Zettner-type brake bracket drawings

[pmbrunelle]

I would like some of these.

Anyone have some that they would like to share with me?

[pmbrunelle]

I had some brackets that I purchased ready-made years ago, but they needed to be redone for a number of reasons. Minor design issues I didn't like, threads I managed to fubar, and some out-of-flatness...

Anyway, I found this reference:
https://www.fiero.com/forum/Archives/Arc ... 48366.html

I ended up taking my own measurements, and in conjunction with my own measurements (mostly relying on my own), I decided to draw up my own.

I did a first revision in "rapid prototyping" this weekend, cut out of PVC foam plastic on a CNC router table.

Brackets.JPG (433.53 KiB) Viewed 2061 times

Rapid prototyping is fun! With some minor adjustments, I'll be able to jump straight to ordering the metal version. I'll probably try sendcutsend... and I'll likely try their zinc plating service for mild steel.

Problem solved!

[Shaun41178(2)]

Interesting. It def pays to know how to do this stuff

[pmbrunelle]

From online file upload to delivered on my doorstep, there was a delay of 12 days. Not bad.

IMG_7235.JPG (488.65 KiB) Viewed 1892 times

I countersunk all the holes because it makes for a better threaded hole, and on an unthreaded hole, to prevent a sharp edge from biting into the bolt shank-to-head fillet radius.

I had to slightly file the caliper opening; the caliper didn't float nicely. If I order more, I'll increase that gap slightly.

I noticed that some of the zinc plating chipped away near the countersinks. Machining after plating can be problematic sometimes. I had already learned this lesson, but then I forgot about it, and then I relearned it this week!

IMG_7236.JPG (516.71 KiB) Viewed 1892 times

[ericjon262]

I'm glad to see you were able to make progress on this, it's unfortunate that the zinc chipped, that said, zinc electroplating at home isn't too hard if you want to re-plate them.

[The Dark Side of Will]

You'll need to use the S10/Seville front calipers, as the 3rd Gen F-body calipers have a projection that will interfere with your front bracket.

[pmbrunelle]

I'm glad to see you were able to make progress on this, it's unfortunate that the zinc chipped, that said, zinc electroplating at home isn't too hard if you want to re-plate them.

How have you managed threaded holes so far?

Tap then plate?
Tap then plate then tap again?
Plate then tap?

These brackets should still last a while, as the zinc plating does not need full coverage to provide the sacrificial anode effect. I may redo them in a few years, but I'll run them as-is for now.

You'll need to use the S10/Seville front calipers, as the 3rd Gen F-body calipers have a projection that will interfere with your front bracket.

I drew the inside contour of the front caliper brackets to follow the shape of my Wilwood 120-11872-RD calipers:

Front brake bracket.jpg (289.5 KiB) Viewed 1845 times

I chose these Wilwood calipers largely because they have a piston area of 4.12 in^2.

My rear parking-brake Seville calipers have a piston area of 3.55 in^2.
https://www.realfierotech.com/viewtopic.php?t=21782

I would have liked equal piston areas, but I think the Wilwoods are "close enough".

The S10/Seville/F-body calipers with 2.5 in pistons have an area of 4.91 in^2. I think that this is way too much area if used with Seville rear calipers.

Perhaps at some later time, if I really want a more "square" brake setup, then I'll run more of the same Wilwood calipers in the rear, in conjunction with a drum-in-hat parking brake setup.

[ericjon262]

I'm glad to see you were able to make progress on this, it's unfortunate that the zinc chipped, that said, zinc electroplating at home isn't too hard if you want to re-plate them.

How have you managed threaded holes so far?

Tap then plate?
Tap then plate then tap again?
Plate then tap?

These brackets should still last a while, as the zinc plating does not need full coverage to provide the sacrificial anode effect. I may redo them in a few years, but I'll run them as-is for now.

I haven't tried plating a threaded hole yet, that said when (if) I do, I would tap, then plate, I don't think the thickness of the plating would have an impact on the thread fitment unless you plated them for a really long time.

[zok15]

Patrick are you using the Seville calipers with Grand Am rotors? If so would you be willing to share your CAD files (or dxf) (or even just a drawing with dimensions) for the brackets used? Currently have Grand Am stuff on all 4 corners and a Blazer MC, no ebrake. I have some Wilwood spot calipers I was planning to use for a parking brake solution, and ultimately will still use at some point (probably with a custom knuckle or part of a bracket to mount a Wilwood rear caliper), but it is going to take a decent bit of fab and all custom cables to work properly (already bought brand new AC Delco ebrake cables), and the brackets used to mount them in my current configuration are not going to be very strong (see WCF solution with the Wilwood ebrake calipers, these are same calipers I have https://westcoastfiero.com/products/e-b ... -1984-1987 )... I would much prefer to have an intermediate setup with the Seville calipers so I have a usable emergency brake and not just a parking brake, I have had to use the emergency brake before and boy was I glad it worked as I sped without brakes towards a stop sign intersecting a busy road with 40mph speed limit.

[pmbrunelle]

My brake setup (car not presently running) is for LeBaron rear rotors at all four corners.

Nevertheless, you can look at my CAD file for inspiration/reference:

STEEL BRAKE BRACKETS REV 02.zip

(9.89 KiB) Downloaded 62 times

Here are my personal notes in in relation to what I ordered:

STEEL BRAKE BRACKETS REV 02 NOTES.zip

(399 Bytes) Downloaded 73 times

Note that in my drawing, there is a 10° rotation between the Fiero caliper mounting ears and the Seville caliper. Kohburn came up with the idea; 10° seems to work OK. This allows the Fiero brake cable to pass nicely beneath the CV joint boot.

If you want to use Seville calipers upside-down, check out my banjo bolt bleeder thread:
https://www.realfierotech.com/viewtopic.php?t=21782

The rotation angle of the caliper will have an effect on the ability of air bubbles to rise and be forced out of the caliper during bleeding.

In my CAD drawing, for the purpose of interfacing with the Seville caliper, you should mostly focus on the red circled area of my drawing:

Relevant area.JPG (109.88 KiB) Viewed 1534 times

I think this part of the drawing is fine, besides the gap between flat faces (see my notes file).

In my drawing, the origin of the file is located at the centre of the rear brake rotor.

CAD Screenshot.jpg (33.93 KiB) Viewed 1534 times

You can count on the Fiero caliper mounting hole positions as being reasonably accurate relative to the origin. I measured them myself. I am quite confident saying that they are within +/- 0.010" of the truth, if not +/- 0.005". Accuracy of the distance between the two holes is within about +/- 0.002".

Arns85GT on Old Europe had Seville calipers with Grand Am rotors.
https://www.fiero.com/forum/Archives/Arc ... 65677.html
No more photos, but nonetheless, it's still information.