D8K or D9N need advice!

Thanks for all the input guys,

As far as selling vs fixing goes… I’m on the same page as check break, with the very limited amount of machines available as well as my budget, no matter what I am going to be working on a machine whether it be this one or the next.

As far as I’m concerned at least I will know the state of transmission after rebuilding and, fingers crossed, won’t have to worry about that for some time.

My theory and from what I’ve learned talking to people is as long as I stick with it and fix what I need to and stay on top of maintenance as I go then the machine will pay itself back to me and then some. It’s a matter of not giving up because when you tap out you lose everything.

A friend described it as having a second wife, you need to give it some love and tlc to keep it going or else all hell will break loose and she’ll make you pay for it in the end…

it seems these 8ks are a good work machine for the ranch work and small jobs I want to do as long as I maintain things and NEVER let it overheat.

bcole4 said:

i don’t believe I do. Was told to roll it back and place a block between the canopy and ripper cylinder to rest it on.

I was planning on leaving brakes, and duocone seals for another time. Financially I can do transmission but don’t have a lot of wiggle room to do everything at the moment. In the future I know it will be work to open everything back up but it is a bad idea to not do everything now? It seems there is an endless amount of work that “can” be done, but as said before that will bankrupt before can get any work done

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What you really need to do pull the 5 drain plugs across the back of the tractor and see what is in them.
You don't have to drain all the oil but have a rag to plug the hole then put the plug back in.
I use a small kitchen strainer to catch the parts in the first gallon that comes out.
Then you will have a somewhat better idea of what is going on.
Bob

Bcole,it seems to me that you have a total understanding of what’s going on here with the feasibility of the project.Yoyve needed a big tractor,and like many of us in the real world,you’ve not had the luxury of having a million dollars to fork out for a new D9 with all the security of a warranty and a nice r@m contract.Instead,you’ve had to play the hand of cards you’ve been dealt.In this case,you’ve had the joker in the pack dealt to you.It could have easily happened with a 7000 hour D9T of D8T that’s set you back $500k and where would you be then?
Instead,you’ve got an old D8K that can,and will be repaired over time and an unknown cost at this point,but you’ll get there in the end,and it will pay you back.I promise you that.Like the wife you mentioned,it will be with you until death do us part.
You’re into this now,and when you’re going through hell,you’ve just got to keep going even if it means you leave it in the yard for long periods whilst you’re earning money and carying on with your life.You can pick away at it when time and money allow.
Any talk of giving up on it,or selling it for parts,simply doesn’t sit will with my business ethic’s.
Keep going with her.

Hi again all,

so had some hiccups but finally got the trans pulled out. Was supposed to have someone very knowledgeable help me rebuild it but that fell through. Now I got it sitting on a trailer and trying to figure out my options.

a friend of mine recently did his trans for his 7 and said it wasn’t too bad just need to keep everything in perfect order and clean.

I’m mechanically inclined however never new to the dozers and haven’t dove into a dozer trans before.

anyone on here done the 8k trans before and have any info if it’s something I can figure out or if I should steer clear from it?

stuck between a rock and a hard place and don’t have a lot of options

bcole4 said:

anyone on here done the 8k trans before and have any info if it’s something I can figure out or if I should steer clear from it?

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@tctractors is your man, He's already commented earlier so hopefully will chime in again.

Meantime take a look through this thread and see if it includes any transmission photos.
https://www.heavyequipmentforums.com/threads/caterpillar-sproket-removal-also-komatsu.41705/

When looking for parts it may pay you to base the search on transmission Serial or Test Number rather than the tractor Serial Number.
See example below.

Get a service manual and sit down with it for a few hours at least and get familiar with what you are looking at. On the D8K as I recall the valve comes off first and then tip the thing up on a couple of blocks with the bevel gear in between them. Take the stuff off that is now the top and then the case comes off by unbolting the base. Lift the case off and the planetaries are right in front of you. They are held together by thru bolts. Take those out and they just unstack.
They are not difficult to take apart and put together. The trouble is in the details, recognize what is bad, worn out, missing parts or where debris came from. The first one is the worst. After that they get kind of routine.

Good to see you’re making progress.
TC tractors has done a number of successful transmissions for me including D8’s.He’s very experienced in knowing what to put back in,and throw away.He knows his stuff and is very concious of the costs of things.I suggest detailed pics that he can study in his own time.He’s on the other side of the world,but he can see things a lesser man (including me) can’t.
As John says,get the service manual and get quality pics of all the parts.
It goes without saying,bearings are an absolute must.Careful scrutiny of carriers etc is a must.Get the pics on here.It’s unfortunate that you haven’t got an experienced man to hand,but you haven’t,so you’ve got to just do the best you can.
There’s plenty of good men in this forum (that will also understand the actual reality of having to make so with less than perfect parts) that can help you.
Good luck,and get stuck in.

