S13/RPS13 5-Stud Conversion and Brake Upgrade - Fronts
This is by far the greatest performance and safety mod that I've done to my car right next to coilover suspension stuts. I was meaning to write this article up ages ago when I first got the conversion and upgrade done but CBS'd coz there was so much to it. But here we go, finally after coming across a fair deal of confusion online, I think it's about time I shared my experience. I hope that you find this an enlightening and helpful read. I've divided this article up into segments in order to keep each post a manageable size. There were lots of parts involved so I will be posting segments that can come under a different title separately.
Disclaimer:
This article isn't written as a guide or as a set of instructions to show you how to perform a 5-stud conversion or a brake upgrade, whatever you do with this article is done at your own discretion. This article is meant to be used as an informative piece that shows the experiences that I came across while performing a 5-stud conversion and brake upgrade for myself.
Intro:
The reason why I went for a 5 stud conversion was to support a brake upgrade I had in mind, and also to push and develop my ability to perform a significant mechanical task. I had always had a defeated mindset as a youngster when it came to mechanical ability, things started to change when I bought myself a Japanese import. This article was written by me as a technical memoir of the time that I as a 24 year old helpdesk decided to undertake a mechanical task that was beyond my means and ability. A 5-stud conversion, suspension upgrade, brake rebuild, and brake upgrade was carried out by me on my 1994 Nissan 180sx SR20DET with factory ABS. This segment will cover the rear wheel 5 stud conversion and brake upgrade. Parts used were:
Rear
Set of rear R32 GTS-T hubs, baffle plates
Set of rear R32/R33 GTS-T calipers
Set of rear RDA slotted rotors to suit R32/R33 GTS-T
Set of ADR approved custom made braided brake lines
Set of R33 GTS-T handbrake cables
Eagle adaptor
 |
| From Phillipses blog |
From Phillipses blog
From Phillipses blog
From Phillipses blog
From Phillipses blog
Other:
BM50 – Brake master cylinder from an R32 GTR with factory abs
Set of stock S15 rims with brand new Pirelli Pzero Nero's 225/40/16
 |
| From Phillipses blog |
 |
| From Phillipses blog |
Tools:
Full set of screw drivers
Full set of spanners
Full set of flare nut spanners
Full set of 1/4” and 1/2” drive sockets with wrenches and breaker bar
1/2” drive pneumatic rattle gun
Rubber head mallet
Steel hammer
8” 3 claw Gear Puller
2 Car stands
Hydraulic Jack
Couple of bricks or suitable tyre wedge stoppers
It's a good opportunity to upgrade brakes while doing a 5-stud conversion and vice versa. 5-stud conversions require you to remove the brake calipers and brake rotors in the process so the opportunity to change these parts makes itself available. Then there's the matter of having to drill out the 4 stud rotors to 5 stud if choosing to stay with the existing brakes which is illegal. By upgrading brakes, the rotors will also need to be replaced meaning you can find a set of rotors already made suiting the 5 stud configuration. I chose to go for R33 GTS-T front and R32 GTS-T rear brakes with RDA slotted rotors front and rear. These rotors are factory drilled to 5 stud so fit the new setup perfectly. Also remember that upgrading your brakes may create issues with clearance. In cases where rims do not clear brake calipers, spacers may need to be employed temporarily until replacement rims can be sourced.
I performed my conversion and upgrade in my own backyard with little more than hand tools and a rattle gun. I'm not a mechanic, I haven't been playing with cars all my life, I only really became genuinely interested in playing with cars at the age of about 22 when I bought my first car. I must say that though that this conversion and upgrade wasn't easy... I spent a lot of time doing research and there wasn't really a whole lot out there, some of the process was trial and error, and I work full time so was working on the car during nights and some Saturday's. It wasn't an extremely difficult task (it's not rocket science) but it does take a keen spirit, patience, and a fair bit of elbow grease.
