Recently snagged a D31A-17 at a local auction. Sadly I got it home and was only able to push over a few stumps before the transmission lost all movement forward and reverse. Thanks to the guys here I was able to see the problem was most likely the strainer plugged so I dumped the fluid and removed strainer and it was just absolutely full of metal. Lots of metal sludge in the bottom of trans, didn't look like it had even been cleaned out and didnt appear to be fresh. I cleaned it all out and thoroughly cleaned strainer. Once refilled with the proper oil to the proper level I was only able to operate the dozer again for about 2 minutes and then lost all movement again with the same cavitating pump sound. I dumped the oil again and it was back completely full of metal this time fresh looking along with plugging the strainer again. Oil looked like paint. I again cleaned the strainer and refilled the oil in an attempt to get the dozer to make it to my trailer so I didn't have to work on it where it was. Of course it died completely in forward speeds with a thunk right here: So my only option is to remove the transmission where the dozer lays, typical. I still had reverse so I was able to get it back up on some lumber to give me some more room to work. I then began the removal process which is pretty simple for this machine. It's tight in places but we made steady progress. She's finally free! At least the bevel gear and trans output look like new. I was really impressed with this for 7600 hours on the machine.... it had to have been done already right?
After about an hour of pressure washing the trans was home and clean enough to disassemble. Front pump removed along with strainer tube etc and the rear output housing also removed: Then I removed the large case to expose the main guts. This is as far as I got I hope to start tearing this main assembly down tonight. The manual states to check and make sure the pistons move with air pressure to actuate the clutches properly but I could only get one to move. Input shaft has about half inch of lateral play.... doesn't make great noises spinning. Anticipating a hefty parts bill but fingers crossed i get lucky though so this doesn't turn out to be a part out. Any advice or suggestions guys? Anything common with the inside of these?
there will be a recommended air pressure , that should be increased a bit if the piston won't move , intermittently .
Got the pump apart yet, I would be tearing that down for inspect as well.
I pulled the main trans down yesterday, what I found was not good. The forward planetary carrier is sheered in half 3 of the planet gears are in peices, and it chipped a tooth on the ring gear where those 3 ride. The carrier is $2550 at komatsu alone and for the rest of the stuff I need (bearings, planets, ring gear, shafts etc, as well as clutches and plates for both fwd and rev) the total comes to $7500. Needless to say that is not happening. Does anyone know a trans builder that may have some used stuff laying around or an aftermarket supplier? I would like to make an effort to fix the machine, but I can't see spending more than 3k on it. I'd rather just sell it as a parts machine and buy something else. Anybody got anything?
After this debacle I did pull the pump down and it looks mint inside. I was really shocked. The needle bearings for the gears want to fall out of the races so it made it a pain to reassemble, although the gears were tight I might get new ones as they typically don't do that.
that is an OWIE!! Might want to pull up machinery trader and dig for a salvage yard with a trans.
I was able to locate a good used planetary assembly used for reasonable money so I bought it, now waiting on parts places to get back to me with the rest of the stuff I need to build it. Shops a mess!!!!
That would save scrapping what may be a decent machine after. Plus running and moving if you still do not trust it then sale of and buy something else!
I really don't wanna just off it I really like the dozer.
Kind of like my Allis, I fit it, it fits me!!
Has anyone ever ordered from AGAParts.com???
Finally got a bunch of parts in the mail along with my used planetary assembly. Lots going on here, got the first and second and 3rd gear packs in the main stack and about to build the fwd/rev assembly. Also over to the left on the lift arm the pump assembly is gutted as I decided to replace every single needle bearing in the trans. (was a good move) Here's a close up of that stack built out to 3rd gear I was in the middle of replacing the needle bearings in the very last planetary and found this. This shaft is where the needle bearings ride and the planets spin on them. Had to order parts again as I didn't have this planetary disassembled for fear of losing anything. Since there wasn't much I could do without parts I decided I'd pull the transfer assembly apart just to clean it out. Found this main bearing race chowdered right to f&*^. Of course this was the next day so another overnight parts order!!! This bearing and race is $300. While I was waiting for that transfer case big end bearing my first order came in so I grabbed that junk and got to work. Main stack all built out. Pump rebuilt (fresh bearings), modulator rebuild and resealed and fwd/rev/shift control all rebuilt/resealed and installed. In the background you can see the main transfer shaft that meshes with the bevel gear as well as the cylindrical seperable ball bearing that is made by NTN for Komatsu and you cannot get through a bearing house. Finally got my bearing and finished the build. She's back to choochin...... until the next failure.
