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brakes

Can anyone recommend a good brake upgrade for my 85.5 944. I'm thinking 4 new calipers and rotors. Would only getting new rotors shorten my stoping distance?

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Old 10-04-2004, 04:04 PM
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You could slap on some big reds or 951 calipers, but its alot of money, If I where you I would go get some drilled rotors and a set of HPS hawk brake pads
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1986 951, Stock for now.
]87 924S Gaurds red- SOLD after 11 years of ownership
Old 10-04-2004, 04:30 PM
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Drilled rotors won't really help you shorten the stopping distance. The simplest upgrade would be to buy performance pads. The next step would be to buy improved rotors (like frozen or brembo). An all out upgrade to a turbo-like set-up with independant piston calipers is a little overkill for this car (stomp on the brakes and you'll just skid). By most accounts the stock system is fine for as light as this car is. What I would do from a purely low cost/max improvement perspective is
new PBR carbon pads
new frozen rotors
new S/S brake lines
ATE Super Fluid (blue or gold)
rebuild and repaint calipers
check for leaks.
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Louie

'85 (Early) 944 - Beater
'87 924S - Crunch/Rebuild
'76 924 - Long Gone
"If everything seems under control, you're just not going fast enough."
- Mario Andretti
Old 10-04-2004, 05:52 PM
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In many many cases the brake fluid has NEVER been fully flushed.
1) remove all rubber lines and install stainless steel braided lines
(little if any flex during brake application)
2) install quality pads (conduct a poll or search for the best pads)
3) drain the entire brake system and fill and bleed system with new fluid.

You will never believe the difference this will make for a really cheap "upgrade"
Rob
Old 10-05-2004, 09:48 AM
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I would suggest FLUSHING the brake fluid, rather that draining it. If the system is completely empty, it is sometimes difficult to get ALL the air bled out. Use a dot 4 fluid - AP 551, ATE Blue, Motul 600, Wilwood 600, etc...

-Put the car up on stands & take all 4 wheels off.
-Use bleed bottles with clear tygon tube so you can see when the fluid changes color.
-start on RH side (it is further from master)
-open a front and rear bleeder at the same time
-making sure that the reservoir stays full, SLOWLY pump brake
pedal.
-continue until you get clear fluid,
-go to left side, repeat.

As for improved brake pads, I use Hawk Blue on the front, and Hawk Black on rear on my car - for both street and club events. There are other companies that make a street/track combo pad...ie....PFC, Pagid, etc.

I agree with lousailor - most drilled rotors are mainly for cosmetic reasons, and if you do use them hard, they are more prone to cracking between the holes. For most applications, slotted rotors will give you "more for the money"

If you are doing any track events, suggest 3" or 4" ducting for cooling front brakes.

Last edited by GUMBALL; 10-05-2004 at 11:34 PM..
Old 10-05-2004, 01:56 PM
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You dont need ducting on the 924/944 to cool the brakes, The brake size is good and wont over heat, Pluse drilled rotors Are not just for looks, the drilled rotors help drop temps fast and they stress releave the drilled holes so they dont crack
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Old 10-05-2004, 02:22 PM
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Fast is right in that a good set of drilled rotors will really help keep them cool without cracking (zimmerman or brembo), but this type of concern is only if you are tracking the car. If you're only going to AX the stock vented rotors are more than adequate, although aftermarket brands have shown decreases in stopping distance.
If low cost improvement is needed for daily driving or minor club events:
performance pads
new rotors
S/S lines
piston seals
flush/repl fluid

Most bang for the buck

Of course I shouldn't be the one to talk since I've gone overboard and replaced my stock set-up with a completely reworked '86 Turbo set-up, incl drilled rotors and SS braided lines on my 924S project.
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'85 (Early) 944 - Beater
'87 924S - Crunch/Rebuild
'76 924 - Long Gone
"If everything seems under control, you're just not going fast enough."
- Mario Andretti
Old 10-05-2004, 04:30 PM
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fast924s:

Please read my post...as in...

