How much Wilwood flex is normal?
 

Has anyone ever looked to see how much their Wilwoods are flexing? Have you noticed flex or crappy pedal feel?

My pedal has felt like crap since I moved to Wilwoods up front. The pedal feel has been very vague, kind of soft at the top and seemingly bottomless. I never hit a hard bottom of the pedal. The pedal does firm up, but it never bottoms.

Wilwoods up front, stock 1.8 calipers in the rear, Wilwood proportioning valve in-line to the rears.

The system has been flushed & bled many, many times. The stock 7/8" master and booster were swapped out with another stock 7/8" master & booster, and I haven't noticed any change.

I just put in a 1" master and larger booster, but won't be driving the car for a few weeks. In the garage, the pedal feel seems about the same.

Thoughts?

What are your pads and how thick are the rotors?

0.81" Wilwood rotors front, stock rotors rear.

Pads are Cobalt Friction XR2 Front, XR4 Rear.

I run DTC60 and a sport master and booster...the brakes feel epic with no flex. You probably have a bad bleed or bad rotors. Ever since I started reverse bleeding after lines went dry, I will never go back to a conventional "top-down" bleed on a dry line. Are you bleeding off all 4 bleeders?

^^That gives me hope.

I use both top bleeders on each caliper for bleeding. Start with the outer, bleed the inner, then the outer again on each caliper. What do you use for reverse bleeding?

The rotors are good, and have like-new thickness of 0.80".

Here's a shot of the driver side caliper flexing. The caliper 'bows out', with slightly more movement on the outside portion than the inside. Pressure being applied is approx 1,000 psi (I have a brake pressure sensor on the line).

Seems like a lot of movement, considering that the caliper is not supposed to move relative to the rotor, and it's not. All the 'movement' is actually the caliper flexing.

http://www.vimeo.com/29330603

When you assembled the caliper to the mounting backet, did you properly measure the gap between the pistons and rotor and make sure it was even on both side and/or shim the caliper on the backet to ensure the caliper was dead-center over the rotor? If it's off even 0.5mm, the caliper will flex as it centers itself to compress the pads evenly. I'd imagein you checked this, but one never knows. I had to add one more "shim" (washer) to the caliper -> bracket area to properly center it over the rotor.

Shouldn't the pistons even out any difference?

Bench-bleed the master cylinder.

Is that a Dynalite or Dynapro? I think the cheaper Dynalite may be stiffer. I don't feel the flex. However, Stoptech is supposedly making a Dynalite replacement caliper, we'll see if it ever goes to market.

Or reverse bleed. I use an old Motive bleeder with a smaller hose and a zip tie. This will also evacuate air from the master so you don't have to bench bleed. Remember to "tap shit with a hammer" when you bleed.

Thanks for the tips.

The master was bench-bled. A 'new' master was swapped in, and it was bench-bled too.

Finally, the new 1" 929 m/c went in, and it was also bench bled beforehand.

The calipers are centered on the rotors, but not perfectly so. I figured the same as Curly, that the pressure would even things out, no? Wouldn't the fluid take the path of least resistance?

That said, I test fit everything on a bench using a spare spindle. The calipers seemed more centered on the test spindle than they do on the car now. At the very most, I'd say they are off by 1mm total. I'll take a closer look at the bracket spacer I'm using.

So, has anyone actually looked closely at their calipers with someone stepping on the pedal? I haven't seen any flex on the stock calipers, but the Wilwoods bow out quite a bit.

I could be wrong, or I could be misinterpreting what I'm seeing, but it seems that the pedal gets pushed down at a smooth, linear rate. The pressure also builds at a smooth, linear rate, and the micrometer also sweeps in a smooth, linear rate. That indicates to me that the hydraulic system is working correctly. No big air bubbles or issues. The pedal force directly corresponds to the flexing of the caliper:

http://www.vimeo.com/29410003

I spoke with Wilwood and they said that some flex is acceptable. According to the rep I spoke with, the DynaPro is stiffer than the DynaLite, and the Radial DynaPro (or any radial mount caliper) is significantly stiffer and less prone to flexing than lug-mount calipers.

