So I am currently in the process of fitting my new big brakes as I find time. It will be a little while yet till I finish them so I'm just going to post the results of my research now while it's still fresh. This information should help others find some new lighter caliper/rotor combinations that may work better with their specific clearance issues, budgets and performance targets. Call it a little Christmas present from the Fiend
I've been looking into new swap possibilities as none of the existing solutions I've seen so far are quite what I want and I suspect others are in the same boat. A rotor about the size of the MPV one is adequate for most (incl me), but sliding 2 pot calipers are not sexy, light nor ideal for performance. Changing wheel offset isn't terribly appealing either nor is taking an 8lb deficit per corner for such a tame sized rotor. The JK BB kit is overkill for many, is very expensive and its dimensions result in control arm interference with many combinations of steering arms and RCAs (incl mine). My plan has always been to find a rotor that I can mount like stock so I can avoid the weight penalty your average over hub rotor incurs. Unfortunately it seems the only bolt to hub rotors that have been made in the last 25 years are for trucks and are rediculously heavy. So I had the brilliant idea that perhaps I could find some over hub rotors with a low overa height to work as bolt to hub rotors with minimal modification. Adapting calipers is fairly straight forward, finding the perfect rotor I figured would be the trick. Of course it turns out, this method has been done. There was some talk of it early in this thread, but this guy actually did it...
FD RX7 with Peugeot rotors
My problem with his setup is that I can't get Peugeot rotors easily over here and that rotor is a little small for my needs.
So I grabbed a copy of the international DBA catalog from here...
and went through the entire thing and came up with a list of rotors that could work with one of the donor 4 pot, aluminium, monoblock calipers I could think of that aren't too hard to find and are affordable. However as many have found out, finding a rotor isn't that hard, but finding a rotor/caliper combo that doesn't foul your wheels can be. It's all about caliper clearance.
Here's the critical dimensions of our hubs and stock setup that you need to be aware of when selecting your rotor;
- Mk2 rotor bolt pattern is 4x100mm. The original rotors wheel stud pattern can cause issues here if it is too similar and 5 bolt.
- The hub center hole is 76mm ("Hub Reg" on Centric diagrams). You don't want to use a rotor with a hole greater then this as you would need a custom centering ring then. You also don't want to trust just the bolts to keep your rotor centered. Not usually a problem though, most rotors are about 64mm.
- Rotor mating surface to wheel mating surface is 32mm. Super important to know when you're calculating caliper to wheel clearance. FYI most old school wheels only have about a 10mm spoke clearance (wheel mating surface to spokes where the calipers sit).
- Rotor mating surface to inner rotor edge is 6mm (with the stock rotor). Calculate this from Centric diagrams by deducting the "Nom Thickness" number from the Height (26mm - 20mm = 6mm).
- Inner rotor edge to tightest point on the unmodified dust shield is approx 3mm. The stock dust shield has a huge recess for the tip of the control arm to fit into. You will need this space if you run Celica gts steering arms without massive RCAs. If you don't, it is possible to cut this recess out and mangle the stock dust shield so that you can gain about 15mm clearance from the stock rotor vs the stock 3mm. The JK kit requires this for instance. That rotor with spacer is approx 42mm in "Height" and I would consider that the absolute tallest rotor you should ever consider. Actually, unless you run an RCA so tall that it pushes the control arm underneath the rotor, I would aim for something thinner or you will have contact problems like people with normal RCAs and JK brakes do.
So your total caliper clearance is Spoke Clearance + Wheel to Rotor mating surface Clearance (32mm) + Rotor mating surface to Rotor Center (which is rotor "Height" - half of Rotor Thickness).
So for example, old school wheels (lets say 10mm Spoke Clearance) with the stock rotor (26mm - (20mm / 2) = 16mm) gives us a total Caliper clearance of 58mm.
To give you an idea, the 26mm 300zx calipers with the letters milled off requires 69mm of caliper clearance. FYI that is the thinnest oem 4pot caliper I have found so far. A caliper's needed clearance is simply the thickness of the caliper from the center point (where the center of the rotor would be) to the outer edge (wheel side). I have provided this number for all calipers that I could find it for (speak up if you can get it for the missing ones!). A calipers needed clearance with a specific rotor is this number with half the rotors width subtracted from it.
Here's the specs on all the calipers I figured were worth considering and the diameter and thickness of the rotor they were designed to work with. Obviously you will need to pick a caliper that was originally mated to a rotor with almost exactly the same thickness as the rotor you are considering and has a similar diameter.
**All front calipers unless otherwise specified. All numbers are mm unless otherwise noted.
My shorthand for dimensions: width = width of rotor it came mated to, dia = diameter of rotor it came mated to, rotor = Center to Edge is the distance from the center of where the rotor would be to the outer edge on the wheel side.
