Hot front brakes after open track session

[red65]

I took my '65 to an open track day just north of Detroit two weekends ago (Waterford Hills for the locals), and had a blast. First time with the 'stang on an open track since its resurrection - very very pleased with the way the car performed, thanks largely to all the advice and cumulative wisdom on this forum. Fast on the straights, nearly neutral handling on turn-in, and good braking...

Here's the question - the track has a number of tight turns after relatively high-speed straights (90-95mph in the straights, down to 35-40 in the next turn). The brakes - SSBC's Force 10 kit with 11" rotors and 4-piston iron calipers on the front, SSBC 11.25" disks on the back - performed great until the second session, when the brake pedal got a little squishy for the first lap. I'm imagining that the fluid boiled after sitting hot following the first session, heat soaked and then cooled after a lap into the second session.

Considering options to keep things a little cooler:

- SSBC recommended upgrading to an aluminum 4-piston caliper (instead of the cast iron on that's on there) for $500

- Air ducting to the brakes?

- Scrap the 11" setup and upgrade to the 13" version?

- Stop driving so fast?

Any opinions from among the corner-carving crowd? Historic?

Thanks guys!

 

[HistoricMustang]

I took my '65 to an open track day just north of Detroit two weekends ago (Waterford Hills for the locals), and had a blast. First time with the 'stang on an open track since its resurrection - very very pleased with the way the car performed, thanks largely to all the advice and cumulative wisdom on this forum. Fast on the straights, nearly neutral handling on turn-in, and good braking...

Here's the question - the track has a number of tight turns after relatively high-speed straights (90-95mph in the straights, down to 35-40 in the next turn). The brakes - SSBC's Force 10 kit with 11" rotors and 4-piston iron calipers on the front, SSBC 11.25" disks on the back - performed great until the second session, when the brake pedal got a little squishy for the first lap. I'm imagining that the fluid boiled after sitting hot following the first session, heat soaked and then cooled after a lap into the second session.

Considering options to keep things a little cooler:

- SSBC recommended upgrading to an aluminum 4-piston caliper (instead of the cast iron on that's on there) for $500

- Air ducting to the brakes?

- Scrap the 11" setup and upgrade to the 13" version?

- Stop driving so fast?

Any opinions from among the corner-carving crowd? Historic?

Thanks guys!

I always bleed the brakes after each session.

Yes, it is a pain the in ass but necessary for consistant laps. Bleeding will remove any fluid that may have reached too high of a temperature and it will bring cooler fluid closer to the brakes.

Always stayed away from anything but Castrol DOT 4.

Of course air ducting will help and perhaps (if you do not already have) a valve in the lines to use just as much rear brake as possible.

Happy Motoring!

HistoricMustang
www.historicmustang.com

URL=http://imageshack.us]

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[red65]

hmmm.. bleeding after every session had not even crossed my mind. Is the purpose to bleed off any gas that's developed as a result of boiling?

Also -- fluid is autoparts-store DOT3 right now - can I flush and replace wtih DOT4 without a lot of fuss?

As for ducting - do you know of any off-the-shelf kits or am I best dreaming up a duct myself (certainly capable, just don't want to reinvent the wheel).

Thanks for your help!

 

[70vert]

Cobra Automotive

Red65,
Whenever I have an urge to be like Historic but want to spend a lot of money, I reach for the Cobra Automotive catalog. Seriously though, I bought their Boss 302 Crossmember and it seems to work well, and they have a brake ducting kit for the front and rear. I have their print catalog but seem to have lost the price schedule, probably out of fear.

http://cobraautomotive.com/Handling.htm ]

They have kits for 11" and 12" brakes and you can download their catalog in PDF form.

hmmm.. bleeding after every session had not even crossed my mind. Is the purpose to bleed off any gas that's developed as a result of boiling?

Also -- fluid is autoparts-store DOT3 right now - can I flush and replace wtih DOT4 without a lot of fuss?

As for ducting - do you know of any off-the-shelf kits or am I best dreaming up a duct myself (certainly capable, just don't want to reinvent the wheel).

Thanks for your help!