Have you checked the snugness of the caliper housing bolts? I'm sure if they were loose you'd have a lot of leakage though. Cool video really. .020" is nothing though.

It's the third law, for every action there is an equal and opposite reaction. The fluid is pushing the piston which is pushing on the pad. The pad then pushes back on the piston, through the fluid, and against the caliper body.

What brand brackets do you have?

FTR- My Wilwood 11" kit (all Wilwood componants) has some flex. I saw this when I was bleeding the calipers and someone else was pumping the pedal. I did have to add 1 shim (provided with the kit) to reduce the movement (thinking like Curly, that a little off would be self corrected). So far, I have not noticed an adverse effects of the flex since putting the brakes on.

The brackets are made by Wilwood - the ones designed for their MINI kit.

In the video, it looks like the dial indicator's stand moves a bit as does the rotor. The test rig could have been setup better. I'd say that the actual maximum flex is 50-100% more than the dial captured. It may not sound like much, but considering that the same amount of flex happens at both calipers, and that the flex more than doubles at on-track temperatures, it adds up. Adding it all up, total flex is likely 2-6mm under race conditions.

All of the bolts were tight, except that there were only 2 lugnuts holding the rotor in place. I loosened the bracket/spindle bolts and caliper/bracket bolts yesterday, then with someone standing on the pedal, I torqued down the bolts. That appears to have squared things up a little, but it was at the end of a long day and I was getting tired.

The spacers I am using for the bracket/spindle mount were machined down 0.035", which should center caliper on the rotor better. Next step is to put it all back together then start on the passenger side.

The Wilwoods are definitely flexing, but perhaps there is something else going on too.

Some observations;

Flex is common on all calipers and based upon line pressure, piston area and caliper construction.

The DPr is not a hardcore racing caliper. It's an enthusiast level part capable of light to moderate track use when fit with proper pad. You're using it because you wanted a compact fit on a smaller rotors and it's in good company there. A larger body caliper such as the FSL or W4A will prove much stiffer for the same input pressure simply due to its size.

DESCRIPTION



The larger the piston, or smaller the master, the higher the line pressure. A 7/8 bore generates pretty high pressure and if you are recording line pressure of 1000psi and expect to see that on the track, it's not happening unless you have a really bad choice of pad in it. Or you're already in a skid headed to the tire wall...Most line pressure use on track will be in the 400-600 range with occasional spikes upwards of 800. If you boost the pad Cf you need even less pressure.

Shimming, centering, bolt torque can hall have some impact but what you're seeing is spread. You're clamping the rotor and the caliper is pushing outward. This additional spreading can be caused from over stressing (like all this 1000psi video work) and from softening of the caliper body from over heating. The older and hotter the caliper has been run the softer it can become.

However on the plus side the flex does not have a huge impact on the braking. What's lost is a bit longer pedal. A bit of time loss and in short some wasted energy being absorbed by the caliper rather than put to use on the rotor.

What can you do to prevent it? Run a proper pad for the intended use, fit a larger rotor, fit a larger piston caliper requiring lower psi or install a larger bore mc generating less pressure. *less psi then boosted by more leg would be the same net result.

I have Wilwood Dynalite's and also have a shit pedal feel. I've never been able to get all the air out of them. I'm going to give reverse bleeding them a shot. That's when I pump fluid into the calipers, right?

Neglected to also mention that piston area has a lot to do with that. The DL calipers should be no more than 1.375 bores.

As for the bleeding, don't listen to anyone suggesting that all four bleeders be bled. The lower bleeders are only there for the caliper to be universal mount- ie. R and L where they switch location. In fact if you want to really do it right; remove the brass fitting and install blanks. (DL is 1/8npt and DP is M10-1.0) Flush seal allen plugs work great in the DL, DP parts are harder to find and must be tapered seat.

