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-   -   Fuchs 15inch brake options (http://forums.pelicanparts.com/porsche-911-technical-forum/1049929-fuchs-15inch-brake-options.html)

Chassis87 01-14-2020 09:56 AM

Fuchs 15inch brake options
 
Hi all,

I know that this topic has been discussed ad nausea.

But I cant find a true solution.

I currently have non boosted brakes, with 3.2 calipers on with a motor pumping 300hp on 15inch ****s which I use on tarmac rallies.

This car does not stop where I want it to, and any attempt to try brake where I should, results in the car to keep going in a straight line, then I have to dump it into engine brake and get in a spin to stop. This is done not to run over people/marshalls. hehe.

Ive been reading the forum and people have mentioned using boxster calipers.

However lets say budget is no problem, I literally need the ultimate, a google search isn't pointing me in the right direction.

So please, name or pm vendors, and if I should maybe install a brake booster (again name or pm vendors) He who can supply a whole package get my monies.

Im fed up of not stopping and being the gift that keeps on giving.:p

Much love

jpnovak 01-14-2020 10:06 AM

930 brake calipers F/R. rear calipers need to be modified for 3" mounting holes on your trailing arms.
930 rotors front and rear with proper rotor hats on the front.

23mm MC to supply enough fluid for the extra pistons in your new brakes.

Done.



Boxster brakes will increase braking torque due to larger pads but uses the same rotors as the 3.2 Carrera brakes you currently have. There is no increase in thermal capacity.

I want to know why you can't stop short enough. Is this brake compound? Pad grip? overheating? wheel lockup? single wheel lockup? The 3.2 brakes up front are usually very good. I tracked a set of a long time without any issues. Just needed proper pads and some cooling ducts.

Chassis87 01-14-2020 10:12 AM

Its actually not a heating issue, its more a cold bite issue our stages are like time trials 50-70seconds long and we don't get enough heat in the brakes.

I use Ferrodo DS2500, which have the best cold bite.

so I actually need more "clamping" power, the lack of heat is my biggest enemy.

Thanks

jpnovak 01-14-2020 10:21 AM

I like the Ferrodo DS2500. They are on both my cars. But they need a little heat to work best.

What other pads have you experimented with?

How much does the car weigh? What wheel/tire setup are you running?

Cory M 01-14-2020 10:35 AM

Sounds like your application is more like an autocross than a racetrack. This will be an interesting discussion because most of brake upgrades (930, Stoptech, Brembo, etc) are designed to increase the thermal capacity of the system so it doesn't overheat. I agree with jpnovak, while they aren't sexy the stock Carrera brakes are very capable with good pads and fluid. You could size down to SC or mid year brakes, which are the same diameter but thinner than the Carrera parts so they'll heat up a little sooner. If you want more initial bite or grab adding the power booster would help, you may lose some sensitivity and modulation.

darrin 01-14-2020 10:39 AM

agree with the booster comment -- even cold, standing on my (boosted) Carrera brake pedal will lock up wheels --

Chassis87 01-14-2020 11:23 AM

Quote:

Originally Posted by jpnovak (Post 10719163)
I like the Ferrodo DS2500. They are on both my cars. But they need a little heat to work best.

What other pads have you experimented with?

How much does the car weigh? What wheel/tire setup are you running?

Approx 1100kg, wheels dont know by heart but appropriate for 255 and 210 pirelli (also do for a change, but that is a different post)

No i haven't experimented with other pads, cause from my other cars i would not change ferrodo.

Chassis87 01-14-2020 11:24 AM

Quote:

Originally Posted by Cory M (Post 10719179)
Sounds like your application is more like an autocross than a racetrack. This will be an interesting discussion because most of brake upgrades (930, Stoptech, Brembo, etc) are designed to increase the thermal capacity of the system so it doesn't overheat. I agree with jpnovak, while they aren't sexy the stock Carrera brakes are very capable with good pads and fluid. You could size down to SC or mid year brakes, which are the same diameter but thinner than the Carrera parts so they'll heat up a little sooner. If you want more initial bite or grab adding the power booster would help, you may lose some sensitivity and modulation.


Any idea from where i can get me a power booster?

Chassis87 01-14-2020 11:25 AM

Quote:

Originally Posted by darrin (Post 10719184)
agree with the booster comment -- even cold, standing on my (boosted) Carrera brake pedal will lock up wheels --

Very good to hear!!

Chassis87 01-14-2020 11:27 AM

Are 930 calipers bigger then 3.2 calipers?

Isnt there an aftermarket for brake kits under 15 inch like wilwood, ap, or the other major players.

Thanks

Cory M 01-14-2020 12:36 PM

Quote:

Originally Posted by Chassis87 (Post 10719240)
Any idea from where i can get me a power booster?

Depends on the year of your car. If you have an SC or Carrera you should be able to just bolt in the factory parts (from your user name I assumed you had an 87..)

darrin 01-14-2020 01:09 PM

930s originally shipped standard with 15x7 / 15x8 Fuchs, so while the 930 calipers are bigger, they were designed/intended to fit under 15" fuchs.

That said, seems a boosted MC is likely the best solution for your issue

Bill Verburg 01-14-2020 01:32 PM

Front brake torque @70bar line pressure for
A or S 1444n-m
Boxster on C3.2 rotor 1815n-m
930 1961 n-m
You get the most bang for the led effort from 930s

You do want to do both for and rear for bias and use a 23.8mm m/c for the best pedal

There are calipers that give you more like 993RS @ 2306n-m but they won't fit under 15s

The limiting mechanism is the tires, any of the above are capable of locking the tires especially if used artlessly

wjdunham 01-14-2020 01:57 PM

Quote:

Originally Posted by Chassis87 (Post 10719244)
Are 930 calipers bigger then 3.2 calipers?

