Front Brakes - Suspension question
 

Is it a 2-piston caliper design or 4-piston?

If it is 2-piston any ideas how to upgrade to 4-piston calipers?

Is the suspension tight enough for track use or it needs an upgrade?

It's a single piston calipers front and rear, the front caliper has the larger piston.

They are common "sliding" type calipers.

To upgrade will require a new caliper, I doubt that anyone makes either a direct replacement caliper or brake kit for the RX-8 yet.

But they will.

By the way, a single piston caliper does not mean cheap or poor brakes. BMW uses this design along with the majority of cars on the road.

A good 4 piston fixed caliper will cost around $600 all by itself. A kit can be anywhere from $2000-$5000, dependent if it's front only and the exact design.

And considering the RX-8 leads its class in braking... why replace them anyway?

Exactly!

And with the large rotors and light weight, fade should not be a problem. Only if the pads or fluid are not up to hard use, but $100 will solve that problem.

Re: Front Brakes - Supsension question
 

if you're thinking (competitive) autocross, you'll certainly need to bias the comprimise the setup far far more toward a high G-load setup, along with a much twitchier alignment (also hard on tyres)... no question.

for track use of course

unless you're going crazy and planning on running it in a heavily modified class on road courses (where speeds get high enough you have to seriously worry about pad wear over one race), you won't need to.

aggressive pads, good ducting, better fluid, maybe stainless brake lines (more maintenance), and frequent refinishing/replacing your rotors as they get used up will probably be sufficient.

I agree for road use they must be excellent brakes. I am thinking of taking the Rx-8 to the track though and you need better brakes there for sure.

Take my Jetta for example. It's got excellent brakes for road use but in the track they are useless.

If the Rx-8 cannot be competitive on the track with $2000 of mods (front brakes and suspension) then it's not the car for me.

Well, I have a friend with a Prelude. I drove it it's got excellent brakes in stock setup. He just put NSX calipers in the front, took it to the track and he saw a significant improvement.

agsid, you can't compare things like that.

The RX-8 has a great pad swept area to ton ratio. What makes a brake system adequate is rotor size, caliper piston size, fluid type, pad type and tires. Plus suspension also.

The Jetta's brakes like most cars are sized for low-heat braking. They have small rotors.

The RX-8 has a huge rotor for it's weight.

All you will need is pads and fluid to be just fine on the track.

Put simply the RX-8 brakes come ready for duty.

Just to give you some comparisons, the 350Z at 250lbs. more has the same rotors. The BMW M3 at 450lbs. more only has slightly larger rotors. Both cars have a lower swept area to ton ratio.

Normally, most cars come with "undersized" brakes for track duty, the RX-8 is not one of those cars.

Prelude doesn't have near the stopping distance the RX-8 does.

The RX-8's brakes are one of the best things about the car... to compare the simplicity in design to a Jetta, is a poor comparison.

The RX-8's brakes will be fine for track use in my opinion... you can waste your money to save yourself a foot or two of distance but I don't see much point, because as pointed out, it's not going to reduce fade much more.

Feel free to waste the cash on the brakes... I'd put my money elsewhere.

I'll take it to the track first and then I'll see how competitve it is. I am not going to upgrade brakes or suspension unless I have to.

That's the wise way to go;)

One suggestion for the brakes: IF you find them lacking, first upgrade the fluid and pads. You may find this does the trick and save yourself some money.

I was about to say, all of this bench-racing and guessing at this point won't help you determine what you need to improve the brakes, until you put in on track a couple of times.

I'm sure that you can upgrade the brakes. What it takes, whether it is worth the cost and other compromises, etc., can only be determined once you've put it on track with your setup.

---jps

True.

But I thought it's good idea to discuss this issue before I spend $45-50k CAD buying this car.

Take my Mazda Miata for another example. Stock, it's got excellent brakes for the track - in the Spec Miata race series, they use stock brakes with race pads. No problems. The RX-8 should do even better with the size rotors it's got. Try it out and see if they're insufficient first!

Regards,
Gordon

As already mentioned, you may want to replace the pads for heavy track use. The stock pads are meant for street use and will heat up quickly to allow good breaking under normal driving. If you are planning to race the car or drive it hard for a long period of time on a road course you will need higher temp pads. Swapping on a set of Hawk Blacks or Performance Friction 93 compound pads will mostlikely be all you need to do. Hopefully PF will make a set of pads for the 8. They stopped making pads for the 3rd gen a few years a go.