ANY time you open the lowers and attempt to bleed fluid you're all but certain to get air in. Air goes up to the top, not the bottom. If you're lazy (like me) you can open one upper at a time and let it just drain out into a bucket. Close and repeat after 15min with the other, just keep topping up the reservoir. Gravity is a wonderful thing!

Air goes out the top, but in the four-bleeder Wilwoods I've disassembled, there is a crossover at only one end of the caliper. If it's mounted on the car so that crossover is at the bottom, you can flush the whole caliper by bleeding only the uppers. If the crossover is at the top, you can get all the air out by bleeding only the uppers, but you must open the lower bleeders if you want to flush all the old fluid out of them.

On a 280 rotor with 1.8 rears, I'd go with 1.25-in. pistons. Don't know why Wilwood's own kit gets that wrong.

I couldn't watch the video earlier. That is actually a much better caliper than a Dynalite. I've looked at it before and thought it's not horrible.

While you are correct about the cross over being on the top or bottom depending upon mounting the bleeding remains the same.

You're right that to drain it; opening up the bottom (or removing the caliper) is needed.

It makes a flush a bit awkward in that as you gravity bleed the situation would be a cross blend of old and new fluid taking time to run clear. Whereas on the bottom you could force it through quicker with pressure.


FWIW, BDL, DPr, DPLM, NMDP, FBDL, PL, DLS and now FSL are all internal single cross feed calipers. (Wow..lot of letters there huh?!)

Todd,

Thanks for your response.

Are you sure about those numbers? The Miata's stock brake proportioning valve doesn't start doing anything until close to 600 psi, so wouldn't a track-driven Miata spend most of its time above that?. I installed the brake pressure sensors before installing the Wilwoods. With a completely stock 1.8 Miata brake setup a large portion of braking time was spent at 800-1,000 psi. I have run Carbotech XP12/XP10 pads and have been running Cobalt Friction pads XR2/XR5 for some time now.

My contact at Cobalt Friction told me that they typically see 1,200 psi though some of the aggressive pro drivers peak at 1,600 psi before they back off. I told him what I was running, and he indicated that my numbers were right what they'd expect. For what it's worth, my proportioning valve is set to about 75-80%, so if front is at 1,000 psi, rear is at 750-800psi. Max braking on my car is -1.4g's, I don't have ABS, and I don't flat-spot tires. ;)

I can't imagine that I'm running mine hotter than some others, and these calipers aren't very old - they've been on the car for 10-12 events.

The piston sizes are 1.38", for a total piston area of 3.0 sq-in, versus the stock Miata's 3.17 sq-in. Pads are proper. Rotors are larger and so is the m/c! I haven't tracked the car with the bigger m/c though.

Any other trouble-shooting type suggestions?

My plan in the off-season is to ditch the power booster as I don't think my car is making much vacuum. This will likely mean going to a longer pedal ratio and dual master cylinders.

Cheers,

Will

Chase your proportioning rearward until it gets interesting, then back off slightly. With that piston area and the larger front rotor, I suspect you'll be close to no prop valve activity.

Here's a screen shot of some recent data from Watkins Glen.
Key is to the left of the graph.
Black trace is front brake.
Red trace is rear brake.
Orange trace is longitudinal g's.

https://www.miataturbo.net/attachmen...9&d=1317099405

Admittedly not a Miata expert I don't have data to prove the numbers I'm suggesting here but I've seen data off other cars and my experience says that psi figures are not normally as high as these. I could see your elevated 800-1000 under extreme braking perhaps but higher than that...? Hard to argue with the data graph however!

If those number are in fact correct your removing the booster would be very detrimental to the driving. You'd need to be able to push with roughly 90 lbs of leg pressure on a pedal (ratios taken into consideration) to get to 1000psi. That sounds easy enough but try it; put a corner scale angled up to the wall and secure yourself against something in a sitting position and push on it. 60-70 is doable but 90 is going to be a work out and I'm not sure I could do it fast enough to match the corner entry speed.

