| Author |
Message |
Rob Lay (Rob328gts)
Board Administrator
Username: Rob328gts
Post Number: 3035
Registered: 12-2000
| | Posted on Wednesday, December 18, 2002 - 2:00 pm: | |
Wow, that's more technical than I've ever been about brakes, but looks like fairly easy things to check out. We're allowed brake ducts (one of the few things) and I've just never done it before. I never have brake problems in a race, just cracking the rotors now and then. Yes, Brembo makes a stock rotor for our cars and that's who supplies Mazda Competition. However, Mazda comp trys to get $110 each for them. I've heard there's only about 3 manufacturers total and all the stores rebrand them. It's a crap shoot at places like O'Reily which one you'll end up with. I'm trying to find a place that I know only gets the Brembo ones. I usually pay about $40 a rotor at O'Reily's.
As I understand blow by in the master cylinder it's when you're actuating the internal piston and the seal is bad, so with fluid rushing "back" you're not getting all the forward fluid pressure you could. |
Rexrcr (Rexrcr)
New member
Username: Rexrcr
Post Number: 46
Registered: 11-2002
| | Posted on Wednesday, December 18, 2002 - 1:45 pm: | |
Rob,
What's "blow by" in a brake system? Air passing into the master cylinder?
Get some temperature indicating paint from a race supply place, I used to order from Hyperco, though their product lines have changed in the last few years, they were the least expensive with the traditional three color (green, orange, red) brake rotor temp paint. Performance Friction has a paint that changes to different colors depending on temp rather than one color burning to white. Monitor your rotor and caliper temps (use the stickers on the caliper). Work on a cooling system. I know the RX7 design makes it tough, but the best way is to duct air to the center of the rotor so it may radiate through the vents in the rotor. Otherwise build a clamshell to cool both sides of the rotor. Usually what occurs is the inboard side of the rotor is cooler than outboard, rotor warps and eventually cracks. Try different rotor manufactures, Brembo actually makes a large number of OEM replacement applications, I purchased a set from NAPA and they were Brembo for a Honda. Metallurgy makes a huge difference. Try cryogenic treatments, lets the molecules get happy with each other.
As for caliper rebuilds, remove caliper from car, place on bench and pop the pistons out one at a time with compressed air (be careful, put a wad of rags in to "catch" the piston as it pops, cover the entire caliper with another rag 'cause brake fluid's gonna fly if you're not careful). Clean and inspect piston and bore for scoring, pitting, burs, anything that may cut the new seal or allow fluid to pass the seal. I've used brake cleaner in a spray can and very mild Scotch Brite to clean. Ferrari pistons are usually stainless steel which is good, durable, lower conduction, cheap to replace if necessary. Some are Teflon coated aluminum, so be careful when cleaning, you can remove the coating easily. I use rubber grease for assembly lube (compatible with brake fluid), some only use brake fluid as a lube. When racing with OEM calipers I usually don't retain the dust boot because it just melts away eventually and I'm rebuilding frequently enough to clean out the debris.
If you're allowed to by the rules, brace the firewall at the master to the strut tower, improves "feel" by reducing flex. Have someone mash the brakes in a simulated panic stop and watch your firewall flex! |
Rob Lay (Rob328gts)
Board Administrator
Username: Rob328gts
Post Number: 3029
Registered: 12-2000
| | Posted on Wednesday, December 18, 2002 - 10:50 am: | |
I crack the rotors on my Spec. RX7 about every 6-8 races. That's stock brakes except for the pads.
What do you do when rebuilding a caliper? I guess you mentioned seals, but just making sure good piston movement?
I have to watch my master cylinder too, a race this summer I had weird brake feel and it was blow by. |
Rexrcr (Rexrcr)
New member
Username: Rexrcr
Post Number: 45
Registered: 11-2002
| | Posted on Wednesday, December 18, 2002 - 10:06 am: | |
"Ford Heavy Duty was the best racing brake fluid"
Castrol SRF is the best, cost no object. Though if you are indeed flirting with 550 degF fluid temperatures, you really need to watch other components like the caliper seals, and improve cooling. The seal material degrades quickly with continued high temperature exposure. There are higher quality seals available for most applications.
In TransAm twelve years ago, we rebult calipers after qualifying each event and then after each race. I routinely rebuilt calipers, on 348 Challenge cars we did it every three races and always before Montreal. With the 360 Challenge the seals held up much better and we'd go four events and never had a problem.
It's easy to reach 500 degF on the fluid if you track the car. Rotor temps go to 1100 DegF without a proper brake cooling system and a heavy foot.