5-Stud Conversion-
5 stud conversions have been popular amongst s13 owners to enable fitment of a wider variety of rims. 4 stud rims in good sizes, offsets and design are generally pretty hard to come by, by going 5 stud, you make available to you a much larger range of rims in a wider range of sizes, offsets and design. Whether it be completely for aesthetics, for the purpose of clearing brake calipers after an upgrade, or to modify your vehicle to fit those elusive rims that you've had your eye and heart set on, 5 stud conversions are definitely becoming popular with the 4 stud equipped community. They are famous for Nissan s13's and Honda Civics and Integras. There are quite a few aftermarket options for replacement hubs that will convert 4 studded Silvia's to 5 stud, these require pressing of the aftermarket hub onto the bearing. I chose to go with Stock Nissan parts to ensure quality, reliability and compatability. I've heard mixed reports on aftermarket parts and concluded not to take that path due to safety issues, but also because I found the Nissan OEM parts were locally and readily available. There is a lot of confusion to what will and won't work with 5-stud conversions on S13/RPS13's. There are so many options that are possible, below is a rough guide of what I learned during my research about the most commonly chosen options.
Rears
S14/S15 rear hubs –
 |
| From Phillipses blog |
Generally, these are sold with the bearing unit attached. I've yet to see rear hubs sold without bearings. The hubs are a direct replacement with the S13/RPS13 units thus do not affect toe, or camber.
R32 GTS-T rear hubs –
 |
| From Phillipses blog |
Pretty much exactly the same as S14/15 rear hubs, these are the ones I've got in my 180sx.
R33 GTS-T rear hubs –
 |
| From Phillipses blog |
I've not had a play with these myself, apparently they're the same as S14/15 and R32GTS-T but I remember hearing a while ago that the number of splines for the half shafts are different to the S13... I've never been able to confirm but I've also come across people recommending R33 GTS-T hubs for 5-stud conversions.
Aftermarket rear hubs –
 |
| From Phillipses blog |
Same deal with aftermarket front hubs, see Aftermarket 5-stud hubs pressed into the S13/RPS13 bearings above
Brake Upgrade-
The brake upgrade is also a very popular modification performed on S13/RPS13 Silvia's. The stock brakes on an SR20DET S13/RPS13 are pretty crap to say the least. They are a single pot setup both for both front and rear calipers. The rear calipers have combined hydraulic and cable utility so that the caliper actions to both foot pedal and handbrake lever. It is common for people to upgrade the front calipers of an S13/RPS13 yet leave the stock rear caliper. This is partly due to the fact that upgrading the rear calipers requires extensive work in implementing a drum handbrake assembly. I chose again to go with Nissan OEM parts as they are cheap, readily available, work remarkably well, are easily rebuildable and are a direct bolt on. I upgraded both front and rear calipers including implementing the drum handbrake assembly. This allows maintaining the balance of brake bias between the front and rear calipers for a more controlled and predictable braking behaviour. There are heaps of options on what is available to s13's as brake upgrades, some of these bolt on, some of these don't. Remember that when calipers are upgraded, rotors must also be upgraded accordingly as well as the Brake Master Cylinder to maintain brake pedal firmness and effectiveness. Below is a list of viable options throughout the Nissan OEM range and the impressions I made of them when I was doing my research.
Rears
S13/14/15 –
 |
| From Phillipses blog |
The S13/14/15 rear calipers are the same as the ones found factory on the S13/RPS13, thus isn't really an upgrade. This unit is a dual action single piston sliding unit. That is, it has both a hydraulic feed that actions the caliper as well as a cable system that is attached to the handbrake to lock the caliper when tightened. Good pads will dramatically increase the effectiveness of braking with this caliper. 256mm diameter x 9mm thickness are the dimensions of this rotor. These rotors are solid and are not ventilated.
R32 GTS-T/R33 GTS-T/R34 GTS-T/Z32 –
 |
| From Phillipses blog |
The rear brake calipers in this range are pretty much one in the same, they are a twin piston unit meaning more effective and even braking over a broader surface area which in turn translates to a more controlled braking experience. The calipers are controlled completely by hydraulic feed meaning foot brake pedal or hydraulic hand brake if one is installed. The handbrake is connected to a drum handbrake assembly located on the baffle plate. Drum handbrakes lock stronger than caliper handbrakes. These rotors unlike the S13/14/15 rotors are ventilated, the dimensions are 297mm diameter x 18mm thickness. The centre hats of these rotors are also significantly higher and larger than that of S13/14/15's as they house the drum handbrake assembly.
