John Deere 8770 4WD tractor and repairs

For those of you that read the Info box :) It is a John Deere 8770 four wheel drive tractor which was in the shop for a check over. We found a few things including too much axle play in the front axle bearings left and right, plus a small oil leak. So it was decided that I fix it and rip it apart :) I love big jobs like this, heavy stuff but when you are smart, you dont do a lot of lifting. I did not have detailed material about the actual repair, because I did not plan on putting it on youtube, lol. Just happen to have taken a few shots for a rough combilation of things I fixed (best biggest jobs). Then I received a couple pms, asking about what was going on with the tractor and decided to make a more detailed video, but I already had everything back together except the 2nd set of wheels. So here we are, hope you enjoy(ed) the Video. If you want more about my work, let me know. I would be happy about having a reason to post more of this stuff ;)

Last but not least, the details of the repair process.

So the front wheels had to come off, including all 4 hubs that the wheels bolt onto.
Then the oil had to be drained out of the axle (2 pails each 20L content).
Then I had to undo some hydraulic hoses and the driveline from the front axle.
Support the tractor safely and remove a couple bolts that hold the front axle on (each bolt is 1000nm tight :O needs big toys to get that off :D)
Once the bolts are removed I was able to remove the front axle that prolly weights around 2000 pounds with the forklift and a palett.
When I removed the front axle with the fork extensions, the forklift had little weight in the back and the forks bent down 1 foot :O (its a 8000 pound forklift)
Still in save parameters, lol
And once the axle was out, I could remove the bolts around the final drives, hook onto the final drive itself and split it off.
Then there was a bolt with another 950nm torque waiting for me, this time in a loose piece plus the axle turns, job for the big impact ;)
After the bolt is out, I can remove the planetary (45-50 pounds) and the axle itself (another 50 pounds).
Punch out the seals and pound of the bearing, replace the seals and put it all back together.
Plus you have to do the shimming.
Means you install the axle and the planetary and you put a couple of lead balls between the 2.
Then you tighten the planetary onto the axle and squish the lead balls.
You remove the planetary again and measure the thickness of the lead balls.
That will give you the measurement for the shims that need to be added between the axle and the planetary.
This way, you adjust a "preload" and a certain amount of "drag" onto the bearings.
Which is a vital step, so you dont wear out your bearings, seals or housing in a few hours.
Plus you will get leaks if it is not done right, just a lot more wear and tear with a sloppy axle.
And ofcourse, you have to clean all the parts and apply new sealant onto the housing joints.
Then you gotta torque the bolts that hold the final drives onto the center housing (well I torque that stuff :P, better safe than sorry) and repeat all the steps above to the other side.
Then the axle had to go back on the tractor and I had to hook the hydraulic hoses and the driveline back up.
After that I torqued the 6 bolts that hold on the front axle with 1000nm.
The other time consuming part is the wheels, you have to measure the position to where they were and torque the wheel hubs like 8-12 times before they are seated right.
That is 450 pounds torque and 6 bolts on each hub (4 hubs) makes 24 bolts times 10 (average) 240 times swing the big wrench and get that sucker tight :P
Last but not least, the wheels themselves with 10 bolts and another 400 pounds torque, this time only twice.
Makes 20 times torquing 1 wheel and 80 times all 4 of them.
Then the oil goes back into the front axle/transmission (the oil reservoir is shared by axle and tranny).
And once you got all that and you testdrove the tractor to seat the hardware, you retorque one more time (all the hubs and wheels).

