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

I like the path of this thread.

I measure 3mm radial clearance on the K1's between the wheel the radial Dynapro calipers. The forged Dynalites require 4.83 mm more radial clearance to fit however. It definitely won't fit without thick wheel spacers.

With the 20mm spacers it gets more tricky. Its right on the raged edge of getting the caliper inboard of the drop section. It will depend on the rounded profile of the caliper, the Dynalight has a bigger radius rounded profile and the fact the caliper is narrower helps.

Whats even more interesting is I put a GenII 6UL 15X9 and it has almost the same clearance but it drops away sooner as you go inboard on the wheel. It will be tight.

The Mini hats I am using have a .83" offset with a .26" thick face. and result in 3mm clearance between the rotor and the tie rod end so you cant go much further inboard with the rotor. I don’t know what Savington is using for those dimensions. The 11" wilwood Miata kit uses .75" offset with a .32" thick face.

Pics of a K1, a K1 with 20mm spacer, and a Gen1 15X8 6UL

Bob

is that the +38 or +32 K1? 15x7? I'm already pretty close with my +38, 15x7 K1s on the Dynalite/corrado rotor combo.

I second that. Very interesting.

On tie rod end clearance... I have non-stock tie rod ends as part of my DIY bumpsteer kit. If they clear the Corrado rotors, just barely but enough, I wonder if I'll be OK with the .83" offset hats with the .26" thick face. I'm using 15x8 Gen I 6ULs right now.

That could be a problem. I measure the Corrado rotors as having a .4875" offset and a .2" face thickness. The Mini rotors are much closer to the tie rods than Corrados. and there is not allot of spoke clearance to the caliper for less offset on the hat unless you run wheel spacers with the 11.75 rotors.

Bob.

I need to carefully measure out and sketch/model my clearances before I buy anything.

It is stamped +38

Bob

Correct me if I am wrong. So this kit from Summit Racing will fit Miata with 15x8 6UL +36 with very little mod ?

ZXtex & Oscar- I can confirm these clear the old 6uls and the +38 Kosei. It's extremely close, particularly on the 6ul. I had to fiddle a little with spacing on the washers used as shims but it works. Doesn't require any modification of the kit to make these fit, just shimming as Bob's cardomain covers. The Kosei you just have to watch your wheel weight placement. With the older 6uls its the spokes that are close, not the rim.



If you want cheap you have to call places. I believe Wilwood has minimum advertised pricing policies. This is the cheapest place I found when I was shopping for the Mini Dynapro set up. http://autofabcart.net/ Have to call or email them for a price. The Mini kit isn't listed on their site but any Wilwood dealer can get them. When I was shopping around a year ago they quoted me around $850 if memory serves. I remember they were over $100 less than Summit at the time.

Good stuff, thanks! That sounds like simple non-offset wheel shim could add some additional spoke clearance if it is wanted. I just need to verify that the rotor will clear my tie-rod setup, which is non-stock DIY to reduce bumpsteer for a non-stock steering rack location due to the non-stock LS1 V8 :)

Thanks cueball. I can deal with a small spacer if needed. Now to find the funds for this :)

This place has good prices and looks like they can customize some parts in the kit like the rotors. The also make allot of there own custom brake kit components for numerous other cars. Which means they might do some custom work. I wonder if you could get them to provide the centering rings needed to mount it on a Miata as well. Or maybe just put together a kit for a Miata.

http://www.tceperformanceproducts.com/mini/kits-16/

$859 for an 11.75” kit with the cheaper straight vane rotors and Radial Mount Dynapro calipers, much better than Dynalites or other calipers typically used based on my personal experience.

Bob

Hi Bob,

This is great info, thanks. I purchased a DynaPro radial mount two years ago for a mock-up, but unfortunately my attention drifted elsewhere (engine = boom!). Wish I had seen your car domain page back then!

Anyway, I've looked in a bunch of different places and haven't been able to find an 11" rotor that would fit those hats (8 x 7" bolt circle). Do you know of any?

Thanks,

Will

I thought the 11" rotor was the VW unit, which doesn't use the hats. Hats were only for the 11.75" rotor rings.

There are BBKs that use Wilwood hats with 11" rotors, like the 949 kit.

