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'89 YJ 4.2 with MC-2150 Carb & HEI, 2-1/2" Ex. AX-15, NP231 SYE, Adams shafts, F&R ARB, 3
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Discussion Starter · #1 ·
Getting ready for my first foray into the wonderful world of transmission work.

I have the BA-10 which leaks after a long drive. I have to drop the plate and get up in there anyway to check/change the fluid. Only thing I haven't done yet.

Once in a blue moon the SYE drips a little from the copper colored plate on the back of the transfer case extension housing. Note the oil pattern on the bottom of the tub. So I thought I would make a day of it and inspect the chain, replace the output seal and do the rear pinion seal.

I was lucky enough to get the jeep with the SYE done already, but I don't know who made it and if that would make any difference in the seals. If anyone has seen this model before feel free to shout out.

Once I get a look at where my tranny leak is coming from It may be time to look at doing an AX-15 swap with an external slave.

Second pic of the back diff has a slight leak also from the pinion. Can't
really tell but the underside is coated with fluid. I've read the FSM on R&R and seems straightforward enough but can somebody break down "preload torque" for me in Dipstick english?
 

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I don't know what kind of SYE that is but the seal should have a number on it. They common SYE's that JB Conversions makes use a National seal #9346 but that SYE might take something else.

The pinion bearing preload is a lot of fun. It uses a crush sleeve instead of shims so it is a huge pain in the ass to do right. To do it right you would need to buy a new crush sleeve and crush it by tightening the pinion nut (it takes over 200 foot pounds). Then you keep tightening till you take up all the slack and it starts to get tight. Then you would need to check the rotating torque with a beam type inch pound torque wrench that cost about $100 from Matco. And keep tightening the nut little by little and rechecking rotating torque until it is in spec.

The half ass way of doing it is to mark the nut and the pinion so when you put it back together you can align the marks and go just a little tighter and hope for the best. It's better to have bearing preload a little to tight than a little to loose.
 
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I think have the same SYE on a basket case transfer case that came along with an engine and transmission that I bought to rebuild. I too, wondered what brand it is.

I went to the Quadratec website and searched SYE. Mine looks to be made by Rubicon Express. Then you can search Rubicon Experss on the net for instructions and maybe a part number.

When I posted my question about who made it, another poster called it a "Hack & Tap SYE". Meaning you have to cut the output shaft with a disc grinder and tap the cut end to hold the red plate in place. Yours may look copper colored if the red has faded.
Or it may be a different brand.

Good Luck, L.M.
 
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'89 YJ 4.2 with MC-2150 Carb & HEI, 2-1/2" Ex. AX-15, NP231 SYE, Adams shafts, F&R ARB, 3
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Discussion Starter · #4 ·
Good Stuff, Thanks, L.M. I tend to agree with you that is was a piece of anodized Aluminum with the Red / Gold anodized coating faded. So i guess I'll head of to the Rubicon express website and Troll around.

The FSM has a nice exploded view of the 231 but I'm not seeing any gaskets between the cases only directed to use Mopar Silicone Sealer. RTV? Which kind? Not sure I'll dig that far in this trip, but just in case.

Thanks again.
 

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I've had good luck with regular Black RTV on the T-case. That's what they come with stock.
 

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'89 YJ 4.2 with MC-2150 Carb & HEI, 2-1/2" Ex. AX-15, NP231 SYE, Adams shafts, F&R ARB, 3
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Discussion Starter · #6 ·
I've had good luck with regular Black RTV on the T-case. That's what they come with stock.
Thanks, ...

Follow up on the SYE adapter, it is a Rubicon Express.

So if I drop the driveshaft should I be able to see the seal part number on the outside of the seal? This is still my daily driver and I'm not particularly looking forward to any downtime waiting for parts.
 

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'89 YJ 4.2 with MC-2150 Carb & HEI, 2-1/2" Ex. AX-15, NP231 SYE, Adams shafts, F&R ARB, 3
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3,969 Posts
Discussion Starter · #7 ·
Got a new seal for my SYE, prior to changing I Dropped the skid plate last week, power washed everything clean so I could check origination of leak. got this one drip forming. Can anyone tell whether a new seal will take care of this, or will I need additional parts. The drop is on the right in the photo. at the bottom Actually. couldn't get the camera to rotate the photo.
 

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If the shaft does not have any movement, and is not cut from the old seal, then a new seal should take care of it, if you have a lot of movement then that needs to be fixed first.
 
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'89 YJ 4.2 with MC-2150 Carb & HEI, 2-1/2" Ex. AX-15, NP231 SYE, Adams shafts, F&R ARB, 3
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Discussion Starter · #9 ·
Thanks!
 
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