881 trans. check

Well, I got the pressure test done on my dad's 881. Tranny hadn't been touched since 1968 and to my amazement the pressures were bang on(180 psi @ 800 r.p.m.) except for the gears 1, 3, 5 and 7. These tested at 150-165. I think I have a leak in C3 circuit somewhere. I'm hoping it's not the C3 clutch itself. These gears don't engage like they should. It happened all at once too(started it up and backed out of shed and they didn't work right). I have to check for a sticky spool valve and through the interlock system as an o-ring might be out. I did notice when I hooked the gauges up that some oil came out of 1 and 2 test ports but not 3(engine not running). Might not mean anything but something could be plugged somewhere. Any thoughts would be appreciated.

Brian
 

There are a multitude of steel seal rings in that transmission. If memory serves, the most likely one is on the C sun gear. There are about 4 of them on that sun gear.
 
Thanks Larry. Is there a way to check the oil circuit using air pressure if I remove either the control valve or the interlock on the side of the trans.? It would make checking it out a lot easier.

Brian
 

Through the C3 circuit at the control valve, air pressure to the C3 port on the distributor plate. You would not find that circuit at the interlock plate.

Likely you know the drill? If it clunks solidly it's good. If it lets out an evil hiss look out. It's about to bite you.

Also check the control valve itself for solid engagement of the C3 spool and for leaks.
 
Got it Larry. I've worked on Case power shifts, but this is a first for me on a select-o-speed, so I have a pretty good idea what they're like. Hopefully I can give an update on how my testing went sometime over the weekend.

Brian
 
I think my pal Kenny is making a trade on a
63? 4000 SOS. The deal won't actually happen
till late spring sometime. He has a 4 sp
w/sherman to put into the tractor and will
have no use for the sos/rear end.
Pretty much scrap price if you need parts.
He's in Mpls.
 
Thanks Larry.
I wasn't sure.
As you know, I'm not a big enthusiast on
those transmissions but still hate to see
them all just go to scrap - which is where
it will go if no one wants it for parts.
 
Removed the control valve today and checked the spool valves, they all work properly and no sticky movement. I applied air pressure to the clutch ports. C1 and C2 work fine. I think I have some seal rings out on the C sun gear shaft and/or the main shaft. When air is applied to C2 port I have a lot of air coming up the C3 port and air on C3 port I have air coming up the C2 port but not as much. Guess I'm going to have to do a rear split and fix it. I checked online and I think I can still get everything I need to do the repair.

On another note. I had to put on a new wire from the trans. lube light sender and fabricated a terminal for the wire to connect to the sender but I think the sender is bad. With the sender removed and wire hooked up if I ground the sending unit (not running) the light comes on, but if I install the sender and hook the wire up the light will not come on. Anyone ever run into this?

Brian
 

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