brake upgrade advice

Isabo · 09-14-2006, 07:56 AM

I had some extensive seat time in a Boxter this week and what I learned is that it has much better brakes than my hotrodded 911. Although my car was born a 2.2E for most practical purposes it is an SC mechanically now with 7 & 9 X 16 Fuchs.
I was budgeting to get the bodywork sorted this winter but after trying the Boxster I think I'd rather upgrade the brakes.
What are the options

Bill Verburg · Bill Verburg's Garage

What specifically did you like about the Boxster brakes? What made you feel that they are better?

Isabo · 09-14-2006, 08:15 AM

Most important was that the stopping distances seemed a lot shorter. But they also felt a lot more progressive.

Bill Verburg · Bill Verburg's Garage

That has a lot to do w/ the boost, pads and tires.

A stock 911 can stop at least as fast if you can generate the line pressures with only your leg.

progressive feel is mostly about ridgeity and pads and temps

Zeke · 09-14-2006, 08:44 AM

Bill is the maestro when it comes to brakes, but you could always put Boxster brakes on your 911 using TRE's kit.

Bill Verburg · Bill Verburg's Garage

Quote:

Originally posted by milt
Bill is the maestro when it comes to brakes, but you could always put Boxster brakes on your 911 using TRE's kit.

But the car still won't stop any better

2.7RACER · 09-14-2006, 09:12 AM

Isabo,
Are you saying you like the "feel" of the Boxster brakes as compared to the "feel" of your existing non-boosted brakes?
If this is the case, would adapting a booster to your existing brakes do the job for you?
Bill V, is this a reasonable thought?

Bill Verburg · Bill Verburg's Garage

Quote:

Originally posted by 2.7RACER
Isabo,
Are you saying you like the "feel" of the Boxster brakes as compared to the "feel" of your existing non-boosted brakes?
If this is the case, would adapting a booster to your existing brakes do the job for you?
Bill V, is this a reasonable thought?

definitely, power assist makes a huge difference in the apparent feel of the brakes.

I have identical brakes on both my 911 and 993 except for pads and boost on the 993. There is a night and day difference in the feel. hot or cold, cold the nod should go to the non boosted set up w/ street pads, but the higher line pressures generated w/ the boosted setup more than compensate.

They can both stop pretty much the same but you need to work at it much harder w/o boost.

yes I am getting older but I still do a couple hundred bicycle miles a week or run if the weather is bad. So don't blame it on old age

dd74 · 09-14-2006, 09:56 AM

FWIW - a huge difference was made when I swapped out the old (and small) front brakes that came with my '74 for SC-sized brakes. I left the rears stock. The brake pads on all four are a little more aggressive than stock, and all-in-all, the brake feel is very reassuring. But tires, IMO, truly make the overall difference in a sorted out braking system. So I wouldn't neglect those either.

Bill Verburg · Bill Verburg's Garage

For sure tires are almost always a limiting factor, as long as you have reasonable high perf tires they don't make a difference in feel.

They do make a big diffference in threshold braking and controll thereof, when brakes are upgraded tires usually need to be upgraded as well.

Peter Kelly · 08:32 AM

I went to Boxster calipers front and rear on my 89 911, along with 23mm master cylinder and custom hats with custom 312mm rotors up front. Brake feel is much better, I can consistently brake at .1 to .15 G more FOR AN ENTIRE TRACK SESSION (no fade due to overheat), and best of all, my PFC 97 pads last for 8 to 10 track days, as opposed to 2-4 days with stock calipers.

My total outlay was < $2000, replacement slotted rotors done by coleman to my drawing are about $ 120 each, and it looks like I will get 2 years out of a set of rotors.

Oh yea, I also have 2 cooling ducts on each front rotor, one below the A-Arm and 1 in the front spoiler.

Could I have done a similar or better upgrade by just buying a kit? probably, but I am not a "kit" kind of guy.

I will be at the Glen with HCR next week if anyone wants to take a look.

Bill Verburg · Bill Verburg's Garage

Peter does not have the usual Boxster upgrade(which is not really much of an upgrade at all) to Carrera rotors. That makes a huge difference. It sounds like he has done it right. The big rotors(at least in front), 312x? compared to the usual Carrera 283x24 makes all the difference in the world.

