720 Rock Shaft Housing Removal

chas036 · Jul 16, 2017

I am getting ready to remove the rock shaft housing on my 720 to replace a leaking power shaft oil seal, and I have some questions.

1)How do you remove the hydraulic oil lines coming from the pump? I have unbolted the retainers but because the lines a ridged steel, they won't flex and back out of the housing.

2)Will a come-along attached to a 4X4 resting on and between two 2x4 rafter roof trusses support the weight of the housing? I used this to lift the pony motor, and had no problems.

3)I have a 620 with an original JD front end loader, would this have enough power to lift the housing and using a front end loader make it easier to reattach and realign it later?

4)What is the correct direction for putting in the power shaft oil seal? The manual says nothing about how to install the seal. Also I read somewhere that it is advisable to use two seals. has anyone done this before?

5 If anyone has pictures of removing the housing , can you please post them.

jd2cylman · Jul 16, 2017

1] Make sure the lines aren't rusted into the housing. Just try to get them moving. Make sure there aren't any line clamps holding the tubes further back along the tubes.
2] Well.... Not sure.
3] Maybe? Not sure either.
4] & 5] Use two seals. Install the first one with the lip facing the PTO. Install the second with the lip facing the transmission.
The original seal was a real double lip seal with each lip facing out.
Hope this helps a little.

rmcky · Jul 16, 2017

(1). To remove lines, first remove floor pan, next remove lines from pump, they will pull out at the pump to give some slack at the rock shaft end. They may be stuck at either (or both) end, so use your favorite penetrating oil liberally.

Dan in Ohio · Jul 16, 2017

These are of my john deere 50. Back a few years when resources were more limited in more ways than one. LOL

My purpose here was to change the rear axel, do not remember the rock shaft unit being real heavy as I was just rolling the shop crane around on the ground.

620 John · Jul 16, 2017

What do you guys do with the pto shaft where the seal rides??? Polish it up with emery cloth??

Sorry if I'm hijacking the thread.

Mike M · Jul 17, 2017

#1 Try keep soaking them in PB blaster and tap tap on them. Try not to dent them up. Use a punch and tap on the more solid end fittings of the pipes. Hopefully they will let go.

#2 I would not try that.

# 3 I would use that front end loader for your shop crane. Maybe even block it up and hook the come along to the loader ?

#4 2 seals used now.Seals go in with lips facing opposite each other. Use some sort of hardening sealer or locktie ? on the outsides of them to make sure they stay put. If shaft is not too grooved you can clean them up with emery cloth.

720 Rock Shaft Housing Removal

chas036

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jd2cylman

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rmcky

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Dan in Ohio

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620 John

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Mike M

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