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Henn
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Rosanna, Melb
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June 2002
How to fit RX7 calipers to an AE86 - Links to pics Mon, 09 May 2005 10:47 Go to next message
Recently I have been getting regular emails about the RX7 brake setup I have on my Sprinter and so I thought I might write this up once rather than responding individually.

The aim was to keep stock struts (whether this is a good idea can be debated) and this is the setup I eventually got to work.

Photos thanks to imageshack.us -
Brakes from front
Brakes from rear showing stepped adaptor
Brakes from rear showing more of the adaptor

It consists of:
Stock strut
Stock hub
Stock lower control arm and steering arm

Calipers-
S4 RX7. Some of the fins on the caliper had to be filed to fit them under 15" rims. Plus the lump near where it says MAZDA had to be filed down to clear the wheel spokes... however DONT FILE IT FULLY FLAT otherwise you open a brake line. Leave at least 2-3mm proud.

Disc-
280mm 180SX (from SR20 variety I think). Needs to be redrilled to suit stud pattern on the BACK of the sprinter hub.

Locator-
Custom locator ring so disc fits snugly on AE86 hub.
Locator pic
Locator drawing

Brake mounting plate-
Custom. This was the part which took ages to make but it worked in the end. I made them from 450MPa steel although I think you could probably make it from good alloy and it would be strong enough. I've been quoted around $6-700 a pair to machine these adaptors.
Pics of adaptor only: 1 2 3
Drawings of adaptor: 1 2 3 4
Models showing fillets on the corners: Front Back
And an old page I just dug up where Garth hosted most of these pics a couple of years ago. Thanks for keeping it up.

Problems-
The main problem I ran into was that if the caliper sat inboard of the spokes of my wheels then the disc rubbed on the lower control arm. My Superlights only have 6-7mm of space between the wheel mounting face and the inside of the spokes. I got around this by running offset roll centre adjusters which pushed the bottom of the strut (and therefore hub and disc) out 17mm.
Offset RCA

If you plan on doing this upgrade and have more room outboard of your wheel mounting face then you could redesign the adaptor to mount the caliper further outboard. This removes the need for offset RCAs and also makes the adaptor both stronger and easier to machine. This would require a new disc be chosen with the correct offset. I seem to remeber Audi A3 discs were an option.

Results-
I've used these for almost 18months and they are great. With EBC greenstuffs I have never had them fade even when trying on track (with 110rwkw).

In conclusion I wouldn't recommend doing this, it is total overkill and I think there are cheaper and easier upgrades out there. However some of you I'm sure will not be put off (like me) and want the bling of 4piston brakes. If so then good luck and please consider the time and effort I poured into this setup and help me out with a favour some day.

Hen
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ShiRi
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June 2004
Re: How to fit RX7 calipers to an AE86 - Links to pics Mon, 09 May 2005 10:56 Go to previous messageGo to next message
excellent comprhensive guide to it henn

hats off
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Big T
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September 2004
Re: How to fit RX7 calipers to an AE86 - Links to pics Mon, 09 May 2005 11:26 Go to previous messageGo to next message
And I'm one of the people that keep pestering you Henn Razz Been doing a bit of research to see what disk would be best for the plate as well.

The A3 disks are the closest you'll get to machining the plate dead flat. There still has to be a 3.7mm step on the plate.

I've looked through almost ALL of the DBA catalogue to try and get an exact match but no luck, (i think there were a couple other matches as well but only had a 260(?)mm rotor)

The rotor height would have to be 33mm in order to machine it flat.

I'm actually trying to find pre-made adaptor plates from Japan for the rx7 calipers. Garth linked me to a site that had Honda disks on a custom adaptor. Trying to find one for the fc brakes.

Eddie.
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YelloRolla
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Re: How to fit RX7 calipers to an AE86 - Links to pics Mon, 09 May 2005 12:11 Go to previous messageGo to next message
That is excellent Henn.

The 24.8deg measurement (drwg of adaptor #4) had me stumped for a bit - I take it to be the angle that the back flat edge of the bracket sits when installed.

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Jimmy19650
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Wodonga
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May 2005
Re: How to fit RX7 calipers to an AE86 - Links to pics Mon, 09 May 2005 12:26 Go to previous messageGo to next message
Great info Hen,

My only question with this setup is whether you need to modify the brake master cylinder at all? Have you got any ideas on rear brakes as well?
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pepsicola
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August 2002
 
Re: How to fit RX7 calipers to an AE86 - Links to pics Mon, 09 May 2005 12:35 Go to previous messageGo to next message
thanks for the info, that's really good description.

-Big T-
try z31 300zx rotors, they're 33.5 height and about 280mm diameter.

only problem is that i've got one of these from a brand other than DBA, the rotor can't be redrill to fit behind the sprinter hub.

[Updated on: Mon, 09 May 2005 12:37]

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pepsicola
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Re: How to fit RX7 calipers to an AE86 - Links to pics Mon, 09 May 2005 12:46 Go to previous messageGo to next message
oh, and what brake hose do u use?
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Big T
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September 2004
Re: How to fit RX7 calipers to an AE86 - Links to pics Mon, 09 May 2005 12:59 Go to previous messageGo to next message
pepsicola wrote on Mon, 09 May 2005 22:35

thanks for the info, that's really good description.

-Big T-
try z31 300zx rotors, they're 33.5 height and about 280mm diameter.

only problem is that i've got one of these from a brand other than DBA, the rotor can't be redrill to fit behind the sprinter hub.