Mike

Agisd, are you talking about Kostas aka ouzo?

For all those saying that the brakes should be good enough for the track, have you ever done some hard laps on track with multiple hard stops from 200-220km/hr to 80-60 km/hr? Just becuase the 8 can stop on a dime on the street a few times means absolutely nothing on a big track. Like others said, we will not know until someone does take it to the track but I suspect that the pads and fluid will have to be upgraded. SS lines won't hurt either. With the upgraded pads, the question of them chewing up the stock rotor comes up.

I might consider giving my rotors the cryogenic treatment.
http://www.frozenrotors.com/frozen101.shtml

Regarding the suspension, unless we're talking Porsche, Corvette, etc I don't think the 8 suspension is tight enough for track duty. But then again that is a personal choice, will the "tighter" coilover suspension make you a better driver? I doubt it. Will it make the car more enjoyable during daily driving? Most likely. The stock suspension on the Prelude is decent, it was voted the top fwd handling car under $30K I think at its time but after I put on my Tein HA coilover setup, it's like night and day.

Yeah, for a living actually.

Well we agreed on fluid and pads.. I feel great now. :p

Yes, I am talking about Kostas. I was at Shannonville with the Preludes the other day (I took the class with Ian Law).

I agree with you, most likely the 8 will need new suspension, brake pads and brake fluid. If I buy it I won't touch anything for a year and then we'll see.

CS or GT?

Gonna move this thread to the Tires/Brakes/Suspension forum(Yes we have one now).
:D

First, just because a brake setup can last a race doesn't mean that it's performance cannot be improved upon. Second, a 2,000 lb race car with low power (some 130hp) doesn't need big brakes, because it doesn't need to scrub off much speed in a braking zone. So it's not going to need more braking than the street car.

A 3,000 lb car with some 250 hp is not going to be the same thing.

---jps

Probably CS.. I'd love the sunroof but I'm not sure if I can fit with a helmet on.

the sunroof opens on the outside. they should have the same headroom.

i would go for the GT (dunno yet about sunroof)...

agsid you know my feelings, but FYI:

StopTech will be introducing a 4 wheel brake kit designed for track duty at the next SEMA show. I have that straight from the "horses mouth".

They did one for the 350Z and actually improved braking performance quite a bit. But the 350Z carries 250lbs. extra mass with about the same braking power as the RX-8.

350Z test:
http://www.zeckhausen.com/testing_brakes.htm

You're absolutely right - but then the stock rotors and calipers on an RX-8 GT are not at all the same thing as those on a Miata, either.;)

My point was simply that you can't presume that because VW brakes aren't up to track use that Mazda brakes aren't either. There's no need to plan an expensive brake upgrade until some experience shows that the RX-8 brakes aren't up to the task. It doesn't hurt to do some research, but it's not a guaranteed requirement.

Regards,
Gordon

They don't. There are still mechanicals and trim that decreases headroom.

---jps

OK I sat in one without a sunroof and it had lots of headroom space. (I am 1.83m tall - 6 ft). I am thinking of ordering one with sunroof. I don't expect any problems with the helmet.

Re: Front Brakes - Suspension question
 

http://www.mazdatrix.com/8brakes2.htm

Factory RX-8 brakes are only single piston.
Check out these bad boys, they look tough!

...those're simply larger calipers... i'd wanna see mass specs, and try out more aggressive pads on the stock calipers before going bigger.

Bigger is not necessarily better. As with all things, proportion and balance are key. 36-24-36...

Read this StopTech article for a better understanding of why slapping larger calipers on can result in worse braking performance.
________
Lovely Wendie99

We located this obscure little company called BREMBO, supplied them with meaningless? things like piston diameters, rotor swept area, width, diameter, wheel specs, corner weights, percentages, (all of that was FRONT and REAR), car weight, etc. etc. and asked them if they had a 4 or 6 piston aluminum caliper that would NOT affect the brake balance of the car - as well as meet the other criteria we needed.

We arrived at the 4-piston caliper we are going to use.


btw - No go on a 6-piston -- would NOT work without major changes front and rear.