Brake Master Cylinder –
|
| From Phillipses blog |
It is important to upgrade brake master cylinders as part of brake upgrade. BMC's retain brake pedal firmness and therefore braking effectiveness... If upgrading all four calipers, it becomes necessary in order for the brake pedal to not hit the floor of the car before 100% braking effectiveness is reached. I upgraded all four SR20DET single piston sliding type calipers to R33 GTS-T 4 pot and 2 pot fixed calipers and used an R32 GTR BMC (BM55). R32 GTR and R32 GTS-T BMC's are a direct fit for S13/RPS13. Just make sure that you use an use ABS enable BMC's in a vehicle equipped with ABS and vice versa with non-ABS equipped vehicles
Installation Process:
Rears
The rears are a fair bit more difficult to install than the fronts... This is mainly thanks to the complex drum handbrake assembly. What we are trying to achieve is a retrofit of the skyline drum handbrake assembly and 5 stud hub onto the S13 uprights.
Start off by chocking the front wheels with bricks and jacking the rear end up with a good jack from the diff, remember to use car stands underneath the rails to hold the car up while working. Having done that, remove the wheels.
Using a 10mm long barrel socket and wrench/driver, loosen the handbrake cable. This is done from the inside cabin, the handbrake tightening nut is located on the handbrake lever. Pull the handbrake lever up until you spot the circular cutout on the base of the handbrake lever cover highlighted above in yellow, the handbrake tightening nut is located in there, place the long barrel socket into the cutout and loosen the nut until there if there is no more tension in the handbrake when engaging or disengaging, leave the handbrake disengaged. Having loosened the handbrake, get underneath the car and place yourself underneath the tailshaft. Look up to the floorplan directly above the tailshaft and you will notice the handbrake cables that connect the calipers to a T-piece that looks like the image below.
Unscrew the handbrake cables from the chassis using a 10mm socket and driver, then detach handbrake cables from the T piece by rotating each cable until it fits through the notch allowing the locking head to disengage. Do not cut the steel wire as the above pic indicates. There are also two screws that secure the handbrake cables, they are indicated by the purple X's above, be sure to unscrew these also.
The caliper can now be unbolted from the upright via the 2 bolts that hold it in place.
Disconnect the the brake hose by using a flare nut spanner to undo the flare nut found on the opposite side of the bracket marked above in yellow. Once this is done, remove the caliper and place it aside. The rotor can then be removed, if the rotor seems stuck onto the hub, try tapping the hat gently with a hammer, or alternatively you can screw in an appropriate sized screw into the screwhole located on the hat which will pry the rotor off the hub. Be sure to use the correct size screw, you don't want the screw threading, becoming stuck or snapping while doing this.
Undo the cottor pin and bearing lock nut cover highlighted above in pink. This will reveal the bearing lock nut which must also be removed. There's a few ways to take care of this nut if it's really siezed. I found that a rattle gun works best however if using a breaker bar, you may find that the axle will rotate under the force of the breaker bar even if the car is in gear. In this case, remove the centre cap from the wheel, fix the wheel onto the hub, drop the car, place the socket into the wheel's centre cap hole and try breaking the nut like this. I've heard of some cases where the nut is so siezed that people will even lean the breaker bar against the ground, start the car up and drive along using the weight of the car to break the nut. This sounds clever enough however I've never had to do it myself. In this case the car will need to move forward to break the driver side nut and in move in reverse to break the passenger side nut. Remember, WD40 and similar penetrants work wonders.
Next, unbolt the half shaft from the diff end, this is highlighted above in yellow. This will require getting under the diff and using 2 14mm spanners. There are 2 variants of half shaft in s13's the 5 bolt and the 6 bolt, however they use the same sized nuts and bolts. Once the bolts are removed, move the shaft so that it is no longer pressing up against the diff.
Slide the half shaft out of the hub assembly. This is often easier said than done as quite often due to corrosion, wear and tear, grit and grime the shaft finds itself quite happily seized, use WD40 generously and if need be screw the bearing lock nut a few threads deep onto the shaft and tap the nut with a soft hammer. Alternatively, what I did was use an 8" 3 claw gear puller which made the job a cinch.