I ran a 100 hp Honda (2200 lbs) at Blackhawk Farms years ago and the rotors were over 1000 degF in four laps. I had no problems though due to fresh fluid, properly broken in rotors and pads (Porterfield R4). |
Marq J Ruben (Qferrari)
Junior Member
Username: Qferrari
Post Number: 153
Registered: 2-2002
| | Posted on Wednesday, December 18, 2002 - 6:19 am: | |
Hans, my manual says the same (88-1/2 328), "flush brake fluid and change/ refill with fresh fluid every 12 months". I do it. Cheap insurance. Overkill?...maybe, but nevertheless I do it.
|
Kurt Kjelgaard (Kurtk328)
Junior Member
Username: Kurtk328
Post Number: 169
Registered: 3-2001
| | Posted on Wednesday, December 18, 2002 - 3:36 am: | |
There are two problems (maybe more?) with water in the braking fluid:
1. Lowers boiling point and
2. Promotes rust inside the system
The rust issue is probably the main reason to
change the fluid at least every two years on normally driven cars. |
Hans E. Hansen (4re_gt4)
Member
Username: 4re_gt4
Post Number: 691
Registered: 4-2002
| | Posted on Wednesday, December 18, 2002 - 12:32 am: | |
My owner's manual says to change fluid every year. Seems like overkill. Comments? |
Rob Lay (Rob328gts)
Board Administrator
Username: Rob328gts
Post Number: 3021
Registered: 12-2000
| | Posted on Tuesday, December 17, 2002 - 9:23 pm: | |
Rexrcr, YOU RAN TRANSAM?!?! I'm a huge Trans Am fan. Anyway, funny you say this because I was told that the Ford Heavy Duty was the best racing brake fluid. I guess there's some truth behind it. I buy a case at a time. But I get the 12 oz. cans because I think the worst killer of brake fluid is air and water. |
Rexrcr (Rexrcr)
New member
Username: Rexrcr
Post Number: 43
Registered: 11-2002
| | Posted on Tuesday, December 17, 2002 - 7:37 pm: | |
On the street, every 2 - 3 years, if you're fastidious, do it once a year. Most (99%) cars probably never get bled or flushed even by dealerships (I'm talking non-Ferrari). Usually it's never changed over fear of breaking a bleeder screw, plus many drivers never experience high brake temperatures.
On the track, before every event if you push the car near the limit. You can get away with less frequency if you baby the brakes, but then what's the point of going to the track? |
Dr. Winston Watson (Drwatson)
New member
Username: Drwatson
Post Number: 2
Registered: 12-2002
| | Posted on Tuesday, December 17, 2002 - 6:29 pm: | |
How often should fluid be changed ?
Regards, WW |
Jim DeRespino (Jimbo)
New member
Username: Jimbo
Post Number: 30
Registered: 10-2001
| | Posted on Tuesday, December 17, 2002 - 6:13 pm: | |
I've run nothing but the Ford brake fluid for years. It is the best kept secret around. I should buy it by the truckload, make up some red labels and sell it at $50/pint "For Ferrari Only".
It is recommended by Baer Brakes along with Performance Friction for all but most extreme use. |
Craig Dewey (Craigfl)
Member
Username: Craigfl
Post Number: 507
Registered: 1-2001
| | Posted on Tuesday, December 17, 2002 - 4:05 pm: | |
This is another example of the discussion we we having some months ago abot the new oild -- SJ or SK or whatever letter they're up to now...
Just because it's newer and "improved" and has the latest SAE mark doesn't mean it's better. A lot of the new formulas are the result of changing manufacturing processes, longer life requirements and EPA requirements about the handling and disposal of ingredients that may be hazardous. Thanks for the reminder Rxrcr! |
'75 308 GT4 (Peter)
Intermediate Member
Username: Peter
Post Number: 2285
Registered: 12-2000
| | Posted on Tuesday, December 17, 2002 - 3:34 pm: | |
I've been using the Ford fluid in my cars since I've had them. On advice of my racing buddy who used it in his Datsun race cars for years with success.
|
Rexrcr (Rexrcr)
New member
Username: Rexrcr
Post Number: 42
Registered: 11-2002
| | Posted on Tuesday, December 17, 2002 - 2:58 pm: | |
Just trying to be helpful and spread the word on "best practices."
For all you budget conscience Ferrari owners, the highest performance brake fluid vs. cost is manufactured by Dow Corning and sold commercially under a variety of brands. Ford Heavy Duty brake fluid (blue can) is one example (Willwood and Performance Friction also market it). It's DOT 3, don't run away, that's just the government test standard this fluid conforms to. The beauty of this stuff is you get the best of all possible fluids: dry boil is 568 degF. Yes, this is higher than the DOT 4 spec if you've read the FMVSS. It's DOT 3 because it conforms to wet boil standards, which are higher for DOT 3 than DOT 4.
So, what does this mean to me, Joe Ferrari guy, lover of all things fast and beautiful? If you don't track the car, you have a great fluid for long term use and can use it in the family truckster, too. If your a track dog, the stuff is ~$7.00/pint, a bargain for 570 degF dry boil. Bleed all the time and buy the stuff by the case.
Yes, there is higher quality available, I only use Castrol SRF in a professional race car, but that's $50/liter in case or pallet quantity, $75/liter individually. Oh, and date open cans, discard for track use after a week or so, street driving use is fine.
I discovered this in 1989 while running a TransAm car. Roush Racing used it rather than AP600, which was too hygroscopic and not worth the cost according to Roush.
Yes, the stuff you've been using is fine, keep using it if you like. I have seen guys at the track with vats of open to the atmosphere brake fluid, rusty old cans, etc. and they didn't crash. I just tend to be cautious and like to use the best available parts. |
|