freestone
Jul 6 2004, 09:53 AM
Car currenrtly has a 2.7 engine and runs 914-6 brakes in back and SC up front.
How do I get a better brake feel? How do I add more stopping power, and is that necessary as I potentially upgrade the engine?
Has plenty of rubber.
Joe Ricard
Jul 6 2004, 11:38 AM
I would think you should have all the braking you may ever need. The way I see it these cars are so lite stopping is very easy. More HP does not equal need for more brakes.
Stupid questions like what do you do with your car most.
When was your last brake service.
What kind of pads are you using
Ans: Race car every weekend = get something bigger in the 4 piston caliper massive rotor and matching hydraulic system. (just throw more money at it as I have come to learn).
freestone
Jul 6 2004, 11:45 AM
I run the car almost exclusively on the street.
Andyrew
Jul 6 2004, 11:47 AM
If you havent got th 19mm m/c, get that.
Rebuild the calipers, get new pads..
What you have is enough. IF you wanted more, you could go 944 turbo fronts, and that would be all you would ever need.
Andrew
SirAndy
Jul 6 2004, 12:16 PM
QUOTE(freestone @ Jul 6 2004, 08:53 AM)
How do I get a better brake feel? How do I add more stopping power, and is that necessary as I potentially upgrade the engine?
here's what i did, in that order:
19 mm master cylinder
'86 carrera front brakes, vented and crossdrilled rotors, carrera calipers
'87 carrera rear brakes, vented and crossdrilled rotors, carrera calipers
replaced brake bias valve with a open "T"
braking is perfect now
Andy
SirAndy
Jul 6 2004, 12:18 PM
oops, forgot the pic ...
lapuwali
Jul 6 2004, 02:54 PM
As stated, the need for braking power is mostly down to car weight and available traction. If you can lock your current tires, you have enough brake power. Any more brake power, and you're simply overwhelming your tires sooner, which does nothing for stopping ability. If you can lock them repeatedly, you have enough heat capacity to avoid fade. If you find you have to press harder and harder as you repeated come to a stop from high speeds, then you need to look into better fluid, better pads, and maybe better rotors.
You asked specifically about brake feel. If the pedal doesn't feel right to you, then it's possible you have to deal with hydraulic compatibility. If the pedal is uncomfortably "long" and/or feels squishy, then you may have a master cylinder that's too small for the calipers you're using. If the pedal is wooden and hard, then you may have a master cylinder that's too large for the calipers you're using. There's a post I made awhile back on the subject you can search for.
If you can't lock your tires no matter how hard you press the pedal, then I'd start with brake pads (find softer compound pads), and make sure the current pads aren't glazed or contaminated.
scotty
Jul 6 2004, 03:57 PM
If you haven't replaced the rear proportioning valve, that's probably the problem... I have a 19mm MC , SC brakes up front, and have replaced the valve with a "t" -- this setup transforms the brakes
TimT
Jul 6 2004, 04:07 PM
My car is set up like Andy's now
QUOTE
19 mm master cylinder
'86 carrera front brakes, vented and crossdrilled rotors, carrera calipers
'87 carrera rear brakes, vented and crossdrilled rotors, carrera calipers
replaced brake bias valve with a open "T"
except that I have an adjustable bias valve for the rears.
Its taken me awhile but I think I have the front/rear balanced to a point that I can brake deep into a corner..
So since I have this more than adequate braking system sorted what would any normal person do? Leave it alone!!!
So Im installing the following:
944 Turbo Front calipers
944 Turbo rear calipers
23mm master cylinder
944T front drilled rotors
Carrera rear rotors
and a spacer to move out the front hubs so the discs will clear..
The calipers are being modified by Doug Arnao (VCI) to a true radial mount..
So now I get to climd the whole brake learning curve all over again
anthony
Jul 6 2004, 04:42 PM
Sometimes I think people confuse the pedal pressure required to stop a 914 with the braking system being inadequate. We don't have power assisted brakes in these cars. My 914 requires quite a bit more pedal pressure than my newer VW to make it stop on a dime. And as others have suggested, if the pads and rotors are old and glazed, then having the rotors surfaced, getting new pads, and bleeding the system works wonders.
Jeroen
Jul 6 2004, 08:42 PM
Bigger brakes won't add stopping power
The modulation will be different and give you the feel of more braking power, but your actual braking distance will be the same
You only need bigger brakes when you suffer from a fading pedal (brakes overheating)
I don't think you'll run into that problem with your current brakes on the street...
cheers,
Jeroen
SirAndy
Jul 6 2004, 09:00 PM
QUOTE(Jeroen @ Jul 6 2004, 07:42 PM)
but your actual braking distance will be the same
this is NOT entirely true, of course ...
