Brake questions

Well he had the Volvo rear axle so I'm sure he went back to the stock Volvo stuff.

---

"Rally racing makes a heroin addiction look like a vague craving for something salty"

Run good fluid, and flush it all the way to the bleeder at the start of every rally. Run a good pad. Its all you really need for that car to be good on brakes.

If you start micky mousing the brakes, you are asking for to many problems.

For good pads for that car, get Cobalt Friction preferably and if they dont make your shape go with Carbotech.

Also dont put in a dual m/c setup. No need and its more stuff to deal with and problems can easily develop if not tuned right. Just remove the booster and redrill the clevis hole closer to the pivot on the brake pedal to gain some ratio. Put a prop valve to the rears and call it a day.

Thanks for all the input guys, appreciate it a ton!

I have a few reasons for wanting to go with a pedal assembly. One to improve feel, two to give myself a lot of range to adjust stuff (I like to mess with things almost as much as I do racing) and lastly/most importantly to free up space on the firewall to brace the strut towers a bit more. There is quite a bit of room under the dash to put stuff, but space in that corner of engine bay is at a premium. Ketchum stage at OTR illustrated that a few things need to get moved around. HAHA

If I can't find a fitment of front caliper I am happy with, I will probably just keep the stock calipers for now and run them with a pedal set. I think they would be "enough" but if I can get more under there, I am always happy to have more if I need it, especially if I get a wild hair and do some track day events with it.

The rear setup on the car seems really good already, Volvo stuff.

---

John Reed
John Reed Racing
www.johnreedracing.com
johnreedracing@gmail.com

What pads are you running currently?

I've only used my '85 Corolla for cone squishing and for Lapping days, so it's not a direct comparison to yours, but here's my take on the brakes I've got on the car:

I'm not caged, but do run a full interior. No undercoating/etc has been stripped from the car. The car was weighed at 2463lbs, with me and fuel and spare tire, before I put the power steering system on. A cage, codriver, and rally spares and tools would probably add a few more pounds, but I'm not sure how much.

That being said, I'm able to out-brake EVO's and STi's and Z06's and Mustangs at HPDE's, particularly at Brainerd MN, coming in to turn 2 at about 120mph in 5th gear, and most other corners as well. (Part of this may be driver input, rather than the mechanical component.

After a 25-minute session last year, I measured the temperature on the front rotors after a cooldown lap and sitting for 3-5 minutes at ~320°F.

I've got stock calipers and rotors. I did actually route some cooling duct from the front bumper to point at the caliper. This may be more difficult to do on a rally car, depending on how your skidplate is set up.

This time I happened to be using some ATE blue fluid (I swap it with clear fluid alternating times, to make sure I get a complete flush.)

The biggest component, in my opinion, is the pads, however. I'm currently running Raybestos ST-45/43 pads front/rear. You get them from Porterfield, so they might just be a rebranded Porterfield pad, like the R4 or R4E, but I'm not sure. I just talked with them about what I was doing with the car, and that I'd used Carbotech XP-10/8's previously. After installing them, and using them, I can honestly say that I've never used a pad that has such a great balance of initial bite and extremely high temperature tolerance. I do a lot of track days at Blackhawk Farms, at which it is not uncommon to go through an entire set of pads through one event, with a re-bleed after every session. I did not have to re-bleed even once with these pads. I don't know the temp of the rotors when actually braking when they're hot, but I managed to get some pad fade on the carbotech XP10s, which have a claimed fade resistance up to 1650°F.

So, long story short, I think the stock calipers on this car are mechanically sound enough to work really well. The tiny size fits under whatever wheel you want.

BUT it doesn't have a lot of mass to be able to absorb/dissipate the heat generated.

My way to be able to work with those temperatures was to add ducting, and go with a pad that can tolerate higher heat.

Putting in bigger rotors with bigger (aluminum) calipers will also help combat the heat, as well as having a larger pad friction area on the larger rotor. Depending on the cost of fabrication/adaptation, that could be the best bang/buck around. For myself, because I like to use 13" wheels for cone-squishing, I needed to stay small, so I went with the ducting and really friggin' good pads.

Just some food for thought, since I don't actually rally (yet) so my voice of experience may not be as well educated as some others.

--Jorden

---

---** To be in compliance with the Anarchy **---
Jorden R. Kleier
Baraboo, Wisconsin, USA
1990 Mazdog Protege 4WD
1973



Edited 1 time(s). Last edit at 06/12/2012 11:11AM by SgtRauksauff.

I am basically running volvo all around now.
steel 4 piston front,
steel 2 piston rear,
volvo wheels, 14 (stock alloy) or 15 (never run stock volvo 15s).
I only had perfect brakes once. and it only lasted a day.
with the stock stuff, I had done a bolt check, replaced the front wheel bearings, and the MC (still boosted).
I think the pads getting knocked around was the biggest reason for the poor feel. everything else had been replaced.

Here is something Australian . . .
http://www.hachiroku.com.au/2009/06/ae86-tuning-guide-ultimate-stopping-power/

---

"I put the hurt on dirt" - adam crane
http://CraneRallyCrew.com
corolla gt-s "Patches"
Op: S.S.