Now it's time to remove the upright and hub assembly. This is done by unbolting all the connection points that hold the upright in place. Place a support unerneath the lower control arm and proceed to unbolt the uprights from the traction, control, toe, strut and lower control arms. These are indicated by the green highlights above. Please note that in the above image, the strut is missing however it serves as one connection point. The lower control arm connection point is a balljoint type and as a result is fixed on by a nut and cotter pin, the cotter pin must be removed before the nut can be undone. The balljoint may be stuck tight onto the upright, in that case, screw the nut onto the balljoint thread a few threads deep and tap the nut with a soft head hammer. When the connection points are all disconnected, take the upright and hub assembly, and place it on a work area like below.
Turn the assembly so that the upright is facing up, use a rattle gun to undo the 4 bolts highlighted above in yellow, these bolts are tight and due to being on a rotatable hub assembly would not be removed any other way. Once the bolts are removed, separate the assembly as shown above.
Now it's time to do the same but with the Skyline unit. Note how this unit has the handbrake cable connected connected into the baffle plate whereas the s13 handbrake cable was connected to the caliper? This is the defining difference between the handbrake function between the two classes. Also note that there is one extra nut on the skyline unit that will need to be removed, this is highlighted above in yellow. Once the nuts and bolts have been removed, separate the assembly as shown above.
Now it's time to swap the handbrake cables. The reason why the R32 handbrake cable must be swapped with the R33 unit is due to the design of the terminals. The R32 unit will not connect up to the S13 T-piece however, the R33 terminal will. Note the difference between the terminals on the two units above. The first terminal is the R32 and the second terminal is the R33. Start by first undoing the screw on the back of the unit that holds the handbrake cable to the baffle plate, then using the above image as reference, use a flat head screwdriver to rotate the screws highleted in yello 90 degrees, they are spring preloaded and will pop out. Next unclip the 2 spring hooks from the anchor highlighted in pink, with these items unclipped, the drum brake unit should slip out with a bit of fidgeting, however will still be connected to the handbrake cable. Note the red arrow, this indicates the handbrake cable anchor point, simply unclip the R32 handbrake from this anchor point and replace with the R33 handbrake cable. After the cable has been replaced, piece back the drum handbrake by going through the last steps in reverse
NOTE: Use the RHS R33 cable for the LHS assembly and vice versa theLHS R33 cable for the RHS assembly. This will be explained.
Next, combine the R32 baffle plate (with R33 handbrake cable), the R32 5-stud hub, and the S13 upright to make a Frankenstein unit. Note that the hole on the s13 upright that the r32 baffle plate anchor fits through will most probably be filled with grime, rust and grit over the years making it highly unlikey for the anchor to be able to fit through, a dremel tool works wonders here, I made do with a round file and some course sandpaper. Try line up all the holes before inserting the screws, it makes it alot easier doing this now before anything get's bolted back together. When that's done, bolt it all back up TIGHT. I used the rattle gun on max setting and kept at it as I knew that this will never be coming apart again.
Bolt the half shaft back onto the diff while the assembly is out, having the assembly out will make this alot easier. Bolt the assembly lower control arm supporting the control arm with a crate or jack. Remember to place the cotter pin back in place. This is a good opportunity to take some dry steel wool to the half shaft and hub splines to get clean the surface and clear up any corrosion that may have built up. Feed the half shaft through the hub, then bolt up the traction, camber, toe and strut arm connection points. Feed the handbrake cable through the rear subframe and just let it sit there for now.
Install the new rotor onto the hub,observe how the rotor fits, is it clearing the drum handbrake assembly? Is it fouling against it? Remove the rotor and using a flat head screw driver, adjust the spline circled in green above to increase/decrease the preset of the drum handbrake. Adjust so that the rotor hat will fit snugly over the drum handbrake with a bit of fidgeting, then loosen it 2 more clicks. Put the rotor back on. Fit the Skyline caliper over the rotor, bolting it tightly into place. Connect the brake hoses between the caliper and brake hardline located on the bracket where the S13 hose used to connect. Screw the bearing lock nut tightly back into place, insert the lock nut cover and secure by threading a cotter pin through the hole in the spline. The 5 stud rims can be bolted back on at this point
NOTE: Use the left caliper for the passenger side and right caliper for the driver side, the bleed nipple should be at the top.
