Chronos

What's the deal with these things only coming in 2? Am I to assume that the stock rear brakes will totally suffice when using these things up front on a long sustained track day running at 450rwhp?? That's some serious speed...I mean how well can the rears really hold up from sustained 150mph full pressure braking? I'm guessing not well enough as so they shouldn't be upgraded as well.

So...why don't I see any suggestions for the rears on N-tech engineering's brakes section??? I have heard that 99specs are the best addition to the 13" AP racing fronts but I don't know if that would really be the best answer for my performance goals. I know about M2's 4 wheel brake kit, but I don't think it's quite as good as the AP racing fronts. What do you guys think would be best to go with for the rears? Or, do you think (or know) that the stocks or even 99specs would really hold up under such hard use?

I'd consider JGTC 500 to be around the performance I'm looking for, and if there was an FD in that series, certainly it wouldn't use the stock rear brakes! Not to mention my car would be a lot heavier).

Cossie

LOSING YOUR PARKING BRAKE

evident in Max Cooper's car....

No upgraded rear wheel brake will allow you to keep your std hand brake.

If they do allow a rear parking brake, it will require you to use your old single pot to link up to a hydraulic hand brake.

Too much money and alot of weight.

Slightly larger disc can be found. But front brake bias is still there.

Requires bias valve..more money again

Chronos

ok, that makes sense...I can get away with just leaving it in 1st or reverse right? :P

Anyways, I still wanna see what kits are available for the rear, with or w/o the parking brake.

EDIT: HOLY ****! Just read the section on Max Cooper's website, he actually DOES use the engine to park the car! Talk about hardcore! I personally have a little problem using a Rotary to hold my car in place .

I'll have to think of something though because I just can't have the stock rears or even the 99specs with the kind of performance I plan to be running. Atleast I'll lose some unsprung weight, lol!

chrisb130

The M2 4-wheel kit allows you to keep the parking brake, for an additional cost.

Chronos

I'd have to get the AP racing fronts for one thing, and aren't the M2 kit brakes the same that Max Cooper used? I wonder how costly and heavy and a pain of an *** that parking brake setup that M2 uses would be...

RX794

It's also probably more cost effective to get 99+ FD brakes, all 4 brakes will be upgraded, and you get to keep your emergency brake, not to mention it's a factory part.

dclin

iTrader: (4)

https://www.rx7club.com/forum/showth...hreadid=118131

maxcooper

The 4-wheel RZ package or the M2 four-wheel package with e-brake option seem to be the only ways to keep the parking brake at this time, unless you do something custom. You could also mix and match (AP fronts with RZ rears, for instance), but I bet the full RZ setup or the full M2 setup offer better balance.

I think that David at Widefoot is working on a bracket to mount the Wilwood mechanical caliper in addition to the 4-piston hydraulic caliper with the RZ rear rotors, but I think he has his hands full with setting up his shop right now, so timing is unknown. When he does offer such brackets, I will install them and write it up on my web site. For now, parking with the car in gear has been working fine, but I haven't had to park on any steep grades.

The complete RZ brakes are a damn good deal and seem to offer excellent performance, as SleepR1 has reported. I am sure the M2 kit is excellent as well, and is still a pretty good deal at $4K for really big brakes at all four corners. I don't know how much the parking brake option costs. I would assume that they use an aftermarket mechanical caliper, but I don't know for sure.

There seems to be conflicting information about whether a rear brake upgrade offers an increase in performance. StopTech (a brake manufacturer that I respect) claims that rear upgrades generally aren't needed with their kits (or don't offer a performance increase that is worth the cost to most buyers) since the larger fronts tranfer more weight off the rear wheels anyway. I am not sure how well that applies to the RX-7, since the tires are the limiting factor in front, and the bigger front brakes move the bias forward anyway. The stock bias is already rather forward on the FD anyway, so it still seems like some performance increase is possible with bigger rears. Even if the front brakes supply 80% of the braking force, if the rears are only operating at 50% when the fronts lock, you are leaving 10% of the total possible braking force on the table. I know that in my car, it felt like the rear brakes weren't doing anything with the AP fronts and stock rears. It hunkers down nicely with the Wilwood/Widefoot rears now -- it feels much better. Lowering the car also reduces weight transfer under braking, so you have more traction available for braking in the rear when you lower the car, as most people who mod the car do. The guys that developed the Wilwood/Widefoot/Essex rear setup (Scott Refert at Essex and a few "track junkies") did some calcs and found the RZ rear caliper to not offer enough clamping force to balance out some big fronts (like the AP kit). That is why the Wilwood NDL caliper was selected for that setup instead. My conclusion based on this info and my experiences is that there is some benefit to bigger rear brakes, so I went for it. I am happy with my choice.

