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ClimberD@HexMods 06-22-2011 02:02 PM

Installing HexMods Center Differential Bulletproof Bushings
5 Attachment(s)
Please reference this thread for instructions to install your new set of Hexagram Modifications Center Differential Bulletproofing Bushings.

Reference for putting everything back together:

If you do not have HexMods Bulletproof Center Differential Bushings, and worry that you may have damaged your center differential, this thread will explain how to open up the center differential for inspection.

First, Download and Print the attached documentation, which is in order of operation. I have highlighted the relevant text, to make your referencing more efficient.


A special thank you to Frank_ster, my inspiration and
mentor for this and other modifications.

ClimberD@HexMods 07-03-2011 11:26 AM

Removing Differential
15 Attachment(s)
Click the attached images at bottom of post to get bigger sizes.

Remove bolts that hold on tail housing:

Use hammer and block of wood or other cushioned impact technique on side of case, to lightly tap loose the housing. It will walk backwards as you tap it from different angles:

When you pull the tail housing cover off the transmission, the rear output shaft will be stuck inside the housing. This will separate the transfer clutch pack. Be aware some clutch pack frictions and steels will fall out. A couple thin metal spacer shims will also fall out. Keep an eye on where they fall from. You can see one shim on the right, on the paper towel. You can stick all shims right back where they belong, with the aid of Vaseline. Vaseline dissolves into the ATF, and is the goop of choice from the RE5R05A rebuild manual, straight from Nissan/JatCo:

Output shaft in tail housing. Clutch pack put back in order:

Clutch pack looks healthy and practically brand new. It has 30k miles on it:

Lightly hammer tap the splined output stub, pictured here. DO NOT HIT OR DAMAGE THE BLACK OIL SEAL surrounding it. A few gentle hammer taps will pop it right out of where it sits.

Use crow bar or back end of hammer to pry the center diff from the transmission. See how it slides out. Take care to slide it out in a straight line. The input shaft to the center diff is very long:

Pull snap ring:

Now the bearing pins can be pulled out, either with a plyers or just turn the diff upside down and they'll probably just slide out as they are in with very little grip:

With gears removed. Keep track of the thin thrust washers that go on either side of the planet gears:

The old bearings inside each planet gear should slide right out. Then insert the new solid bulletproof bushings.
The first production bushings of pre-2013 have a mild interference fit, and a slight taper. For these, use a press, or be very careful if using a C-clamp or some other means.
All current-model bushings are drop-in fit, no press or tools required!

The pin fits!

Top left: stock bearings. Perhaps now you get why these things can't handle launches.
Top right: bulletproof bushing installed.
Bottom: empty gear.

My trick to get gears back into the carrier housing. Install pin with ever so slight protrusion, then put thrust washer on. Then slide gear in, and push in pin halfway. Lastly slide in other thrust washer, and spin the gear on the pin to center it, while slowly and gently pushing pin through further:


ClimberD@HexMods 07-03-2011 11:26 AM

7 Attachment(s)
Now that the center diff is all reassembled, put it back in the transmission. Cool tip: Put Vaseline on the o-rings and plastic bits on the shaft. Rotate it to get it to seat right. I had to tap mine in gently to get it in all the way.

Now put the output shaft into the diff. This requires a lot of twisting back and forth to get all the gears to line up. Then it should just slide right in.

Put clutch pack in, one piece at a time:

This is what mine looked like with the entire clutch pack installed.

Here is a shim, but you may have two or three, and there will be others in other places. This one goes in the tail housing. Use Vaseline to hold it in place if it keeps falling out. Put back all shims where they belong:

Now it's in place:

Now you gently put the housing back on, being careful to keep the output shaft AWAY from hitting the oil seal. Recommended: Use a new metal gasket. I didn't, most don't need one, but risking a fluid leak is up to you if you don't want to replace it. My gasket looked fine and even, and it sealed right back up. I was able to push my housing on 95% of the way until the alignment pins hit at 1/4" inch from full mating, with just gentle taps to help it along. Do not force the cover on. Using the bolts to draw it on will crack the housing!
Once alignment pins are aligned, gently tap together with wood, hammer:

I used my electric drill on a low clutch setting to zip in all the bolts:

Then I used a torque wrench, and torqued everything exactly to spec. This is the key to getting the gasket to seal right.

Now go launch.

doccrowley 07-03-2011 12:00 PM

now you're talking! Great work!

Folks just can't be in a hurry to put the tail housing back on, thinking they're home free once the busings are in and the clutch pack is back in place.

ClimberD@HexMods 07-03-2011 01:14 PM

Done! It's really not bad to install. Just stick to the instructions, and it goes together simply. 30 minutes between unbolting and bolting the extension housing is about right. It took me 4x as long to put together this write-up.

doccrowley 07-04-2011 02:11 PM

Q: What are the torque specs for the housing bolts?

A: Uh, if I'd just read the schematics you've included I'd know that it is 25Nm or 18 ft lbs.

Thanks for the schematics!

ClimberD@HexMods 07-04-2011 02:32 PM

Yes, the Factory Service Manual PDFs should always be the first point of reference, unless noted to the contrary. Pics are just a supplement. Pulling the diff apart and installing the bushings is the main value added instruction here. Also my notes on putting the clutch pack back in should help a lot. My first time in, I hadn't figured that out yet. Thanks to Frank_ster for making life easier.

Misfire 12-10-2011 05:27 PM

Got these installed today. I followed ClimberD's steps, and overall the process went rather smoothly.

A tip though.

I was unable to fully insert the the bushings into gears by hand, even after freezing the bushings and putting a torch to the gears, I was left about a half inch of bushing protruding from the gear.

I was able to completely insert them using two blocks of wood, one of the spacers that was in between the old bushings, and a vice. I lined the spacer up on the end of the brass bushing that was protruding and pressed it the rest of the way into the gear between the blocks of wood. The reason for using the spacer was to get the ever so slight recess of the bushing into the gear.

doccrowley 12-13-2011 11:53 AM

mine were no where near the difficulty to insert. Removal however from one diff to place into another, were not easy to remove. Tapping with a drift deformed the bushings to some degree. Be careful!

and Enjoy the happy launches to come! :) Love ClimberD's mods with frank_ster's pioneering efforts!

Thanks guys!

ClimberD@HexMods 12-19-2011 01:54 PM

By popular demand (sort of) the latest run of these bushings is all drop-in. No more interference fit. This is more along the idea of what Frank_ster originally made for himself. There should be no actualy performance difference in the end, just a different way to accomplish the same end. So when you have the gear in your hand, just drop in the new brass 544 bushinds, and you're done. Per usual, machined to .001", so there is absolutely no slop or play, just free rotation. Enjoy.

I'm not sure what future runs will be, but either way they should all work.

05LGTurbo 03-12-2012 10:53 AM

how to these work as bearings? fluid/journal bearing? instead of a ball/needle/cone?

ClimberD@HexMods 03-12-2012 10:56 AM

They work fine for this function, since the center diff rotates minimally or not at all most of the time. They're exactly the right material for the job, which I'm sure doesn't hurt.

05LGTurbo 03-12-2012 04:35 PM

hmm. alright. i know my center diff is making some noise. not sure if its going to the those bearings or the input/output shaft bearings. need to get the time to tear it out.

ClimberD@HexMods 03-12-2012 06:15 PM

Yup definitely open it up!

Rome_STI 11-26-2012 09:25 PM

Climber is this restricted to a certain model of 5EAT or is the centre diff the same across the modes? I have what I believe is the equivalent of an 08+ 5EAT in your market...

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