TC35D Final Drive Leak & More

RDrancher · Feb 28, 2012

Today, on the second day of a 1,200 cubic yard landscape grading job I noticed a small leak around the final drive housing. I checked the tightness of all the bolts but within an hour it was a total mess. I couldn't really tell where the leak was coming from with all of the select fill dirt mixed in.

I pulled off the job and headed back to the shop to investigate. After removing the wheel I cleaned the final drive housing top to bottom but still couldn't find the leak. I replaced the wheel and drove it around and immediately found hydraulic fluid pouring out of the wheel flange shaft / seal area.

I drained the housing and removed the final drive cover along with the wheel flange and shaft. Removal was simple since it comes off as a unit. Inside the final drive housing I found metal chunks laying around the pinion gear and down in the pinion bearing area, so I removed the bottom housing cover and found quite a few metal shavings and more chunks.

Checking out the final drive gear assembly I found a shattered bearing race and keeper. The shaft spun nice and smooth, so if the seal hadn't started leaking I wouldn't have been aware of a problem inside. This could have lead to a very expensive repair.

Long story short, I took the assembly to my dealer who had it rebuilt with new style bearings and a new seal in less than twenty minutes. Noticed the leak at noon and had it back together by six and only missed a half day of work. Not too bad.

Thanks go to Messick's for their online parts diagrams and to McMasters New Holland for getting me back to work tomorrow. :thumbsup:

RDrancher · Feb 28, 2012

Here's the assembly with part of the bearing retainer showing on the shaft.

A couple of chunks.

Pieces and shavings on the bottom housing cover.

The inside of the housing showing the lower pinion bearing and shaft.

The final drive assembly with new style bearings ready for installation.

jinman · Feb 29, 2012

Nice job RD. That makes me a bit concerned. I had a small leak in my final drive seal on a very hot day and attributed it to heat/pressure buildup inside the casing since it is not vented. It leaked some and stopped. Now, I'm thinking maybe I should do a bit more investigation.

RDrancher · Mar 1, 2012

Jim, the mechanic said that this was the first one he'd seen that failed without baling twine in it. Of course I use it commercially, so it gets worked pretty hard. I read on a Kubota thread that the seals can leak when its hot and the tractor is turned off and left in 4wd with hydro pressure on it.

djradz · Mar 15, 2012

I always wondered why the front is not vented. Can't remember if my 1720 was or not. I guess NH figured that a little leaking once in a while is preferable to getting condensation in there?

raeuber · Apr 24, 2012

RDrancher said:
I read on a Kubota thread that the seals can leak when its hot and the tractor is turned off and left in 4wd with hydro pressure on it.

I guess that might be true for a Kubota, but doesn't the TC35 have a mechanical shaft driven 4WD? Why would hydraulic pressure matter in this situation?

jinman · Apr 25, 2012

raeuber said:
I guess that might be true for a Kubota, but doesn't the TC35 have a mechanical shaft driven 4WD? Why would hydraulic pressure matter in this situation?

RDrancher is not talking about hydraulic pressure, but rather the fact that the front axle on the TC35 (and your TC55) has no vent. When it gets hot inside the differential and wheel drive gearboxes, there is nowhere for it to go. If you open/unscrew the cap, there's an outrush of pressure. On a hot Texas day, pressure can get really high and the wheel seals blow out. I won't defend this design without a vent, but it is what it is. Maybe a good venting cap is the answer. One thing for sure is that you don't want to overfill the front differential or wheel gearboxes. You need some air space to allow for oil expansion when hot.

raeuber · May 1, 2012

jinman said:
RDrancher is not talking about hydraulic pressure, but rather the fact that the front axle on the TC35 (and your TC55) has no vent. When it gets hot inside the differential and wheel drive gearboxes, there is nowhere for it to go. If you open/unscrew the cap, there's an outrush of pressure. On a hot Texas day, pressure can get really high and the wheel seals blow out. I won't defend this design without a vent, but it is what it is. Maybe a good venting cap is the answer. One thing for sure is that you don't want to overfill the front differential or wheel gearboxes. You need some air space to allow for oil expansion when hot.

So what you (and RDrancher) are saying is that if it is 100F outside my front end will build up more pressure when left in 4WD compared to 2WD when I turn off the tractor? Hmm....

jinman · May 2, 2012

raeuber said:
So what you (and RDrancher) are saying is that if it is 100F outside my front end will build up more pressure when left in 4WD compared to 2WD when I turn off the tractor? Hmm....

:laughing::laughing::laughing:

No, I looked through this thread and nobody said any such a thing except for you in your last post. The sun heating up the 4WD front axle is the same whether the tractor is moving or not as long as the sun hits the axle. It does not matter if 4WD is engaged or not. If you are working in the shade, it might be different. Also, when you are in 4wd and actually driving the tractor, the front differential and drivetrain turns exactly like it does when 4WD is OFF. The only difference is the wheel drop boxes and the differential are driven by the wheels when not in 4WD and are driven by the transmission when the 4WD selector is engaged. In one instance, torque comes from the wheels and the other torque comes from the transmission through the transfer gear. I think RDrancher and I are talking about parking our tractors outside in the direct sunlight where its angles never change. On a very hot day temperature and pressure builds up much more than on a cool or cloudy day. 4WD or not matters little.

djradz · May 2, 2012

Last weekend helped my father (85 years now) change the fluid in the front drive and final drives on my old (his since 2001) FWD Ford 1720. No vents there either. Looks like NH just carried on the same Ford design, which other than a rare/occasional oily film around the pivots, seems to be the way to go. We've changed the fluid twice now in the almost 25 years of owning and no moisture in the drainage and no blown seals. Tractor sits in an unheated barn and did the same when I owned it. Seems like the design (not-vented) is for the most part sound.