Bigger rotors; apply more torque and are bigger heat sinks

They will stop the car faster, still constrained by tires, run cooler and as a result pads and rotors will last longer.

The 'feel' still comes from the stiffness of the components and the master/slave ratio. When the master /slave ratio gets into the "feelin really good" range(which the 23.8mm m/c w/ Boxster calipers does), power boost makes a huge difference in the actual line pressures that can comfortably be generated. I am not saying that you can't push like he** w/ non boosted brakes, it's just a whole lot easier and makes for a more enjoyable experience.

This setup sounds to be roughly equivalent to true 930 brakes

DW SD · 09-15-2006, 10:18 AM

Quote:

Originally posted by Peter Kelly
I went to Boxster calipers front and rear on my 89 911, along with 23mm master cylinder and custom hats with custom 312mm rotors up front. Brake feel is much better, I can consistently brake at .1 to .15 G more FOR AN ENTIRE TRACK SESSION (no fade due to overheat), and best of all, my PFC 97 pads last for 8 to 10 track days, as opposed to 2-4 days with stock calipers.

My total outlay was < $2000, replacement slotted rotors done by coleman to my drawing are about $ 120 each, and it looks like I will get 2 years out of a set of rotors.

Oh yea, I also have 2 cooling ducts on each front rotor, one below the A-Arm and 1 in the front spoiler.

Could I have done a similar or better upgrade by just buying a kit? probably, but I am not a "kit" kind of guy.

I will be at the Glen with HCR next week if anyone wants to take a look.

Peter,
Could you give some info on the coleman rotors that you bought? And from whom did you buy them?

Doug

randywebb · 09-15-2006, 10:59 AM

Isabo,

Do you have any thoughts on what you'd like to do re your brakes?

"Softer" pads might be one inital thing to do. They will give more initial "bite" tho they may also negatively affect how well you do on a track.

Feel like describing your leg strength to a bunch of males?

A power booster seems out of the question on an early car....

I don't know what is easily available in Italy either.

tc-sacto · 09-15-2006, 11:38 AM

bump,
interested in the rotors also. as I have boxster brakes all around with carrera rotors and 23.8 mc. Peter, what rear rotors do you run?

Isabo · 09-15-2006, 11:41 AM

I would like my brakes to work more efficiently and feel better.
I don't know the practicalities of fitting servos to an early car but my car is a very bastardised hotrod, it started life as a 2.2 E with sportomatic and the funny front suspension. it was already an RS clone with a manual box and regular dampers when I got it. It is now effectively an SC mechanically and I'm pretty sure has the SC brakes AND servo assistance.
For availability anything Porsche OE or Brembo or Tarox is easily available or I can import.
My thoughts were to rip everything out and install the best set-up for fast road use with occiasional forays into hillclimbs.
My leg strenght? I've never thought about it but I think quite good. Soft pads may not be a good idea as even my road use is "intense", I've tried EBC green and they were not very satisfactory.

rfuerst911sc · 09-15-2006, 12:03 PM

Bill Verburg is the brake expert but here is my opinion for what it's worth. For a early light car like yours the best bang for the buck would be going with 1984-1989 Carrera 24mm rotors and calipers. They are bolt on ( I believe ) readily available, relatively cheap with good performance and feel. Add a power booster and good performance pads with some additional cooling and you have a great street setup and a good track setup. You can then "fine tune" with different pads as required. The Boxster calipers will give more clamping power but the "normal" application of 24mm rotors the calipers can easily overpower the rotors so what have you gained?

Peter Kelly · 09-15-2006, 12:04 PM

I run poweslot rotors on the rear. the front rotors are coleman heavy duty with curved vane, gas slotted and stress relieved, custom machined per my drawing. Hats are machined from billet aluminum per my drawing. Caliper brackets are obviously custom too. Hardware is all NAS. If you included engineering time I probably have a $ 6000 brake system, but hey, this is fun for me.

Peter Kelly · 09-15-2006, 12:16 PM

pic

randywebb · 09-15-2006, 01:11 PM

It sounds like you have or think you have SC front struts...

Can you post a pic?

I can't recall if the SC struts have the right spacing for Carrera calipers or if that was only changed for the Carrera struts.

Also, how old are the rubber hoses? Or were they changed to the metal braided ones at some point?