RB26 S13 – GTR Rear End

After adding a couple new things to the rear end of the S13, I don’t see it having any problems with mechanical explosions.

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Ever since deciding the rear wheel sizes, I knew I would have run into problems with diffs and driveshafts exploding. The standard Silvia R200 diffs and stock driveshafts don’t seem to like big tyres and big power, so of course I had to get something that would cope with all the hard work.

What factory Nissan drivetrain is stronger than a Silvia? And has pieces that are almost directly interchangeable across all platforms? Pulsar? Not quite.

GTR of course. Everything they have is a much more beefy option compared to the little things that Silvia’s got stuck with. Sure the standard stuff can handle a bit of power, but if you have big wheels and a bit of torque, don’t expect them to stay in one piece for long. Lots of people have done this setup before because of how easy it is to fit. There is four main things to doing a GTR rear end and they are readily available at most wreckers.

First up is an R32 GTR rear diff (no, front diff won’t work for anyone that thinks otherwise).

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To make a standard R32 GTR diff fit into your subframe, you need an R200 four bolt rear hat. Most Silvia’s come with these from factory so you shouldn’t have a problem finding one. Standard GTR hats are much bigger but only use two mounting points. S13 subframes have four mounting holes for the diff to sit into so without the four bolt hat, this swap is useless.

One of the other major positives about these is that they are a 2-way centre from the factory. So no need for any welding or replacement centres until this one goes!

I picked one up through a friend, unfortunately there was a LOT of cleaning that needed to be done.

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Yuck.

The next pieces are a pair of rear GTR hubs so the driveshafts will sit into the splines properly. All non GTR hubs have openings for driveshafts with a few less teeth and an overall smaller diameter, whereas GTR hubs have a slightly bigger opening for the shaft and have a few extra teeth.

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Again, these needed a solid clean to get them looking half decent. I went over both with a wire wheel hoping to get it back to the shiny steel that used to live there.

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When I finished with the hubs I spent a bit of time going over the diff and diff hat to prep it for a few coats of paint.

I did three coats of black onto the hat to give the top coat something to bite into. They had very little prep work and the surface wasn’t perfect so I’m surprised how great they came out!

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Then hit it with some fancy stuff.

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Looked pretty sweet after four coats of metallic green.

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I took the diff outside and sprayed it for a good half an hour with a pressure cleaner. Most of the disgusting crap covering the diff was gone but a couple bits needed some finer cleaning.

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Fitted the new rear hat, setup was almost finished!

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I figured while I had time, I would paint the rest of the diff housing as well. I covered up the shafts and the nose, then went over it with a few coats of the green.

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The finished piece looked pretty good!

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A couple days earlier I had pulled the subframe out of the car so I could fit the GTR bits as well as my new PBM knuckles and Wilwood calipers.

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Took off everything and got the subframe down and out in about ten minutes. World record time!

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Subframe still looked fresh from the paint I put on a couple years ago!

First job after getting it on the ground was swap over the knuckles and fit the new GTR hubs. At this point I was really keen to see how it looked with the new drop that would come with the knuckles.

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Fitted all the arms and tried to set the coils at a reasonable height.

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It’s quite easy to tell the difference when you fit the knuckles, the drop looks very noticeable even when the subframe is on the ground.

While I had the car in the air, I thought I may as well fit the front knuckles and brakes as well.

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Now do you see what I mean about the drop? Very noticeable. As well as that, the super short tie rod mount will make for a fun time with big wheels. I just hope I don’t over correct and put it in a wall.

Hello old knuckle.

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Goodbye old knuckle, hello my new golden friend.

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Next up was fitting the front Wilwoods, but first I had to build a couple things for them. I put on the caliper adapter so it would work on the car, then paired the rotors with their hats.

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All fitted and good to go! These are a little oversize for what I’m doing but thats ok, they will save me from destruction!

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They only just fit under my wheels too.

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Once the fronts were done, I opened up the Wilwood boxes for the rear calipers and started putting them together.

These have to be one of the simplest calipers to change pads on. All you need is some pliers, or even just a flat head screwdriver. There is a triple return clip that secures the top and to get it off all you need to do is lift the centre bend over the holder and slide the whole thing out.

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Then grab your pads and throw them in.

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Get the clip, slide it through the mounting holes in the pads, re-mount the centre bend in it’s holder and you are done.

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I’m actually looking forward to replacing pads on these when they are bolted in, they look like a very convenient setup and realistically shouldn’t take any longer than a minute to change pads on one caliper.

They have a mount on the PBM knuckles so they are a direct bolt on. Simple.

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I fitted the diff and cleaned everything on the subframe, just to get a few photos!

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The final thing you need for the GTR rear end is GTR driveshafts. One thing to keep in mind is that you want non V-spec driveshafts. The V-spec diffs are larger than the normal R32 GTR diffs and from what I have researched, they will not fit so be careful if you are trying to do this.

I picked up a pair of R32 GTR driveshafts to match the diff and bolted them in.

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There was one issue that I needed to get fixed though. Because of how low I wanted the car, the driveshafts and camber arms were rubbing up on each other.

So, how can we fix this problem?

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Take a pair of brand new $350+ SPL camber arms.

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Look at them very closely and take some measurements..

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..then proceed to cut them up.

Pretty nervous about this but it came out a lot better than expected!

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They had to be rotated to give it a higher angle so the boots on the driveshafts would clear the camber arm.

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I refitted them and everything had just enough clearance to move around. I really hope they don’t have any problems under full compression, but the only way I’m going to find that out is by driving it.

With everything fitted to the subframe, it went from somewhere around 50kg to weighing something ridiculous. I could barely slide the thing by myself, but eventually got it onto the jack and loaded back in the car!

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New knuckles, new calipers, GTR diff, GTR hubs, GTR driveshafts and some modified camber arms later and it was ready to go back on the ground.

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Back on the ground, speechless at how cool it looked!

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The rear went down a fair way and the front was at the point of having wheel under guard which is crazy! I have since raised the front a little bit so it will actually turn and I’m hoping to leave the rear at this height unless it has problems driving.

I’m really looking forward to seeing how much more responsive the rear end is in terms of suspension travel. I can only compare it to what I have in the 180sx which is just PBM arms and standard knuckles.

Only a few weeks until I get to drive it!

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