ianuk

Sorry to butt in here. I've been searching around the web (and here) for the dimensions of the FD (FC) 4 pot caliper (I gather they are basically the same). Failling so far.

I'm interested in whether I can use them for a brake upgrade for an mx5/miata instead of the generally used Wilwood 4 pot billet dynalite. Your caliper appears to be superior and pads are readily available for it in the UK.

Can someone please point me to a dimensioned diagram of the part. Or just let me know the the max hieght (width?) of the caliper above the disk surface and where the max height occurs relative to the disk edge (To check wheel clearance). Also the piston size (to check if enough master cylinder to drive them).

Thanks Ian

RETed

I believe the fronts are 1.30" for each piston.


-Ted

ianuk

Thanks Ted

Oddly I thought I'd had determined (after I posted here)that the bores were 1.42" front and 1.37" rear (taken from 87 techdata on the mazdaformance website. (No FD bore data at mazdaformance). Those data sheets have been wrong before though.

See: http://www.mazdaformance.com/technical2.htm

Also it seems the 87 rx master cylinder is the same bore as the miata/mx5 one (0.785") so there should be enough capacity.

I also noted (in the mazdaformace data) that the FD models are shown as having two different thickness front pads 10.3mm (outer) and 9.3mm (inner). Does this mean that the FD caliper is mounted offset from the disk centre? FC pads seem to be listed as only 11mm. However most aftermarket pad manufacturers seems to sell one size for 86-93 4 pots. Mazdatrix sells 2 OE pad types 86-92 and 93-95 as well as 3 types of OE 4 pot caliper 86-92, 93-94 & 95. Just one rebuid kit for all year though implies all the same bore size.

see: http://www.mazdatrix.com/j-1brake.htm

Anyone got 4 pot caliper external dimension data? I'd be happy with a ruler placed against the disk and a quick and dirty estimate of the max height needed between the wheel spoke and the disk to clear the caliper and where the high point is relative to the disk edge. Looking at photos of the caliper I'm guessing 1.7" clearance required. A 2" figure would probably rule this idea out with my wheels.

Thanks again
Ian

RETed

Yeah, I've been perusing my 1988 Mazda service manual, and all I can find is:
front disc brake
cylinder bore
36.12mm/1.42"
except 14 in. wheel vehicle

I dunno why the discrepency!

I physically measure the brake piston off of my 1987 Turbo II, and it was 1.30" off the dial caliper.&nbsp We were looking for big brake kit options with Wilwood calipers, and we sized them up to a set of Wilwood Billet Dynalites that had 1.36" bores.&nbsp I got them on my car right now, and they SUCK! If the stock bores were 1.42", I don't think I would have this mushy brake problem.&nbsp Wilwood also makes a "step-down" caliper with 1.25" bores, and I think that would've been the better choice right now.&nbsp Who'd have thought a 0.06" increase in diameter would make THAT much difference in pedal feel!



-Ted