Help me make a decision

Alright so I have a classic fiat 124 spider and im looking to upgrade the braking system, being an old Italian car there are few options (bolt on). Stock the classic fiat 124 spiders have solid front rotors. So here are my choices: I could either get this kit from vick auto: http://www.vickauto.com/newstore/index.php?main_page=product_info&cPath=5_6_45&products_id=3840 that has vented rotors with a single piston caliper setup (larger caliper than stock) 

Or I should get this kit from Auto Ricambi: https://autoricambi.us/collections/brakes/products/big-brake-kit-with-wilwood-calipers-and-10-rotors which has solid rotors but with 4 piston wilwood calipers

keep in mind the latter option is 300$ more

In your guys opinion which is the better sacrifice; worse cooling but better brake force, or better cooling but less brake force. I plan to drive this car on the street and on the track

What are you trying to improve?  What is the limitation you have now?  Is there a problem with cooking the front brakes on that car?  Europas have solid front brakes, for example, but as their weight is maybe 1600 lbs, they are not known to cook the brakes, even on a track and a vented disk is really not needed.  Esprits, on the other hand, weigh about 2 Europas, and even with vented disks will cook a standard set of pads in 3-4 stops from 100.

Also note that 4 piston calipers don't necessarily stop easier than 1 piston calipers.  There's a very good braking article here on the site somewhere.

In reply to Dr. Hess :

well I have gone from the stock 80 horsepower to 240 horsepower. The car weighs 2000lbs do have any better idea which way I should go now? I could see how a greater number of pistons couldn't necessarily stop better if it had same surface area, but if a 4 piston one has a much greater surface area wouldn't that mean better stopping force?

An easy way to think about it is: 

if you add weight, you need to add brake force.

if you add power, you need to add Thermal management.

i’d go with the vented kit

In reply to AngryCorvair :

Any adjustment for intended usage?

I was going to say that if the usage is autocross/street I'd go with the Wilwoods, and if track days with the vented rotors...

When I do brake stuff, I tend to go deep into research, but sometimes it yields awesome things.  A good example; on my 67 LeMans, I can use the stock drum brake spindles with an open-source bracket pattern and late-model F-body rotors and calipers.  You won't get that lucky, but keep in mind that bearings and components are sold by OD and ID.  It is not outside the realm of possibility that you can find a rotor/bearing/spindle combination that would let you toss on some Accord, S10, or Scion rotors.

I did a similar thing on a 66 Bonneville when I put 3/4 ton Chevy truck brakes on it.  It only really required a different inner bearing with a smaller ID for the smaller spindle diameter.

Ransom said:

In reply to AngryCorvair :

Any adjustment for intended usage?

I was going to say that if the usage is autocross/street I'd go with the Wilwoods, and if track days with the vented rotors...

sure, the usage is always a factor.  i will confess to not looking at any of the linked products, but for the OP's stated "on the street and on the track" i think thermal management is more important.   even if the tires and/or piston sizes will only allow 0.8g decel, thermal management is still a bigger deal than OMG I NEED MORE DECEL.

that is my opinion, anyway.

Better venting is probably going to be more important if you are planning on more stops from a higher speed than before.  Remember that it is the tires that stop the car.  For more stopping, you need more tire.  After that, you need enough force to lock up the fronts, then enough venting to dump that heat.  If you want more force, you need better leverage, more force at the pads.  More pistons doesn't mean more force.

Ransom said:

In reply to AngryCorvair :

Any adjustment for intended usage?

I was going to say that if the usage is autocross/street I'd go with the Wilwoods, and if track days with the vented rotors...

I would say this is a solid assessment.

The In reply to manladypig :

Don’t waste your money!  Stock brakes likely can be just as effective  as expensive aftermarket brakes.  Just have fresh  race fluid. Good pads, and cooling air going to them and they should be fine.  

I raced my MG with stock drums  fresh fluid before every event, and decent linings on the race track known to be hardest on brakes. Elkhart Lake. 3 long straights, 14 corners, most tight 90 degree.  Never had a problem. 

Indy cars Can Am cars, etc all brought their best brakes. 

Augie Pabst raced the 600 horsepower powerful Scarab there with the original drum brakes. My Jaguar Special was in the same class and even with 4 wheel disk brakes I could never out brake Augie, even at the end of the race!!!! 

Fresh fluid, cooling air, good linings, now spend money on more power!!! 

You can always add brake cooling too. Are the solid rotors and vented rotors the same thickness, giving the solid rotors more thermal mass? Not sure how likely it is, but it wouldn't shock me to see a solid rotor with more thermal mass and cooling ducts resisting cracking/warping better than a vented rotor with less thermal mass

In reply to AngryCorvair :

Thermal management can be met by good fresh fluid, cooling air,  and better linings.  

You’d be amazed at the number of people who go racing with old brake fluid that’s absorbed plenty of moisture just sitting around. Remember brake systems are open!    Brake fluid absorbs water just sitting around!  

In reply to Dr. Hess :

Chances are too he can gain force by going to a smaller master cylinder or longer pedal. 

AngryCorvair said:

but for the OP's stated "on the street and on the track" i think thermal management is more important.

Oops. You have precisely located the reading comprehension failure which led to my question.

Question: "Hey, I'd like to use my car for X. Should I do A or B to it?"

Me: "Well that depends on what you want to do with it. X or Y?"