Isnt there an aftermarket for brake kits under 15 inch like wilwood, ap, or the other major players.

Thanks

There is a Stoptech P-car kit for 15" wheels, but about the same price as 930 brakes based on prices I've seen for a good set of 930 caplipers plus the rotors, hats, etc...

Bill

Chassis87 01-14-2020 02:04 PM

Quote:

Originally Posted by Cory M (Post 10719322)
Depends on the year of your car. If you have an SC or Carrera you should be able to just bolt in the factory parts (from your user name I assumed you had an 87..)

haha no no I was born in the 80's, car is a swb 68, but I had changed the struts for the 3.2 calipers

Chassis87 01-14-2020 02:08 PM

Quote:

Originally Posted by Bill Verburg (Post 10719373)
Front brake torque @70bar line pressure for
A or S 1444n-m
Boxster on C3.2 rotor 1815n-m
930 1961 n-m
You get the most bang for the led effort from 930s

You do want to do both for and rear for bias and use a 23.8mm m/c for the best pedal

There are calipers that give you more like 993RS @ 2306n-m but they won't fit under 15s

The limiting mechanism is the tires, any of the above are capable of locking the tires especially if used artlessly

So 930 it is....and from where do I find these please together with master cylinder?

Do I also need to change discs, or can I use the one's I have?

Thanks

Bill Verburg 01-14-2020 02:17 PM

Quote:

Originally Posted by Chassis87 (Post 10719427)
So 930 it is....and from where do I find these please together with master cylinder?

Do I also need to change discs, or can I use the one's I have?

Thanks

yes, you need rotors and discs it's a system
a pile of parts
http://forums.pelicanparts.com/uploa...1579039972.jpg

front
http://forums.pelicanparts.com/uploa...1579039972.jpg

assembled front
http://forums.pelicanparts.com/uploa...1579039972.jpg


original rear is trailing 3.5" mounts which need to be machined for leading 3" front mount on a 911
http://forums.pelicanparts.com/uploa...1579039972.jpg
stock rear bottom, modified rear top
http://forums.pelicanparts.com/uploa...1579039972.jpg

additionally if you buy '87 up rears the fluid intake will need to be modified
http://forums.pelicanparts.com/uploa...1579039972.jpg



http://forums.pelicanparts.com/uploa...1579039972.jpg

for a non boosted car you need an ATE ports left m/s

It's best to buy a kit which includes the m/c actuating rod anfluid feed lines and fittings
http://forums.pelicanparts.com/uploa...1579039972.jpg
http://forums.pelicanparts.com/uploa...1579039972.jpg
http://forums.pelicanparts.com/uploa...1579039972.jpg

darrin 01-14-2020 02:23 PM

Still think you only need a boosted MC -- If I got in my '86 Carrera now, immediately drove it to 30mph and slammed on the (still stone cold) brakes, I'd lock up my front wheels immediately and be backing off to modulate. You should be able to do exactly the same thing with stock calipers/disks -and your limitation appears to be stemming from a lack of vacuum assist. While 930 calipers and a 930=compatible master cylinder will get you to the same place, the primary benefit of 930 calipers and disks (yes, yo will need to change disks too -- this gets $$$$) is fade resistance.

Recommending a specific MC for your application and retrofitting vacuum assist to your early SWB car is beyond my (very limited) scope of knowledge -- but others should be able to easily chime in -- and get your desired result (increased stopping power, not increased fade resistance) for a lot less $$$$ than a 930 brake retrofit

Bill Verburg 01-14-2020 02:28 PM

Quote:

Originally Posted by darrin (Post 10719449)
Still think you only need a boosted MC -- If I got in my '86 Carrera now, immediately drove it to 30mph and slammed on the (still stone cold) brakes, I'd lock up my front wheels immediately and be backing off to modulate. You should be able to do exactly the same thing with stock calipers/disks -and your limitation appears to be stemming from a lack of vacuum assist. While 930 calipers and a 930=compatible master cylinder will get you to the same place, the primary benefit of 930 calipers and disks (yes, yo will need to change disks too -- this gets $$$$) is fade resistance.

Recommending a specific MC for your application and retrofitting vacuum assist to your early SWB car is beyond my (very limited) scope of knowledge -- but others should be able to easily chime in -- and get your desired result (increased stopping power, not increased fade resistance) for a lot less $$$$ than a 930 brake retrofit

It's a fairly complicated procedure to add a vacuum booster to a non boosted 911

Chassis87 01-14-2020 02:31 PM

Quote:

Originally Posted by darrin (Post 10719449)
Still think you only need a boosted MC -- If I got in my '86 Carrera now, immediately drove it to 30mph and slammed on the (still stone cold) brakes, I'd lock up my front wheels immediately and be backing off to modulate. You should be able to do exactly the same thing with stock calipers/disks -and your limitation appears to be stemming from a lack of vacuum assist. While 930 calipers and a 930=compatible master cylinder will get you to the same place, the primary benefit of 930 calipers and disks (yes, yo will need to change disks too -- this gets $$$$) is fade resistance.

Recommending a specific MC for your application and retrofitting vacuum assist to your early SWB car is beyond my (very limited) scope of knowledge -- but others should be able to easily chime in -- and get your desired result (increased stopping power, not increased fade resistance) for a lot less $$$$ than a 930 brake retrofit

Darrin I feel you completely, I'm also contemplating on the power brake option.

Was reading a post on how to do...seems complex for my knowledge too.


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