Now onto feeding the handbrake cables to connect onto the T-piece. The above image explains why the LHS handbrake cable must be used on the RHS and vice versa. The R33 handbrake cables have a little more length to them than the S13 handbrake cables, thus if the lines were not criss-crossed as shown, there would be too much slack in the line which will cause the line to foul against the tail shaft and/or the rims. The lines need to be fixed where the pink X's indicate, the brackets on the R33 lines will be a little off so will need to be loosened with pliars and relocated so as to have an even amount of slack along the line.
Affix the eagle adaptor with 2 screws in the screw holes underneath the car along the floor plan above the tailshaft where the previous s13 handbrake cables used to be fixed near the T-piece. That is, where the s13 cables used to be screwed into, screw the eagle adaptor instead. The two bottom holes should line up perfectly. The other holes should face towards the front of the car. Note that the nuts on the eagle adaptor should face upwards towards the chassis, thus what you see from underneath should be completely flat. Next, screw the R33 handbrake cables to the eagle adapator remembering the lines need to criss cross after the rear subframe. After this has been done, check to make sure that the slack along the line is even and not fouling against any moving part, in particular the tailshaft, half shafts, rims, rotors or calipers.
Tighten the handbrake up using a 10mm long barrel socket and driver, the tightening nut is located on the handbrake cable and is accessed via the cutout indicated above in yellow. The handbrake should be tightened until it feels as it did with the old S13 setup or set as desired.
Lower the car and voila! Time to move onto the Brake Master Cylinder. Do NOT drive the car as there is now air in the brake lines and the car will not be able to brake effectively.
Brake Master Cylinder (BMC)
The purpose of upgrading the BMC is to increase the pedal firmness under braking after a brake upgrade. Without upgrading the BMC after a significant brake upgrade, it is possible for the brake pedal to to hit the floor before 100% braking efficiency is acheived. ABS model BMC's must be used with ABS equipped vehicles likewise non ABS model BMC's must be used with car's not equipped with ABS. Note that my car had come equipped with a BM50 which is the same model as the R32GTR ABS model, meaning I didn't need to upgrade. If this is your case, then you also can retain your BMC.
Start by opening your bonnet, the BMC is located on the firewall where the steering wheel is located.
Unclip the power cable highlighted in green, and using a flare nut spanner, unscrew the flare nuts from the threads marked in yellow. Be careful as flare nuts are very easy to round off. Unbolt the BMC from the firewall via the bolts that yu will find where the blue markers are. Reverse the process to install the new BMC.
Flush/Bleed Your Brakes
This is a very important step. Modifying your brake system has caused air to become trapped in the lines. Unlike brake fluid, air is highly compressible so drastically hinders your braking performance. Bleeding will cause all the air to exit a brake system, whereas a flush completely replaces the fluid in a system with new fluid. Flushing/Bleeding your brakes works best with 3 people. One to compress, and one to bleed, one to keep the BMC filled. Purchase the correct brake fluid, I purchased DOT4 and used 2 standard service sized bottles for a full flush and it was JUST enough. Do not use the wrong brake fluid as it may cause damage to your brake system which can lead to failure. Start from the caliper furthest from the BMC and work your way to the closest one. So for Silvia's and Skylines from Japan and Australia
(ie right hand drive), that would be rear passenger first, rear driver second, front passenger third, front driver fourth. Place a brick or similar spacer behind the brake pedal so it doesn't bottom out, brakes bottoming out is a big no-no as it destroys BMC's. Do not ever let the BMC run dry as this will suck air into the brake system defeating the purpose of flushing/bleeding the brakes. This takes a bit of team work and coordination as one person will call as he compresses the brake, and the second person will have to open the nipple during compression, but close it when the pedal is released. The third person must always make sure that the BMC is at full. This should continue until there are no bubbles in the fluid and when the new fluid starts to bleed. You can usually tell by the colour change.
Before you go out to test the new brakes
The wheel alignment is going to be crazily out due to all the major surgery, so see a wheel specialist right away and get a full wheel alignment.
The difference it makes
As I mentioned at the beginning of the article, the brake upgroad is by far the greatest performance and safety mod that I've done to my car right next to coilover suspension struts... After the wheel alignment, I noticed the difference right away... ABS works as normal but braking effectiveness has increased dramatically... Slamming on the window now propels me out of my seat like crazy. I've also got some fat wheels since starting this article taking advantage of the 5 stud conversion
