This is a bit of a work in progress, so please bear with me and keep checking back the first 2 posts to see updates.
After being dissatisfied with the brake options out there, I started looking into what could work well on my RA28 which shall see occasional track use. As I intend on racing sprint and hillclimb, I wanted to keep the unsprung weight as low as reasonably possible while gaining braking capabilities not possible with current options.
The most popular currently is the Hilux/Pug/Rona, where you take a Hilux 4 piston anchor designed for a 302mm diameter 20mm thick rotor, a Pug 206 rotor which is 266mm diameter and 20.5mm thick, and whack it on a Corona *T13* strut, with varying forms of shock, spring and top hat to suit your vehicle.
The problems here are that the callipers weren't designed for that sized rotor, the rotors are getting hard to find, and the brake pads available are suited to offroad 4wd'ing, not track work. So I set about looking for something better.
Many hours of searching the DBA catalogue showed that the Mitsubishi Cordia had promising rotors. Going over to the Cordia forums, I asked about what 2 piston calipers they used. The helpful people at www.cordiapower.com/forums advised that they ditch their brakes, get Galant VR4/Lancer Evo/Magna (ABS model) brakes, a set of 15" wheels and throw them on. There are subtle differences, the Magnas run 5 stud, and the Evo's have slightly bigger piston calipers, but the pads are the same and they all run twin piston calipers much the same size as VT Commode Door units.
So... the answer?? Evo rotors (DBA catalogue code 402, will get back to you on the RDA code), which are 276mm diameter, 24mm thick, TR/TS Magna or KR/KS Verada ABS version calipers, EBC Red Stuff DP3954 pads which are suited to street and track work, and RA40 Celica struts.
Things you will need to know/do:
1. This conversion involves changing to hat type rotor. You will need to mill the outside of the hub down to suit the inside of the rotor. Will get back with measurements. DON'T GRIND THE THINGS DOWN, HAVE THEM MILLED ON A LATHE
2. Your studs will not be long enough due to the hat type rotor. Will get back to you on part number for the studs
3. You cannot use less than a 15" rim, don't bother trying
4. To have a clearance of 10mm or better to your strut, you will need a maximum rim offset of +25mm based on a 16x7 rim. 15x7 may need to go down to +15/20 to ensure strut clearance.
5. You will need to make a caliper adaptor with 12mm plate steel and another plate welded to the back. This should be laser/water cut for accuracy. I will post up an Autocad drawing of the plates once I have measured it and checked for accuracy.
6. Magna calipers have different pistons to Evo units, don't buy Evo caliper rebuild kits if you are using Magna items (and vice versa if you use Evo)
So, first pictures (more will come as I progress with this conversion)
Corona RT133 twin piston on the left, Evo/Magna on the right. Note that the Rona pad is pretty much 75x49mm, where the Evo/Magna pad is 120x56, which is about 180% of the pad surface area of the twin piston Rona brakes. You will also note that there are some extra holes in the rotors to suit the EVO, which includes threaded holes which will allow you to push the rotor off the hub should it lock on.
Side on shot. This is more for info now that I have decided it easier/better to go with hat type for the setup.
I am now at prototype No. 3 which is a bracket machined from HDPE plastic. Why HDPE? Cause I get it free, it doesn't wear machining tips, and it's pretty tough. So essentially I can make lots of prototypes and not have a care in the world if I stuff a few up.
This is the bracket shown edge on. Thickness currently is 10.5mm, but the plastic was bowed. This thickness may get altered to around 11mm, though the clearances as is are pretty good.
Face on, the pads sit pretty good, but I will bring them in toward the spindle about 2mm as they do sit slightly proud of the outside of the rotor.
The brakes look pretty good under 16" rims. They would look better under 15", but tyres might become a little more difficult to get, plus your sidewalls will be getting larger, which means more flex.
I am looking at heat treated 6000 series aluminium as the final material for the brackets. This shouldn't be too hard to get, and with the right milling burrs will be easy enough to machine. I'll do some stress analysis in Solidworks before determining the final material. If I can't get the aluminium to take the stress, then I'll go with mild steel as that would be more than strong enough, but would need more machining to try and drop some weight out.
To make up the final products, another member here is looking to use his own mill to make the brackets. I'll talk to the board about selling them on here, if not, Ebay will be the place to find them. Looking to make 25 pairs as a starting point (to make it worth making a jig). These should be finalised pretty soon, I am keen to get the old girl back down on her shoes so I can put the donk in.
Evo rotors - $315 (I got the gold version which is slotted/dimpled and has a non-ferrous electroplated coating to prevent the non-pad surface sections from corroding)
Magna calipers - $60
Caliper rebuild kit - TBA
EBC Redstuff pads - $130 (got them from the UK, $240 and up from Aus)
Braided lines - TBA
Caliper bracket - TBA
Machining - 1 Carton?
Studs - TBA
On top of this add for new bearings, fasteners where necessary and any other parts needed to refurbish the struts.
Hope this helps/inspires people.
Just a question. Why did you get the discs re drilled at 4x100. Old toyotas are 4x114.3, except for a few early corollas I think.
Looking for a new toy. If you have something 18r powered let me know.
RIP, where ever you are :- 1974 celica, 3tgte and 186.5hp at 6500rpm
It's 4x100 as the discs are mounted to the rear of the hub, not the front.
