Replacing Dropbox Seal on 1720

[valudude]

Hi All,
I'm working on replacing a seal in the left drop box on my Ford/New Holland 1720, manufactured in 1987. I have the manual, the
tools and a good mechanical aptitude, but little experience working on a tractor so am seeking some input and advice here.
Following the procedure in my manual, I'm stuck on removing the wheel hub case from the lower assembly. It appears to have had
some type of liquid gasket applied to the machined faces before it was painted in the factory. I've tried using a piece of wood
and a hammer to loosen it with no effect and am at a place where I see two options to separate these cases.

1. Using a wire wheel, or sanding disc to remove the paint at the joint between the two cast parts and trying to get a knife
edge in at the seam to separate them
2. Grind the edge of a chisel flat to remove the cutting edge, then placing the flat edge against a spot where the hub case
protrudes about 1/32 outside of the dropbox case then hitting that with a hammer to break them open. My worst nightmare would
be breaking one or both cases with this method.

Does anyone here have experience on how to safely split cases that are stuck together like this? The seal that needs to be
replaced is marked #3 in the attached image figure 17 and the stuck case cover is #2 in figure #15.

Thanks in advance for any thoughts on this.

 

[acresgreen]

I did those seals on a 1520 last year. Scored the paint /gasket with razor knife. Then used a brass punch to the outer case all the way around. Once it starts to separate I was able to get a chisel in between. Just be gentle, those parts are hard to come by!

 

[Bern]

What I do is find a spot where the cast iron is heavy and use a cold chisel to apply a little shock and awe to it. Using a block of wood takes away the shock effect.

 

[Daniel in PA]

I replaced that seal also on a 1520 and only removed the 4 bolts on top then separated the bottom half from top, lifted out shaft and pried the old seal out. I didn t separate anything else. I was careful not to flip the lower half around to much so that lower gear didn t get out of position.
I left the top half on tractor.

This post was edited by Daniel in PA on 02/11/2023 at 05:17 am.

 

[Daniel in PA]

 

[valudude]

Thanks for the input on this everyone. I got it disassembled yesterday morning and am going to have a machinist press the new seal in on Monday morning. A previous owner buggered up the oil filler plug on this to the point that a wrench or socket slips on it so I'll have him get that out for me as well. With a little luck it'll be put back together and ready for action by tomorrow afternoon.

 

[acresgreen]

That particular seal is actually a seal the turns within itself. almost like a bearing. Just want to make sure you have the right one before installing. bought mine at the NH dealer, something like $80. good luck!

 

[valudude]

This repair is complete and the tractor is back in service. I was able to use the time the machine was indoors to complete a few other tasks that have been pending as well, so everything worked out great and I appreciate the input from everyone here.

The seal was $52 from my closest Ford/NH dealer, who had only one seal in stock. I had them order me another one, assuming the seal on the right side will fail before too much longer.