In reply to Curtis : exactly!  ID, OD, width, spacing!  

Then realize that you can swap bearings and hubs around too!  Use a different ID bearing or OD bearing to fit a strange hub onto a different spindle.  

Or even more creative use the stock suspension links and maybe a different end to use say a Chrysler hub and spindle on a totally car.  

We made Buick finned aluminum brakes work on a Chevy  using all stock parts just moving things around a bit.  We converted a rear steer set up to a front steer by swapping left with  right.  

Went into a bearing supply house with the pieces we needed to work and found the right bearings.  Who cares what the application was originally intended for.  All  you have to ask is will it fit and is it capable  of working with a margin of safety.  

STM317 said:

You can always add brake cooling too. Are the solid rotors and vented rotors the same thickness, giving the solid rotors more thermal mass? Not sure how likely it is, but it wouldn't shock me to see a solid rotor with more thermal mass and cooling ducts resisting cracking/warping better than a vented rotor with less thermal mass

Don’t forget, that cooling can be achieved a whole lot of ways.  Sure ducted  air is really cheap but look at the wheels too!  No very little air actually blows through even the most open wheel but a lot of heat is lost through radiation.  Open wheels radiate a lot of heat.  It’s one reason Ferrari held onto wire wheels and drum brakes as long as he did.  

Look at your wheels!  Can you see the brake disk and calipers easily?  If you can then that combination will provide plenty of cooling. 

alright after much discussion here and opposing views and this: 

what i did to my integra's vented brake rotors (picture sideways for some reason) I think im going to go with the cheaper kit that has the better cooling

frenchyd said:

In reply to AngryCorvair :

Thermal management can be met by good fresh fluid, cooling air,  and better linings.  

Cross off "good fresh fluid" and "better linings" and i will agree with you.

Fluid does not manage heat.   Better linings do not manage heat.

Since we are discussing how to make a proper system for this vehicle, i will assert that a proper system does not overheat the fluid or the pads.   if it does either of those things, it is by definition not a proper system.

i can't believe i just argued with frenchy.  goddamn it, this is never going to end.

I can't believe anyone said (and I paraphrase) "Angry, this is how brakes actually work" 

In my 49 years on this planet I have learned three inalienable truths:

Patrick Caherty knows brakes

Eric Storhok knows fuel systems

Steven Griffiths knows whisky

In reply to JmfnB :

49?  You look much older.

AngryCorvair said:

frenchyd said:

In reply to AngryCorvair :

Thermal management can be met by good fresh fluid, cooling air,  and better linings.  

Cross off "good fresh fluid" and "better linings" and i will agree with you.

Fluid does not manage heat.   Better linings do not manage heat.

Since we are discussing how to make a proper system for this vehicle, i will assert that a proper system does not overheat the fluid or the pads.   if it does either of those things, it is by definition not a proper system.

i can't believe i just argued with frenchy.  goddamn it, this is never going to end.

You are technically correct. Good fresh fluid doesn’t manage heat.  It just allows the system to deal with higher temperature.   Brake fluid  absorbs water from sitting around.  ( I know the word hydro- but can’t remember how to spell it)  That water causes the fluid to boil at lower and lower temps and boiling fluid feels like brake fade.  

 Same thing with linings.  Race pads/ linings deal with higher temps while still working.  

There are cheap ways to deal with heat transfer causing brake fluid boiling.  Brake ducts are the cheapest. Use air picked up from the high pressure areas in the front of the car.  Arguments still exist where to aim the ducting. Sold rotors  they go to the calipers but ducted rotors can be aimed at the center of the hub or at the rotor.    Ceramic insulators are another one but not ever caliper has them commercially available. Plus you lose pad depth  or need spacers which may interfere with the wheels.  

frenchyd said:

In reply to Dr. Hess :

Chances are too he can gain force by going to a smaller master cylinder or longer pedal. 

Wait, what? A SMALLER master? I would think the opposite would be true... learn me?

AngryCorvair said:

In reply to JmfnB :

49?  You look much older.

Holy crap, I'm glad I didn't have any whiskey in my mouth- it would be all over my screen right now!

BTW, Pat- it's ok that you tried to argue with frenchy- like John said, we all know who to believe.  For sure, the published author from GRM....

TheRX7Project said:

frenchyd said:

In reply to Dr. Hess :

Chances are too he can gain force by going to a smaller master cylinder or longer pedal. 

Wait, what? A SMALLER master? I would think the opposite would be true... learn me?

Simple pressure physics.  10lb on a 1in^2 piston is 10 psi, 10lb on a 1/2in^2 piston is 20psi.  Half the area, double the pressure with the same force. Apply that to the same diameter piston in a different place, and you have double the force from the same original force.  One of the cool mechanical advantage mechanisms.  Like the wedge.

But it's still constrained by conservation of energy.  

With fresh racing  fluid and new pads and rotors, go out and find the limit to your braking that you want to improve on.

Do ten threshold stops on a quiet country road from 60 mph and measure each one. Take a cheap IR thermometer along so you can measure the caliper and rotor temps at the end of the test.

If you can still lock the wheels up after that, you need stickier tires.  If you cant, take note of the temp and do whatever it takes to make it lower after the same test.

Questions for those that might know...does removing the backing plate help or hinder temperature management with a disc brake system?

Pete