The hardest part is removing the Transmission and getting it sat on the floor, now its out you can remove all the main case drain plugs and jiggle out any lumps, on the trans'pull down its best to remove the lid and valve block, then remove the oil feed line to the pinion, sit the trans on its end so you can unbolt the outer case and lift clear, now you can see how simple it is so mark all the sections and I use a tippex pen to mark all the speed and direction identification on them, then start pulling things off and stacking things in tidy order, the pinion bearings are pin locked in the case but easy to remove, post a few pictures and plenty of people here will help you sort out the rebuild.
tctractors.

Hi guys,

thanks for the support, wouldn’t be able to do it without you all.

Schemed up a plan of how to get it off the trailer today since my excavator is on a job site and I don’t have a shop.
Used a engine hoist to move it to back of trailer, then set up hoist in my shed so I could lift it up a bit and drive the trailer out from under it. Finally got it on the ground and turned over properly.

After all that I was able to get the valves taken off, cover pulled off, and top housing removed. Here’s some pictures of it. As I break it down I will take more pics of everything.

So far the damaged I’ve noticed is some the “locks” on the bolts were broken off, and one of the planetary gears on the top clutch is very sloppy

More pics. Hopefully this can help someone else one day if they’re in my shoes and don’t have many options…

Welcome back everyone, man that felt like forever…..

so after diving into my trans I found what I thought significant damage to the carrier and planetary gears. Attached are some pictures.

Long story short, I ended up tracking that reman trans I had mentioned before, popped it open and everything seemed in good order and truly was a reman. Was able to get that for $7k. Just installed over the last couple days, got all my hoses hooked up.

Now I need to check the backlash, any tips or tricks to this? Do I definitely need to track down the dial gauge to measure it?

Also a friend told me to open a port on the trans pump when I first get it started to help bleed the air out and make sure I get oil to the pump quickly. Any suggestions or things I should do, or not do, when I fill up oil and initially start her up?

The backlash thing is a fair handful to get a good reading when you still have the steering clutches in place, even trickier with the tracks on, anyhow the idea is to push the pinion forward towards the engine and measure the lash as best you can via the bevel gear, this will involve a long spanner on a clutch mounting bolt, 3 arms are handy to tackle this task and manage to get a satisfactory reading, I always like to re-bearing the cross shaft as it is easier with the transmission removed to set-up the pre-load, the lash adjustment is set with moving the shim stock from the bearing housings as required, the DTI is better at telling you if you are on target than a strip of card that you might think of using, as for venting the transmission pump, well as it's a K it will have a constant prime line fitted, so all I do is prime the pump before fitting, if you want you can open the purge plug on the high pressure filter lid by first cracking it loose then with the engine running undo it with a spanner a small amount until oil starts flooding out, half a turn on the plug will make a mess fast enough. tctractors

Thanks for the reply TC. I was reading the manual and in there it looks like the measurement is off of the pinion, which is the gear coming off the transfer case, am I correct?

And then am I correct in that I need to remove all three of the covers below fuel tank as the bearing cages and shims are in left and right side, not accessible through the bevel gear inspection plate?

If you are going to do a proper job you will be sorting the cross shaft with the transmission out and the clutch packs removed, it gives you a chance to clean out the main case, the target on the lash is with the DTI on the pinion, this lash is checked at 4 points around the bevel gear to check for a bent cross shaft and tight spots, most people would just bolt up a new transmission and not think about pinion clearance, some end up with the transmission bolts snapping off or working loose or the bevel bolts snapping, if it was my job I would re-bearing the cross shaft, set the pre-load, fit the transmission, then set up the lash, ending by fitting the clutch packs. there would be a picture of this in the rim pulling thing of mine. tctractors

@bcole4 - A couple of photos of an empty hole............. © tctractors
What you should be aiming for before refitting the cross shaft (c/w new bearings - 3rd photo) and before setting the backlash.

Note carefully TC's comment regarding the risk of transmission mounting bolts breaking or loosening, or even bevel gear bolts breaking if the backlash is not correctly set.

Thanks for the info and pictures!

The last K we bought had a transmission swap like this. The tranny worked loose from the bevel gear compartment and stripped out the threads. I had to have studs made that extended through the mounting holes far enough to add a mechanical lock nut. Works well since. Wouldn't have had to do that if the prior owner had reshimmed the cross shaft at time of R&R. Best to follow Tony's advice and set up the cross shaft by the book.

bcole4 said:

Thanks for the info and pictures!

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You're welcome. They all came from that 47-page thread of TCT's. It was relatively easy for me to find them because I knew what I was looking for.

That thread should form some essential bedtime reading for you .............. https://www.heavyequipmentforums.com/threads/caterpillar-sproket-removal-also-komatsu.41705/

Yes it is good reading! I’ve gotten 11 pages in, having a hard time making enough room in my head for all the knowledge!

Nige said:

You're welcome. They all came from that 47-page thread of TCT's. It was relatively easy for me to find them because I knew what I was looking for.

That thread should form some essential bedtime reading for you .............. https://www.heavyequipmentforums.com/threads/caterpillar-sproket-removal-also-komatsu.41705/

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