 

[HistoricMustang]

hmmm.. bleeding after every session had not even crossed my mind. Is the purpose to bleed off any gas that's developed as a result of boiling?

Also -- fluid is autoparts-store DOT3 right now - can I flush and replace wtih DOT4 without a lot of fuss?

As for ducting - do you know of any off-the-shelf kits or am I best dreaming up a duct myself (certainly capable, just don't want to reinvent the wheel).

Thanks for your help!

Bleeding is just a good idea to keep fresh fluid at the brakes and in the system and you will have no problem putting in the DOT 4 but I would go ahead and just flush the entire system with the 4. Get a buddy and a six pack and get at it!

The duct tubing can be found at most of the catalog suppliers - I think mine came from Summit. Ten foot section (fireproof) runs about $30. You can make a bracket at the brakes using simple aluminum flat bar and cap the tube using nothing more than a chrome kitchen sink "drain" (been trying to tell everyone you can do this stuff on a budget). Here is my set up!

HistoricMustang
www.historicmustang.com

 

[HistoricMustang]

Red65,
Whenever I have an urge to be like Historic but want to spend a lot of money, I reach for the Cobra Automotive catalog. Seriously though, I bought their Boss 302 Crossmember and it seems to work well, and they have a brake ducting kit for the front and rear. I have their print catalog but seem to have lost the price schedule, probably out of fear.

http://cobraautomotive.com/Handling.htm ]

They have kits for 11" and 12" brakes and you can download their catalog in PDF form.

If you have the bucks they have great stuff and they have outrun me on numerous occasions. The cool thing about CA is that they race their early models "period correct". The problem I have is with the "Joe Blows" that come and go here at StangNet and want nothing more than your hard earned money!

I simply lost count of the "XYZ" companies that have "lurked", done some posting and then are gone!

HistoicMustang
www.historicmustang.com

 

[red65]

Thanks much, fellas!

 

[Mach1steve]

another "add-on" option

There is a company called Muggzi Performance www.muggziperformance.com that has "bolt-on" replacement rotors for your car that Crossdrilled & Slotted.

These do not require larger rims, 14" are fine, and it is a straight bolt in peice that replaces the factory rotor, works with all your factory components (calpers, wheel bearings, etc.)
I know they keep these in stock for all years of Classic Mustangs.
I have a set on my 70 Mach1, and I found I could brake a little later, and less brake fade. Alot cheaper than an aftermarket brake kit.
Probably good for the occasional lapping day, but the stock brakes I don't think are up to high track usage unless you under "period correct" rules.

Just thought some of you might be interested.

Mach1steve

 

[70vert]

uh oh, here we go

(begin side thread about how Wilwood and Baer both say crossdrilling and slotting were for older pads that offgass, but newer high quality pads do not and so crossdrilling and slotting are a waste of money and crossdrilling can weaken the rotor and overall all this reduces the surface area of the rotor that acts as a heat sink and pulls heat AWAY from the brake pads and gets cooled by the wind)



seriously though, they do both say in their FAQ that crossdrill/slot are for bling. The one thing about slot that might be nice is that they can "wipe" the pad and give you more even wear, it's like a scraper but would wear down the pad faster I think. Anyone else care to comment?

 

[Edbert]

Drilling and slotting just looks good, only reason I spent the extra $35 on my 13" rotors.

Ever notice how thick the rotors are on race cars? Anyone care to discuss rotor thickness and it's effect on heat sinking and dissipation?

 

[chepsk8]

Just to toss in some more input, getting your brakes hot shows you were running good and hard! It's one of the smells you get after a good session.

As noted above, if you plan on doing this alot, definitely upgrade the brakes.

 

[Hack]

(begin side thread about how Wilwood and Baer both say crossdrilling and slotting were for older pads that offgass, but newer high quality pads do not and so crossdrilling and slotting are a waste of money and crossdrilling can weaken the rotor and overall all this reduces the surface area of the rotor that acts as a heat sink and pulls heat AWAY from the brake pads and gets cooled by the wind)



seriously though, they do both say in their FAQ that crossdrill/slot are for bling. The one thing about slot that might be nice is that they can "wipe" the pad and give you more even wear, it's like a scraper but would wear down the pad faster I think. Anyone else care to comment?

