Radial mount caliper discussion
 

This thread was broken off from savington's 11.75" rotor discussion, please keep on the topic of radial mount calipers here, and rotor clearance and interest in new brakes in the other thread. Good stuff in here.

~curly

There shouldn't be a problem with the brackets should we decide to use the dynopros, right?

Radial or welfare class mounting?

No, should be no problem. The lug spacing between the Dynalites, Dynapros, and Dynapro6s are all the same, assuming you are using the lug mount caliper.

And before it's asked again, we won't do a radial-mount design because the spindle is still lug mount, which negates any major stiffness advantage the radial mount provides. In order to do a true radial-mount setup, you'd have to redesign the spindle.

Dynapro Lug mount not the same as a Dynapro radial mount. In my opinion the extra cost of the Dynapro Radial is more than made up for in brake pad life due to the thicker pads as well. Wilwood already makes an off the shelf bracket that fits them to a miata, the ones made for a Mini are a direct fit and the same bracket can be used with either 11 or 11.75” rotors by changing some spacers and the mounting posts.

Dynapro Radial
http://www.wilwood.com/PDF/Flyers/fl119.pdf
6.57” outside radius on a 11.75” rotor, 1.96" into spokes from rotor face

Forged Dynalite
http://www.wilwood.com/PDF/Flyers/fl104.pdf
6.76” outside radius on an 11.75” rotor, 1.71" into spokes from rotor face

Dynapro4 Lug mount
http://www.wilwood.com/PDF/Flyers/fl195.pdf
6.76” outside radius on an 11.75” rotor, 1.67" into spokes from rotor face

Dynapro6 Lug mount
http://www.wilwood.com/PDF/Flyers/fl205.pdf
6.78” outside radius on an 11.75” rotor, 1.64" into spokes from rotor face

Bob

I agree. After researching it a bit and talking with Shandelle (V8R), we decided we would need a different spindle entirely to reap all the benefits of a radial mount. He's working on a new version of the spindle protos we have been messing around with for a few years now. At some point, we may have drop spindles with radial mounts. As they're swamped with other projects, that could be a year from now though :(

fap fap fap

I don't get it; an adapter bracket has two fasteners that mount it to the spindle and two fasteners that mount it to the caliper. The overall design of the bracket is important to the overall stiffness, the orientation of the fasteners however has pretty much nothing to do with it. No little flexy ears sticking off a radial mount caliper either and the longer through bolts make a stiffer connection between the caliper an the adapter bracket on a radial mount caliper.

FWIW I have spent a good amount of time reserching and analyzing, testing and correlating analysis to testing the stiffness of different bolted connections in structures as an engineer and a structural analyst.

Eliminating the adapter would be better but if you have an adapter it is what it is and the radial through bolt attachment to the caliper is still better.

Bob

I am in complete agreement with Bob. FWIW I am also a Mech Engineer that has done some structures work.

OK, wait a minute, if there is already a radial mount caliper adapter bracket for the Miata, then all it needs is some spacers and maybe longer bolts/studs for the caliper. If this is true, this bracket is already done. Holy shit Bob. I am looking for the kit and/or brackets now.

EDIT: This?
http://www.mini-madness.com/mini-coo...brake-kit.aspx

Notice the post date :facepalm:
http://forum.miata.net/vb/showthread...highlight=mini

And here I was about to try to make my own radial mount bracket for my '94, for the reasons Bob mentions above. And wondering what rotor offset I need. Geez.

I have an SV650 with GSXR front forks; I did the conversion. It has the later style radial mount calipers. I got a deal on a GSXR front wheel that had some very nice aftermarket 320mm rotors. Stock GSXR for these forks is 300mm. All I had to do was shim the calipers to compensate with some Lowe's Racing washers. Easy mod, track tested, works great. That mod is geometrically analogous to this situation. Need to change rotor size for whatever reason? Just add/remove caliper shims. Done.

