Brake Upgrades????????

[KIRASIR]

A couple of points:



a) The size difference between the M3 calliper piston and a 328 calliper piston is 6mm.(60vs54mm) The difference is far from "huge".



b) Bigger callipers, rotors, pads, etc in your case = more braking power TO THE FRONT WHEELS ONLY, which doesn't necessary mean shorter braking distances. You are currently comparing your new setup (brand new pads/rotors/fluid) to your worn out old 318ti brakes. Of course, your car now stops better than before. BUT! your quote:

"and the wheels look full... (talking about the front ones... cause the rears looke like the calliper and rotor came off a geo metro!)"



What's happening is that you changed the bias of the braking system towards the front, so now the front tires are doing all the stopping. The brakes don't stop the car (not directly) - tires do. The shortest brake distance is the one where all 4 wheels are on the limit of loosing traction (the weight distribution is 50/50 during braking), which is carefully archived through calliper/rotor sizing and brake cylinder valving. Changing any of the components affects the braking bias of the system and increases the stopping distances as in your case where your braking weight distribution is probably now around 60/40 (arbitrary numbers). It's simple physics.



Don't get me wrong, I've done a very similar swap to what you have (330 brakes) and the difference between the new brakes vs. the old worn out ones are a night and day. HOWEVER, changing only the front callipers/rotors alone to the 330/M3 setup does not make your car stop quicker than a car with the 328 brakes.





In the local BMW chapter we have several BMW instructors that do laps around M3s and Porsches in their 328s with stock brakes without any brake fade or problems with stopping. 328 brakes are perfectly capable of stopping any e36 model around the track, and are much cheaper alternative to the M3/330 swap. If you already have 328 brakes the money can be spent better somewhere else. All you need is a decent set of pads and some fresh fluid.



You have to understand that M3 stops better not just because it has bigger brakes but because the WHOLE system was designed and tuned for M3 and for M3 alone. Most of the tuning is usually done by proper sizing calliper pistons and brake cylinder valving. The brake cylinder for M3 IS different than for a ti. It is bigger, and should be valved differently (I don’t have the specs data for it right now).





Cheers,



SL

Originally Posted by maurolin

The size difference between an M tech caliper and a regular is HUGE.
Rotors are so much bigger, which means there is more braking surface, bigger rotors are cooler, and bigger calipers and pistons mean more braking power.

No offense to anyone, but I have known some People do a mediocre upgrade to 328 calipers JUST because they don't want to spend the extra $ replacing the Spindles that are required for an Mtech Upgrade. WITH THE EXEPTION of people that DON'T TRACK OR RACE THEIR CARS. Don't get me wrong, 328 brakes are great street brakes, but under high speed high temp this is not the set up to go with. Also, if you have a turbo or SC... Upgrade to AT LEAST M is a must.

And if 328 brakes and rotors brake as good an M3 brakes like some one mentioned... WHY did BMW Motorsports even bother spending the time and money upgrading the setup?? I mean let's face it... Steel bradded lines STIFFEN your pedal, Dot 4 or 5 brake fluid DOES NOT GIVE YOU ANY BETTER BRAKING it just prevents the fluid from BOILING under really hard braking or track driving. Better rotors will help and better pads will definately help. but after you've spent the cash on new UPGRADED rotors and pads, new lines... you'll have upgraded 328 calipers and you've reached your limit, but you could have had M tech setup, for the same price, and still have room to grow.
This is MY example: I paid $200 M calipers $200 M spindles $110 Brembo slotted rotors $50 Axxis pads, $100 steel lines and $10 blue racing fluid. I will put any passanger through my winshield with a hard brake. and the wheels look full... (talking about the front ones... cause the rears looke like the caliper and rotor came off a geo metro!)
but that's just my 2 cents and opinion.

[maurolin]

sure agree... but the M caliper is almost 2 inches bigger THAT"S HUGE. the piston may be close, but we are talking 2" more on the rotors, larger pads, larger housings etc.

No matter what, your car ALWAYS has more braking on the front than the rear... (rear pads last twice longer than fronts on an M3 or any other unmodified brake system)
Front caliopers are ALWAYS bigger as most of the braking is done by the front wheels. same in motorcycles.

changing only the front callipers/rotors alone to the 330/M3 setup does not make your car stop quicker than a car with the 328 brakes.

yes it does. MUCH quicker.