Taking some of that into consideration you'd certainly not want to increase the mc bore- you'd make it even worse. That dual mc and pedal set up could we be the answer for you but based on total area of the current bore you'll run some rather small cylinders too- ie. your combined area being roughly equal to what you like (1" or .875) will net you the same 'feel'. Pedal ratio not withstanding.

Moving to the 1" bore with the booster might help the pedal feel for now and at the same input (leg) pressure will lower the pressure at the caliper. But of course if your demands for torque are the same you'll push harder and boost the line pressure back up to where it was. As you know you're not making more or less brake torque relative to what your demand is, only changing how you get there.

At that pressure you may well need to consider moving to a more robust caliper to keep up with the pressure demands. You're certainly not going to get that out of a mid class caliper body. Moving to an FSL or more perhaps? With many successful MINI apps out there also running a very small mc I've had no negatives comments on that body under hard use. Doing a W4A or such...not sure you can do so on a small rotor.

If the caliper/pad/rotor system is losing efficiency for whatever reason (this one "might" be), then the driver will try to make up for it by pushing harder on the pedal to increase pressure.

Sure would be nice if there was a kitten-sized version of something you'd see on the line at the 24 Hours of Daytona.

Maybe. Not sure how much that might have an impact. If the right pad is in use and all, then the flex is a byproduct. I think you'd find that there'd be no more pushing on the pedal to get the torque- it would be constant relative to piston area, pad and rotor math. But the flex would lead to a longer pedal to achieve that.

That flex is looking quite disturbing. Do the midilites have less flex?
I have heard of caliperflex before with Wilwood. If so, is it worth the upgrade? I do like the 4-wheel FM 11" kit...

What's a midlite ?

Those:

https://www.miataturbo.net/attachmen...ine=1317363018
they seem to be sold in europe only. They have dustseals.

http://www.rallydesign.co.uk/product...oducts_id=8317

That's a radial mount Dyna Pro. This is the caliper used on the Miata and shown in the pictures/video. They've been here in the US for many years now. First appeared on some kits like the VW and quickly the MINI, Eclipse, WRX and others.

DYNA PRO

That is a Radial mount Dyna Pro. You can get them with the dust seals and thermlock pistons or with the stainless pistons. I’m not using the ones with dust seals just the stainless pistons that come in the Mini Cooper race kit.

I was the first I think to install this caliper on a Miata Back in 2005. FWIW I have run Dyna Lite 11" kits and the Dyna Pro 11.75" kit. I never measured flex but the Dyna Pro kit was a substantial improvement in feel over the Dyna lite kit. Also the Corrado rotor Dyna lite kits were a total failure for me in terms of capacity or longevity. The 11.75 kit had substantially better thermal capacity and front pad and rotor life nearly doubled partially due to thicker pads to start with. The Dyna Pro has better Radial clearance than the Dyna Lite and made fitting 11.75" rotors in some of my 15” wheels possible where it wouldn’t work with Dyna Lites.

My brakes.

Front. 11.75” directional vane two piece rotors. Dyna Pro Calipers. (Off the shelf Mini Cooper 11.75” race Kit) now running Colman racing friction rings.

Rear 11.44” two piece rotors with the larger piston OEM sport brake calipers on relocation brackets. Rotors are again supplied by Colman racing but they are custom.

I am running a 1” master cylinder from a 929 with a late model NB booster and have a MC support brace.

I like Cobalt Friction XR2 pads on all four corners for the track.

I have never been in a Miata that has better feeling brakes and I drive this thing between 5 and 10 seconds under Spec Miata Lap records on most any track I have been to running down into GT car territory.

After seeing some of the data presented here I could possibly see bigger pistons with lower line pressures as a possible improvement and I have also thought about doing this to loose the booster all together. But honestly I can say I don’t have any complaints about brake performance at this point.

