D8h 46a Trans. rebuild

blackkw, sounds like a lot of work ahead of you. The deeper you got to tear into it, the more I would be willing to pay the extra amount from cat to make sure it's a top quality replacement part. Defiantly don't want to do it again.

Hi Blackkw,
alas, there are many parts that would be damaged by the small pieces of the hardened and crushed up Planet Gear bearing rollers. The entire trans. and TC will need to dismantled and inspected closely to determine what needs replacing.
For a start you will be up for all bearings and seals.
There will be planetary shafts and gears--usually these fail in Fwd and First as these are the most used range and gear.
There will be sun gears and maybe a ring gear or two.
Some clutch plates can be swapped between Fwd and 3rd. Rev pack uses larger inner diameter discs/plates than the other packs.
Hopefully the trans has had an easy life and the planet carrier shaft bores are OK.

Some clutch pack piston seal rings--cast iron--will be worn and the most used clutches again will likely need to be machined Over Size and oversized rings fitted to correct wear steps and grooving from the hard bearing metal pieces--have been known to bronze up the tip of one side of the ring gap--use a pencil lead or similar to stop the tension spring drilling being closed up by the bronze and file gap to (from memory) 0.005" to 0.010"
Be sure to run a blunt fine file around the sharp edges of all piston ring seals to remove the sharp edge which invariably catches when trying to assemble the parts and causes ring breakage. Also this chamfer allows the rings to work past wear steps and/or depressions left that polishing may not have totally removed after polishing the running surfaces, this helps stop putting undue side loads on the ring grooves etc.

The valve packs should survive if not already worn from many hours use with dirty oil. These will need to be dismantled, cleaned and inspected for erosion from dirty oil at all the sharp land corners of both the valve spools and the body ports.

In the TC there will be bearings, bushes (in the center of the input flange) and seal rings and their replaceable carriers and retainers--one is the scavange pump drive gear.
The TC main shaft, from memory has a ring groove that is machined into the shaft--if so, the groove can be machined to take two rings by machining the groove a bit from each sidewall of the groove.

The TC impellers can crack at the junction of the vanes to the inner vortex ring and/or to the outer cover and also at the mounting pad for the scav pump drive gear--they can frett here too.
The turbine hub splines wear but can tolerate some wear and fretting--be sure to center punch the shaft and the turbine to enable reassembly in the same splines.

The stator vanes are swaged into the inner and outer rings and do come loose and wear causing inefficiency--if only one or two are loose we have welded the swaged areas after setting the vane to the correct angle with a suitably made spacer to fit between the vanes and hold them at the correct spacing and angle.
The good book gives the clearances for the labyrinth seals between the impeller, stator and turbine NOTE these are half of the actual running clearance,ie, radial clearance and from experience the diametral clearance can be larger than the maximum permissable by about 0.010"-0.015" without causing overheating or power loss.
Man this is going back some 20 years since I worked on one of these.

The Torque Divider Planetary on the TC Input flange and output shaft will need new planet gears shafts and bearings--be sure to dig the crud from all the inside surfaces of the Main converter housing, the flywheel splines that drive the converter, the ring gear teeth of the divider ring gear--in fact anywhere that centrifical force can catch metal and dirt within the rotating pieces--clean oil dislodges some of this and starts the failure process again after the filters block.

Clean out the pockets in the flywheel housing at the mounting cavities inside the flywheel housing--may need to remove the flywheel to do this.

The TC scavange pump--in the bottom of the TC main housing--remove this pump before and refit after the TC is removed and refitted--bent drive shafts result.
The Trans/Steering pump--at the front top right of the flywheel housing will need at least new white metal bearings and seals. Grind 0.020" off the end of the trans pump drive shaft to stop end pressure from worn drive splines--This especially if a new pump is fitted--saw many new pumps seized by excessive end pressure from wear steps in the pump drive gear in the back of the engine.

Remember to pour at least 2 gallons of oil into the flywheel housing before startup for the TC scavange pump to pump until the TC fills and leaks enough oil for the pump to pickup and survive!!!!

Also the steering valve, brake booster pistons and all lines, screens, and filters will need to be removed dismantled and flushed out to remove the metal.
In fact anywhere that uses the Trans systems oil needs to be dismantled and cleaned out--this is a big job make no mistake--if you short cut it you will surely be back into it again.

