Sealing it up is a good idea--I'll probably do the same. There's enough air in there that, even with a big temperature swing, there shouldn't be enough change in pressure to hurt seals or pull fluid from the ring / pinion case. The dessicant should reduce condensation damage. I'm also trying the Vapor Corrosion Inhibtor capsules--supposed to be good for 2 years in a sealed space--to prevent surface rust on the clutch discs. Zerust is the one I got--there are others of the same chemistry. But the best rust prevention of all is USE. Look at the brake rotors on a car that sits just a few weeks--already covered with rust (at least in this climate--central NY state).
I got all the new parts in today from the good folks at SteeringClutch.com . Tomorrow, I have to build a tool to assemble the clutch pack and start back together. It's certainly nice to have everything clean and painted for reassembly.
Those parts look way too nice to bury inside the clutch case--maybe you should make a window in the cover so as to watch everything turning! Do you plan on coating the splines and other bare metal with anything? The drums and clutch discs would wear clean, of course, but anywhere else it might help.
All threads and splines are coated with never seize. Today, I built a compression tool and assembled one steering clutch. More pics and progress tomorrow evening.
A compressor tool is needed to assemble the clutch pack. This is my rendition of the “A” tool as mentioned in the Komatsu service manual. I made the two guide pins from M8 fine thread by 4.5” bolts. 1- Place the spring collar on the tool base and install two guide pins. 2- Place all springs and spacers in position and install the spring bolts, (less flat washers), only about two threads.
1- Lay the inner hub in position, install upper compressor adapter and compress the springs until the spring spacers are slightly proud of the surface of the hub and remove the bolts but leave the guide pins for now. Install the plates starting with a friction and ending with a friction. 2- Lay the thrust plate into position. There is only one position where the bolt holes and inner teeth align. Rotate the plate until everything lines up.
1- Align the external teeth and install the brake drum. 2- Remove the guide pins and install all eight bolts and tighten to specs or your “feel”. 3- Remove the tool, install the brake band and you’re ready to go!
The clutch throwout assembly has been beadblasted, no damage found, painted and is ready for assembly. The bearing is assembled on the gimbal and clutch fingers and this is mounted into the throwout lever. All pivot and sliding points are greased and the bevel gear flange is fitted into position. At this point, a neat modification has been added. Cxprestige offered a suggestion concerning the ball and socket at the bottom of the throwout lever. The ball doesn’t ride in the bottom of the socket but, rather, is suspended in the bore of the socket and the whole throwout assembly is suspended on the bevel gear flange. Grease can be placed into the socket and a boot assembled over the ball and socket to prevent any trash from entering the socket. This boot is derived from an early Volkswagen axle but we’re not exactly sure which model.
The clutch throwout arms are installed and ready for the clutch assemblys. There is a world of difference in the smoothness of the action before and now with everything clean and lucubrated.
A rainy, drizzly day is always suitable for inside work! The throwout assemblies installed and ready for the steering clutches. I attached two 3/8” lifting eyes on the opposite flange wheel and inserted a pipe to lock the bevel shaft while we tightened the first flange. Due to the restricted clearance between the two flange wheels, I shortened a 2 1/8” socket just enough to grab the nut.
At this point, it cannot be stressed enough to pay attention to the orientation of the brake band on the drum. It would be a shame to get the clutch in and tightened and then realize the brake is on backward! Been there, done that on other similar projects! Lower the clutches into position using a comealong. Instead of using a bottle jack to rotate the track I used a pinch bar and levered the sprocket teeth to align the bolt holes in the flange wheels. A lot easier and quicker.
Bravo Don, Wow you made this process look easy and fun. Glad you got the girl back up and running. Did you drill and tap grease fittings on the housings? One note that you may not ever need to know but people reading this may is.. On both the final drive and bevel gear flanges Komatsu put 2 threaded holes used for large nut lock that can aid in pulling the flanges off. Just use longer bolts than you took the lock cap off bolts. Built in puller really..
I didn't put grease fittings on the brake control shaft. Since it has seals on both ends i just packed the bearings full of grease. It should last until I'm gone anyway! Tomorrow, I'll lower the covers into place and purge the case with nitrogen. More on this later. I made a nifty lifting sling to allow one person to lower and align the covers. More pics coming tomorrow evening.
I devised this little hangar thingy to help suspend the steering case cover while I aligned the brake band controls. The other end I just hooked on an adjusting cover bolt.
I fashioned three stud locaters to hold the cover gasket in place and hold the cover in alignment while the bolts were installed. After adjusting the brake band and everything is closed up, I’ll purge the cases with nitrogen to remove all moisture.
Steering clutches rebuilt, closed up, and the brake actuating cylinders also rebuilt while I'm at it. Just waiting for new cross hoses to be built.
This is an easy machine to work on but there are still a lot I have to learn about it. Searching thru the manual but I have not found out anything about this device. Hopefully, someone can shed some light on the purpose of this thing located at the rear under the seat platform.
I finally got my new hoses for the steering brake cylinders installed and the rest of the plumbing in place. Also, I deduced the two solenoid valves have to do with the blade angle control. All I have now is to reseal the spools on the blade control. Hopefully, tomorrow I can crank up and check for drips and squirts. I'm looking forward to experiencing the operation after all this rebuilding.
I reached the point where I could start the dozer today and all connections were dry. There was only one preexisting slight leak on the bottom of the blade control. I'll have to remove the complete valve assembly to repair so I'll wait until next winter for that. Otherwise, the clutches and brakes worked super smooth and positive control. Even the direction reversing was a lot better with no jerking. All I have now is to install a battery main disconnect switch and the new seat. I'm using a Smitty Bilt seat on a Jeep CJ adjustable frame.
