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Dual front brake calipers

Old 09-23-06, 07:54 PM
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Dual front brake calipers

Respeed is going to be making some brackets for a dual brake caliper setup. In the formula D series Rhys Millens Pontiac solstice has the same setup. Now my question is how effective would this be for racing use? A decent brake upgrade for a FC would run close to 2k or more. But they also use larger rotors to disapate the heat. Now with dual calipers, would the stock size rotor be able to handle the heat or would it just cause the rotors to fry to quickly, even when air cooled?

http://www.mrcmfg.com/respeed/catalo...13941636760b24
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Old 09-24-06, 10:13 AM
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The limiting factor is the size of the rotor, not the amount of pad area or number of calipers. Pointless.

Besides, with dual calipers you've now got twice the piston area and are going to need a larger master cylinder.

Anybody offered a reason as to why they want dual calipers? Multiple calipers are legal in most racing series and yet nobody does so. The rotor is always the limiting factor.
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Old 09-24-06, 10:30 AM
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But it looks totaly cool now doesn't it? No legit need for it especially in drifting, but it does look trick. In the past it was used since aftermarket race calipers and rotors were not as available as they are today. Better braking setups are easily found and installed without the use of two calipers and if using the same rotor it will not perform any better than one.
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Old 09-24-06, 01:02 PM
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Not sure about on a TII, but the FD is already over biased towards the front anyway. So why would you want to do this?

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Old 09-24-06, 01:10 PM
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Originally Posted by Fish
Not sure about on a TII, but the FD is already over biased towards the front anyway. So why would you want to do this?

Fish
I always thought all brake systems were biased to the front because ~70% of the braking is done by the front brakes (seeing as the weight shifts forward).
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Old 09-24-06, 01:26 PM
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If you have a over emphasis of rear braking that can lead to scary oversteer situations under heavy braking, due to the front being lighter, and causing the rear to lock.
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Old 09-24-06, 03:33 PM
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Originally Posted by run_rabbit_run
I always thought all brake systems were biased to the front because ~70% of the braking is done by the front brakes (seeing as the weight shifts forward).
And the OEMs want the front brakes to lock first, because when that happens the car plows straight ahead, being stabilized by the rear.

If you lock the rears first, the car becomes greatly unstable since you lose lateral stability and your braking force is in front of the CG. Very easy to spin.

Many OEM designs shuttle 90% of the braking force to the front brakes for this reason. I don't have the stats on the FD, but in a 1st-gen, the brake bias just from caliper piston area is on the order of 67%, and we haven't figured pad area or the proportioning valve into it yet. Hell, I *removed* the proportioning valve from my car and it still locks the fronts well before the rears...

AFAIK, all rear calipers have the same bore, and the 4 pot calipers have the same hydraulic area as the single-pots. The 4 pot calipers are an advantage because they are lighter and more rigid.
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Old 09-24-06, 05:39 PM
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I just want to point out that the brackets were manufactured for a customer who specifically requested them. We have put them up on the site to get a feel if our customers would want them.

As DamonB and Tims stated the rotor diameter is a limiting factor in the braking system. Two calipers will not give more stopping power. It will help dissipate the heat in the system though. The rotor is the largest heat dissipater in the system. Help with the heat can be done through diameter and thickness, when possible for the application.
If not possible in the application, increasing the pad and piston area can be the next best thing, although no where near the amount resulting from changing the rotor.

Is this old school, yes
Is this as effective as a rotor change, no
Is there a benefit, yes


This specific customer was experiencing fade at track days. He has way to many 13" wheels and did not want to fit the larger rotor. Otherwise he was going to go with our FC brake package.

-billy
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Old 09-24-06, 05:41 PM
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Seems like just trying out better brake ducting would have been a better idea...
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Old 09-24-06, 10:39 PM
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Oh, it's for a 1st-gen!

Someone on Mazspeed did this years ago, just took a couple caliper mounting brackets, sawed the appropriate half off, and welded it together.

My question is, does the "front" caliper interfere with the swaybar? I am interested in moving my existing calipers to the front in order to make strut changes easier. (I use studs in the bottom of the strut housings, so the only way they come off is to yank the caliper bracket, and the ***-pains which that entails)

I do understand the ramifications of moving the weight of the caliper ahead of the steering axis as regards to steering feel and such. That is secondary IMO relative to making it easier to swap out strut housings, which only seem to last a few thousand miles before the spindle is bent/worn out.

Last edited by peejay; 09-24-06 at 10:43 PM.
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Old 09-25-06, 07:27 AM
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Peejay, it does not interfere with the sway bar. The stock brackets should work well flipped to the front and oposite side. Not sure about the backing plate though, you may need to drill out the spot welds and remove t from the brackets.

Where is your strut housing bending? It is near where the cast knuckle meets the tube?

-billy
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Old 09-25-06, 09:40 AM
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Originally Posted by Turbo23
If you have a over emphasis of rear braking that can lead to scary oversteer situations under heavy braking, due to the front being lighter, and causing the rear to lock.
Three words: Brake Proportioning Valve.

The front also gets heavier under hard braking, not lighter.

Also: why on earth would any sane racer actually want to increase unsprung weight?

Final word: senseless ricer bling.

-b

ps. posting this from the VIR North Paddock, watching the Porsches roll onto the track. Ain't the Internet a wonderful thing?

Last edited by wrankin; 09-25-06 at 09:44 AM.
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Old 09-25-06, 10:57 AM
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All adding a second caliper can do is increase pad area and thus allow the temperature of the brake pads to be lower. If the brake pads were fading this could help (although you'd be much better off just running the proper pad). A second caliper cannot somehow reduce rotor temps though. The rotor has to absorb the amount of energy necessary to slow the car and no matter how the calipers or pads are made that energy will be the same in each case.