Bob

Todd,

Yes, I have been considering all of the points you mentioned. The biggest problem is finding calipers that fit. I spent a good amount of time choosing calipers and designing brackets. Shortly before I pulled the trigger, I found bbundy's post concerning the Mini kit. I ended up ordering the MINI kit's brackets, the 3" DynaPro4 calipers, and using the aluminum hats I had. I hoped to find a staggered piston caliper that would fit under the 15" wheels I use, but it hasn't worked out. The only 6 piston caliper I know that could fit is the DynaPro6, however it is lug mount, not radial mount.

Thanks for your advice. What is your shop's website?

Bob,

What is your pad wear like? Even? Tapered at all?

Our brakes have several things in common. I kicked myself for not finding the MINI kit post you made back in 2004 or 2006 earlier. After spending a bunch of time looking for the right caliper & mount then designing my own, I couldn't believe that Wilwood had what is virtually an OTS solution for DIY types. I'm also pretty irritated that Wilwood couldn't make things easy. I asked them many, many times about the different radial mounts they have, but they were unable to give me any dimensions of their car-specific kits. I would have thought all that data is in a searchable database or spreadsheet, but apparently it is not. Anyway, thanks for posting what you have.

The 1" 929 m/c and '99+ sport non-abs booster I'm running were also taken from that long post on the other Miata forum.

My brakes are:
DynaPro 3 sq-in front calipers with
10.75" rotors and
Cobalt Friction XR2 pads.
Stock 1.8 rear calipers with
stock 1.8 rear rotors and
Cobalt Friction XR4 pads.

I just installed the 1" m/c and bigger booster, and haven't tracked the car with 'em yet.

With the stock m/c (7/8") and booster, the brakes pedal feel has been horrible.

The stopping power of the car is there, but the pedal is vague and sometimes inconsistent. I'm also getting radial and longitudinal pad taper, which are the two problems I was trying to solve by going with the Wilwoods in the first place!

Race weight of the car is 2380-pounds, and the naturally-aspirated engine makes 186hp. I also run significantly faster than SM records to the point where it doesn't make sense to use SM as a measuring stick.

I'm wondering if I'm running out of vacuum assist. The booster gets 14" of vacuum at startup & idle, then goes up to 22" as soon as I get on the throttle. When I hit the brakes, it seems that the vacuum drops to about 14" by about 1/2 the pedal stroke and stays there. At 1/2 strock, front line pressure is about =~600-700psi. Getting from 700 to 1,000 psi takes a good amount of extra pedal pressure.

New spacers have been cut to center to calipers exactly on the rotor. I now understand why Wilwood includes shims with all of their kits: manufacturing variances. Oddly enough, the caliper spacers on each side (driver/passenger) are different. In order to center the calipers on the rotors, the passenger side spacer needs to be about 0.0275" thicker. This is not a lot, but new Cobalt Friction pads are so fat that the pistons have to be completely retracted to fit, and even then, it is close.

I also took Hustler's advice and went with the reverse bleed.

At this point I've thrown everything I can at it. I may pick up a cheap vacuum canister and place it in-line. Everything should all be back together for a test-drive onto the trailer and thrashing at the track next weekend. I'm very much hoping to finish the season with more answers than questions. Got to have something to do in the off season.

The flex shown in the video is interesting, however I wasn't looking for it, just trying to solve the brake/pedal issue. I'll be psyched if the 1"m/c, big booster, and everything else solves my issues. That said, I'll be looking into upping caliper piston area F&R, going with an aftermarket pedal with dual m/cs, reducing overall line pressure (to reduce caliper flex). If all of that can be achieved and can result in a firm, reasonable-throw pedal, I'm in.

Cheers,

Will

Fit within a 15" wheel is always an issue Will. I've done some drag kits of late and we are down to 11.5" to make them work. When you do a road racing deal you really have some limitations on rotor size. And honestly; I'd take rotor size and mass over caliper value any day. I'd rather have a larger rotor and a DynaLite then a real small rotor and an FSL. Rotor value is not to be overlooked; mass, leverage, cooling etc.

You're dealing with one of the most popular (and probably successful) medium class calipers I've ever seen. You can find some old AP parts off open wheel and sports racers maybe but they're all big bore and cumbersome in size.