For anyone who wants to read debate on the subject, clicky. http://corner-carvers.com/altimathread.php.html

Have a great day!

Edit: oh, and the reason to bleed is that brake fluid absorbs moisture. Water will boil when the system gets hot, and then the car won't stop.

And for racing you want to get some racing pads that are meant to run hotter. Before an event just change your pads to the race pads. Don't run them on the street, because they will never get warm enough to function properly.

 

[1966conv]

Brakes

Do the SSBC's allow for the use of DOT 4? I wouldn't change unless knowing for sure.
Ford has a DOT 3 that has a boiling point higher than nearly all but the most expensive fluids. (PL-?) I'll have to look for the number. I use it with good results.

I'd definately flush the system, use the recommended fluid, find a performance pad, and then see how you do. A performance pad maybe crap on the streets though, so be prepared to change back after open tracking.

Good luck, have fun and be safe!

 

[LMan]

You havent said what pads you are using/used. Best calipers in the world dont mean anything if you dont have a good pad in there.

If you are using stock pads, its no wonder they got squishy after a session. Try a better pad for more data.

Plus, if you are trying hard out there, anything *but* a full-on race brake setup is going to get a bit spongy after a few sessions. You can mitigate it, but you wont completely eliminate it.

 

[HistoricMustang]

You havent said what pads you are using/used. Best calipers in the world dont mean anything if you dont have a good pad in there.

If you are using stock pads, its no wonder they got squishy after a session. Try a better pad for more data.

Plus, if you are trying hard out there, anything *but* a full-on race brake setup is going to get a bit spongy after a few sessions. You can mitigate it, but you wont completely eliminate it.

I have always run a Raybestos stock pad (Granada Taxi Cab style) with no problems so be careful before spending big bucks on pads that may only be used for one weekend of haulin' the mail. I never could justify the price difference and stayed with the stock pads. Also, with an aggressive pad you will go through rotors like a knife through hot butter and not really gain very much if any.

HistoricMustang
www.historicmustang.com

 

[ericl]

I would suggest dot 4 or dot 5.1. Please note that dot 5 and dot 5.1 are two EXTREMELY different types of fluid. As noted on this forum dot 5 is a silicone base and does not absorb water (this is a bad thing) which can cause issues with cars not designed for this type of fluid.
Dot 5.1 is glycol base like dot 3 and dot 4. The dot 5.1 has similar dry boiling point as dot 5 but glycol base.
some charts
http://www.evilplastic.com/bfluid.htm

http://www.swedishbricks.com/700900FAQ/Brake Fluid Comparison.htm

BTW, I run Motul 600 in my daily driver and parts store dot 4 in my mustang. I plan on switching to the 13" MS kit and new Motul 600.

 

[hsr]

The duct tubing can be found at most of the catalog suppliers - I think mine came from Summit. Ten foot section (fireproof) runs about $30. You can make a bracket at the brakes using simple aluminum flat bar and cap the tube using nothing more than a chrome kitchen sink "drain" (been trying to tell everyone you can do this stuff on a budget). Here is my set up!

Historic,

Forgive me, I'm slow. Can you please provide some additional information regarding the use of the sink drain. How it caps the tube or is attached? Do you have any pictures with the spindle turned out that will show your setup more clearly?

Thanks in advance,

 

[mdjay]

Well one thing is for sure, Historic's point of view is always refreshing for the sheer "can do" attitude. The posts have gotten considerably more interesting with the smiley graphics though! So keep us smiling

 

[HistoricMustang]

Historic,

Forgive me, I'm slow. Can you please provide some additional information regarding the use of the sink drain. How it caps the tube or is attached? Do you have any pictures with the spindle turned out that will show your setup more clearly?

Thanks in advance,

It is early and I am headed out to work. Will attempt to get up a better pic this evening.

HistoricMustang
www.historicmustang.com

 

[HistoricMustang]

Well one thing is for sure, Historic's point of view is always refreshing for the sheer "can do" attitude. The posts have gotten considerably more interesting with the smiley graphics though! So keep us smiling

It is amazing what a younger woman can do for an old man!

HistoricMustang
www.historicmustang.com