Replacing my Brakes Options

[So.Cal.914]

Purple, do you have a camara? Take some pic's, lets have a look.Your just to far

away. The stock brakes are very good and will stop you quick. I went to a

19mm M/C and submarined my passenger. You just need to work out the bugs.

Don't take it personal, the car doesn't hate you. They really

are fun when squared away. Best of luck.

[markb]

I've had a love/hate relationship with my car for years. Just ask my friends. I can't tell you how many times they've talked me out of selling it. I always finally get whatever is wrong fixed, and enjoy the car a while before I have to fix something else. I'm lucky to have people around me who know what they're doing and can talk me thru it. Brakes a finicky. So are carbs. Keep at it. I'm willing to bet that once the issues are resolved, and you get to drive it while everything is working good, that you'll enjoy it. Just keep at it.

[purple]

Okay, I've calmed down a bit and realize a mistake I made.... I didnt do the venting clearance correctly. if you dont set it very well, does that make the brake pedal feel miles long? I must have incorrectly thought that any pressure on the brake system will make the brakes work. I didnt realize they have to be really close. I thought the front brakes would at least work well.

The venting should be done with the pad seperators off, as I read from pelican. I did mine with them on, I guess that was the wrong thing to do (IMG:style_emoticons/default/sad.gif) I'm having a friend come over (has two porsches, a 993 and a 76 911) and have him help me with the brakes (he's done lots of bleeding and can tell me what to do if I mess up)

the engine tuning I probably will have done by a professional and from there I can maintain it. i'm just not experienced enough to get it right, and I'm afraid I'll kill the engine if i keep this up.

[Spoke]

You wrote:
"if you dont set it very well, does that make the brake pedal feel miles long?"

Yep. In reality, brake pad/pistons move very little when you press the brake pedal. If the venting clearance is big, even maybe less than 1/8 inch on each pad, the entire pedal depression may not bring the pads to the rotors and no stopping power.

Not sure about the pad separators on or off as you mention, I adjust the venting clearance with the brake caliper/pad fully assembled. Using the adjusters on either side of the caliper, I turn them so the piston pushes in until the pad drags on the rotor, then back off slightly. I'll wiggle the pad to tell when it bottoms out on the rotor.

I put the wheel back on and rotate the tire to see if the rotor drags at any point. You may not notice a wobbly rotor until the wheel is torqued on.

If you adjust to a big venting clearance, you'll notice the pedal going down more. Smaller clearance means less pedal depression. I'll drive the car a bit, stop and touch the centers of the rear rotors to make sure neither is dragging. They should be just a bit warm, not hot. Don't touch the actual rotor part or you may burn you fingers.

Once you get the venting clearance adjusted, your car will stop on a dime. If Eric's calipers are anything like his 5 lug rear hubs, you will be very happy.

[purple]

Okay!

The reason I think to take the spacers off is because if I adjust them with the spacers on, they go towards the rotor at a severe angle. I can adjust the tippy point to .004 but the side with the spacers will be MASSIVELY far away. I guess I just keep cranking em in? I dunno when they will become parallel and stop being angly.

[davep]

Don't forget that the correct venting clearance is 0.004" between the pad and the rotor. You basically have to jig the feeler guage (move up down a bit) while turning the adjuster and 'feel' the drag on the feeler increase up to the point where the drag is not quite clamped. If you get it too tight, you have to back off and try again. It will take a few tries to get the right 'feel'. Then spin the rotor to see if you get it to rub anywhere in the rotation. At the tightest spot, you may want to reset the clearance one more time. You have to do this for each of the 4 pads. Make sure you lock the outer adjuster, and securely cap the inner adjuster. You may want to remove one of the inner adjusters before capping and put away in a secure location. The inner caps are supposed to have a copper washer under the head. You may have to rap on the rear calipers with a rubber mallet to dislodge bubbles deep in the adjuster mechanisms. If you apply the brakes (foot on pedal) then that will compress the bubbles and make it easier to dislodge bubbles in the various components of the brake system.

Since the front calipers do not have an adjustment mechanism, you have to use hydraulic pressure to force the pistons out to make the pads contact the rotors.

I always remove old fluid from the reservoir with a syringe before starting, clean with Q-tips, and fill with fresh fluid. Keep brake fluid away from paint!!

When bleeding, the person pumping the pedal may have to pump several times to build up pressure, then hold the pedal down while the other person opens the bleed nipple to let the fluid and air out, then close the bleed nipple again before the brake pedal is released. With old master cylinders it is not recommended to allow the pedal to go to the spot. In such cases a wooden block can be used to spot the pedal perhaps half way. The reasoning is that an old cylinder may have faults in the bore (caused by rust or dirt) that could damage the seal on the piston. To reduce the chance of damage to the seal you restrict the stroke. Most times you get lucky and no damage is done, however if you have only s**t luck, then take the extra precautions. Normally I use my wife or daughter to pump, and call out PUMP, HOLD, and RELEASE while I open and close the bleed nipple. Carefully watch how much fluid comes out, and every two ounces go and refill the reservoir; never let the reservoir empty or you will have to start again.