Do you have any pics of whats inside the fwd/rev selector? My d31P-18 has always been slow to engage reverse when cold but would eventually "pump up" and "catch" then work fine for the rest of the day. Well it finally quit "catching" and i have no reverse. Im guessing theres a seal thats leaking control pressure. Thoughts?
I don't but it's just a bunch of spool valves there are no seals inside that assembly there are many other places it could bleed fluid pressure off though. there are test ports on that assembly so plug in a guage put it in reverse and see what pressure does. Under that assembly and going into the main trans case are little round tubes with orings on both ends.... possible but unlikely you are bleeding by there. Other than that the only easy places to bleed by are inside the trans maybe a piston is bleeding by etc. Check pressure go from there.
Thanks for the reply. I gotta track down a service manual and figure out what ports get what pressure.
i have a manual for mine i can send you?
Oh what a blessing that would be, thank you so much, i appreciate it! Mike_Belben@yahoo
i've hosted it for you. https://drive.google.com/file/d/0B5V9wT7hn54WNm1JcFpha29LdUk/view?usp=sharing
Downloading now, thanks a bunch. Id bought a CD manual but wifes laptop couldnt open it and a 14 mile trip to the library every time wasnt working good. Cant even find it now.
I have to thank you again. Dove into schematics today and realize i didnt have a prayer of figuring this control system otherwise. Really appreciate your help sir. God bless
any chance you could rehost the manual please? i have d31a 17 with trans issue
Mike I'm really happy to have helped out. I hope your project turned out good. Sorry for the late response. Ask and you shall receive my friend. Sorry the old link broke, friggin google. https://www.dropbox.com/s/xze3220cl..._D31p-17_Workshop_Service_Manual_Pdf.pdf?dl=0
Thank you so much !
Thank you for the great thread with pics etc.
Thank You for the Manual
I love this place! Thanks for the manual! I printed it all out tonight! Ol2Stroker, thanks again!
Well i need some other brains to mull this one over for me and im hoping my own will pop into gear while typing this. Ive had my d31p-18 for years now. It has had fussy steer pedals at times and over the years ive redrilled worn out control rod link yokes to oversized tighter pins and restored the consistency. My steer spool cam follower rollers were all sloppy and wallered and thats all pretty well sorted out now. The quirk its always had was itll engage firmly and go forward from the start even stone cold, but not going in reverse for quite a while. When youre getting close youll see a track start to tense just a hair but you sit and wait a while longer.. its like someone riding a clutch so they dont roll back on a hill. If you went forward about 20 feet first itd go in reverse, or if parked against something, you had to let it warm up a long time and revved way up before itd eventually "catch" reverse. Once it catches bam youre off, full power in either direction forward or reverse, it pushes trees and skids them no problem. Once reverse is working, itll shift forward and reverse and steer at idle. But in the beginning it wont engage reverse at all, from idle to full throttle It was getting fussy to steer the past season so i went in to do some maintenance. Id be slamming the pedal to the floor and itd drive thru the brakes without the clutch uncoupling drive power from the track you wanted to stop. Smash pedal down to the brake and itd go straight. To turn i had to go to neutral, push pedal all the way down then engage gear for it to turn correctly. Pivot turns only from a stop, no gradual ones. Both sides same way to the same degree. I took the slop out of the control rods under the floor and then the steering was gone. Itd go forward with full engagement but not steer or reverse at all after that adjustment. I read the theory of operations a few times and went into the steer spool block, the fwd reverse speed and inching valve block, and the modulator valve, which sets pump pressure via a counterbalance spool. I didnt find any catastophe but did replace a few o rings just because they were nicked or hardened. Put it all back together and i set the steer spool rollers so they just barely spin but are nearly touching the spool tips. My pedals have full stroke to depress the spool plungers and i set the brake bands to engage at a comfortable stroke and equal to each other. Before they were grabbing way down low at the end of the stroke so i tightened them to advance engagement up higher. Not by a lot, theres plenty of slack and you can tell by exhaust note they arent hanging. Next startup it wouldnt really engage forward or reverse.. it was doing the almost shift into gear thing that normally only happens with reverse while cold. I dont have an 1/8" npt to jic fitting to test port pressures yet but reasoned out that this is low pressure in the control circuit, since it takes pressure to engage the fwd/reverse planetary and to fill the steer slaves which push the clutch yoke to uncouple power to either final. So i shimmed the modulator double spring with a washer. It now goes forward and reverse from cold equally well, which is the best reverse engagement it has ever had and that suggests i am going the right direction raising pressure. when i try to steer it will occasionally steer, but mostly it just stops the machine completely without any steer action. both tracks will stop by depressing one pedal and im starting to get confused. If the steer slaves were vented of pressure the clutch springs would apply full coupling power. I know the clutches are good because it pushed trees out last week with full power. Is it possible i have the roller follower wrong on the tips of the steer valve spools? I dont have any external leaks. I changed the trans fluid years ago and had no trash, strainer was pretty clear. Oil still looks good n clear on the stick, never heard any bad noises. Im kinda chasin my mental tail on it. Thoughts?
