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Hi all!

BEC middy builder in Sweden here!

I'm building a mid engined "car-thing" with a Hayabusa engine. Plan is to turbo charge the engine. I've bought a set of uprights (spindles) from a -91 Mazda Miata. Now the part where I'd like some input from you guys in the US:
I intend to use 4-piston calipers. The thing that anoys me a bit are the prices for "custom" calipers, such as Brembo and Wilwood. Some of the Alfa Romeos, and a couple of French cars, are equiped with 4-piston aluminium calipers (supplied by Brembo). They are a bit more reasonable to buy second hand (and the pistons have dust boots, which not many of the after market calipers have). Since I'm building a middy I plan on using 4-piston "front" calipers for the rear axle (center mounted for low unsprung weight). Good weight balance for large stopping powers on all four wheels...

What calipers have you found are easy to adopt to the Miata front uprights/spindles? I understand a lot of you guys use these parts from the Miata?
If it's of any value the design weight is around 650 kg (1 430 lbs).

Hoping for some interresting tips/ideas!

You are using brakes that stop a 1200 kg car and you are concerned about them stopping a 600 kg car?

Not to mention because it's a Middy, the load on the fronts before would have been 7 - 800 kgs under braking on the Miata and now will be 300 kgs on a BEC Middy.

Parts for Alfa's, or any French cars, are in pretty limited supply here in the US...So I don't think you'll have much luck finding people who have done similar here. I believe most people who have upgraded the brakes to fixed calipers on their Miata have used setups based around Wilwood calipers.

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-Justin

"Orville Wright did not have a pilots license." - Gordon MacKenzie

Flyin' Miata does have a new small "big" brake upgrade kit, I'd take a look at that... and as was mentioned, you're knocking 800lbs off the thing, it should stop fairly quickly. The typical US-built 7 with stock Miata parts stops pretty well...

But if you want a cheap 4 piston caliper, I'd hit the local J-yard and grab some Volvo calipers... There were a few that came with them stock, late 80's, early 90's...

You can try looking for RX-7 turbo front brakes or the RX-7 with upgraded brake package. They are 4-pot. Or Porsche. the P..... may be more readily available. Used ones should be relatively inexpensive if they need new seals. The issues with mounting the 4-pots on a given spindle goes away if you are mounting them inboard. No matter what you choose, it will be new ground. Still, I agree with Cheap. 4-pots are very much overkill in a 1400# vehicle. I used them because they were free with my donor and I was going for low-cost rather than performance. Have you planned on using parking brakes if you use a front caliper on the rear wheels?

_________________
Chuck.

“Any suspension will work if you don’t let it.” - Colin Chapman

Visit my ongoing MGB Rustoration log: over HERE

Or my Wankel powered Locost log : over HERE

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+1 on the turbo RX7 calipers (both 2nd gen and 3rd gen) for inexpensive 4piston source. Some additional info: caliper housing is aluminum, the pistons are 1.25" dia and the design rotor thickness is .81". The mounting ears are relatively wide spacing at 6.25".

Older model Jag sedans (Series III and back) had inboard brakes which might work for your project. I don't think they were 4-piston calipers, however. Perhaps the rotors and mounting system would work, coupled with s set of the 4-pot calipers suggested earlier.

JDK

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JD, father of Quinn, Son of a... Build Log
Quinn the Slotus:Ford 302 Powered, Mallock-Inspired, Tube Frame, Hillclimb Special
"Gonzo and friends: Last night must have been quite a night. Camelot moments, mechanical marvels, Rustoleum launches, flying squirrels, fru-fru tea cuppers, V8 envy, Ensure catch cans -- and it wasn't even a full moon." -- SeattleTom

RockAuto.com has rebuilt RX-7 front 4-pot calipers for as low as $35 bucks each right now. That is CHEAP! I mean Locost. You can't buy used ones on eBay right now for less.

_________________
Chuck.

“Any suspension will work if you don’t let it.” - Colin Chapman

Visit my ongoing MGB Rustoration log: over HERE

Or my Wankel powered Locost log : over HERE

And don't forget my Cushman Truckster resto Locostusa.com/forums/viewtopic.php?f=36&t=17766

Yupp, Volvo calipers would be an alternative. Function wise they're very good, but living in "Volvo-land" and having worked on quite a few I know they weigh a lot ... casted steel.

Wow! You can't find the parts unless you know year of manufacture? How do I find the calipers?

You all have a point in pointing(!) out that the weight is very much reduced! That alone will reduce the amount of energy the brakes need to absorb. However, the energy to be absorbed is proportional to the square of the velocity (double speed = 4 times the energy). Since I do intend to use the car on track as well I'd prefer "more than enough" stopping power. 1440 lbs and +300hp will be able to provide for quite some speed approaching corners and who wants to brake first!?

By the way, servo is out of the question.

And I would never admit that "showing of with my neat 4-piston calipers" has anything to do with it ...

Look up 1991 or '92 RX7 Turbocharged. Make sure you are looking at the 4-pot versions. There are pictures.

In my original post, I forgot to include the core charge. The Nastra rebuilts outright are $72 each and A-1Cardones are $83 each outright.

Another thought is you could go to RX7Club.com and search their for sale section. Last set of used 4 pot brakes I saw sold for $55 for the pair.

Advanceauto.com has the rebuilt 4-pot calipers for $70 each outright plus you get free shipping and 15% off if you order by 9/28. That works out to $119 for the pair delivered

_________________
Chuck.

“Any suspension will work if you don’t let it.” - Colin Chapman

Visit my ongoing MGB Rustoration log: over HERE

Or my Wankel powered Locost log : over HERE

And don't forget my Cushman Truckster resto Locostusa.com/forums/viewtopic.php?f=36&t=17766

Yes it is, now take in the weight factor and bingo, you're back to standard Miata calipers.

Another bonus is Miata racing; I'm sure they have pad material well sorted out and readily available and that's just as important as the caliper itself.



Why is that?

For the budget conscious, you can also still improve the braking capacity via direct bolt-on components too...The 1.6L NA Miata have 9.24" (234.7mm) diameter by .71" (18mm) thick rotors that weigh a scant 8.50lb. But it is apparently possible to upgrade the system to the 1.8L NB Miata "Sport" brakes that are 10.61" (269.5mm) diameter by .87" (22mm) thick vented rotors that give you 12.87lb of heat absorbing mass.

_________________
-Justin

"Orville Wright did not have a pilots license." - Gordon MacKenzie

Using a turbo charged bike engine (Hayabusa) doesn't provide much vacuum and a "vacuum unit" with hoses and stuff does add weight and requires space. Besides, with the low weight it's not required in order to get the car street legal where I live.

Double speed => 4 times the energy. Reducing the weight by 50% reduces the energy by 50%. Hence double speed and half the weight gives twice the energy?