[purple]

I think something else is at play...

I just adjusted the rear pads nice and close to the rotor, they seem to have gone parallel while i wasnt looking. i adjusted them just as described...

I drove it up to 20 mph and braked hard. this got the car to slow down rapidly. i then did it again and again, until it started to make my tires squeal, then until it made them lock up. I think what's going on is that new pads + new rotors that arent turned very neatly makes the pedal feel a little slippery at first. I think i need to run it up to 60 and then do some good hard stops, not quite to locking, right? to bed the pads?

the pedal is still a little long for my tastes, but it's better than it used to be. I guess I'll just have to keep bleeding it and making offerings to the sun goddess until the pedal firms up a bit. it's like stepping on a really big spring, instead of a solid column.

I wish there was a system that would pressurize all 4 calipers hard and then push the bubbles up to the mc reservoir... hydraulics are hard to mess with.

i'm not happy with the pedal, but the brakes do stop the car

[flesburg]

Purple. I have been fooling with 914s since 1974. I suspect that you were very young or not even on earth yet at that point.

How many cars have you driven without power brakes.

These things will stop you easily, as long as you run stock engine and tires. BUT they will NEVER be as hard as you think they should be compared to a modern car with power brakes.

I think you will be bothered by this for awhile. Drive the car more.

PS: Do not expect many "looks" in a 914. Although for awhile I had a bright red 914 with flairs, 9" wide wheels, 5 lugs and the works. Neat car. (Still have the car, altough now it has evolved into a DE car). (And its brakes are no longer stock, but they are Porsche brakes...930 front and Carrera rears, with a 23mm master, and it is NOT hard like a modern car with power brakes, but it will stop like a modern car). And at the same time I had a white 930 with gold wheels. Gorgeous car. Fast. Just Awesome. The 914 would turn more heads.

All depends. Stick with the 914. It will grow on you. And just think, in 34 years you may be near my age and we will both still be driving 914s, and they will be 68 years old.

[Spoke]

Sounds like you got the venting clearance under control. Good job.

I would imagine that new rotors/pads may take a little bit of working together to properly seat and provide even braking.

About the long pedal, it could be the venting clearance is still larger than it needs to be or the brakes still need bleeding. You can tell if they need bleeding if when sitting still and you haven't touched the brakes for a minute or so, the first pedal press will go further down than the next few quick presses. If the pedal goes down the same amount on all quick presses, then bleeding is ok.

[John]

If you really want a firm brake pedal, you can replace the stock 17mm master cylinder with a larger master cylinder.

The 19mm master cylinders offer a much more firm pedal. However, you will have to go through this agonizing process all over again.

I suspect that if you keep bleeding the brakes, eventually you will get the firm pedal that you are looking for.

I also suspect that you got yourself used to the "impossible to press" brake pedal that you had when your brake lines were restricting fluid flow and your calipers were sticking or stuck. Now that your brakes are more functional, learn how to drive the car.

In my experience, you will find that you use the brakes less the better you get at driving.

Good luck with it.

[purple]

You know, you guys are right. I've never driven a 914 with good brakes. They have always had rotten calipers, so i dont know what it's supposed to feel like. I bedded the pads last night and the pedal feel got a bit firmer, but what was surprising is that it REALLY did haul the car down fast. I can overpower the tires now easily with the brakes. I did around 10 runs up to 60 and down to 10 mph(on deserted roads, texas is great for those ) and while the pedal isnt as hard as I remember, the car also doesnt pull as badly to one side or the other anymore like it used to. it also seems to accelerate faster, probably due to less brake drag.

They seem to get better the more I drive it. I AM used to power brakes and have only ever owned cars with them. I've driven 60's era trucks with non boosted brakes and those were scary! I was born in 1981 and my parents had a 914 when i was very young(rode all 9 mos in the womb in a 914). my parents sold it for a pinto after the engine went sour...

[rjames]

I drove it up to 20 mph and braked hard. this got the car to slow down rapidly. i then did it again and again, until it started to make my tires squeal, then until it made them lock up. I think what's going on is that new pads + new rotors that arent turned very neatly makes the pedal feel a little slippery at first. I think i need to run it up to 60 and then do some good hard stops, not quite to locking, right? to bed the pads?

I always thought the following proceedure was supposed to be used to bed new brake pads:


1. Find an area where you have plenty of room and very little traffic.

2. Bring the car up to 60 mph and use normal braking to slow to 5-10 mph. Do not stop. Repeat 3-5 times. This brings the brakes up to operating temperature.

