D8K or D9N need advice!

Ironically,those pics that Nige has put up are one of my D8’s Tony did for me.Never been back in there again.
Had a D9H on hire years ago that would bust a tranny every 1000 hours or year.The bolts would allways come loose on it first.Was never right

I do feel slightly worried that I have forgotten the fact that I have near every important service tool for flat drive CAT's, it's very hard to work on this equipment without this tooling, I know people manage to an extent but it often lacks the confidence in the finished product, should I apologize for possibly leading events to what might be a tricky spot, it's easy for me as I have done this task many times but this can take a bit of doing as the clutch flanges have to be removed and re-pressed in the case, the top pinion flanges can be pressed off and on in a standard workshop press but Bevel gear work is all in the hole.

tctractors said:

should I apologize for possibly leading events to what might be a tricky spot,

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I don't think so.Tony The owner of the D8K needs to be made well aware of the potentially disastrous consequences of getting it wrong.
It's not simply a case of stuffing the replacement tranny into the hole in the back end and hoping for the best.

Nige said:

I don't think so.Tony The owner of the D8K needs to be made well aware of the potentially disastrous consequences of getting it wrong.
It's not simply a case of stuffing the replacement tranny into the hole in the back end and hoping for the best.

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Correct.Fore warned is forearmed

Yes thanks for the forewarning it’s nice to know the downside on different circumstances.

so I set the back lash on the pinion.
Finished hooking everything up and installation. Filled it up, bled the pump and hooked up a pressure gauge to it.

now I only get about 100 psi when machine is running and nothing happens when shifting into gear.

I don’t know the pressure before doing the swap but is there a reason the pump would only be putting out 50-100psi after?

No noticeable leaks where oil is pouring out from.

any advice on where to start?

Update: found the problem, the valve inside the priority valve on the front of trans was missing. Removed the cover on the trans and started it to find this out.

Unfortunately, either from previous damage or from running it without the pump pressure, the scavenge pump bit the bullet. Was super happy because it was was shifting in all gears and started closing everything up when I noticed trans oil coming out by the starter, did some research on HEF, found a diagnostic with running the machine stalling the converter and seeing how much oil comes out in 60 seconds. Pointed towards the scavenge pump.
Pulled the pump off and the gear was sheared off and sitting in the torque converter. Took the pump apart and one of the teeth on the gears inside broke off and wedged itself against the others and the casing making it frozen.

Out of curiosity, any thoughts on whether this was previous damage, or possibly caused by the lack of pump pressure

anyways I’m heading to a friends place tomorrow to grab a scavenge pump off a parts machine he has and use that one for now. Cat wants $1600 usd for an aftermarket one. I read the article on here between cheap and cat parts and seems like TC supports cheap replacements for this. I’m going to try the used one and see how long it lasts and possibly order another one down the road to have on hand

Inside the Priority valve slug is a filter that needs dinky little Circlip pliers to remove, it's worth checking this valve correctly before you start pump and hose damage? the scavenge pump often seems to suffer damage most usually from removing the Torque with this pump still in place as it snaps off the gear or bends the shaft, the strainer filter will need checking in the bottom of the case, the gear snapping off inside the pump is most odd as this sounds like something was passed into the gear teeth to cause this, it could have been due to running dry of oil but not a common thing to happen, I suppose you just checked that you had an amount of Lash on the Pinion / Bevel gear, as long as you have some movement things will be O.K. to tight will fail fast, to loose will make a bit of Music. tctractors

tctractors said:

Inside the Priority valve slug is a filter that needs dinky little Circlip pliers to remove, it's worth checking this valve correctly before you start pump and hose damage? the scavenge pump often seems to suffer damage most usually from removing the Torque with this pump still in place as it snaps off the gear or bends the shaft, the strainer filter will need checking in the bottom of the case, the gear snapping off inside the pump is most odd as this sounds like something was passed into the gear teeth to cause this, it could have been due to running dry of oil but not a common thing to happen, I suppose you just checked that you had an amount of Lash on the Pinion / Bevel gear, as long as you have some movement things will be O.K. to tight will fail fast, to loose will make a bit of Music. tctractors

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I will take it back out and check out that filter. Thanks for the tip.

Attached are some pics of the broken parts of pump. I read another thread, (I think on HEF), where it sounded like the guy had the same thing happen as me. I’m just happy that it was the pump and not the torque. I bumped the starter a few times to check the cover on torque and didn’t see any cracks.

The strainer filter is accessed through the drain plug of the torque?

Ya I checked backlash but didn’t do the bearings and all that. I might regret it down the road but for now I need to get operational and don’t have much more to spend on repairs at the moment without getting some work done.

TC- inside the slug I got a retainer ring, cap, spring and plunger. Is there another part inside that needs to come out?

thanks!

There should be a little filter screen if its off a K.
tctractors

Well guys, as of now I’m up and running!

one of the hardest things of the entire project was bench pressing the plate that connects the two belly pans, note to future self: clean it out good so you done have to do it 5 times….

I will let you guys know as things progress and i so greatly appreciate all of your help with this!

Hi all,

been running the machine and she’s been doing good for me. Few small things here and there but nothing too bad except for a problem recently….

the last job I was on i sheared the bolts on the master link. I think that some of them got loose and then the last one in there sheared off. Was able to get it back together and get some new bolts back in.

now I’m on a new site and the same thing happened. Is there something going wrong? Or is there something I can do to prevent this? Did I not crank the bolts down enough when I put the new ones in?


thanks in advance for the help!

The threads inside the bottom half of the master link are now likely to be worn if the bolts were running loose.
How tight did you tighten the bolts.? Do you have a big torque wrench.?

Nige said:

The threads inside the bottom half of the master link are now likely to be worn if the bolts were running loose.
How tight did you tighten the bolts.? Do you have a big torque wrench.?

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I used a 3 foot pipe on the end of a breaker bar and cranked them down with that. I don’t think I have a big torque wrench but I can borrow one if I need to.

if the threads are worn is there something I can do short of replacing the link? Can I threadlock or weld something in there?

bcole4 said:

I used a 3 foot pipe on the end of a breaker bar and cranked them down with that.

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A 1"-square drive socket I hope.? You probably need a pipe something of the order of 6-8 feet in length to get those bolts fully tight. The spec is 250 ft pounds plus an additional half a turn of the bolt after reaching that torque. PLUS the threads and the underside of the bolt head have to be lathered in anti-seize before assembly.

Ok thanks for the info. I will try again then and hopefully it will stay this time….

bcole4 said:

Ok thanks for the info. I will try again then and hopefully it will stay this time….

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Fingers crossed for you but TBH if the master link has come loose a couple of times already it is likely to do so again. It's not just the bolt threads that will be worn it's the crocodile teeth too.

Here is a couple pictures. Are these considered to worn already?

is it possible to weld the teeth together after torquing the bolts down properly?

or is the only remedy to replace the link?

You need to clean the dirt out of the teeth and use all 4 new bolts.
The new bolts should thread into the holes finger tight.
Bob

Bluox said:

You need to clean the dirt out of the teeth and use all 4 new bolts.
The new bolts should thread into the holes finger tight.
Bob

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thanks for the tips. Last time I cleaned it all very well also I just didn’t get it cranked down enough I guess.

ordered the new bolts they’ll be here Thursday morning