No the 11" kits use a smaller bolt circle and less bolts for mounting the rotor to the hat. You could buy the hats they sell with the Miata kit for 11" rotors separately though. I’m not sure what off the shelf hat offsets are available and if they would work though.

It is interesting that wilwood didn’t make hats hub centric for their own Miata kit they use centering rings just like I use to fit the Mini or Honda hats.

Mostly I think going this route is for the serious high hp track cars. There is a major advantage in pad life by going with the Radial Mount Dynapro setup over any of the other calipers. And if that is what you are concerned with you probably want 11.75” rotors anyway.

Bob

Great Info Bob! If they made a kit with the right lines and centering rings, I would jump on it. Seems like we have enough interest here that we should ask them if it is something that they would be interested in.

Thanks again for the info Bob.

My goal is to have these fit with Enkie RP-F1 wheels. I have about 4 sets of them! None of the current big brake kits work with the RP-F1s, which is why I started digging around a couple of years ago. I'm still using stock calipers and have had about enough of 'em. I do not need the thermal mass of 11.75" rotors, but I do want all of the other improvements over the stock calipers, and to have it fit under my 8.8-pound wheels.

I'm familiar with the 6x6.25" hats and know there are plenty of 10.75-11.75 rotors that fit them. Problem is that the closest back-spacing is 0.75", whereas the Mini kits hats are 0.83" backspace. From reading your post, it seems that the 0.75" backspace would require a 3.5mm shim between the caliper bracket and the mounting bosses on the spindle (where you are using a 1.5mm spacer).

As it turns out, a good friend of mine was the original designer of the BBKs sold by the better-known Miata vendors that are selling them now. Custom rotor hats, Wilwood calipers and rotors. His kit was designed to retain the stock rotor offset (~0.81") and the center bore is correct for the Miata, so no centering rings are required (rotor hats are hub-centric). I'm going to re-measure the offset of those hats - he has a few sets and hopefully I'll get a pair. :)

Cheers,

Will

I just called Autofabcart to see how they compare with TCE. They quoted me $883 for the standard 140-8740 kit which includes the GT directional vein rotors. TCE is $959 for the same. Wilwood has minimum advertised pricing policies and $959 is the minimum for that kit, that's why Summit has the same price. Autofab doesn't post pricing, you have to call but it saves you $75 to make the call.

It's nice that TCE can customize it but if you don't care about that give Autofab a call.

Tce
 

I had a couple of email exchanges with Todd at http://www.tceperformanceproducts.com/mini/kits-16/

He indicated that he is willing to offer "the same 'kits' as the MINI (P1 and P2) and supply the hoses and centering rings for the same price structure." Since it is not an officially a kit we are ordering, he stated that "Clearly I'm not hanging my butt out in the wind to read/hear of the problems with it and how I created them...! I'd want assurances from anyone who did it, or you with an order, that what we have put together is satisfactory."

I believe it is reasonable. It saves me from having to track down the centering rings and brake lines. I think I am going to go ahead with this and I thought I would share this everyone.

What I would recommend is the P1 but with HD directional instead of GT directional rotors. It is the same rotor same cost without the slots on the face.

As far as the brake lines goes the ones wilwood sells for the Miata 11" kit work.

Also need
Longer ARP studs ---ARP-AJ3150-1LB (4) ARP 3/8-16-24 stud 3.15” long

3/8” by 3/8” spacers 4 of them. I can’t remember there might be a different spacer combo that would work better than stacking them on top of the supplied spacers like I did.

What I did can be seen here.

http://www.cardomain.com/ride/737924...ta-mx-5/page-2

Todd should thank me at least.

Bob

If 'Todd' assembles this kit, but with no pads (I want Cobalts) for comparable pricing, count me in. So the P1 kit, but with HD directional rotors, Miata brake lines, and Miata hub spacers.

The proper caliper spacers and longer studs would be a bonus if he wants to include them as well, but if not no big deal. I can get them myself.

Bob,

One more questions for you. I just got a note from Todd about the centering ring stating:

"My notes on some old Miata stuff says 55mm or 2.166" but not sure of the year Wilwood tells me the ones they have are 95-05 and have a bore of 3.06 or 77.7mm"

Could you share with us what size bore we need?

Thanks,

1990-2005 Miata hub bore is 54.1mm or 2.12992126".

