520H Transaxle refurb

[Aussie 98]

I am rebuilding a 520H and have pulled the rear axle assembly down to clean, replace bearings and seals and repaint. I haven't gone into the hydraulic unit.

The tractor had a severe trans leak, I found the temp sensor broken so that is an easy fix.

I am now ready to reassemble everything and have a couple of questions. I have the repair manual for the 8 speed but haven't found one for the hydro transaxle (have got the Eaton pump repair manual) - is there a shop type manual for the axle? Should I use a lubricant other than oil in the bearings for assembly, either grease or vaseline, or is that likely to cause problems in the pump? Does any-one have a torque speci for the casing bolts - the diff centre is 30 - 35 ft lbs but I can't find a value for the housing.

any assistance appreciated

thanks

Aussie 

[Martin 2,131]

there is this one in the manuals section....

http://www.wheelhors...-eaton-11-1100/

per the manual, case bolts are 30-35 ft lbs

Edited January 14, 2013 by Martin

[sorekiwi 761]

Way too many damn Aussies in this thread...

I always lube the bearings with the oil thats going to go in the box when its done. Personally I dont like the idea of grease in an oil lubed bearing, I'm always afraid of it blocking the oil from getting in there.

[Martin 2,131]

:flags-australia:

[tiggercl 28]

And another one !

[Martin 2,131]

who let the kiwi in this thread?

[sorekiwi 761]

[Aussie 98]

Thank you Martin and Mike. That was exactly the manual I have been looking for Martin. Agree with your theory on the grease Mike, I was worried about it finding its way into the hydraulic pump. I will see if I can get the transaxle back together this weekend and then need to make up a new front axle pivot pin so I can get the tractor back to a roller.

regards

Aussie

[sorekiwi 761]

Wow, very nice job!

[Martin 2,131]

keep us updated with pics on your build, looks real nice so far........

[Aussie 98]

This rebuild got put on hold for a couple of years due mainly to work and higher priorities. I have recently been able to resume reassembly of the tractor and have started a new thread in restorations, modifications and customs. I ended up rebuilding the rear axle assembly and the Eaton transmission. While I didn't document the rebuilding in detail I have a few photos which I am posting in the hope they may be of use to some-one. I used the Wheel Horse and Eaton manuals as guides. Prior to this I had rebuilt the 8 speed transmission in my 416-8, and the success of that gave me confidence to tackle the hydro. I had a lot of help from Red Square members with the 8 speed rebuild as there are some very detailed guidelines that have been posted.

 

I don't profess to know a lot about these transmissions, and am just another backyard hobby tinkerer, but once I got into the Project it all went along smoothly.

 

There are two main parts to the Wheel Horse hydro transmission - the cast housing that contains the axles, differential and reduction gears (which I will call the rear axle) and the Eaton transmission that is bolted to the rear axle assembly. The Eaton can be simply unbolted from the rear axle assembly if desired and set aside, it will not fall apart nor can any parts fall out. I tackled the rebuilding of the rear axle assembly first. This comprised strip down, inspection, replacement of seals and repainting. The main reasons I decided to inspect the final drive train was because of a bad oil leak and some of the horror stories and photos of manual transmissions that have had water in the oil. This doesn't appear to be such a problem with the hydros which are much better sealed.

 

My tractor was filthy underneath, the previous owner had kept the exterior clean and tidy and regularly blown out areas he could reach with an air hose, but he obviously wasn't one to remove any panels. The area in front of the fuel tank under the seat was packed solid with grass clippings and chaff. All of the hydro cooling fins were blocked solid. Combined with the leaking oil spread throughout by the hydro fan the whole area was a mess.

 

Here is a view of the rear end with the seat and rear mudguard pan removed, and the bulk of the grass and mess scraped off. Plenty more to still clean up though.

 

 

And a couple of views of the left side;

 

 

 

The gunked up hydro fins;

 

 

The right side;

 

[Aussie 98]

Next I unbolted the rear axle assembly from the frame and then unbolted the Eaton from the axle unit. There are four bolts securing the hydro to the axle assembly.

The rear axle assembly separated from the frame;

 

 

And this is the view from the right side with the four bolts and hydro unit removed.

 

 

My first look inside was positive, it all looked clean and no signs of water up top.