-Max

dclin

iTrader: (4)

Thanks Max - I believe you mentioned somewhere the Widefoot racing bracket also allows for a comparable (to the Wilwood NDLs) AP 4 piston caliper? I think you said it was a bit more expensive. Just FYI for **** people that want to 'keep it all the same' (like me!).

Any thoughts on maybe organizing a 'buy' for the rear brackets w/mech emergancy/parking brake, to maybe get Widefoot to put more (priority) thought into this? I don't have his contact number, and the widefoot site is not up yet.

I have emailed Roger Mandeville to see if he can do a two piece version of the RZ rear rotors. Have not heard back yet. Since his front replacement rotors sell for roughly $300, can't see it being too much more. Would make for a good alternative to the stock one-piece.

maxcooper

There are some AP calipers with extremely similar mounting details to the Wilwood NDL, I think. Scott Refert at Essex gave me the impression that he could find some AP calipers to use, though we didn't discuss it that much. I am sure that you could find something by talking to Scott (Essex) and David (Widefoot) about it. It would be nice to have the same name on the brake calipers front and rear. I don't have any regrets, but if I did it again, I migth spring for an all AP setup. Or save some dough and match the Wilwood rears with some Wilwood fronts.

I've got a bunch of other projects going on right now with my car, so I don't have much time to organize things. I just sent David an email to ask about the status and let him know that some interest is brewing.

It would also be nice for people to be able to buy a complete rear brake kit with a parking brake. I am not sure AP makes a mechanical spot-caliper, though. The Wilwood one says Wilwood on it, though perhaps you could have them make them without a name on it if you were using AP calipers otherwise.

That sounds great on the Mandeville rotors. I am interested to see what he come up with. The rotor size is 0.8" thick, 12.2" in diameter or so.

-Max

WidefootRacing

iTrader: (3)

Hi Max,
Thanks for the "heads up" on this topic, I don't get a chance to check out
the forum as often as I'd like. Working a little too much, so I can spend money on stuff for
the shop. It's coming along, and I hope to be open for business in May.

Max's correct on the genesis of the Widefoot NDL caliper bracket, some of my
very hard-core RX7 buddies wanted to balance out their big front brakes, so after consulting
with Scott (who's (AFAIK) no longer at Essex), they settled on the Wilwood NDL in 1.38 bore,
and the RZ rear rotor. After taking some location data, they came to me for the prototype and
"production" brackets. All of these guys have track-only cars, I think Max is the only guy
using them on the street. And fortunately, he doesn't live in San Francisco...

For the folks who may not know, one important thing to appreciate is many of the
track cars have either a rear brake bias adjuster, or a full-on duel master cylinder with balance
bar. When you start getting serious with brakes, you have to do the math to check out front/rear
weight bias, CG height, effective radius for the front and rear brakes, caliper and master cylinder
bore ratios, pedal throw, etc. And then you really should get on a track under controlled
conditions and try different settings to see where the car is happiest. And it all changes when
the track gets wet, 'cause now you're not transferring as much weight...


dclin, I would consider a group buy for the new Widefoot NDL with spot brake adapter,
but I do need to make clear that this still might not be considered street legal by the Feds. I
doubt if Wilwood's spot brake is DOT approved, but then that's not stopped (no pun intended)
a lot of us. BTW, getting my website up is one of those things I've GOT to do ASAP, but I can
be contacted via email - david@widefootracing.com works.

