Komatsu D41p-6 slips going forwards

[davecampbell]

I think my transmission went out, but I'd like to figure out how I can be sure before I tear it out. It's weird to me that it slips in all 3 gears forward. I'd have thought it would have been in just one gear. So that makes me wonder if it could be the steering clutches slipping instead. But then I would expect it to do it forward and reverse.

 

[John C.]

It is most likely the forward clutch pack in the transmission. Two clutch packs have to lock up in order for the machine to move. To go forward, the forward pack and a range pack have to engage for the movement to go all the way through the transmission to the output gear.

 

[davecampbell]

Thankyou

 

[kevinnguyen]

I think my transmission went out, but I'd like to figure out how I can be sure before I tear it out. It's weird to me that it slips in all 3 gears forward. I'd have thought it would have been in just one gear. So that makes me wonder if it could be the steering clutches slipping instead. But then I would expect it to do it forward and reverse. View attachment 228159

is it for sale

 

[southernman13]

Make sure your inching pedal. Far left pedal. Is retiring all the way back. We have same machine and at it was slipping and hesitating. Realized we had to physically pull the pedal back. It didn’t take much either. I finally pulled it apart cleaned the shaft and installed new bearings. It travels freely now! Good luck

 

[davecampbell]

Make sure your inching pedal. Far left pedal. Is retiring all the way back. We have same machine and at it was slipping and hesitating. Realized we had to physically pull the pedal back. It didn’t take much either. I finally pulled it apart cleaned the shaft and installed new bearings. It travels freely now! Good luck

I will check that, thanks

 

[davecampbell]

is it for sale

I dont think I can get much of anything for it with it slipping. If I could I would sell it and go buy a working one. Im not looking forward to pulling that trans.

 

[davecampbell]

What is the life expectancy of the transmission? I pulled the trans out today and it has been repainted so Id say this is at least its second rebuild. Machine has about 6700 hours

 

[Shimmy1]

What is the life expectancy of the transmission?

Factory assembled or rebuilt? Factory transmissions should last 7500 to 10k if properly operated and maintained. A rebuild done by a competent technician with good parts, could be close to the same. However, if it was rebuilt by a probie in some jobbers rebuild shop, possibly not very long.....

 

[John C.]

I've seen plenty of transmissions in the 15,000 to 20,000 hour range. The issue is always maintenance. Most of the power shift units are modulated to the point of an operator not being able to hurt them unless they run out of oil. Change filters and oils on time and usually there are no issues.
Hystats are another issue though. I've seen some wheel loader boxes break in the 12,000 hour range and trash the entire hydraulic systems. It makes for a hard decision, completely tear down the machine or just scrap it.

 

[davecampbell]

I'm going to try this one myself. I feel a bit like the guy in the AAMCO commercial that says "I want to try a transmission boss"

 

[Shimmy1]

I'm going to try this one myself. I feel a bit like the guy in the AAMCO commercial that says "I want to try a transmission boss"View attachment 233034
View attachment 233035

God speed, my friend.

 

[Dave Neubert]

Never been in a Komatasu looks like a Cat though you can check the clutch packs with air when you put it back together

 

[davecampbell]

Never been in a Komatasu looks like a Cat though you can check the clutch packs with air when you put it back together

I was able to improvise all of the special tools except the one to apply air to check clutch pack travel. It gave me the pressure you use, but not where to apply it. I'm thinking the travel should be greatly reduced with the new frictions in there.

 

[Dave Neubert]

The flat part with the 4 holes in it and the 2 holes that have the red o rings should be your clutch packs. I put a piece of heater hose over a blow nozzle and blow air that way. Did you replace all the clutch seals and seal rings on the shafts if they have them

 

[davecampbell]

Did you replace all the clutch seals and seal rings on the shafts if they have them

I did not, but I can because I'm going to pull it back apart anyway. tonight when I was lowering the case onto the assembly I noticed that the punch marks from a previous build were not aligned on the most forward clutch pack. I dont know if its important or not, but sure would hate to have to pull it back out of the dozer to move that.

 

[Dave Neubert]

Well usually its the clutch seals that go out and cause the clutch to leak not a good idea to not replace them. There are oil ports that have to line up so make sure the packs go back the way they came apart

 

[davecampbell]

Well usually its the clutch seals that go out and cause the clutch to leak not a good idea to not replace them.

These are the seals in the pistons you are referring to?

There are oil ports that have to line up so make sure the packs go back the way they came apart

I was trying to be very careful to line up oil ports correctly. Not sure if I just missed one or if the assembly somehow twisted before I installed the bolts.

 

[Dave Neubert]

Yes and there should be some on the main shaft to feed the bottom packs the ports should be where the red o rings are look at the forward clutch pack especially

 

[Shimmy1]

Are you using a manual or just *winging it?