..."SUGGEST" cooling ducts if you are tracking ..........

also, please make up your mind:
- you say that cooling ducts are not needed because the brakes won't overheat.....
-then in the same sentence, you say that drilled rotors are much better because they make a big difference in cooling ???
At the very minimum, you might not need cooling ducts, but this is one instance where MORE IS BETTER !!! During a track event, the better the pads and rotors are cooled, the longer they will last.
If you are NOT tracking the car, then you will not need cooling ducts......

lousailor:

Please read your posts and make up your mind:
-one post you suggest against drilled rotors
-the next post you suggest the opposite???
...and I did not say that drilled rotors were bad, what I did say, was that drilled rotors will crack BEFORE slotted rotors.......
And unless you already have a severe brake cooling problem, you will not notice the difference with drilled rotors.....and if you DO have that severe a braking problem, are you prepared to throw away a set of rotors after EACH event?????

Last edited by GUMBALL; 10-06-2004 at 12:03 AM..
Old 10-05-2004, 11:32 PM
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Gumball,
If you approach the issue as if this is a track car you are correct. What I was trying to say was that unless you are tracking the car there really is no overheating problem with the OE vented rotors.
The original poster was looking for a way to shorten his stopping distance, and seemed to be looking for the quickest and cheapest way. For daily driving drilled or slotted rotors will not directly shorten your stopping distance since they effectively decrease the amount of frictional surface compared with stock.
Drilled rotors have a large affect on brake cooling, but this is only required in situations with consistent hard braking during a short period. Also when done correctly cross drilling does not significantly weaken the rotors when used in most club events which is why Brembo markets them for Street and High Performance applications.
Slotted rotors are more suited for racing applications, where the brakes will be operating at higher temps for extended periods. This will make the pads more susceptable to glazing, and the slots effectly resurface the pads when braking is applied. Of course this means you will grind through pads very quickly which is fine for race applications since you will probably swap out pads each event. Slotted rotors are not suitable for street applications.
The worst rotors you can buy are those that are both slotted and drilled, they significantly reduce the frictional area, weaken the integrity of the rotor, and burn through pads, without reducing tempatures any more the slotted or drilled alone.

So what I said is correct. In street and most club applications drilled rotors are not needed, but a good set of drilled rotors will not lead to early replacement in those same circumstances.
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Louie

'85 (Early) 944 - Beater
'87 924S - Crunch/Rebuild
'76 924 - Long Gone
"If everything seems under control, you're just not going fast enough."
- Mario Andretti
Old 10-06-2004, 08:55 AM
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lousailor:

PLEASE read before you reply....
permit me to clarify (for the third time):

-I did not say that cross-drilling will weaken good rotors.
The good "drilled" rotors have holes that are cast in and not drilled (only chamfered), that way there are no stress risers to initiate cracking. The "good" rotors are usually cryo-treated also. With the "cheap" rotors, the holes are drilled after casting, leaving stress risers. When you said that "good" ones are made by Brembo, you are correct (AP does them also)
What I DID say is that drilled rotors usually have a shorter life than slotted or plain rotors - that was a general statement, NOT an absolute!

In regard to slotted rotors:

-I have had a set of slotted rotors on my street car for about 4 years now (in conjunction with Hawk pads) and they work very nicely, thank-you.
-Unless the rotors have been slotted incorrectly
(slots too wide or the wrong angle) they will not cause undue pad wear, or noticeably reduce friction area of rotor.
-What slotted rotors will do on the street (same as track) is clean the pad, and under very hard braking, will allow the gas layer to dissipate, which helps prevent glazing of the rotor - which allows the brakes to work better, which in turn produces less heat, and therefore allows a shorter stopping distance, especially during repeated applications. The slots also clear water faster when driving thru puddles or driving in the rain.

Several of these points we have both stated, and we both agree on.....


Last edited by GUMBALL; 10-07-2004 at 09:55 AM..
Old 10-06-2004, 10:35 AM
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