Andy
Aaron Cox
Jul 6 2004, 09:46 PM
i have an interesting brake issue.
rebuilt m calipers up front, stock / 4 rears , pads from pelican.
i just put falken azenis sticky stick tires on, and can no longer lock up the brakes easily....
car grips the road like a mofo on crack....but stopping fees...inadequate <_<
SirAndy
Jul 6 2004, 09:48 PM
QUOTE(acox914 @ Jul 6 2004, 08:46 PM)
car grips the road like a mofo on crack....but stopping fees...inadequate <_<
welcome to the world of sticky tires!
now you
need bigger brakes!
Andy
Aaron Cox
Jul 6 2004, 09:50 PM
lol...huge difference betwwen 165 bike tires.
i JUST upgraded to M calipers....
volvo 240 anyone?
skline
Jul 6 2004, 10:34 PM
The Volvo pad is almost twice the size of the M caliper. I was a little shocked to see how small the M caliper pads actually are. What is the big deal with the M calipers? And I hear the S caliper is smaller yet with smaller pads. In fact, the 320i pads are even bigger than the M ,
Aaron Cox
Jul 6 2004, 10:55 PM
well if only 2/3 of the volvo pad even touches the rotor....which is better? how do you fix that?
skline
Jul 6 2004, 11:04 PM
That is an exageration, there is only about 1/4 inch overhand, not even close to 2/3rds.
DrifterJay
Jul 6 2004, 11:05 PM
I thought you fixed that?
skline
Jul 6 2004, 11:18 PM
enough to run it like it is for now.
Andyrew
Jul 6 2004, 11:54 PM
911 A pads are about the same size as the 320i pads. Maybe a little bigger. But I think its all in the pad compund...
I know theres a bunch of difference between my dads stock pads, and his racing pads. Like really big. He can lock up the tires with both, but the pedal feel, and quickness of the racing pads are amazing.
Gotta get me some....
Andrew
fiid
Jul 7 2004, 01:58 AM
Andy - did you diagnose the proportioning problems you were having at the autocross????
What was it???
JmuRiz
Jul 7 2004, 07:37 AM
What would cause a right rear lockup under very hard breaking at the track? I have carrera rotors w/ monoblocks up front and stock calipe rears and a T.
Someone there said it could be the venting clearence...what do you guys think. I should have WAY more brake in the front, so having just the right rear lock seems very odd...I'd think the fronts would lock way before the rear.
SirAndy
Jul 7 2004, 12:25 PM
QUOTE(JmuRiz @ Jul 7 2004, 06:37 AM)
so having just the right rear lock seems very odd...
sticky piston(s) ...
time for a rebuild!
Andy
nine14cats
Jul 7 2004, 12:27 PM
how much for the carrera struts/brakes/rotors from a dismantler?
Just curious...
Bill P.
SirAndy
Jul 7 2004, 12:29 PM
QUOTE(fiid @ Jul 7 2004, 12:58 AM)
Andy - did you diagnose the proportioning problems you were having at the autocross????
What was it???
yes!
well, let's see,
- i had the carrera brakes in the front, stock 914/4 brakes in the rear.
fronts would always lock up first (way too early).
- replaced prop valve with a "Tee". helped a bit, but still the same problem.
- went to carrera brakes in the rear and voila!, problem solved ...
i simply didn't have enough braking in the rear with the stock brakes (compared to the front).
now the brakes are well balanced, in fact i haven't had a single lockup at AX since,
and trust me, i'm trying
Andy
SirAndy
Jul 7 2004, 12:30 PM
QUOTE(nine14cats @ Jul 7 2004, 11:27 AM)
how much for the carrera struts/brakes/rotors from a dismantler?
Just curious...
i can get 'em cheap for you.
Andy
J P Stein
Jul 7 2004, 12:38 PM
Bill:
Since we're spending your money.
If you need/want different struts, the price (when all is said & done) difference between stock 9eleben struts and them new Fox jobbies isn't too much to over come.
When one considers the advantages of double adjustables and adjustable spindle height, it would be a slam dunk for me...using your money
Seriously, when my fronts wear out....and their getting close (the housing, not the insert), I'll pinch some money outta myself. I would like to see some feed back from users tho.
A good set of 'S' calipers usually go for around $400....tho finding a good set is gettin tough.....'A's are half that.
JmuRiz
Jul 7 2004, 01:24 PM
QUOTE
sticky piston(s) ...
time for a rebuild!
Sticky as in they aren't fully coming back out when you are off the brakes...therefore get max pad pressure too early on that one? I'll look into it, thanks for the tip though!
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