Sounds fun eh? Took me around 1.5 days to finish this job.
Installing 1 wheel takes approximitely 30-35 minutes (install hub, measure, toque).
The repair job on the front axle itself took me half a day.
Taking it apart took some time, testdriving etc.
This job was a first for me on a puppy like this and I sure enjoyed it :)
Hope you enjoyed it a little bit with me :D

Category:

Autos & Vehicles

Tags:

• John
• Deere
• 8770
• 4WD
• Four
• wheel
• drive
• tractor
• repairs
• front
• axle

[wildrice1983]

i have some broken gears in the trani, 1 in the transfer box which spins the mfwd drive shaft and also the gear that spins the mfwd box.Some of the teeth have broken off because the switch for the mfwd was not working and the drive was on constantly.i have never worked on the trani before so i'm a bit worried don't want to get in over my head. Any advise would be much appreciated.THANKS

[oBseSsIoNPC]

@wildrice1983 ouch, I will have a look into the repair manual tomorrow. But one other thing. Was the switch not working or was it the solenoid? We get a lot of bad MFWD engage solenoids. The solenoid should sit on the MFWD drop down box with a 2 wire connector. With ignition key on have somebody activate the MFWD and see if the magnetism changes on the coil. A screw driver on the nut retaining the coil will tell. I think this system is OFF with coil under power.

[oBseSsIoNPC]

@wildrice1983 Ok, sorry it took so long, but I am really swamped it seems. Now to remove the trani you really HAVE TO tilt the cab (if equipped) which is a big job even with special tools. You also need to remove a small drive shaft from the rear of the rangebox, there should be a small access plug just below the hitch arms but center rangebox. I suggest to see a dealer with this.

[wildrice1983]

hey buddy do you know how to remove the transmission on a jd 6410 thanks keep up the good work

[oBseSsIoNPC]

@wildrice1983 I do so, I have done lots myself. You have to drive the back end out. It doesn't matter which trani, you lift the cab slightly off the rear, undo some lines under the cab, the mfwd drive shaft comes off and 6 bolts on the back. I might even have some pictures how that looks. I will post them and send you the links when I find them.

It is a fairly big job and best with the splitting stand. Why are you taking it off?

[oBseSsIoNPC]

I come to think of it, the 7-8000series you drive it out. The 6430 you tilt the cab and remove the trani with a engine crane...now I can't remember if it was the 6410 that is the same as the 6430 or is it like the 7000....damn :P Well it is easy to tell by looking at the final drives. Are there 3 bolts infront of each of them or not. If there are you split the back end off. If there are no bolts, you tilt the cab...jee...brain failure 8X

[eyeboltman2]

Cool big an d green love it Nice shop it big big big thanks for the video Eyeboltman2

[oBseSsIoNPC]

Hehe, thanks my friend, I appreciate the great comment. As a matter of fact, I am working in Alberta for a John Deere Dealership called Martin Equipment. My experience isn't that much, 4 years to be precise, but that involves everything around agriculture not only JohnDeere, but reaches from the push mower to the big guns. This has been my first axle job and I always try to find challenges, which is what teaches you the most ;)

I am glad you like the Vid, I will post more in future.

Take care!

[oBseSsIoNPC]

@jz310HD15 Uhh a guy from the factory :D I am happy to see you here, hehe. Yeah, I replaced the cups and bearings with the newest available. The planetaries sure can take a lot and looked great. I must say we have not done any 9000 series 4WD axles yet. They seem to hold up great. More the 6000s in which the axle housing were not hardened properly. 4000 series tractors are most common, just age and heavy wheels.

JD drive trains are tough alright!

[jz310HD15]

Have you fixed any more recently?

Did you replace the bearing cups in the housing, and the bearing cones on the axle shaft? If so what bearings did you use? How did the wear on the planetary gear look?

How did this job compare to the 9000 series 4WD's? John Deere hasn't changed the design much in the last 20 years, so curious to know what service techs deal with on a day to basis. I work in the Drivetrain Factory in Waterloo, and see these parts everyday. Feel free to reply with ?s. Mark

[oBseSsIoNPC]

@travisg130 Hehe, thanks, I know what you mean :P

[travisg130]

Thanks for putting some chill downtempo muzak with this vid. I get sick of hearing some slack jawed hick jams just because its farming related.