I sold a couple of the MINI conversions in production form (yes thanks in part to Bobs help) and have not had any negative replies on them. The smaller DL class parts are simply not what you want for a road race car unless very light.

Speaking of weight...you want better braking? Take a weight out of the car. What's that mean to braking and flex? Less strain on the entire system. While I run DL parts pretty much all around they are on a 1500lb car and I have zero issues with them. I think you can make some improvements if you can cut some pounds here.

The DP6 is the only differential bore part in the medium caliper class. It's really a revised DL model with staggered bore. The staggered bore thing however won't make for much better braking, only better pad wear. A standard DP6 can be compared to a 1.625 bore DL, both are the same size with regard to area: 4.06 vs 4.1 so it's just a sub part. The DL and DP6 (and other DPLM parts other than NMDP- you got all that??!) are all .490 thick pads. Frankly for a road race car that's crap. Even .62 is marginal. But you're back to that fit issue again. Big pads take big calipers.

Not sure what I can do to help but you can reach me any time. HERE

I get some longitudinal pad taper but never any radial taper. I flip the pads occasionally and the taper evens itself out as the pad wears through. I assumed some of this is caused because the pads are thicker and at full thickness there is a bit more of a mechanical force couple that gets generated from where the pad contacts the rotor and the longitudinal force gets reacted by contact between the caliper body and the backing plate. This force couple makes the leading edge of the pad tend to dig in. I also experienced the same behavior when I had Dynalites.

The vague pedal feeling your describing I am not feeling at all. The brakes feel spot on and right now. Pedal is solid so and doesn’t move much so heal toe throttle blips are consistant with varying levels of braking. Quite a bit of braking force can be generated with very little pedal force as well.

I assume you ment 11.75 and not 10.75 for the front.

I will say that putting on sport brake calipers in the rear made a fairly dramatic improvement. Even with my 11.44” rear rotors before going from the 1.25” piston stock rear calipers to the 1.375” piston stock Sport brake calipers I always had the Wilwood Bias valve set full rear. The larger piston rear calipers gave me some adjustment range to where I could just get it to the really sketchy point on rear bias and the whole braking system felt more responsive. If your running just the 9.88” stock 1.8 rear brakes with the smaller pistons there is no way you will get the bias right. I think minimum you need the 10.84” sport rear brakes with this setup, really any of the wilwood front kits available you need a minimum of the sport rears.

Bob

Pad taper you describe is due to the "equal or square" bore aspect of the calipers, rather than them being differential bore. A differential bore caliper applies less bite to the lead area of the pad and more to the trailing. This counteracts the gaseous build up or boundary layer created by the friction and balances out wear.

There are no small size calipers in this class however that offer the split size. At one time years ago there were some split bore DL parts but it's too costly to produce them that way so only the larger parts and six pot are that way now.

Pad wear spacers are also a nice benefit to that pad swapping that Bob is doing- exactly what I'd have suggested too.

Thanks Bob, good to know. FYI, I had some slight chunking on the inside corner, leading edge of the pads. Cobalt chamfered the latest set of pads for me, hopefully this will stop the chamfering (though I can't say that the previous chunking caused any obvious problems).

Also good to hear!

No, I am actually running 10.75" fronts. This is a custom setup which fits perfectly inside an Enkie RP-F1 15" wheel. As much as I like the weight of the RP-F1, I've picked up some Enkie PF-01 wheels and 949 6ULs, which would allow larger rotors. I'll likely bite the bullet and move to all 15x8 & 15x9 Enkies/949's for next season.

I picked up a set used sport brake calipers, brackets & rotoer and rebuilt the calipers. Tried them with the Wilwood front calipers &stock m/c and found that the pedal travel increased way too much, so I swapped 'em back.