Chronos, I hope to have roughly the same power that you're talking about, but the car
will be pretty heavily modified from a stock chassis. For my car I'm starting with 14 x 1.25 rotors
front and rear, and because I hope to get rid of the power booster I'll be making my own calipers
that move the effective radius as far out on the rotor as possible. I also hope to have a very low
CG, with the weight balance moved to roughly 45F/55R, so my rear brakes will see some
serious loads (Ah, the fun of being a designer/machinist :-). You might benefit from going
to a larger rear rotor than the RZ to match the performance levels you want.

Hope some of this has been of use, if you want to email me please do.

David Breslau
Widefoot Racing Co.

maxcooper

It is too bad that Scott isn't at Essex anymore (AFAYK ); he was really great to deal with. Perhaps my setup is slightly different than the others, but I think my NDL calipers are 1.12" bore.

I look forward to trying out the brackets when they are available. It would be nice to have an emergency brake in the event of an emergency.

-Max

WidefootRacing

iTrader: (3)

Rassen frassin, you're right, they're 1.12 bore
calipers. I was going by memory, and should have
checked.

David

dclin

iTrader: (4)

Good to hear it's under consideration and, as you said, federalizing issues are probably not at the top of most of our list. Heck, I've got a pretty long list of offenses against any transportation code with all I've done to my car already, hehe. Totally understand and acknowledge that.

As that I have not heard from Mandeville, would you consider offering a two-piece RZ spec rear rotor? are you setup to be able to do this? Might as well keep the whole thing from one source for simplicity's sake.

Thanks!

Daniel

jimlab

There's one option that no one has mentioned which retains the parking brake, besides the '99+ RS/RZ rear brakes, and that's the '02 Spirit R rear brakes.

The '02 rotors are even larger than the rotors used by the '99+ RS/RZ, I believe, which are larger than stock. More swept area, at the very least, and I'm trying to find out more details on the piston sizing, although they remain a single-piston "floating" caliper design. They also come pre-coated in red, with cross-drilled rotors.

Here are the '02 Spirit R fronts...



and the rears...



Notice much difference in comparison to the diameter of the wheel? Neither do I. Mazda says that 17" rims are required, apparently.

I'm waiting on final pricing for just the components I need, although I was quoted $1,800 shipped for everything (calipers, rotors, pads, backing plates, etc.) by one Japanese vendor. A little steep, but without backing plates, and if I can find aftermarket pads, the price will be a bit better, although still more expensive than the '99+ RS/RZ components.

jimlab

BTW, the reason I want red calipers it to match my AP Racing front kit...

Chronos

Dave, I don't understand what you mean by 45rear/55front, are you talking about weight distribution? If so, are you doing this intentially or does it just work out that way with the way you're setting up the car (ie rollcage)?

Jason

P.S. Jim, nice crossdrilled/slotted rotors...didn't I remember reading a post by you a while ago that such wasn't nessassary in rotors with modern pads?

btw, nice looking brakes...love the color matching scheme

Edit: Check out those tires! Potenza S-07's!? and here I thought I was top of the line with my S-03's Inukai was also just saying something about Yokohama A048's on his car...what's going on here??? Lets have some of this premium rubber brought over seas!

jimlab

It's not, but sometimes you don't have much choice in what style rotors you receive.

I would have opted for slotted only, just to keep the pads clean, but would have had to wait an unspecified amount of time and wouldn't have got the deal I did. However, the "blingalicious" rotors have now grown on me a bit.

inukai

I will post my car tomorrow.

Thanks

WidefootRacing

iTrader: (3)

[QUOTE]Originally posted by Chronos
[B]Dave, I don't understand what you mean by 45rear/55front, are you talking about weight distribution? If so, are you doing this intentially or does it just work out that way with the way you're setting up the car (ie rollcage)?

Jason


Jason,
I just checked myself, and I did say 45Front, 55Rear (whew). I'm doing
this on purpose (having a small rear weight bias), as there's some handling advantages
to having a little more weight in the rear due to inertial loading during braking. The "ideal"
50/50 weight distribution only works during steady-state cornering, and usually we're under
some combination of braking or accelerating on the track.