If the pads are heat fading you go up to a higher heat range of pad. If the rotor is the limiting factor you do a better job of cooling the rotor. If the rotor still isn't cooling enough you move up in size. You can't make a rotor run cooler by adding additional calipers.

If I were going to carry around a bunch more unsprung weight I'd put it in the rotor, not in extra calipers. What if my wheels limit my rotor size? I can still go to a thicker rotor and I can still add cooling to it. If this still isn't enough that's just how life will be. A second caliper can't offer anything.
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Old 09-25-06, 11:41 AM
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Originally Posted by DamonB
All adding a second caliper can do is increase pad area and thus allow the temperature of the brake pads to be lower. If the brake pads were fading this could help (although you'd be much better off just running the proper pad). A second caliper cannot somehow reduce rotor temps though. The rotor has to absorb the amount of energy necessary to slow the car and no matter how the calipers or pads are made that energy will be the same in each case.

If the pads are heat fading you go up to a higher heat range of pad. If the rotor is the limiting factor you do a better job of cooling the rotor. If the rotor still isn't cooling enough you move up in size. You can't make a rotor run cooler by adding additional calipers.

If I were going to carry around a bunch more unsprung weight I'd put it in the rotor, not in extra calipers. What if my wheels limit my rotor size? I can still go to a thicker rotor and I can still add cooling to it. If this still isn't enough that's just how life will be. A second caliper can't offer anything.
You'd think with that second caliper covering that area it would reduce the cooling to the rotor, too. Seems more counterproductive for our cars. I'm with Damon on this being a big waste of money. Go big brake or keep it stock.
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Old 09-25-06, 11:45 AM
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If it is fluid boiling try the thermal pad backing kits from HRP world. If its pads getting cooked(are they crumbling?) get better pads. And get as much air to them as possible.
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Old 09-25-06, 02:14 PM
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Ya sorry got the words mxied up, the rear becomes lighter and front becomes heavier under braking. Just thought Id throw the idea out and see if there were any advantages to it. I know carl was running stock calipers on his FC and seemed to be doing fine for alittle while. However thnaks for all the input!
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Old 09-25-06, 06:24 PM
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Originally Posted by bwaits
Peejay, it does not interfere with the sway bar. The stock brackets should work well flipped to the front and oposite side. Not sure about the backing plate though, you may need to drill out the spot welds and remove t from the brackets.
Not sure what you mean about spot welds and such.

Unless you mean the little dust shield/air scoop things. Every 1st-gen strut I've had was either missing those or had them mostly rusted away. The first time I have one apart, I peel the junk off by hand just for preventative work.

Where is your strut housing bending? It is near where the cast knuckle meets the tube?
The spindle itself gets tweaked, right about the same time that the outer bearing starts spinning on the spindle and wears it down. At that point, you can have significant play in the wheel with the bearings preloaded. I do not know if bending causes the bearings to spin or vice-versa, but slowly and surely I am cleaning the Ohio area out of Series 3 strut housings
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Old 09-25-06, 06:49 PM
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Originally Posted by peejay
Unless you mean the little dust shield/air scoop things.

the outer bearing starts spinning on the spindle and wears it down..... I am cleaning the Ohio area out of Series 3 strut housings
Yea, the dust shield.

We always had to reinforce the strut tubes but never the spindle area.

We used to run every year in Chillicothe...I seem to remember the place smelling bad....paper plant or something.

-billy
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Old 09-25-06, 07:20 PM
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what if you used all ceramic?

ceramic rotors disperse heat like its nothing
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Old 09-26-06, 08:00 AM
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Liv - If he can't afford to buy decent diameter wheels to clear bigger brake rotors, then how can he afford to buy ceramic brake rotors??
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Old 09-26-06, 05:24 PM
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bwaits,
Not a knock on your company for building the brackets for a customer who requested them. just commenting on the design thinking(his not yours). there are plenty of larger rotors(than a OEM 1st gen) available for 13" wheels that would be larger and heavier. You would be surprised what will fit, but if someone wants dual calipers I would make them a bracket too. And it never hurts to see if anyone else in the world wants the same thing. Lots of better ways to improve the braking performance but if the customer wants them fine.
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Old 09-26-06, 06:32 PM
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Originally Posted by tims
bwaits,
Not a knock on your company for building the brackets for a customer who requested them. just commenting on the design thinking(his not yours). there are plenty of larger rotors(than a OEM 1st gen) available for 13" wheels that would be larger and heavier. You would be surprised what will fit, but if someone wants dual calipers I would make them a bracket too. And it never hurts to see if anyone else in the world wants the same thing. Lots of better ways to improve the braking performance but if the customer wants them fine.
No offense taken at all. You pretty much nailed it on the head, we have the design, we have the ability, we put it out there to see how many more could use them. If customers want them we will make them. We really bounce through so many ideas and prototypes around here and not all of them go anywhere.

-billy
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Old 09-26-06, 09:33 PM
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Now my question is weather or not there are options for improving breaking on my FB while keeping my 4x110 bolt pattern. As far as I've seen there is only powerslot rotars and ebay rotars. As well as hawk HP+ pads. Is there any other upgrades available? After my car wreck a few weeks ago I deided breakes are the next upgrade. couldn't stop in time. damn drunk drivers!
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Old 09-27-06, 12:38 AM
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Hmm, a new caliper bracket to fit a larger disc that would still fit with stock wheels... Now that would be nice.
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Old 09-27-06, 02:44 PM
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Kentetsu has the idea. Custom bracket or adapter, better caliper, and bigger/heavier rotor with custom rotor hat that fitts inside of the rims you are using. a few measurements and a look through the various brake manufacturers catalogs and some machine shop work and you in business. It would take some homework but it should be an easy project.
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