I have been doing some technical drawing homework. Its for that pounded idea of a brake upgrade.
There is one dimension I need to find before even trying to get stuff together. It should have been an easy one. Should have been able to find it on the net, but not so lucky. Can't pull my car apart right now. It has become my daily.
However the dimension I need is the distance from the center of the front spindle to the center of the caliper bracket bolt holes.
If someone has a spindle off a car this would be a simple measurement.
If that number works with some of the research and other math I have done, I will describe what I have in mind.
It involves newer, popular, relatively cheap aluminum caliper, bracket and pads. Popular rotor. And still keep a 48mm diameter piston.

We need to know you are talking about the 84-87, or the 88, which is completely different....I have the 84-87 in the back yard...If that is what you're looking for I can get it.

You are probably more interested in the 84-87, but I happen to have a couple of 88 front spindles lying around. It's not the easiest thing to get a really accurate measurement, but I got 3.22" from the center of the spindle to the center of the holes (they are both the same length). The red line on the pic below shows the measurement I was taking...just so there is no confusion.

Neils88 that is what I need but for 84-87.
Have to look, but I think there is a center drill point in the rear of the spindle shaft. Where they would set it up in a lathe while turning.
From that center, to the center of one of the caliper bracket mounting holes.
Measured the caliper, bracket with pads today, that i am trying to use.
The caliper application calls for a rotor that is 11.4" with working thickness 18.5-20.5 mm/ Which works very close to the LeBaron rotor.
However the measurements I had taken today shown. Pad maximum 26mm with new pads. 26 mm between hardware and 27.5 between the bracket. Which makes up to a 24mm width rotor possible.
This makes for a lot more options. Though the centers would have to be machined, there are several Toyota and Subaru rotors that fit the bill. 275-312mm diameter 10.8"-12.2". With hat depth within 4mm of the 9.7" Grand AM hats.
The pad surface is close to stock Fiero. Maybe 5% less, but thicker and without the odd "ears" on the outer pad. Also the caliper does not hold the pads, the bracket does. This setup tends to wear better in my many years of observation.
The bracket mounting holes are 76mm (very close to stock Fiero) apart and 62-65 mm usable area from the center of the mounting holes to the outside.
10mm offset to the outside on the brackets.
Depending on the curvature of the pads and the distance of the spindle center to caliper mounting points, this may be an easy swap for the GM Grand Am, Berreta performance rotors at 10.25
However the caliper bracket is not tapped and would need to be and the Fiero caliper bracket threads drilled out for a spacer bolt on.
The calipers and brackets fit rear S10 from 1998 to 2003. All have 48mm pistons. Some use staggered arrangement so you would need to make sure to get non staggered application. Varies by year and 2WD and 4WD.
I had did some preliminary measurements off a 2001 Blazer 2WD last week. They were non staggered (proper bleeder arrangement left/right).
The one thing that may not make this work is the brake line interference.
[URL=http://www.ebay.com/itm/Completely-New-Rear-Right-Brake-Caliper-18B4713-fits-98-04-Chevy-S10-Olds-GMC-/172252298578?fits=Make%3AChevrolet%7CModel%3AS10&hash=item281b097d52:g:zVQAAOSw4DJYf1vF&vxp=mtr]http://www.ebay.com/itm/Com...AOSw4DJYf1vF&vxp=mtr[/ URL]
Some other stuff those spindles were used on. http://ozgemini.com/forums/...328&highlight=fiero.

[This message has been edited by cmechmann (edited 01-31-2017).]

I just went down in the basement and was able to measure it; I used a cheap manual caliper, but then carefully compared to a metric ruler- and I did measure both to make sure they are, A. the same and B. That I wasn't screwing it up....2.81" or 71.5 mm.

Just pounding a few numbers.
If those numbers are right it looks like a 273mm/10.75" rotor would be on order. I think the radius of the S10 pads will work down to that. Just over .50" difference or near .25" for half the diameter.
With the added room or easily cutting the outside diameter of the rotor a 275mm/10.82" looks like it would also work.
Now this is also with only using spacers and not an adapter, being both the S10 caliper bracket and the Fiero spindle to caliper bracket bolt holes are near 76mm. Not confirmed but seen 2 different reports for the Fiero dimension. One being 77mm/3.03" and 74mm/2.915". The caliper bracket would need to be tapped and the Fiero spindle threads drilled out. Which should leave enough "wiggle" room to have it bolt on. With just spacers and no adapters, it is not likely that there would be brake hose interference. Further reading from some adapter manufactures shows 2.98"/75.6mm-2.992/75.9mm. Even closer to the 76mm I measured on the S10 brackets.
Now for some other numbers. There have been many successes with the rear Lebaron rotor on front of Fiero.
These numbers are going to be total rotor height.
The LeBaron rotor height is 51.5mm/2.03". But about 8mm of the is the inside of the drum and not measured at the inside of the rotor surface. So it is closer 42mm/1.6" With the S10 calipers would need an adapter to make it work for the larger diameter.
The (Grand Am, Berreta, etc.)GM 9.7" and 10.2 vented height is 48mm/1.89" Won't work. can adapt out, but adapting in makes for a whole other slew of issues.
Front Celica from 02-05 and Corolla 1.8 03-08 Matrix/Vibe 1.8 03-08 use a rotor 275mm/10.8" 49.3mm/1.94" (the more the better) height.
22-24mm width
With 5x100mm bolt pattern. But the center bore is only 54mm instead of 57.1. Just under 1/8" difference.
There is also front Legacy and Outback non turbo 00-09 with rear drum that is 276.5mm/10.89" (would need to cut) but has 56.7mm/2.24" height. Also the center would need to be opened 3.1mm.

Looks like enough close numbers to go to a pick&pull to start mocking up.
good pdf fot rotor numbers. http://www.duraintl.com/pdf/Drum-Rotor_Catalog.pdf

[This message has been edited by cmechmann (edited 02-01-2017).]