Need solid rotor brake calipers

As the title states....I'm thinking of using a solid rotor on the front of my challenge car to save weight and rotating mass. The car is a 1973 Corolla , so it came with solid rotors and fairly small calipers stock. If I wanted a larger piston for a solid rotor what's available in junkyards that might work? If I can salvage the Corolla calipers , I will, and they'll be on considerably larger diameter rotors, so it might all work. I'm assuming that a normal front caliper would allow the pads to fall out with the thinner rotor. Any ideas? 

VW Vanagons used a solid front rotor and (I think) a 2" piston. You're right that you'll want a caliper designed for a thinner rotor.

Why do you want a larger piston?

Datsun z car.

Miata rear, mazda5 rear

Toyota 4x4 from the early 80s was 4 piston solid rotor

Samurai front brakes and 4AF(E)-powered Toyota AE9x/10x front brakes are solid rotor, but those aren't great candidates for junkyard availability these days.

Dusterbd13 said:

Miata rear, mazda5 rear

This goes back to the "why do you want a larger piston?" question. The Miata rear has either a 1.25" or a 1.385" piston which is awfully small for a front caliper. You need to start by identifying the piston size first. Unless you're redesigning the whole braking system, the easiest way to do this is to simply match the piston area of the original. Go bigger and you'll have a soft pedal and may run out of travel in extreme cases. Go smaller and you'll have a hard pedal and may not be able to generate full brake torque.

For the Challenge, I don't see the benefit in doing a big brake kit or messing with piston sizes unless the base car has a specific problem. It's an autocross, which doesn't usually get into heat management. Just get a set of aggressive pads that work from cold and spend your time on something else.

In reply to Keith Tanner :

I haven't even looked at the Corolla pistons yet. I'm ASSuming they're relatively small, given the original weight and power of the car. They're seized on the rotors, too, so may need to be replaced. I'm looking at putting the complete front suspension from a late NB on the car and I've got the larger diameter front and rear rotors already. I noticed the weight difference and started trying to figure out a lighter setup. 25-30 years ago it was common autocross practice to put base model brakes on cars like Civics to reduce the weight, so I thought I'd give it a try. The default position would be to just install the stock Miata front rotors and calipers. My parts pile didn't come with any calipers or caliper brackets, so anything I do will be a budget hit.

Also, I will probably have to put a  larger rearend in the car, so the rear brakes will change ,too. Getting everything sized right will be some work.

E36 rears are solid but I don't know the piston size.  Or the rotor size.  What are you gonna do about brackets?

In reply to JBasham :

I'll either go with the whole stock Miata setup, or fabricate brackets for whatever calipers I get. Obviously, the "easy button" is make it all stock Miata.

Datsun z cars do.  I’m not sure the bore though.  It’s not good timing or i’d give you mine.  Not quite ready to do my brake upgrade yet.  

Autozone actually lists the Corolla calipers. So, if I can find the piston diameter the easy thing may well be Corolla calipers on Miata rear rotors. Just need to fab a bracket. 

In reply to Patrick :

Datsun Z has a solid front rotor ? Calipers might be an option then.

According to the info on Autozones site the Corolla piston bore is 1.9374". Bigger than I expected.  NA Miatas are 2.01" . Might be good enough.

If you're willing to go so far back as Zs, you might also look at Mk1 Capris.  They had solid front rotors with two piston (non sliding) calipers.

pkingham said:

If you're willing to go so far back as Zs, you might also look at Mk1 Capris.  They had solid front rotors with two piston (non sliding) calipers.

Getting calipers for a Capri could be a problem.  RockAuto lists remans but also notes "Out of Stock" for all of them.

How do I know this?  I'm rebuilding a Capri as part of a "get it back on the road after 25+ years in a garage". It's a friends car, not mine.

I'm rebuilding the ones I have BTY.

Keith Tanner said:

 You're right that you'll want a caliper designed for a thinner rotor.

in the sake of challenge shenanigans would it be a terrible idea to make some kind of spacer that went between the caliper piston and brake pad to make a modern caliper for a vented rotor work on a thinner, solid rotor?

In reply to edizzle89 :

The inner pad will slip off the end of the slider area and fall out of the caliper before it actually contacts the rotor. You MIGHT get away with it with brand new pads because the rotor thicknesses differ by 12 mm and new pads MIGHT be thick enough to not fall out. BUT, I won't be the one to try it out.  

I'll have to get the Corolla caliper off the car and do some test fitting of caliper, wheel and rotor. The Corolla calipers are an odd shape and protrude from the rotor face more than the Miata caliper.  Other differences are Corolla MC is 11/16, my Miata one is 15/16.  Rear brakes will almost certainly remain drums. Keith's point about getting everything to work is certainly in play.

Pretty much anything British with disc brakes will have a solid rotor.

Front and rear disk brake rotors are solid on a 914.

DeadSkunk said:

According to the info on Autozones site the Corolla piston bore is 1.9374". Bigger than I expected.  NA Miatas are 2.01" . Might be good enough.

I'd call that good enough. I've found that most manufacturers end up pretty close on the front.

Useless info:    The 83 and 84 Rabbit GTI's used the same calipers as the regular rabbits but had vented rotors instead of solid so the GTI pads are thinner to fit the wider rotor. Used to cause a lot of trouble at the parts stores way back when    :/useless info

In reply to Jumper K Balls :

Not useless info. This means a Rabbit set might work in my application. I still may need a junkyard solution if the Corolla units happen to foul the wheels. Anything other than the originals will be a budget hit, per Challenge rules.

240 Volvo had both vented and non vented up to about 1980.  Calipers were 4 piston.  

 Like Keith Said spend Time And Money on the Car not so much Brakes. If you make them Good as New and Lighten the rest of the Car they will be OK on a Short Course.  Get to the Show,  do things like these Mods AFTER the Challenge, Next Winter!

you could weld a second set of backer plates from a used set of pads on to a new set of pads. This would give you the 12 mm you are looking for.