The z31 rotors are 35.5mm and the centre hole is massive (81mm) in comparison to the sprinter's one. I'm no engineer so i don't know if using a rotor with a centre size difference that large would be advisable.

I was looking at the closest possible match in all the categories. The A3 disk is 280mm wide, 36.7 high, 22mm thick and the centre hole is only 1mm larger than the sprinter at 65mm.

Eddie.
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barned01
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Adelaide
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September 2003
Re: How to fit RX7 calipers to an AE86 - Links to pics Mon, 09 May 2005 13:02 Go to previous messageGo to next message
although the stud pattern is different can you use a honda NSX 91-98 model.
the rear disc has the following dimensions:
model 485
vented
282mm diameter
hat height 32.5mm
rotor height 21mm
centre hole 69 mm
5 stud pattern (this could be the killer)

would that make it pretty close?
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Big T
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Re: How to fit RX7 calipers to an AE86 - Links to pics Mon, 09 May 2005 13:14 Go to previous messageGo to next message
I was actually trying to source out the disks 2nd hand so i automatically dismissed that one. I mean how often do you see an NSX being scrapped!!! Laughing

Obviously the audi disks won't be easy to find either which is why i'm not committing to any plans yet. If i find a suitable adaptor plate from Japan, i'll post up the link.

And i don't think the actual stud pattern matters on the rotor. The A3 disks are also 5 stud but they can easily be re-drilled to suit the sprinter hub.

Eddie.
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barned01
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September 2003
Re: How to fit RX7 calipers to an AE86 - Links to pics Mon, 09 May 2005 13:17 Go to previous messageGo to next message
is there a reason why you wouldn't buy them new?
expense?
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oldcorollas
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Kita-Ku, Sapporo, Japan
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January 2003
 
Re: How to fit RX7 calipers to an AE86 - Links to pics Mon, 09 May 2005 13:35 Go to previous messageGo to next message
yes. they are also an "option" for oldcorolla brakes, but at around $300+ per disc from DBA, they are a little.... pricey...
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Big T
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Re: How to fit RX7 calipers to an AE86 - Links to pics Mon, 09 May 2005 13:36 Go to previous messageGo to next message
barned01 wrote on Mon, 09 May 2005 23:17

is there a reason why you wouldn't buy them new?
expense?


That's my reason at the moment. My turbo conversion has just passed into the 8k bracket so if i can get comparable stuff 2nd hand, i'll look at that 1st.

I mean stuff like head gaskets, piston rings, bearings etc you have to get new but brakes are doable well with 2nd hand bits.

All them little bits and pieces keep adding up. Confused If i can't find decent 2nd hand gear then i'll have to go for new but i'd like to exhaust the other options 1st.

Eddie.

p.s. sorry for the semi-hijack of the thread Henn!!
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pepsicola
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Re: How to fit RX7 calipers to an AE86 - Links to pics Mon, 09 May 2005 14:38 Go to previous messageGo to next message
um...have u thought about putting the rotor over the hub instead of put it behind the hub?

i think i've seen it done this way, by machining the hub diameter to a bit smaller, redrill the rotor (stock rx-7 maybe) to 4x114.3 stud pattern. put it over the hub and use longer studs.

this way, u should be able to use rotors that has around 60-70mm.
and u could probly get more clearance between the caliper and the wheel spokes.
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Jonny2TG
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Tasmania
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May 2002
Re: How to fit RX7 calipers to an AE86 - Links to pics Mon, 09 May 2005 14:57 Go to previous messageGo to next message
The RX7 brakes are a common converion in Japan, with adapter plates sold on YahooAuctions at times. Some of us need to spend more time on the Japan websites to see what disks they use with the adapters they have. Whats the biggest diameter disk you can use in a 15" wheel?
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Henn
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Rosanna, Melb
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June 2002
Re: How to fit RX7 calipers to an AE86 - Links to pics Mon, 09 May 2005 23:41 Go to previous messageGo to next message
Pepsi - I never thought of sliding the disc over the hub when I did this, however thinking about it since it seems like it could be a good idea. I think Mrshin has done something similar.

Yellowrolla - the 24.8 degrees is just so the caliper sits in about the same orientation as the factory caliper. The centreline of the two mounting holes is 24.8 deg below horizontal when the bottom strut mounting bolt is vertically below the centre of the hole the stub axle sticks through (a result of the way I drew the pictures up)

Jimmy - I run a 15/16th master off a Corona which I had to redrill. However there are bolt up 15/16th and maybe even 1" masters available. Starion and MA70 Supra spring to mind but I am not sure on either. The stock master will apparently work, according to Mrshin again, but just give you a really soggy pedal feel.

I've heard similar things are avavilable off the shelf from Japan and may end up being cheaper and definitely easier, but the info is also here in case it's any use.

Hen
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takai
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Location:
Adelaide
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May 2003
 
Re: How to fit RX7 calipers to an AE86 - Links to pics Tue, 10 May 2005 00:20 Go to previous message
Thanks for that Henn, ive added it to the sticky.

As for master cylinders there are a few out there you can use which bolt up.
Mitsu Starion is a 15/16th master, and is currently paired up nicely with my Hilux 4spots.
Nissan R32 GTR is either a 1" or 1 1/16th master depending on which version you get (BM50 or BM57) Ill probably use this when i try and fit GTSt calipers under 14" rims.
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