Here is the Eaton 1100 hydrostatic transmission;

 

 

The next task was to remove the rear hubs. I used a hydraulic puller and after soaking with PB Blaster the left hub reluctantly parted from the axle. No such luck with the right side though, despite repeated soaking it refused to budge. Realizing that the cast iron hub wouldn't bend very much before breaking, I was reluctant to apply too much force and finally gave up defeated.

 

 

I supported the rear axle assembly on its side and removed the bolts to split the case halves. I was lucky that the left hub had come off, as this is the correct way to split the housing - with the shallow section up, same as the 8 speeds.

Here is the left side casing half removed. Note that the two sections are aligned by two dowel pins.

 

 

This next photo is out of sequence, but it shows the complete gear train sitting in the right casing section.  I didn't get a shot of this on disassembly.

 

[Aussie 98]

The inside of this rear axle unit was really clean with no discernable wear in the gear train.

The two intermediate shafts and gears simply lift out and you are left with the axles and differential. This should now lift out as one assembly, but of course I still had the right hub on there. This is where I got lucky, I was able to manipulate a spanner under the diff centre and undo the four bolts that hold the centre together. I could then dismantle the centre and remove the circlip holding the right axle in, allowing it to be removed from below.

A friend took the right axle to work with him and using a combination of heat and a 50 ton shop press was able to separate the hub and axle without damage.

I was really happy with the condition of everything inside the rear axle housing. The bearings all felt smooth and tight and no corrosion evident anywhere.

I decided not to replace the bearings but ordered new axle and brake shaft seals. I also found the source of the oil leak - the temperature sensor has a brass probe that sits inside the rear axle housing in the oil. This probe was bent, and the brass had split, allowing oil to escape through the sensor body. How this probe got bent is beyond me, there is absolutely no sign of any damage anywhere else.

There aren't any photos of the next part of the process which involved thorough cleaning and degreasing all of the components. I used paint stripper and a wire wheel in an angle grinder to remove the paint from the exterior surfaces of the housing halves. Pried out the old oil seals from the axle housing ends and brake shaft, and cleaned the outer ends of the axles up with a fine file, sandpaper and steel wool.

I made up a frame from some scrap timber to hold the right side housing on a couple of saw horses for reassembly.

Right side housing painted;

and cleaned inside, ready for reassembly;

and supported by the frame;

I repainted the exterior with KBS Paints, a system similar to POR. There are four coats, two primer, a tie coat and the redtop coat, all brushed on. The interiors of these rear end housings are painted with primer from the factory. This was found to be in good condition and didn't require any attention.

[Aussie 98]

Reassembly is fairly straightforward, a lot simpler than the eight speed.

All of the parts cleaned up ready;

As recommended by Mike I used only clean oil for lubrication during the assembly. Note that the pinions are staggered.

A bit of masking tape over the keyways so as not to nick the axle seal on the way through, plus plenty of oil to help it slide through.

I used all new Grade 8 bolts, locking nuts and washers to secure the centre. note the special thin washers go under the bolt head, not the nut. Torqued up to 35 ft lbs (thanks Martin);

and slide the assembly back home;

next in goes the intermediate shaft and gear;

the brake shaft with its' gear;

and finally the input gear also slides down over the brake shaft;

I used a new gasket between the case halves with some hardening sealer and dropped the left half over to close the assembly. There are a number of through bolts and two or three that are tapped into the case. Those are 3/8" UNC but I discovered that 10mm bolts would fit the through holes. These are slightly bigger in diameter and easier to get here where most fasteners are metric. I was able to use Grade 8 zinc plated bolts with nylocs torqued to 35 ft lbs.

Seat the new brake shaft seal with a bit of sealant, and here we have it, a refurbished rear axle assembly ready for at least another 25 years of work.

These Wheel Horse rear axle assemblies are a very well built heavy duty unit and I think it would take a fair amount of abuse to break one.

next - the Eaton 1100 refurb.

[woodchuckfarmer 333]

Great post I think this should pined in the trans section. Looking forward to see the 1100 hydro rebuild. Keep up the good work......Wayne

[ti-jean 44]

Hi nice poste you got , I have a toro 516h and yesterday after blowing the snow in my yard so back in my garage I see oil leak behind the wheel hub of the trans axle so I lift the rear of the tractor and i see a lot of play between the casting and shaft so my question is do I af to separate the trans axel to replace the oil seal ans needle bearing if so can you give the tow parts number like timken or a outher brand or size .

 

thank and i wish you  health and a happy new year     

Edited January 3, 2017 by ti-jean