I had shimmed the modulator valve springs with a washer and didnt seem to have any real improvement. Got sick, few days later i put a gauge in the modulator port and had a bit excess pressure, about 350 when it calls for 285ish. Got it down to around 300 and now i have immediate forward, reverse and steering under all conditions with one exception. 2nd gear is gone whether forward or reverse. It drops to zero psi as soon as you shift like it should, but never ramps up to engage pressure, which is whatevever the modulator valve is regulated to. The modulator valve is basically a relief valve with a counterbalancing delay mechanism so that all shifts are ramped in softly.
looking at purchaing a d31-17 where about is this transmission filter like to inspect it to see whats up with it, and any other advice on what to look for or how to test, I currently have a D20 so im pretty familar just want to make sure thanks!!
Where ya located at?
South Texas just north west of Corpus Christi,tx im in Orange Grove,tx
Its under the belly pan. There is an access panel but its often mangled. When on the machine its under your left heel. Theres a 90* pipe elbow bolted to a cover plate. Its behind that inside the trans and all fluid will be drained in the process. A bit of a chore but it does reveal alot. If the trans engages quickly from a cold start in every direction and goes in every gear consider it very good. It seems many of them by now have a lag time to get going from a cold start. The steering is pretty easy when you have everything adjusted correct. If it takes stomping on a pedal a few times and wants to drive thru the brakes there is worn pins and yokes in the control linkages. Simple but tedious little things that stack up.
Gotcha. Just wondering if you were one of the fellas looking at the d31 I have for sale, lol! Its not you tho!
thank you
Good Afternoon mike i have a d31p-18 i just replaced the steering clutches and brake bands before i replaced the brake bands i was out of adjustment on the brakes on my right side only now i have everything back together and when i pull my brake handles it will stall the engine my clutches seem to want to disengage could i maybe have air in the clutch hydraulic system or is there an adjustment for the clutch system
not to familar with the d31 but from what i have seen its very similar to the D20 when you pull back on the lever it should be disengauging that side of the steering clutches so its taking away power now when you pull back more then the steering clutch should be almost fully disengauged and the brake band starts clamping down on the drum slowing your track and if you pull back farther then it will lock it up. So thats how its supposed to work so if your pulling back on the lever and its stalling the engine then my guess is that your steering clutch is out of adjustment so full power is going to the track and when your pulling on the lever its clamping down on the drum so its trying to stop the track and the engine, I would check as you pull on lever that the first part of movement is on the steering clutch and not the brake band it should be steering clutch for the first half when pulling on lever then the last half it should have steering clutch engauged then engauging the brake band hope that helps
Thank you sir
ok hope you understand what i was trying to explain if you still have some questions just pm a phone a i give ya call once you understand how it all works then you will be able to fine tune it to your liking on pulling of the levers, have a great day
I just have a question. I have a d31e-17 and my transmission shaft endplay is about 1/2 inch or so. Once you had your trans back together do you remember how much endplay you had? I’m just looking for a direction before removing. Thanks