...that's all well and good, i'm just saying we don't have any metrics which prove they're better, yet.

a hit in unsprung weight (supposing they're heavier) might not justify the supposed increase in heat disappation ability.

A caliper transfers fluid pressure through the pistons and pads into force applied on the rotor.

A sliding cast iron caliper does this just as well as a fixed aluminum caliper.

Just getting an expensive caliper does not mean superior braking performance. It will more than likely mean superior pedal feel.

All to often people confuse performance and feel, making the leap that if the brakes feel better they must also be performing better.

Nope.

Brake performance is dictated purely by the unbending laws of physics and thermodynamics:

Vehicle mass, center of gravity, wheelbase, weight distribution, tire friction, brake pad friction, caliper piston area, rotor effective radius (the distance from the center of the rotor to the center of the pad), heat dissipation, heat conduction and heat convection.


In this list the critical parameter is tire friction ( and everything in the suspension that ensures best contact).

Your brakes will produce brake torque. This torque is translated into stopping power by your tires. Once your tires lock-up or ABS is activated any brake torque increase after that is useless.

Therefore, if you have no problems going into ABS or lock-up any money spent on improving brake performance can be better spent else where.

It's no different than having 400lb-ft of torque and trying to put it down on the road in a hard launch through 195 width Pep Boys specials tire. The last 300lb-ft is used to make smoke not acceleration.

And it's not just the tires, but also the road surface. Any tire will have far worse friction on a concrete highway or dirty city street than on a flat, sticky race track.

So, even if you upgrade to some very aggressive summer tires chances are the street your driving on will not allow a very high friction force compared to a race track.

Which is why for 85% of cars driven on the street those $2000 plus brake upgrades are completely wasted money.

If you drive the RX-8 solely on the street or at best around orange cones in a parking lot. Then save your cash. You will not see a performance gain. Especially by changing just the caliper design. Same piston area means same force, no performance benefit at all!


Fade (brake torque loss) is a bit different. But the caliper design is a very small part of the fade equation. If your worried about fade the big things are:

Rotor size and mass, air convection, pad compound material, brake fluid wet boiling point.


Now to feel:

Yes a very stiff caliper like the Brembo will improve pedal feel, probably a lot.

Question is how much is that worth to you?


BTW- Chance are the Brembo caliper (which is aluminum) is 30% lighter or ~ 5-7 lbs. lighter than the RX-8 cast iron caliper. That's the norm, but GET REAL DATA FIRST!

Here's more on brakes:

http://mysite.verizon.net/romano.michael/

I like to thing my stuff on there is good, but please follow the links (especially to the StopTech and DBA site) too.

Thank you RomanoM -- I agree 100% with everything you have said.

For everyone reading this thread:
At this time I am not going to claim there will be any braking performance "increase" (we have not even DRIVEN my car with them on -- still need to make the brake lines -- and "increase", on a street car, can be a little hard to pin down).

I have an RX-8. MANY customers and friends have seen it these last few weeks. More than a few have commented on the "ugly / wimpy looking / ONLY single piston? / OLIVE DRAB!" etc. front calipers.

I have been driving real race cars since 1972 (SCCA, IMSA, Trans-Am, etc. - currently driving amatuer SCCA again, and I just won the E/Production race at the June Sprints/Road America - led ALL the laps and set a new lap record). I do not expect any noticeable brake performance "increase" (maybe a firmer pedal?) with these Brembo calipers as the RX-8 (and a LOT of other cars today) should not be anywhere near the "limit" of their brakes while driving on the street. The RX-8 seems to have excellent OEM brakes.

There are car owners out there who purchase rather expensive parts/kits for their cars mostly for an improvement in "looks".
We have already had more than a few inquiries on bigger front brakes. I will be putting the first kit on MY car (along with the drilled and slotted rotors).
They are going to LOOK SOOOO much better than the OEM calipers and rotors.

Dave Lemon --

BTW- FEEL IS IMPORTANT.

A car with 0.95g of lateral grip is good, but only a car with great steering is a GREAT handler!

Think of brake feel the same as steering feel. It makes the whole experience more satisfying.

If all that mattered where pure numbers we would all buy a Mustang Cobra.