onsdag 14 december 2011

Big Brake update

I have had two adapters water-cut to their basic shape in 20mm steel (actually, they measure slightly thinner than 20mm) and have drilled and milled the first one according to my CAD model and drawing. It does seem to be a perfect fit. Now I have to do the same for the other one and then give them some sort of surface treatment. Galvanizing and painting perhaps?

For the record, the material for the adapters is steel with a yield stress rating of 355MPa. As far as I can remember, my last analysis gave a max von mises stress of 200MPa. And yes, steel is denser than aluminium and my adapters are heavier because of it. But there are other considerations as well. Besides, why worry about the small extra weight from the adapters being made from steel instead of aluminium when I'm adding huge cast-iron rotors anyway.

torsdag 23 juni 2011

Vette caliper modelled

A semi-accurate (hand measurements) model of the vette caliper has been added to the assembly:




before ordering the rotors, which I nearly did, I realized it might be a good idea to see what the guys over at rejsa.nu would say. After all, they have some experience with these sort of things.

onsdag 15 juni 2011

Corvette brake upgrade adapter - second revision




As you can see, I did a bit of work on the design of the C4 brake upgrade adapter. The model of the rotor was modelled from measurements given to me by Art at corvette central. I guess I should be placing an order for those rotors soon now that I finally have the money.



Here we have a slight quirk. Although I consider this design better than the original design mainly because it makes use of the original threads (the original design, which can be found over at pennocks fiero forum or bubbajoe's website, required the threads in the upright to be removed and the adapter threaded to take the M12 bolts) it's not without quirks. I think I will make use of longer bolts and add nuts behind the upright to secure them. Probably not needed, but better safe than sorry.

fredag 6 maj 2011

The virtual guitarbuilding project

If you have visited iguitarer.blogspot.com you might have seen this project. As I've said, this blog is for showcasing my projects and it would be a shame not to mention this considering the time spent on it. These pictures are of the assembly, which is of course the easy part, but they give a good overview of it all.









For more information on this, head over to iguitarer.blogspot.com and search for "virtual guitarbuilding"

tisdag 29 mars 2011

Caliper bracket analysis



As you can see, I put my bracket through the FE analysis of my CAD package. The intention was to get loads to use with the adapter.

So what did I put into the analysis then? Well, for restraints I used the normal type of constraint. The two faces which are in contact with the adapter were locked from sliding along the adapter. On the opposite side, the edge of the hole was locked from moving perpendicularly to the bracket. I realize now that this version is not entirely true as the bolt is threaded into this hole in the bracket. well, I'll see some other day if it makes a difference.

The load was applied where the pad backings make contact with the bracket.

The load was determined by a few calculations. First, I aimed for a stopping distance of 30m (which is unlikely, but something to aim for) which means an average deceleration of 1.3G. I then calculated the balance at this rate of deceleration which gave me the normal forces acting on the wheel. The formula then was:

my x N x D/2 = F x d/2

where "my" is the friction coefficient between tire and ground (1.3 to reach the deceleration rate I aimed at), "N" is the normal force acting on each wheel, "D" is the wheel diameter and "d" is the effective diameter of the rotor. "F" then is the force acting on the bracket.

I calculated F to be about 13.2kN. However, for the analysis I set F to 15kN.

And the end result is the picture at the top.

måndag 28 mars 2011

Putting a stop to it



Behold, my current car project. "What is this?" you ask. Well, this is my take on the Corvette C4 12" brake upgrade for the Pontiac Fiero. This swap was described in detail over at the fiero-forum (fiero.nl) and was an obvious choice. But there were things I did not particularly like about that swap. The major thing was that it used M12 bolts in place of the original fiero (M12 fine) and Vette (M14) bolts, requiring the threads in the fiero spindle to be drilled out. So what you see here is my first attempt at improving the adaper.



So today I got some information from Gus at corvette central regarding the C4 brake rotor dimensions and the difference between the 84-87 and 88-96 base rotor (11,5 vs 12 inch diameter and a difference in offset). Once I had this, I included it in my assembly:





No, that is not an optical illusion. I have a design flaw, causing rotor to bracket interference. Well, that will be an easy fix. I think. I also need to add a wart on the adapter to act as a steering stop.