NP231 Oil pump question/issue

Sluder

New member
Installing megashort SYE. I just noticed that the oil pump teeth aren't mating with the splines in the shaft. I thought it was a new sye issue but when I put my stock shaft back in to compare, the same thing? I haven't ever looked inside the Trans case and didn't notice this during disassembly. What am I doing wrong? Shouldn't the teeth in the pump be connecting with the shaft splines?
 

Sluder

New member


New SYE shaft. You can see the splines on the shaft don't reach the teeth in the oil pump. I think once I install the new housing and tighten the large nut, it will pull the shaft up into the teeth but that's a guess and if I'm wrong I can't see it to know before I damage it.
 

Sluder

New member


Old shaft left and new on right. The old shaft has longer splines but the are the same height up top in this photo so that's not the issue. Neither shaft reaches the oil pump teeth now? Case is torqued and pump is flush
 

ehall

NAXJA Member
NAXJA Member
Something reassembled wrong if the rear output shaft is hanging that low. Missing a snap ring or something

Any chance the pump is upside down? haha
 

mtbxj87

New member
Once you have the rest of the case together and the last snap ring on, the pump will set right. You have to pull the main shaft back then install the snap ring. It's normal
 

Sluder

New member
Instead of putting the shaft in place and then closing the case, which didn't help the pump issue, I assembled the pump and and new yoke housing and set the yoke, housing, oil pump and both shafts into the other half of the case together. It seems like putting the pump and shaft together with the new yoke housing, the shaft fit into the notches and the new yoke bolt held it in place?

Otherwise, there's no good way to do it? If I close the case and put the housing and yoke on, when I go to tighten the yoke nut, it doesn't necessarily pull the shaft straight up into the oil pump grooves/teeth. I'm afraid if they don't slide together right and I keep tightening the nut (which isn't in the hole but off center) it will only bent my oil pump?

So I pulled both shafts and chain out, fit the rear shaft into the new sye housing and installed the yoke and nut. It looks and feels like the shaft is now into the oil pump but you can't actually see it to say for sure but it feels right to me. Now I'm putting the entire case half with new housing and yoke and both shafts with chain back into the other half. I am assuming if I ever remove that yoke nut, the shaft will fall further inside the case and out of the oil pump?

Does all this make sense to you experienced folks? And do you think I'm safe to move forward?
 

Sluder

New member


By the way, the new MEGA SHORT SYE (on right) from Rugged Ridge says the new housing already has bearing and rings installed.

To remove my stock setup (left side), I had to remove 2 snap rings in the housing near the yoke and bearing. The 3rd ring was about halfway down the shaft and holds the gears in place. While reinstalling, the gear snap ring has to be put back but the new housing and bearing eliminates the need for the other 2 snap rings......or at least that's what I read. And there's no way to install them anyway.

Like I mentioned earlier, once I saw this issue with the new shaft, I put the old one back to compare the difference and it doesn't reach the oil pump teeth either. My case is sitting on the studs with the rear half facing upward (rear shaft and cone housing pouting up). The only way to get the shaft in the oil pump teeth is to grab the threaded tip and pull it up into the oil pump by hand. When you let go to install the housing, the shaft naturally falls back down and out of the oil pump. Installing it separately and installing the yoke and bolt to hold it into the oil pump is the best I can figure.

Having this forum and getting tips from more experienced folks is awesome. This is my first t-case teardown and I don't want to tear anything up.
 

ehall

NAXJA Member
NAXJA Member
It may be that the cup bearing at the bottom of the planetary is too deep to hold the shaft in the correct position when the transfer case is standing vertically

Snap rings front and rear are what hold the shaft in place during normal operation
 

Sluder

New member
Yeah, I agree with the snap rings. That's what held the shaft in place on the stock setup. The new set up however doesn't use the snap rings to hold the shaft in place. It appears that the yoke nut holds it in place. This is what the instructions say.

NOTE: the housing should already have the bearing, seal and bearing C-clip ring installed by the factory.

Unlike the stock house where the snap rings hello the shaft in place to the housing, the new set up will slide in and out until the yoke and nut are put on.
 

ehall

NAXJA Member
NAXJA Member
Yeah, I agree with the snap rings. That's what held the shaft in place on the stock setup. The new set up however doesn't use the snap rings to hold the shaft in place. It appears that the yoke nut holds it in place. This is what the instructions say.

NOTE: the housing should already have the bearing, seal and bearing C-clip ring installed by the factory.

Unlike the stock house where the snap rings hello the shaft in place to the housing, the new set up will slide in and out until the yoke and nut are put on.
Do you have a close-up pic of the "bearing c-clip"? It may be just holding the bearing in place instead of holding the shaft. Is there a groove in the shaft?

Sorry I don't know anything about this setup. Trying to help, might be making it worse
 

md21722

NAXJA Member
NAXJA Member
I don't have the mega shorty SYE. I have a 242HD SYE. I never experienced any need to pull the shaft forward with the yoke for the oil pump to seat correctly. The only trouble I had was figuring out why, after disassembly, that the oil pump seal was damaged - crooked, worn down and the rubber part was hard and chunks were missing. It turned out that someone had been into the case before and put RTV around the tabs of the oil pump. When the rear tail housing is installed, the RTV it gets behind the ears of the pump it ends up running crooked.
 

Sluder

New member
What blows my mind right now is that the stock shaft barely gets into the oil pump now. The rings on the old bearing and shaft must have held it in the right position? Other than placing a penny or a washer in the cap/cup where the shaft end rests, I can't see how it will reach the oil pump other than the yoke nut pulling it upwards.
 

ehall

NAXJA Member
NAXJA Member
You can pull the planetary assembly and tap the cup bearing forward with a socket from the rear. Make sure to leave a gap, its not supposed to rub against the cup during normal operation
 

Sluder

New member
That makes sense and goes with what I'm seeing then. Right now, it's sitting on the cup so if it was lifted of a little it would let rub and it would reach the oil pump. I think I'm feeling better about putting the housing on with the 2 shafts and chain connected. I'll tighten the yoke nut which I'm pretty sure is holding the shaft into the oil pump While keeping the other end of the shaft from rubbing the cap. Going to attempt a video shortly.
 

md21722

NAXJA Member
NAXJA Member
The oil pump is held in position between the rear case half and speedometer/tailhousing cover. The ears on the pump line up with recesses machined into the speedometer/tailhousing cover. Once the cover is installed the oil pump can't move.
 

Sluder

New member
The pump itself won't move. The thing I'm not sure of is if the teeth in the center of the pump are contacting the teeth on the shaft itself. Unless I install and tighten the yoke and nut, I don't think the teeth will touch. My concern is if I put everything together and then tighten the yoke nut, it may pull the shaft up but maybe not catch the teeth right and end up bending the oil pump as I torque the nut. I'm thinking I need to install shaft to case half and output housing with pump first and then set into other case half.
 

md21722

NAXJA Member
NAXJA Member
What position is the transfer case shifter?

What happens if you nice it to 2hi and try?

I've done my SYE installs in the vehicle, not on the bench.
 

Sluder

New member
I suppose I can try shifting and checking it. I was thinking the shaft stays in place while the fork and gears move?
 
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