That should feel Diff…erent…

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MADDinc Sessions 4 2014
January 29, 2015
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Making lists, not progress
June 8, 2015

Now that I’m finished making everyone cringe with a terrible pun, lets bust out a re-shim on a r200!

We all know that spinning a single is less than fun, especially when you can spin two for less than the cost of a six-pack of XXXX. So this article should help those of you who are mechanically minded, yet have never looked inside a diff before. So before we get started, I am going to assume you have removed the diff itself from the car. If you cannot get to this stage by yourself, I would strongly recommend you pay a workshop to do the job on your behalf.

I should also add that during this re-shim, I had two diffs available so I swapped out the centre and half shafts for 5 bolt items from an r32 Skyline. You will see images from both diffs, but have no fear, they are almost identical and the process is no different.

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To begin, drain the oil then remove the bolts holding the rear cover on.

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Generally, the cover will stay due to the gasket or gasket goop holding the cover in place. Use a soft faced hammer (not a hardened steel one, please) on a solid part of the rear cover to gently persuade it to detach. Make sure you don’t damage the cooling fins, mounting faces or bolt holes/threads in the process.

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Having access to an oil bay is worth its weight in gold. I left the diff to finish draining for about 20 minutes before continuing.

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While the s13 ABS diff was draining, I moved onto the r32 diff and quickly disassembled the rear cover. It had previously been drained of oil and was fairly dry. What you are left looking at is the centre, crown wheel and bearing caps.

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Place the diff in a vice and undo the bearing caps.

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If you are having a bit of trouble removing the caps, use the bolts in the caps to ‘wiggle’ them about a bit. They will lift out without any major effort. DO NOT under any circumstances use pry bars, hammers or wedges to remove these. You will also need to make sure they go back in on the correct side, with the correct orientation. Use a paint pen to mark them if required.

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Now it is time to remove the half shafts. Use a soft face hammer to ‘gently’ remove these. I ended up using a brass drift and a 4lb hammer to free them of the circlips (not shown). Do not hit the tabs with the bolt holes directly, as it can bend them giving you much grief down the track.

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I did end up marking the shafts, but it isn’t necessary. Repeat the process for the opposite side.

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Now it is time to remove your centre. I like to avoid using sharp tools in case of scratching or marking a surface, but it isn’t really necessary. Two pry bars can be used here to lever the whole shebang right out. Once you hit this point, it will free up and you can lift it out by hand. Take care with the bearing outer races as they will fall off as you remove it, and also take care with your pre-load shims. Ensure you keep the sides correct. Again, mark with paint pen if necessary, just remember to wipe the paint pen off with some brake cleaner or thinners prior to reinstallation.

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No more center. This one has been apart at some point – probably for a re-shim. Also take note of the shims sitting in the bearing carrier. These are not the shims you are replacing, they are to align your crown wheel and pinion. DO NOT LOOSE THESE! For the love of god, don’t put your diff back together unless you are certain you have them in the correct location. Otherwise you will need to measure and shim the diff correctly. We’ll save that for another day.

While you’re here, clean the mating faces for the rear cover. I had a case of the dumb as you’ll see later and put it back together first as I was rushing slightly. Clean it now to prevent dirt and excess filings from entering somewhere that you can’t clean. Cover the pinion and it’s bearing before you do this.

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Make sure you use rags to protect your bearings too. I didn’t care too much about this diff as it will be getting rebuilt properly at a later date prior to sale.

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These are your crown wheel bolts, I have been informed by Blingcommander of ns.com fame that there are two different sizes in r200 diffs. I haven’t seen it before, but double check before you try to change your crown wheel/pinion and centre between different models.

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All out. Bulk loctite. Ew.

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Mark your orientation before removal. Not necessary, but I like making sure it fits correctly. Remove the crown wheel by pressing down, be careful not to crush your fingers doing so. If you are using a hammer, you are doing it wrong. If you get it stuck, use a plastic dead blow hammer to get it straight. DO NOT HAMMER THE TEETH!

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Rounded off locating screw. Again – ew. Lucky I have replacements from the other diff.

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Remove these and flip the diff. Be careful not to let the centre fall apart as you flip it.

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Orientation is marked from factory. If you are having trouble splitting this flange, use a soft hammer to gently tap the faces apart. Use a screwdriver or pry bar to lift the top and free it. Take care not to damage the flanges as they are fairly soft.

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Most people will get to here, remove the flange and jam another shim on top. This works, but I had to replace the centre anyway so I worked out that I wanted under 3mm of shims total and continued to pull the diff apart.

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Remove the flange and flip the centre to remove the planetary gears, centre and clutch packs.

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You will be left with this.

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I worked out that I had 1.9mm of shim in the diff total. It has been a few years since I drove on that centre, but I remember it only left elevensies in the wet. There is a procedure to work out how much shim you need, but I decided that with what I had, a 1.4mm shim on the bottom and two 0.8mm shims on the top would suffice.

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Now for the fun part of putting it back together.

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I didn’t take any images of what I consider the ‘correct’ process, but I removed the circlip from the longer half shaft and re-assembled the diff on top of it. This ensures your clutch packs are aligned correctly when inserting the half shafts at the end of the re-install. You will see this image again later.

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It was a bit hard to hold all of the parts and the camera to show how to correctly re-assemble this part, but it goes back together as it came apart, and the whole thing will sit on the half shaft. You need to do this to align the spline. Otherwise it will all have to come back again later. Install your shim/s and the cover. Use the locating marks from factory to align it and screw back together with your two locating screws. Do not use loctite or sealant on the faces or screws.

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It will look like this. You can then remove the shaft.

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Install the crown wheel back in its original orientation, make sure you clean the threads out with a bit of brake cleaner to remove any excess loctite and oil residue before installation. Clean the bolts in the same way.

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Place the centre into a vice and use a torque wrench to tighten the bolts. Remember to use loctite here to ensure the bolts do not come out at a later date. Use a torquing sequence to tighten the bolts correctly. I.E. 12 o’clock, 6 o’clock, 3 o’clock, 9 o’clock, etc. Do this first at 132Nm, then again at 152Nm. This will ensure correct bolt stretch. Use a paint pen to mark the bolts. It takes about 2 minutes longer and ensures you have done all of the bolts correctly.

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Pic just for wank factor of my fancy new SnapOn torque wrench. #thisiswhyimbroke

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All torqued down.

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I would recommend using the shaft to check spline alignment again at this point. It fits! Time for install.

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Clean the bearing faces and check for damage. If they’re marked slightly on the outside, it won’t make too much of a difference, just use a small amount of retaining compound on the surfaces to prevent it happening again. If you have large scoring, replace the bearings immediately and have a serious look at replacing the housing.

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Again, I couldn’t take a photo of installing the centre itself, but squeeze it in between your preload shims and then use the bearing caps to pull the centre into position. Do this by hand and make sure the crown gear meshes with the pinion gear as you go. Otherwise you’re going to have a bad day.

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Once seated, torque the caps down to 88Nm, then to 98Nm. Again using a torque sequence.

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You should be able to push the shafts into the splines by hand. If you hit the circlips you can use a soft faced hammer to push them past this point. Don’t whack it too hard for fear of damaging the spline. Use oil to lubricate the spline for easier install.

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That was all the battery power I had left, but the remainder isn’t too technical. Use a new gasket or goop to reseal the rear housing and torque the bolts down to 39Nm then 49Nm.

You’re all done! Time for that beer…

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