Quote
Cosworth
Also dont put in a dual m/c setup. No need and its more stuff to deal with and problems can easily develop if not tuned right. Just remove the booster and redrill the clevis hole closer to the pivot on the brake pedal to gain some ratio. Put a prop valve to the rears and call it a day.

who are you, and what did you do with Cosworth?

---

KF7RWG
http://www.utahrallygroup.com

Quote
acrane
I am basically running volvo all around now.
steel 4 piston front,
steel 2 piston rear,
volvo wheels, 14 (stock alloy) or 15 (never run stock volvo 15s).
I only had perfect brakes once. and it only lasted a day.
with the stock stuff, I had done a bolt check, replaced the front wheel bearings, and the MC (still boosted).
I think the pads getting knocked around was the biggest reason for the poor feel. everything else had been replaced.

Here is something Australian . . .
http://www.hachiroku.com.au/2009/06/ae86-tuning-guide-ultimate-stopping-power/

The RX7 setup in that link is what I was looking at (but was worried about fitment), but I talked to T3 today (also in that link) and they have their Wilwood 4 piston setup in a size to suit 13"/14" wheels (using a 10" rotor) so I decided to take the plunge and order that setup. Will make it nice to have such a wide range of pads/compounds available too. Not sure what is available for the rear (I think I have the same Volvo two piston as you).

---

John Reed
John Reed Racing
www.johnreedracing.com
johnreedracing@gmail.com

Adam, I have brake feel issues on my Volvo at the track, I am pretty sure it is the rear axles moving and pushing on the pistons. It did not change with new front wheel bearings.

Quote
Aaron Luptak

Quote
Cosworth
Also dont put in a dual m/c setup. No need and its more stuff to deal with and problems can easily develop if not tuned right. Just remove the booster and redrill the clevis hole closer to the pivot on the brake pedal to gain some ratio. Put a prop valve to the rears and call it a day.

who are you, and what did you do with Cosworth?

Paul is an engineer and works for Performance Friction.

---

Grant Hughes

Quote
NoCoast

Quote
Aaron Luptak

Quote
Cosworth
Also dont put in a dual m/c setup. No need and its more stuff to deal with and problems can easily develop if not tuned right. Just remove the booster and redrill the clevis hole closer to the pivot on the brake pedal to gain some ratio. Put a prop valve to the rears and call it a day.

who are you, and what did you do with Cosworth?

Paul is an engineer and works for Performance Friction.

I'm aware of that part. It's the "don't do dual m/c's, its not needed" that seemed different than his previous posts.

---

KF7RWG
http://www.utahrallygroup.com

Quote
Aaron Luptak

who are you, and what did you do with Cosworth?

I'm aware of that part. It's the "don't do dual m/c's, its not needed" that seemed different than his previous posts.

Ha. I read that literally, like what work, not what set of stairs did you stuff him under.

I'm guessing Paul's point is, if you are looking to hodge podge a braking system together using junkyard parts or 25 year old calipers, you are probably more likely to end up with a fucked up system that doesn't operate correctly and are better off just keeping the system stock, tossing good fluid and pads at it, and going out and having fun.
We won the regional overall at Rally Colorado against three different $40-50k Open class Subarus in a GC with a nearly stock junkyard sourced 2.2T engine, $1000 used DMS struts and stock discs front, stock drums rear with Porterfield R4 pads. We even drove the car to and from the event...

---

Grant Hughes

You're right Grant, but Aaron is also not out of line, because I would normally recommend the proper stuff. BUT since the guy is looking at doing a mix match of parts and adaptations, too many things can already cause problems, so then why add another denominator in this equasion of fuck up?

Tandem master cylinders need to be properly setup, the fill ratios between the front and rear hydraulic factor need setup so that the initial timing comes on at the same time, or at least a safer the front before the rear. All of this is not counting the proper positioning of the balance bar because that also can cause issues. More than 3 turns from 50/50 (middle point) causes severe bias migration due to the bar pivoting on the master with most resistence.

So with all the mix match and adapting old equipment and machining, etc... all you need is the caliper mounting face not to be perfecly square with the centerline with the disc for you to have a long unpredictable pedal with a constant mild brake drag.

So with all of that being said, why not just run some good pads, good fluid and a prop valve. Less stuff to go wrong and the performance is not too far off from what you would gain with all the other equipment.

Good advice from all, I appreciate it! I wasn't really trying to mix and match old parts, more trying to find the best solution that fits under the 14" wheels that are already existing (so I don't have to waste time doing something custom) and the RX7 calipers are the most popular with brackets readily available. I just find them a little too tight for comfort. I like the idea of the wheels being a "fuse" and being able to take some damage without causing me other issues. Plus I really need to move the master cylinders, for a variety of reasons.

I guess we will see how it all works out when the parts show up. Tilton was very helpful in spec'ing out the pedal set/master cylinders so hopefully I didn't sign myself up for too much fiasco. No matter what, the brakes can't get much worse than they were at OTR. HAHA Next step was to cut the floor out so we could drag our feet.... :-)

---

John Reed
John Reed Racing
www.johnreedracing.com
johnreedracing@gmail.com