10.75" front rotors and stock 9.9" rears are due to wheel fitment. My rain tires are on the Enkies, and I have a couple of sets of Enkies with other tires on 'em too, so I've been a bit reluctant to change over. I could see selling the Enkies and gettting a cheap set of wheels for rains. WIth these rotor sizes, the stock 1.8 calipers actually work well. Full brake pressure to the rear is too much, and threshold braking, not to mention trail-braking, can get pretty...exciting.

What wheels are you running that fit those rotors?

All that said, I haven't had issues with managing heat in the brakes. The car stops reasonably well, the pedal feel is just crap.

I also swap the pads around to even out the wear...it definitely minimizes the taper. I've thought of pad spacers for a while, but never had any made. Closest I have are 0.5mm thick titanium backing plates from hardbrakes.com. Seems spacers would be a very good idea for stock floating single-piston calipers.

The Light weight of RPF-1’s in a 15X7 may feel fantastic and make the car ride nice but my own testing back to back on the track showed

8” is faster than 7”
And later test showed
9” is faster than 8”

Even though the 9” were ~3 lbs a piece heavier than my Sprint Hart CPF 7”. I’m running 949 6UL’s now.

It wasn’t just a matter of more grip for which I do believe the wider wheel gave a little more. It was the improvement in the way the brake away was at the edge of traction. The limit becomes much less abrupt. The tire contact patch I believe stays more consistent at different cornering loads so the contact patch doesn’t snap to a different shape once you exceed the traction limit as much as it does with the narrower wheel. They also allow the peak tire performance to be with a few pounds less air so I believe it also increases the size and compliance of the contact patch to grip uneven surfaces.

Bob

^^^ I agree with a lot of that, certainly with my car now that it has a bit of a built N/A motor. I stocked up on the Enkies for the car when it was a 1.6 ITA car, then with the new 1.8 ITA car (where max wheel width is 7"). I picked up a set of 15x8's and preferred the 7" (slightly faster lap times).

With 186 n/a hp and not having to worry about ITA legality anymore, wider wheels and wider still tires are certainly faster.

That said, if I ditch the Enkies all together it will be to go to bigger rotors, and when that happens, I'd like to find cheap 15x7 wheels for rain tires that fit over the larger rotors, which is why I asked about your wheels.

Thanks for the info!

I got my old set of ATS comp lights in 15X8 for rain tires. Just mounted a new set of 225/45/15 Hoosier H20 Wets on them. The tires look like they have nearly an inch wider tread than the 225 Nitto's almost closer to my 275/35/15 A6's.

Bob

Was flippping through an old copy of Race Tech Magazine (March) today and found this. Looks kinda prototypey. Anyone going to SEMA to check it out?

https://www.miataturbo.net/attachmen...ine=1319688196

Just noticed there appears to be pretty significant hysteresis in the proportioning valve function. On the initial release of pressure, the rear doesn't drop in proportion to the front drop, and by the time the fronts are down at 760-770, the rears are still up around 10-20 psi less. On the apply side of the chart, when the fronts are at 760-770, the rears are still down about 100 psi lower.

Wondering if this difference is consistent from stop to stop, or is it variable?

If Stoptech doesn't use the "Outlaw" pad shape they're making a huge mistake.

You mean the 7112 plate?

https://www.miataturbo.net/attachmen...ine=1319715901

I'd highly doubt they would. First the caliper shown has the bridge bolt to help stiffen it. That means at the least they'd need to do a 7812 plate for that. Secondly as a racing caliper (by the description how I interpret it) the 12mm thick pad would really surprise me. That's not their normal way of doing things- they'd take heat for under engineering it to that level. *But then if they were trying to be competitive at this level...dumbing it down could help too.

I'd suspect either a stock, smaller Porsche plate or one that is modified from that shape will be fit. Right now it looks more dedicated track than oe plate however with only the bridge bolt.

Wildo, with what you have in your engine and wheels alone I can somewhat guess your race budget. There is no reason to be chasing your tail with this. Copy Bob's setup exactly, it works.

Bob gave me a link to check if the Mini BBK will clear the rims:

Thanks for sharing Bob!

http://www.wilwood.com/PDF/DataSheets/ds492.pdf