I'll be looking at upgrading the front brakes soon on my RA28 and I've also noted the Pug rotors being harder to find, will be watching this thread.
I am confused about changing the PCD though, if the wheel studs are different diameter couldnt you just change them out? Why are you changing stud spacing to 4x100? My celica is 4x114.3 as are most old Toyotas, as lilcrash said...
I am also considering the option of milling down the outside of my hubs and running the disks in a hat configuration. If I do this, I will probably run with RA40 struts instead, as these have removable calliper mounting plates which I can get re-made, and the hub face is ~5mm closer to the strut, which will help to reduce the effect that the addition of the rotor on the outside will have on the relative position of the wheel rim. It will also mean the rotors won't need modification when I have to replace them. I'll get the RA40 hubs milled anyway and keep you posted on the results (have a pair which are propping up the RA23 and doing f-all else at the mo)
Owen, i was thinking of how they'd fit on other struts.
edit: but i think this is a good thread as it give you another route to go for a minor-to-medium brake upgrade when you need to fit small(ish) rims on the vehicle.
I think your chances of this one fitting just right like the $250 brake upgrade (RA6*/MX62/*T13*) will be fairly slim on any Toyota strut. I'll measure anyway and if anyone comes up with a good'un then well and good, however I won't hold out much hope. Main reason being is that the callipers are really wide compared to any single or opposing twin piston unit.
New tack. Have measured, and milling down the hubs to suit a hat type arrangement is a better option than redrilling and milling the rotors. I have moved to the RA40 struts for this, which will give the same track using rotor over hub as the Rona struts will with rotor behind hub. Have updated the first post to suit.
Bolt spacing for the Magna callipers is 128mm (approx - within a mm)
while I think your work here is excellent and really good reading I am wondering why not the Mini cooper disk /RX7 4 spot combo?
I'm sorta interested as I'll be running 15" rims on the Soarer which unfortunately rules out my Z32 calipers unless I strike it lucky with a set of compomotive rims (he says sounding not confident at all).
While its always great to see someone trying something new, your choice of parts is a little odd.
I find it strange that youve selected parts by choosing a rotor first.
Did you consider going with a floating rotor (mounted on wheel side of the hub) to increase your range of choice?
Increasing rotor size is much more important than increasing caliper/pad size when looking to track/race a car.
I hope that caliper bracket isnt going to be too complex
The caliper bracket will be of similar complexity to the Hilux diff disk brake conversion caliper brackets. They weren't real expensive.
Have a bit more of a read. The Evo rotors are actually hat type (or floating as you call it). I based the rotor selection on a number of measurements compared with the Rona rotors and I was going to convert them for rear mount use, however once I got the rotors and did some measurements against the RA40 strut setup, it seems better to use it that way. This means I don't need to modify the rotor every time I have to replace them. It also makes them a piece of cake to remove so I can de-glaze them (no doubt this will be needed after every track day). I didn't want to go more than a 15" rim for the every day wheels due to the craters in the roads up here (occasionally they fill them in to pothole size). Another part of my parts choice reasoning is that the callipers and pads are specifically designed to suit this rotor. Thus they don't need any mods.
Sam, haven't seen the mini cooper/rx7 setup before, sounds intriguing. One thing I would want to watch out with though is the X-factor on the rotors. I know that certain wheels don't fit with the Lux/Pug/Rona setup due to this (stock Toyota 4 spoke alloys).
I have only heard of second hand info on the mini cooper rotors but various forum searches like on ae86dc should bring it up, AJPS has brackets for ae86 rotors:
they are a pissweak 230mm though but from what I understand they can suit vented 262mm disks. This X-factor, is it a reference to the offset from the front of the hub?
X factor is the amount of clearance from the hub face to the back of the wheel spokes. FC callipers on 230mm rotors would mean half the pad is exposed and not used... this isn't good. Mini Cooper rotors that are in the DBA catalogue, are either 190mm for the early ones, or they start at 276x22 for later ones. Since the FC RX7 are also 276x22, this rules out the post-R50 mini rotors. Lancer Evo are 276x24, so what you lose by going to a 2 piston rather than 4 in the calliper, you gain in rotor thickness. If my calculations are right, then the X-factor required will be minimal with the Evo setup. Both the RX7 and EVO setups require a 15" wheel (the AJPS setup runs a 14" wheel, but does not appear to use all the pad).
I've got the AJPS setup, works really well, I'll pull the pads out next week when I get home and take some pics for reference on how they've warn.
Does the braking surface of the rotor cover the entirety of the pad?
The more I look into the EVO setup, the more I like it. With the way I am going, there will be no modifications to the rotors or pads required, so all consumables will be off the shelf, readily available items. This is a BIG plus when you discover that you have somehow munted a rotor down the track and need to replace it straight away. It also allows you to run 2 sets of rotors and pads, one set for street, the other for track (though I won't be at that stage for a while)
Ok bit of an update. Got my RA40 hub back all machined so the rotor slots over the front. Put it back on the strut, installed the rotor, and set up the Magna calliper mount and pads on the rotor with a G clamp holding them in place. Visual inspection shows that there is room to put a decently thick calliper mounting bracket (stock bracket is an edge folded 4mm thick unit - this would be closer to 10-12mm thick). This method means that there is no drilling of existing equipment required, and no tapping of any threads needed. The stock bolts and stock bolt threads can be used.
Things are looking easier as I go with this. I'll post up photos tomorrow night.