You will be up for a new or warranted flushed used Trans Oil Cooler Core too.

Have likely missed some things but this should get you going and initially answer your query in part at least--sorry never good news when thes things fail it is always big Dollars.

Non genuine gears in all applications are cheaper than Cat gears for several reasons but the main one is that they do not have the necessary crown shaving to allow misalignment that must take place between the panetary systems gears.
All Cat gears are crown shaved as nothing can be built in true alignment or hold it when under severe loads.
See pic below for explaination of crown shaving. To check for genuine gears I just used to lay my 6" rule along the gear tooth and if I could rock the rule on the tooth it was likely genuine--had customers try on re-work one time in regards to a final drive failure--for a start reports with serial numbers did not tally--client had 2 machines--but the ruler trick finished all arguments then and there--his answer was along the lines of --"oh well, it must have been the other machine then!!!!
The BB has become unstable with all this I have written so are going to post it before I loose it.
Ask more questions as needed and I will try and help out further.
Hope this helps,
Cheers,
Eddie B.

I woud like to thank you ebd, your post is vary informative especialy since i have never taken one of these apart. It sure does sound like i have a lot of work ahead of me but i think itl be worth it when i get this thing fixed. I agree that CAT parts are the best available for the repair, but since i dont plan on using this dozer for commercial use and not sure if the price of cat parts will be in my price range. what other options are available for parts??

I woud like to thank you ebd, your post is vary informative especialy since i have never taken one of these apart. It sure does sound like i have a lot of work ahead of me but i think itl be worth it when i get this thing fixed. I agree that CAT parts are the best available for the repair, but since i dont plan on using this dozer for commercial use and not sure if the price of cat parts will be in my price range. what other options are available for parts??

Frist off ,I would highly recommend that you get a d8 46a service manual and parts book before you attempt this project .The service manual shows pictures of how to go about dismantling ,and assembling the trans .The parts book along with giving you the part numbers you will need ,it also shows a good discription of all the parts in proper location in the assembled trans ,and converter
When I disassembled a trans ,I punch marked each clutch housing in sequence to the next housing ,so there was no confusion on assembly .You will need a long table to lay out each clutch pack and planatary gears ,and sun gears next to each clutch pack
The roller bearings in the trans screen probably came from inside one or more the planatary gears in one or more cluch packs .Replace all of the bearing in the planatary gears. they come as a needle cage assembly ,check the gears to see that they are not chipped . Look inside each gear to see if the metal is flaking where the needle bearings ride
to tear down the trans ,set it on 6 or 8 inch blocks with the input shaft facing up . Service manual shows this procedure .
Wish you luck !

Just in case you don't have enough to think about......LOL.... The steering clutches and bevel shaft run the same oil. Yep you guessed it, they should come out also to be d/assembled and cleaned. Bevel gear brg preload will have to be checked if they reused or replaced and backlash checked. The bevel gear shaft flanges will have to be pressed off the shaft in situ and pressed back on when assembling.

Cheers djcat

It might also be worth checking the rear engine mountings as they often manage to slacken the fasteners or rattel about on the frame, the rear off-side (right) mount is the usual 1 to manage this, it would seem the U.K. is 20 years behind the U.S. as I still work on D8H/K tractors as a large part of my working time, the advice posted is right on the dot and should help you sort your way through this sort of repair, good weather helps this task no end for me as its usualy an on site (outside) task, the valve block is a good lump of Iron to lift so take care.

tctractors

I woud like to start by thanking every one for there reply's, it will probly be a couple weeks befoure i get into takeing the trans apart so at that point im sure i will have a lot of questions. In the mean time its vary helpful to hear recomendations from those that have do in before. Thanks again !!

Well I got the trans apart and found that the fwd. planetary gears had worn threw the shafts and then continued to wear threw the carier assembaly. Found that it also needs 3 ring gears due to the friction discs wearing into them and gear damage. Pulled apart all the planetary shaft/gear assem. and found that thay are all gauled and going bad along with a buntch of other parts. started checking availability threw cat and found that most of the parts supersead to cat classic parts that are 1/3 of the price. my question in regard to the parts is it doesent seam like a part that use to be $598 and is now $233 coud be vary good quality? whats your opinion are the cat classic parts any good or are they poor quality aftermarket parts ?