3. Bring the car up to 60 mph and stop as HARD as possible without locking up the wheels. DO NOT COME TO A STOP. Repeat 3-6 times. This burns off the protective layer on the pads and rotors and leaves a layer of pad friction material on the rotors. You may smell the hot brakes, this is perfectly normal and expected.

4. Drive the car normally for 10-15 minutes without touching the brakes. Do NOT stop. This is the cooling down period. If you stop, you may leave an imprint of the hot pad on the rotor and this will cause a vibration like a warped rotor.

5. If done correctly, your rotors should have a cool gray/blue color from the heat cycle. If you need to, let the brakes completely cool and repeat the process. You can also do this bedding procedure at any time in the future if your pads need it or you want to restore good braking power.

[rhodyguy]

if you don't have them you really need to order a set (4) of speed bleeders. cheap(relatively) and turns bleeding into a one person op. get a REAL long piece of clear tubing so you can place the catch jar on the floor next to the dr side door.

[Eric_Shea]

I was born in 1981 and my parents had a 914 when i was very young (rode all 9 mos in the womb in a 914).

Ahhhhhhhhh... it's in your blood!!

Don't pull anymore of that "I'm gonna sell it" shit with us Mr.! (IMG:style_emoticons/default/biggrin.gif)

Good to see you're making progress. (IMG:style_emoticons/default/wink.gif)

[cwpeden]

Just a note for those of us who are using a 19mm M/C without changing the rest of the brake system. You are actually loosing mechanical advantage.

The closer the M/C size gets to the piston size of your calipers the less brakin pressure you have.

Example:

M/C : 10mm Brake piston : 40mm = a 4:1 advantage
M/C : 12mm Brake Piston : 40mm = a 3.33:1 advantage

[John]

Just a note for those of us who are using a 19mm M/C without changing the rest of the brake system. You are actually loosing mechanical advantage.

The closer the M/C size gets to the piston size of your calipers the less brakin pressure you have.

Example:

M/C : 10mm Brake piston : 40mm = a 4:1 advantage
M/C : 12mm Brake Piston : 40mm = a 3.33:1 advantage

Precisely why this would yield a firmer pedal.

[Eric_Shea]

Precisely why this would yield a firmer pedal.

And less mechanical advantage. (IMG:style_emoticons/default/wink.gif)

Frankly, I think way too much fuss has been made over the 19mm MC. As John had stated earlier, you need to get used to it. It being a 17mm or a 19mm. The 19mm will give you a harder pedal but really gang... not at the expense of that much in mechanical advantage. Not so much as your leg will get tired, you'll not have enough leg to pedal the brakes etc.

Bottom line: A 17mm MC is fine for a 914 with stock brakes. So is a 19mm. Neither one is going to muck up the system. The 19mm will make it feel a bit more stout but you will have to push a bit harder. By the end of day 1... you'll be used to your new MC. Not "that" big of a deal.

[davep]

Frankly, I think way too much fuss has been made over the 19mm MC.

(IMG:style_emoticons/default/agree.gif)
Further, the VW411 from which the front brakes were taken also used a 19mm master cylinder, and the rear wheel cylinders were smaller than the pistons in the 914 rear calipers. I have never understood the reason for the smaller MC in the 914/4. On top of that, the 911S used the same piston sizes as the 914/6 and used the 20mm MC. And if you want to use exact dimensions of the MC to calculate the mechanical advantage, use these figures:
17.46 mm = 11/16"
19.05 mm = 12/16" or 3/4"
20.64 mm = 13/16"
However, you need to use areas not diameters to calculate the advantage.
The observant will notice that the master cylinders are in inch sizes.

[Smitty911]

One thing to remember on working on any Car, is that you will get Frustrated.

Frustration Errors occur and lead to.

1. More Broken Parts
2. More money spent to repair broken parts
3. Lack of enjoyment in Project
4. No Progress
5. Sell Project at Huge Losses

The "FIX" for the above.

Walk away for a couple of days. Recharge and come back on it.

You are the Alpha Dog, act like it, You are the Boss, You can fix what ails it.
(IMG:style_emoticons/default/biggrin.gif)

'65 Mustang Fastback
'66 Mustang Coupe
'71 Ranchero
'71 F-250

'72 914 1.7 20 years ago Gone
'75 914 1.8 12 years ago Burned
'74 914 2.0 Current Driving

'70 Opel GT
'69 VW Bug
'70 VW Van I sure miss it

All of these cars wanted my life, but I'm still here.

Hell, anyone can make a Chevy run, try that with a Ford, you need Patience and Money. Same with the 914, LOL.

Smitty