Big Brake Conversion Using your old bolt on style hubs

[85_Z31]

Ok guys this is my write up I posted on z31performance.com It is based on using Z31 Pentagon 5 Stud front hubs and Z31 Struts

This process should also work for other types of Nissan's/Datsuns which use a bolt on style rotor as the process to convert them to slip on rotors is the same.

There is huge emphasis buying impossible to find Jap DR30 Hubs or the impossible to find 1988 Z31 5 stud hubs.

This conversion will take your existing square or pentagon hubs with bolt on rotors and convert them to take a slip on rotor.

The machine work cost me about $100, and it uses the Hubs you already have, vs paying out of your ass to get other types on slip on style hubs.

My Engineer was Justin Neil, and he has done this other Front hubs that have Passed VVTA cert via Wayne Martin

Also please excuse the Idiot Step by step nature as this was written for Americans on an American forum. ( good guys nothing against them but half the time they just can't understand )

and enjoy....



So you want to fit 4 pots & Decent rotors on your 84 -86 Turbo or any YEAR Non Turbo and you can't find 88 Turbo Hubs ?

You will Need the following before you begin

Tools

1) A decent Place to work
2) Jack stands & typical hand tools for working on cars
3) Brake line clamps & Drip tray
4) Something to chock the wheels

Parts

A) Z32 4 pot calipers
B) Brake rotors to suit your z32 calipers ( there are 26mm and 30mm versions so make sure get the correct ones )
C) Longer wheel studs x10
D) Front wheel Bearing kit ( optional but you should probably do it while its apart )
E) PDM conversion Brake lines > http://www.pdm-racing.com/products/brakeslines.html" onclick="window.open(this.href);return false;
F) New Bolts for the brake calipers -
G) Machined Spacer for Brake Caliper
H) Fine washers to match the Machined Spacer

Services

you will need some time with a reasonable good fitter / turner / somebody who can operate a lathe reasonably well


Note !!!!

If you wish to keep your stock wheels with the 4 pot brakes this is possible however you will need a full set of 20mm Hubcentric adapters for the front and rear

Step 1
Jack up the car and put chassis stands at the front on a flat and level surface and remove the wheels, now is a great chance to throw a drip tray under the brake caliper and fit the brake line clamps so you don't get brake fluid everywhere.


Step 2
Loosen the bolt that holds the brake line onto the caliper , DO this while the brake caliper is still bolted down or its a PITA
after you have removed the brake line you can go ahead and unbolt the brake caliper.

Step 3
Remove the front hubs as per the NISSAN FSM, remove your wheel bearings as per the NISSAN FSM & clean all the grease out of the hubs so you don't piss off the person who is going to machine them


-- By now you should have a stack of shit looking like this




Step 4
Remove the old brake rotors from the hubs but don't throw away the rotors as you will need one later

--By Now you should have 2 fully stripped hubs to send into the engineer to be machined.

Supply your friendly engineer with the following
1x Z32 Brake rotor ( Sample for measuring from )
2x Z31 pentagon or square front hubs
1x original Nissan wheel ( Sample for measuring from )


Step 5
Have the OD of the hub turned down to the measurement shown


Once the Rotor slips onto the hub nicely it is time to machine a sleeve to be pressed onto the spigot so that the brake rotor is not going to slop around IE it needs to be Centric to the HUB

Tell the engineer to machine down the hub, so that he can then turn up a sleeve that locates the brake rotor and the wheel snug. The sleeve i had made is high tensile alloy to a 4 thou interference shrink fit.

it should look like this


NOTE
It is very Important to provide the wheel and brake rotor as a sample so that the engineer can make a sleeve to accurately locate the wheel and rotor. If you engineer can't figure this out GO SOMEWHERE ELSE

[85_Z31]

Here is a comparison of the Hub Before & After



Step 6

Put two hubs side by side on a flat level surface, Refit a Z31 rotor to the first hub then fit a Z32 rotor to the second hub

Take measurements to the center-line of the rotor from both the Z31 & Z32, this is so you can make a spacer for the 4 pot caliper as it needs to be pushed out further. Subtract the diffidence and use this value ( i got approx 10mm ) and go make a spacer. You will also need thin washers in addition to your spacer so you can get this perfectly centered up.



I have used an oversize nut ( FOR MOCK UP PURPOSES ONLY ) as a spacer, this is to allow trial fitment so that a spacer can be machined from round stock, to the correct dimensions. As Stated before use thin washers to "fine tune" until you have the caliper centered over the rotors



You will need to re check your spacers after the hubs have had their wheel bearings fitted, because if you do a "Dry run" to take your measurements they may change when the hub is packed with grease & torqued down onto the spindle

Note

When comparing the heights of the rotors , you can see why the 4 pot caliper needs to be spaced out.
I am using 30mm thick rotors, this will look different if you use the 26mm thick rotors.



Step 7

Take your caliper and fit it to the Strut with your spacers ( reuse the bolts from your original Z31 brake calipers ) Bust out your Calipers and use the height measure thingy so you can decide how much longer the bolts need to be.



now go out and buy the highest grade shanked Bolts you can find that are approx 6-8 mm longer.
USE YOUR OWN MEASUREMENT HERE as my spacer isn't thick enough.


Step 8

If you decided to put in new wheel bearings Refer to your FSM and do this now

if not carry on and put shit together ( my photo's show it a bit out of order but you get the idea )








My Pictures show a 20mm spacer and fitment of a factory 85 Turbo wheel, clearance

Step 9

Get your PDM conversion brake lines and fit these as you would any other brake line, follow your FSM procedure and you should be fine.

It is also a great Idea to get your brake calipers rebuilt and use BRAND new Rotors and Pads.

[DJZ]

Looks good man, I had the same problems when I went to do mine 3 odd years ago.

I ended up finding a rotor that had the correct offset so that the caliper didn't need to be spaced out (AU or AU2 Falcon, can't remember which), they are 280x28. I had the hub machined down so that rotor would slip over it then had the rotor drilled and countersunk for 3 locating screws that screw into the hub rather than machining up a locating collar which probably would have been a better idea. Had to fit longer wheel studs as well.

What size is the Z31 master cylinder? The factory 280Z 15/16 one has been pretty good with 4 pot fronts & standard rears, a little soft if anything. I'm going to fit a 1" Z32 master for the R33 brakes I'm changing to.

[85_Z31]

Looks good man, I had the same problems when I went to do mine 3 odd years ago.

I ended up finding a rotor that had the correct offset so that the caliper didn't need to be spaced out (AU or AU2 Falcon, can't remember which), they are 280x28. I had the hub machined down so that rotor would slip over it then had the rotor drilled and countersunk for 3 locating screws that screw into the hub rather than machining up a locating collar which probably would have been a better idea. Had to fit longer wheel studs as well.

What size is the Z31 master cylinder? The factory 280Z 15/16 one has been pretty good with 4 pot fronts & standard rears, a little soft if anything. I'm going to fit a 1" Z32 master for the R33 brakes I'm changing to.

I know that the Z32 master is an upgrade on the Z31 but a lot of people in the USA Z31 community have told me that providing i use Stainless braided lines I won't even notice a difference, the pedal felt good with the old brakes so as long as its pretty close i think I will be happy.

I would have gone your route with the AU ford rotors if i had known about it - I already had the R32/Z32 rotors brand new in a box on the shelf ( from 2 1/2 years ago before i joined NZ Datsun ) , I had no choice on the locating collar as i have the 20mm spacer, but its a pretty tidy solution