So having a little more weight to the rear helps under braking (ask Porsche), and
during acceleration you've got more rear traction. This does mean I'll need to bias my
tire sizing somewhat larger in the rear, but not hugely. And there usually is a small loss
of handling potential during low longitudinal loading conditions, but again that's a very small
part of the racing dynamic. I don't want to get near F1 ratios (40F/60R), as my power to
weight is nowhere near what they have.

David

WidefootRacing

iTrader: (3)

Daniel,
I could do it, but I'm a little cautious about offering more than basic parts (adapters) for
brake systems. I've got to find out more about liability issues before I would consider making
(for sale) things like hat's, calipers, etc. I'll do it for my cars, as I can keep a careful eye on
them, and if I come up with something that I feel is really good I may follow through, but not
until I've got lots of track time on it.

I do hear you on the simplicity issue...

David

WidefootRacing

iTrader: (3)

Jim,
I've said it before - I wish I had your money (actually, I've gotten
some of it . I'm not a fan of single piston rear calipers, due to risk of pad
taper or binding (not that this can't happen with four piston calipers), but there's
no denying it's simpler to get what the factory's already proven.

David

Chronos

Yeah, sorry, my typo , I meant 55rear.

Just messing with you Jim I would have prefered slotted over the slotted/cross drilled combo as well but sometimes you get what you can get, especially if you're getting a discout . I'm glad that they're grown on you though. When I was first looking for my FD I HAD to have MB, but now after I got VR, I much prefer it to MB.

That sounds like an excellent idea. It seems that if you're running signifigantly more power than stock then that would definately help under acceleration. The energy transfered to the front rotors will also be significantly higher constantly braking from higher speeds due to increased power (getting up to higher speeds on a track) so having the rear brakes absorb a greater percentage of that would definately increase the longevity of the front rotors. I'm not sure if it would help slow the car down any faster because I don't have enough information to say.

Stock, I beleive the 50/50 ratio is ideal for scooting around as it gives the car a great feel and like you said, works best for stedy state cornering. The 45/55 ratio seems like it would be a lot better for a race oriented setup (which I'm going for). How are you planning to obtain this 45/55 ratio and where do you plan to distribute most of the weight, more towards the tail end of the car or more towards the center? I've always beleived (but not known for sure) that having a greater majority of the mass in the center of the vehicle would give it better handling characteristics.

Feel free to correct me on anything I'm not totally accurate on. Having no real knowledge of physics yet or experience, all I really do is speculate .

Chronos

argh, looks like Dave doesn't have time to reply . Max, do you by some weird chance know how Dave's getting that 45/55 weight ratio? I don't know if you know him or whatever but I'd really like to know!

maxcooper

I don't know for sure what David is doing, but I do remember one person with a roll bar and track-oriented FD mentioning that his weight distribution was measured to be 48/52 with driver (and stock turbos, I think).

Anything that moves weight out of the front of the car or adds weight in the back will move the CG back. "Front" and "back" are defined relative to the current CG position. Here are some things I can imagine:
- add roll bar (rear weight)
- move battery
- shrink battery
- swap heavy stock turbo unit out for a lighter single setup
- get rid of unneccessary solenoids, air pumps, wiring, etc. from the engine bay
- use light hoses for the remaining engine bay systems
- move radiator back (FMIC install, but of course moving the IC forward will conteract that a bit)
- lighter front wheels than rear wheels
- lighter front brakes / heavier rear brakes (not likely on David's car since the Widefoot rear setup drops more weight than even the light front kits)
- remove AC and power streering
- remove stereo stuff (head unit + front speakers usually weigh more than the rear speakers unless you have a sub box or something)
- add ballast weight to the rear (don't add ballast unless you are under the min. weight for the class you want to compete in, however)

There is no "magical best" weight distribution, but many race cars shoot for 40%F/60%R or so. Of course, that is usually with a mid-engine (behind the driver) chassis layout. Most front engined cars are front-heavy, so the stock 50/50 distribution on the FD is pretty good for the basic chassis layout.

-Max