That is wrong though the hat bore is slightly larger than the wheel hub bore there is another step on the hub for the hat. I don't know for sure what it is. I just took a hub and a hat to my machinist and said make me something that fits.

Might be able to figure it out by searching miata rotors at Rock Auto and looking at drawings. Possibly look up the ring that wilwood uses for the miata on there site they usually have drawings as well.

Bob

wilwood is using hub centering rings as well for theire miata kit part# 300-11653 but I cant find the specs on them. The hat hole is huge for some reason. it is interesting that they use more shim washers for the caliper brackets on a kit designed for a miata than you need with the Mini Brackets on a miata.

http://www.wilwood.com/PDF/DataSheets/ds786.pdf

Bob

I have the 11" Wilwood kit sitting at my house, but unfortunately I don't have any measuring calipers. Let me see if I can borrow some and get the specs on the hub rings.

Can someone provide a list of measurements that are needed?

The measurement that is of the most interest to me is the inner bore diameter of the centering ring. Also the outer diameter of the ring will be nice to have. It is item #5 in the pdf doc http://www.wilwood.com/PDF/DataSheets/ds786.pdf

Thanks for helping.

Checking the drawings for rotors on Rock Auto the ones that give the demension say "hub register" 55mm I bet that is it.

Bob

I will be changing the brakes soon on my Corrado rotor setup. I believe the centering is the same dimensions as what is needed for the Wilwood hats, no? When I have it apart I will measure it carefully with digital calipers.

The Corrado rings weren’t the right size I made that same swap. The Corrado rotors have a really low offset as well.

Bob

Thanks to all of your help, I think I am getting ready to place an order with Todd. He will be getting back to me with a price with everything included, meaning the studs, miata lines, centering rings, spacers, HD rotors, etc.

I am thinking about going with the "Poly B" pads. Any words of wisdom on the pads, Bob or anyone else?

Thanks,

I wouldn't run any of Wilwood's pads - go with a Cobalt XR2, Hawk DTC70, or Carbotech XP12 for the track, or a hawk HP+ for the street.

^ A big +1 on that.

The Poly B pads are definitely track worthy bit abrasive on rotors and don't feel real well until you get them up to temp. Once up to temp they have great feel and consistency on the track but dont last particularly long. They were my track pad of choice until I found better stuff, and becoming addictied to Cobalts.

The BP10 BP20 stuff is about equivalent to Hawk HP or HP+ but you would be surprised how much less heat the 11.75" directional rotors retain than any of the 11" setups. They work surprisingly well.

My favorite pads for the track are Cobalt Friction XR2. I run BP10's on the street and for autocross and put in Axxis ultimate’s in the rear. No problem at all swapping back and forth between track and street pads with the Cobalt’s and no need to bed anything in.

Bob

Here's the link to the Hub Ring pics I took. Couldn't find my camera so cell pics will have to do.

http://picasaweb.google.com/ian.rohd...eat=directlink

Savington, Bob, Zx-Tex, thanks for info on the pads. Cobalt XR2 it will be.

Trackwhore, thanks for the pics. It is always nice to have visual confirmation.

I just placed the order with Todd. He is getting everything for me and it will be here sometime next week. I will let everyone know how everything works out.

I just purchased a set of Dynapro radial mount calipers.

I will be adapting them to my current BBK which is the Chikara one using 10.8'' Sport Rotors.

I will be moving to stop tech rotors from the OEM ones and making this set up as small as possible as I am going to be running 13'' wheels. Stop tech rotors are also lighter and a better design than the OEM's.

Radial calipers were the only way I could achieve this since they are a bit slimmer than lug mount calipers.

I'll post up with results in a few weeks when it's done.

Overall brake diameter will be under 310mm including the caliper. The Panasport C8's I will be using have a barrel clearance of 320mm. :D

I think the caliper you want for that is the PowerLite. I have done a little thinking about smaller as well.

http://www.wilwood.com/Calipers/Cali...name=Powerlite

Then I just noticed this guy which looks like it could have some advantages as well.

http://www.wilwood.com/Calipers/Cali...%20Low-Profile
Bias would be an issue because it only comes with small pistons however.

The standard Dynapro Radial Mount really wants to work on 11” rotors or bigger. I'd recommend you go with the Powerlite radial mount calipers

Bob