[GDB]

Originally Posted by maurolin

sure agree... but the M caliper is almost 2 inches bigger THAT"S HUGE. the piston may be close, but we are talking 2" more on the rotors, larger pads, larger housings etc.

No matter what, your car ALWAYS has more braking on the front than the rear... (rear pads last twice longer than fronts on an M3 or any other unmodified brake system)
Front caliopers are ALWAYS bigger as most of the braking is done by the front wheels.same in motorcycles.



yes it does. MUCH quicker.

I agree with you completely, there is no way you will have 50/50 weight distribution during braking unless the car is incredibly rear heavy/nose light. But I have seen a couple cars with larger rear rotors than front rotors. I am yet to understand the reasoning behind this but I'm sure it's there.

[KIRASIR]

OR if you have front springs that are infinitely stiff, and all the suspension links are solid. Take go-karts for example, most of the basic karts have only brakes in the rear. Springs rates, shocks, center of gravity, everything comes into play when manufacturers design brake systems.

I think a better question for this thread is:

What brakes fit in the back of a ti? Are there any other alternatives to the the ///M Z3s rear brakes and the hassle that comes with the upgrade(subframe/trailing arms)?

SL

Originally Posted by GDB

I agree with you completely, there is no way you will have 50/50 weight distribution during braking unless the car is incredibly rear heavy/nose light. But I have seen a couple cars with larger rear rotors than front rotors. I am yet to understand the reasoning behind this but I'm sure it's there.

[maurolin]

What about E30 M3 brakes? I don't know too much about them although I have a set of calipers and rotors.

Brembo, Willwood and Stoptech make and upgradded kit.

I agree Ti's are in DESPERATE need of rear brake upgrades, but I still know and belive Front brakes are 75% of your braking AT LEAST if not more.

For example... whe you do a burnout.... Heel and toe the brake and gas... you are BARELY pressing on the brake and the front wheels are locked, but the rear wheels anre smoking.... TOO MUCH REAR BRAKING will make the car loose control. Try pulling your Ebrake... c'mon... do it... for the heck of it.... the rear end will go CRAZY @ high speeds. (I am not saying yank on the brake.. I am saying GRADUALLY pull rather hard... but not locking.)

"go karts" or and shifter karts are WAY different. Go karts are cheaply made, and having undependent front brake systems is very costly and requires too much maintenance. They use 1 rear rotor.
Shifter karts, use 2 front rotors and 1 rear rotor.. Once again, MORE BRAKING POWER to the front... you ARE going forward right? so under braking the car's weight and mass mover to the front. now try going backwards fast and slam on the brakes.... that's a slow stop and a wierd sensation too! haha.

[aceyx]

sorry to resurrect this but after reading L8s thread, i ran a search and came across this.

1. do not include motorcyles and karts into this discussion. karts brake at the motor (thus, why they only need one rotor), not at the wheel like cars do. motorcycles have slightly more advanced braking systems (multipot calipers, floating discs, etc), but that's because it's the only thing between you and that brick wall SUV you're flying at.

2. a 6mm difference in diameter is in fact, huge. i can show you the math if you're interested, but it basically allows you to add an additional 400lbs of force (200lbs per wheel) with the same amount of brake pedal travel.

3. m3 brakes will not stop you faster. the only thing they do is a) allow you to apply less force to the pedal (but c'mon, are you really that weak?) b) allow your brakes to undergo longer, and much more rigorous conditions without fade than normal driving. will you ever see those conditions? maybe, but you're probably going to be at the back of the pack if that's your driving style.

4. a brake upgrade will not make you stop any faster.

5. upgrading your brakes will not make you stop any faster.

6. ein bremse aufsteigen stoppt nicht schneller.

7. the only thing that will make you stop in a shorter distance is a) a tire with a greater contact patch (note: this does not necessarily mean a wider tire, but it often helps) or b) a tire with a softer (stickier) compound.

[pdxmotorhead]

My non shifter kart has front and rear brakes because I weigh 100 lbs more than the
kids I race against (Sucks to hit 40 but better than the alternative.) and it lets me
hit the apex harder. YMMV

Dave

[318ti_Portugal]

What about the added weight the M3 iron calipers and larger rotors make?
That turns of the balence of the car because it is upsrung weight...