Does anybody have the torque specs for the 8 bolts on the thrust plate?
M10 8.8 structrual steel zinc plated bolt "googled" 30 ft/lbs... Other websites may say differently so I'd compare and use your best judgement.
Thanks Darin! Just wanted to make sure there wasn’t a specific torque I was missing in he manual.
Hi Don, A very impressive job you have done on your dozer! I am just reassembling a D-21A-6 with support from Darin at DM Machinery 716 942-6318 I know you are in contact with him, I’m posting his number for others as he has been great support With parts and experience on these machines. Today this seems to be the end of your posting however on Saturday I thought I saw that you got your machine running and were driving it but found it jerky I can’t find those posts now perhaps I’m missing something just curious how things are going and hoping you’ll post some updates.
The machine really just needed to be exercised a bit. After a few hours, the jerkiness has disappeared and everything is operating very smoothly. The steering clutches and brakes are very sensitive and positive in action. I didn't even have to "bleed" the hydraulic lines as they purged themselves during operation. Last week I resealed the angle and tilt cylinders and didn't even have to bleed them either. Darin now has the tools I made to assemble the clutches so contact him for more information concerning their use. For a relatively small dozer, this D21 is a pleasure to operate. I've been pushing dirt and clearing small trees, bamboo, and underbrush with ease. The joystick controls, to me, are more desirable than lever operation and less fatigue. The utmost, main thing to consider on clutch overhaul is to positively seal all those bolt holes in the rear of the clutch housing to keep moisture and trash out. Also, new gaskets and seals will result in an air tight assembly.
Yes I’m sure all those clutch surfaces need a few hours to get seated in, glad things are working great you sure did a fine job, Darin is sending your tools to me today, I am so grateful, they are masterpieces. Thanks for your advice, I really appreciate the time and effort you put into posting this thread the Komatsu books give so little detail
The more I operate this machine the more I appreciate the hydraulic power controls, and being an older model, the lack of computer controlled systems, idiot switches, buzzers, and DEF **** fluid. This is the epitome of crank 'er up and get 'er done!
Hi I am Bill Pedrick new member just read post and was in pressed . my 21a quit steering yesterday no power to left track . thinking clutch went on that side will start there . can any one tell me the best place to get manual and parts thanks headed back to farm-camp will check in later
Manuals are available on Ebay. Caution on the repair manuals, I have not been able to find one that has any decent pictures. They are all blurry and mostly unusable. Check with Darin Mitchel for new and used parts. dmmsales.com Also check steeringclutch.com
So I installed my rebuilt steering clutches today. Good traction on both sides and good brakes on both sides but neither steering clutch disengages. I am thinking since I had the hydraulic lines off and fluid leaked out I may have air in the lines. Will pull partially apart tomorrow to see if actuators are moving at all. Any thoughts? Thx.
Remove the rear cover from the brake adjuster and check if you can see the throw out yoke operating the clutches. My control lines seemed to bleed themselves and have worked properly ever since I reinstalled them.
Will do, thx, will let you know.
My bad, I had read an article stating that when installing new clutches you did not have to adjust the yoke stud. (steering valve assembly)? Anyway, stud was not pushing clutches to disengage. Made some adjustments and works perfect. Now I just need mother nature to get the frost out of the ground up here so I can have some fun. Thx again.
It sure is nice when things come together. I spent today pushing up small trees and making burn piles. When all the burning is done I'll start pushing dirt and contouring the area to turn it back into hay production.
Hey Don, what grit was on that belt sander? Great thread, your pictures are awesome, saved me from guessing what the heck my manual picture was trying to depict. Thanks for all your time and knowledge. Jb
I believe that was a used 100 grit.
dose anyone know the trick or how to get the cover back on the steering clutches?? For the life of me I can figure it out
All components have to be assembled on the cover before lowering it in place. Notice section #3 of this post to get an idea. As you lower the cover into position, use a long screwdriver to attach the brake band. You MUST be able to suspend the cover about 1 inch while you attach the brake band to the adjuster. Otherwise, it can be a real bitch to accomplish.
well on mine that dang seat bracket is in the way and another bracket just above the battery area is in the way as well, I have to turn it somewhat to get it to clear and at best I got a 1/2in , been trying to put pin/bolt in first then push thur the hole and attach the addjustment nut but the back part of the clutch band is not engadge by that keeper thing i think i might try some elmers glue to possibly hole in place or some zip ties but so far no luck at all
Mmy seat bracket was removed as well as the fuel drain on the left side clutch.
The adjusting bolt should be assembled in the top cover. When you lower the top, you must engage the bolt cross pin into the brake band hooks.
I can get eveything to line up but as soon as I get it all in place and go to pull on the arm its rock solid it wont move, had Komatsu come out the guy tried this and that and kept running into the same problem either we couldnt get it to catch or we get it all hooked up but you cant tell untill you bolt it down and pull on the arm and it either fells wrong compared to the other side or its rock hard wont move at all, Paid $1100 for 4hrs and he would have stayed longer but he didnt have anyother ideas on what to due, said he call around on Monday to the other shops and see if anyone had every worked on one of these and might now how to due it, printed out the repair manual for that section but it didnt help at all
Well, I don't know. When I assembled mine I put the adjusting nut on with only 2 threads. With the top cover suspended and free to move a bit, I was able to visibly engage the adj bolt onto the brake band and then lower the cover in place. I had a come along supporting the cover.