mike_belben
Well-Known Member
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
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Komatsu D31A-17 Transmission problems
- Thread starter OL2STROKER
- Start date
Josh2356
New Member
any chance you could rehost the manual please?
i have d31a 17 with trans issue
i have d31a 17 with trans issue
OL2STROKER
Well-Known Member
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
Josh2356
New Member
Thank you so much !
rob fong
Member
Thank you for the great thread with pics etc.
MaddogMike
Member
Thank You for the Manual
Old Growth
Well-Known Member
I love this place! Thanks for the manual! I printed it all out tonight!
Ol2Stroker, thanks again!
Ol2Stroker, thanks again!
mike_belben
Well-Known Member
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?
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?
Last edited:
mike_belben
Well-Known Member
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.
The modulator valve is basically a relief valve with a counterbalancing delay mechanism so that all shifts are ramped in softly.
Krackerjack9
Well-Known Member
- Joined
- Dec 3, 2007
- Messages
- 171
- Location
- working at Camp Anaconda,Iraq
- Occupation
- working in Iraq right now
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!!
Old Growth
Well-Known Member
Where ya located at?
Krackerjack9
Well-Known Member
- Joined
- Dec 3, 2007
- Messages
- 171
- Location
- working at Camp Anaconda,Iraq
- Occupation
- working in Iraq right now
South Texas just north west of Corpus Christi,tx im in Orange Grove,tx
mike_belben
Well-Known Member
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.
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.
Old Growth
Well-Known Member
Gotcha. Just wondering if you were one of the fellas looking at the d31 I have for sale, lol!
Its not you tho!
Krackerjack9
Well-Known Member
- Joined
- Dec 3, 2007
- Messages
- 171
- Location
- working at Camp Anaconda,Iraq
- Occupation
- working in Iraq right now
thank you