My Car Domain page on it. I did this in late 2005 so I have had it for a while now.
http://www.cardomain.com/ride/737924...ta-mx-5/page-2

Note: there are two sets of wheels I have that fit tight enough they won’t work with anything but the Dynapro Radial mount with 11.75” rotors. Kosi K1’s and the Sprint Hart CPF’s would not fit with a Dynalite. I think the 949’s would but I don’t have the calipers to verify that any more.

A pair of caliper brackets by themselves with hardware 250-8694 which can be used to mount dynapro radial mount calipers on a Miata are $136.95 from summit racing.

http://www.summitracing.com/parts/WIL-250-8694/

Calipers are much more expensive than Dynlites $203.95 each. Whereas forged dynalites are $124.95

http://www.summitracing.com/search/?...120-8538&dds=1

You can look up any wilwood part number for pieces of any kit and buy it from Summit. Wilwood generally gives enough info you can figure out what fits. Do a lot of research and it is like playing with a Lego set to come up with stuff.

Bob

Bob, once again, you are the man. I do not mind spending more on the calipers because there are benefits to doing so. And, there is no way I can beat $137 for brackets (buy versus DIY) when considering what my time is worth.

Sorry to jack the thread.

There Is some minor mods. The 10mm mount holes in the spindle need to be upped to fit 7/16" bolts and I used some thin washers to get the right lateral spacing centering the caliper over the rotor. My car domain page describes the parts for the longer ARP studs.

Bob

Yep I saw that on your cardomain page. Thanks

I think you are assuming we would use an adapter if we did a radial version of the spindle, which we wouldn't. Caliper would bolt directly to spindle as the Lord intended.

I never graduated high school and used the calculator on my droid to figure that out so I win.

I said not using an adapter would be better. But we are not making new spindles here yet.

Using a lug mount adapter to a lug mount caliper is no better than using a lug mount adapter to a radial mount caliper however. And the fasteners that connect the radial mount caliper to the adapter are better than the fasteners that mount through a lug mount caliper with aluminum ears on it to an adapter. Fasteners that are longer and pass all the way through the body of the caliper are inherently better weather it is mounting it to an adaptor or directly to the spindle.

I have personally done experimental and analytical research on different bolted joint connections with different geometries studying stiffness in terms of both natural modes and force versus deflection. The effort was used to develop better methods for modeling simulating the behavior of bolted assemblies with linear FEA models.

My cell phone sometimes rings when people call me.

Bob

I think bob is saying that a half radially mounted caliper is better than a completely lug mounted caliper, if you can't have new spindles. My buddy had a source for new spindles, so he could fit corvette c5 rotors and calipers on his firebird. Wheres the love? Apparently in the works.

I'm still in agreement with Bob.

Cheapest place I have found for wilwood stuff is Summit racing
http://www.summitracing.com/parts/WIL-140-8740/

11.75" Race kit. $959.99 kit minus lines. you can just buy the miata lines from the miata kit.

$150 cheaper for the 11.75” race kit than from Mini Madness. Ideally in my opinion it would be better if it came with HD rotors instead of GT rotors with slots though.

Bob

Agreed. In fact I was thinking about piecing it together myself since I can eliminate the kit's pads and rotors and get what I want. I found a Wilwood illustrated parts breakdown (IPB) for the Mini kit and the caliper part number from that matched what you posted previously. 1.63" pistons IIRC or whatever the smaller ones are.

But for some reason, when I search on the part number in the IPB for the Wilwood hat, I cannot find it at Summit or anywhere else really. Do you know what a good part number is for the hat and/or know the offset offhand?

? The mini 11.75” race kit 140-8740 comes with Dynapro Radial calipers 120-8538. They are stainless pistons calipers rather than the aluminum pistons with dust boots they put in the 12.19" street kit and the diameter of the pistons is 1.38”

I have been using wilwood calipers with these pistons and no dust boots on the street and track for ~10 years and never had an issue with them not having dust boots.

hat part # are 170-10650 $124.95 each from summit
http://www.summitracing.com/parts/WIL-170-10650/

The BP10 pads that come with the kit work real good for me as street and autocross pads. They are cheap too. put in Axxis ultimites in the rear. Cobalt friction XR2 all around goes in for track duty.

Bob