- 90-96 z32 300zx 30mm width, 280mm dia. 74mm Center to Edge (Incl 2mm tall letters). Available in aluminum (6.5lbs) or iron (10lbs). Bonus, same bolt pattern as the stock ra/ma6x calipers.
- 1990 z32 300zx 26mm width, 280mm dia. 71mm Center to Edge (Incl 2mm tall letters). Available in aluminum (6.5lbs). Also same bolt pattern of course.
- 92-95 FD RX7 22mm width, 296dia. 72mm Center to Edge (Incl 2mm tall letters). Available in aluminium (5.7lbs).
- "4 Pot Subaru" 06/07 Subaru WRX, 24-25mm width, 294dia. ??mm Center to Edge (Incl 2mm tall letters). Available in aluminum (Approx 10lbs). Made by Sumito, very similar to z32 calipers.
- 92-94 Lexus LS400 32mm width, 296dia. Approx 73mm Center to Edge. Available in Aluminum (Approx 10lbs). At least 3 different sizes of rotors/calipers are used on different LS400 generations/years. Every few years the diameter goes up but the rotor width, and essentially caliper design and pads stay the same. MK4 Supra uses essentially the same caliper (but half iron so heavy and also very expensive) with a 330mm rotor. 2006 LS430 is the last year to use this design, 30mm width 315mm diameter. 2007+ gets crazy, 35mm thick 360mm diameter.
- 05-12 Acura RL 28mm, 319mm diameter. Approx ??mm Center to Edge. Available in Aluminum (Approx ??lbs). Radial mount unlike all the others. Very common for swaps in the Honda world, especially on NSXs.
Possible Rotor Donors
All of these rotors should work as bolt to hub rotors with a little machining (bore out the inner bore and redrill for 4x100mm). Note: I searched for these rotors with the "Height" (outer edge of rotor to hub/wheel mating surface) of the Jim King BBK front setup in mind as my max spec. I assumed the spacer was 5-7mm so I didn't look at any rotors over 39mm. Turns out it is 42mm and I overlooked many in the 40-42mm range. You may also want to go through that catalog yourself if you are in a different region of the world as I ignored all models not available in North America. However, the JK's height is extreme so it's a good idea to avoid rotors in that range if you can (like if you have slim calipers, run spacers or have wheels with awesome spoke clearance).
***All front rotors unless otherwise noted. All numbers are mm unless otherwise noted.
My shorthand for dimensions: dia = diameter, rotor = actual rotor thickness ("Nom Thick" for centric), tall = total rotor height ("Height" for centric), hole = hub center hole ("Hub Reg" for centric)
- 2000-2002 Audi TT front rotor: 312dia, 25rotor, 34tall, 65hole, 18lbs
3.2l 06 v6 model is the same except 334dia, 23.5lbs.
- 2004-09 Chrysler PT Cruiser Turbo/Limited: 280mm, 28rotor, 39tall, 17.5lbs.
- 2008-12 Dodge Journey 2.0td, 2.4, 2.7: 302dia, 28rotor, 38.2tall, 72mm hole 16.9lbs.
2012+ HD JC series are 330dia.
- 91-96 nsx front: 282dia, 28rotor, 36tall, 70mm hole 14.2lbs.
Rear: 282dia, 21rotor, 32.5tall, 64mm hole 13.5lbs.
97+ front: 297dia, 28rotor, 36tall, 70mm hole 16lbs.
Rear: 302dia, 23rotor, 32.8tall, 64mm hole 15lbs.
- 94-98 Golf VR6, 95-98 GTI: 288dia, 25rotor, 28tall, 65mm hole, 15.8lbs.
- 2003/04 Golf r32: 334dia, 32rotor, 35tall, 65hole, 24lbs.
- 99-04 Golf 1zq, 1lq: 312dia, 25rotor, 34tall, 65hole, 17.9lbs.
If you want to see the centric diagram for any of these you can look it up here...
So when thinking about weight, keep in mind that the stock front rotor is 10.5lbs and that the Jim King rotor is 308min in diameter and with its aluminum center hat and extra hardware is nearly 17lbs. Obviously any rotor that you machine material out of the center will lighten up and there are cross drilled options for many too, but you quickly cross a threshold when going bigger in diameter where aluminum center hats start to make a difference. But for smaller diameters, there are some nice options that are lighter. And if cost is a bigger factor then weight for you and you want diameter, there are some good options there. What's also nice with this list is there are a bunch of actual performance cars in there so you get some nice aftermarket rotor options (at a significant cost of course). Many of those models listed are pricy cars and have expensive part prices but I've found that generally the entry level Centric rotor is pretty cheap at least. Happy hunting, I hope this information helps some of you! If you run across any other calipers, rotors or missing info that you think should be added to this post, speak up and I will make an edit from time to time.